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1 | Module installation manual | Users Manual | 159.20 KiB |
SB555 Embedded Modem Hardware Integration Guide Addendum Original Document 2130075 SB555 Hardware Integration Guide Revision 1.0 (April 2002) 2130271 Rev 1.0 1: RF Integration Receiver sensitivity Matching Antenna options Receiver sensitivity 1 Page 79 of the of the Hardware Integration Guide includes Table 7-1: Radio specifications. This table has been corrected to:
Table 7-1: Radio specifications Transmitter power Maximum 224 mW into 50
(+23.5 dBm) 150 Hz Closed loop frequency stability PCS band Receiver sensitivity Transmit band Receive band Channel spacing Cellular band Receiver sensitivity Transmit band Receive band Channel spacing
< -106.5 dBm 18501910 MHz 19301990 MHz 1.25 MHz
< -104 dBm 824849 MHz 869894 MHz 1.25 MHz The receiver sensitivity in the PCS band has changed from
-104 dBm to less than -106 dBm. The corrosponding sensitivity on the Cellular band now indicates less than -104 dBm. Matching antenna and cable The text on page 83 refering to antenna gain and cable loss should read: Overall system antenna gain, with cable loss should be +9 dBi. Keep in mind that your achieved value will have an impact on radiated power and RF exposure. Antenna options Page 83 text refering antenna requirements to Table 7-1 is specifically for frequency band information. 2130271 Rev 1.0 Nov.02 1 2 2: FCC Approval FCC Mobile vs. portable Mobile approval and RF exposure Product labeling The Sierra Wireless SB555 embedded modem for CDMA2000 has been approved by the FCC for mobile applications. Chapter 7: RF Integration has been amended. A section headed FCC should be added, as follows. FCC For operation in the United States, your integration is required to meet appropriate regulatory requirements for stand-alone operation, including FCC parts 2, 15, 22, and 24. FCC Part 15 tests must be performed on the whole device and are therefore your responsibility. Mobile vs. portable devices The Federal Communications Commission Office of Engineering & Technology has published a bulletin, Evalu-
ating Compliance with FCC Guidelines for Human Exposure to Radiofrequency Electromagnetic Fields, OET Bulletin 65. This provides a detailed description of the difference between mobile and portable devices. The FCC guidelines differentiate between these devices according to the antennas proximity to people, either the user or others nearby. Mobile The FCC defines a mobile device as being designed for use in other than fixed locations and to generally be used in such a way that a separation distance of at least 20 centi-
meters is normally maintained between radiating structures and the body of the user or nearby persons. Mobile devices include vehicle-mounted systems designed to be used by people that are typically well separated from the antenna. This also includes wireless devices associated with a personal computer, provided the antenna is kept at least 20 cm away from people. These devices are normally evaluated for exposure potential with relation to Maximum Permissible Exposure (MPE) limits. The FCC rules for evaluating mobile devices for RF compliance are found in 47 CFR part 2.1091. 2130271 Rev 1.0 Nov.02 2 Hardware Integration Guide Addendum FCC Approval Portable A portable device has a transmitter designed to be used with any part of its radiating structure in direct contact with the users body or within 20 centimeters of the body of a user or bystanders under normal operating conditions. This category includes hand-held cellular telephones with the antenna built into the handset. Portable devices are evaluated with respect to the Specific Absorption Rate (SAR) rules. These can be found in 47 CFR part 2.1093. Mobile approval and RF exposure requirements The SB555 module is approved for mobile operations only with respect to CFR 47 part 2.1091. FCC ID: N7NSB555 Note: If this module is intended to be used as a portable device, you are responsible for separate approval to satisfy the SAR requirements of part 2.1093. To ensure that the module meets the current FCC RF exposure guidelines, a separation distance of at least 20 cm (7.88") must be maintained between the modules antenna and the body of the user and any nearby persons at all times and in all applica-
tions and uses. Additionally, in mobile applications, maximum antenna gain must not exceed 9 dBi to comply with FCC regulations limiting both maximum RF output power and human exposure to RF radiation. Product labeling requirements For mobile devices, using the FCC approval obtained by Sierra Wireless, a label must be affixed to the outside of your end productinto which the authorized module is incorporated with a statement similar to the following:
This device contains TX FCC ID: N7NSB555 You need to provide a manual with your end product that clearly states the operating requirements and conditions that must be observed to ensure compliance with current FCC RF exposure guidelines (as detailed above). 2130271 Rev 1.0 Nov.02 3 Hardware Integration Guide Addendum FCC Approval The warnings must appear in a prominent location in the User Guide for your product and may include:
CAUTION Unauthorized modifications or changes not expressly approved by Sierra Wireless, Inc. could void compliance with regulatory rules, and thereby your authority to use this equipment. WARNING (EMI) This equipment has been tested and found to comply with the limits pursuant to Part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference in an appropriate installation. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instructions, may cause harmful inter-
ference to radio communication. However, there is no guarantee that interference will not occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of the following measures:
Reorient or relocate the receiving antenna Connect the equipment into an outlet on a circuit different from Increase the separation between the equipment and receiver that to which the receiver is connected Consult the dealer or an experienced radio/TV technician for help 2130271 Rev 1.0 Nov.02 4
1 | User Manual | Users Manual | 849.85 KiB |
SB555 Development Kit Hardware Integration Guide Proprietary and Confidential 2130075 Rev 1.0 Important Notice Safety and Hazards Preface Because of the nature of wireless communica-
tions, transmission and reception of data can never be guaranteed. Data may be delayed, corrupted (i.e., have errors) or be totally lost. Although significant delays or losses of data are rare when wireless devices such as the Sierra Wireless modem are used in a normal manner with a well-constructed network, the Sierra Wireless modem should not be used in situations where failure to transmit or receive data could result in damage of any kind to the user or any other party, including but not limited to personal injury, death, or loss of property. Sierra Wireless, Inc., accepts no responsibility for damages of any kind resulting from delays or errors in data transmitted or received using the Sierra Wireless modem, or for failure of the Sierra Wireless modem to transmit or receive such data. Do not operate the Sierra Wireless modem in areas where blasting is in progress, where explosive atmospheres may be present, near medical equipment, near life support equipment, or any equipment which may be susceptible to any form of radio interference. In such areas, the Sierra Wireless modem MUST BE POWERED OFF. The Sierra Wireless modem can transmit signals that could interfere with this equipment. Do not operate the Sierra Wireless modem in any aircraft, whether the aircraft is on the ground or in flight. In aircraft, the Sierra Wireless modem MUST BE POWERED OFF. When operating, the Sierra Wireless modem can transmit signals that could interfere with various onboard systems. Rev 1.0 Apr.02 Proprietary and Confidential 1 SB555 Hardware Integration Guide Limitation of Liability The driver or operator of any vehicle should not operate the Sierra Wireless modem while in control of a vehicle. Doing so will detract from the driver or operator's control and operation of that vehicle. In some states and provinces, operating such communications devices while in control of a vehicle is an offence. Note: Some airlines may permit the use of cellular phones while the aircraft is on the ground and the door is open. Sierra Wireless modems may be used at this time. The information in this manual is subject to change without notice and does not represent a commitment on the part of Sierra Wireless, Inc. SIERRA WIRELESS, INC. SPECIFICALLY DISCLAIMS LIABILITY FOR ANY AND ALL DIRECT, INDIRECT, SPECIAL, GENERAL, INCIDENTAL, CONSEQUENTIAL, PUNITIVE OR EXEMPLARY DAMAGES INCLUDING, BUT NOT LIMITED TO, LOSS OF PROFITS OR REVENUE OR ANTICIPATED PROFITS OR REVENUE ARISING OUT OF THE USE OR INABILITY TO USE ANY SIERRA WIRELESS, INC. PRODUCT, EVEN IF SIERRA WIRELESS, INC. HAS BEEN ADVISED OF THE POSSI-
BILITY OF SUCH DAMAGES OR THEY ARE FORESEEABLE OR FOR CLAIMS BY ANY THIRD PARTY. 2 Proprietary and Confidential 2130075 Patents Copyright Trademarks Preface Portions of this product are covered by some or all of the following US patents:
5,515,013 5,748,449 5,890,057 6,199,168 D372,248 D452,495 5,617,106 5,845,216 5,929,815 6,327,154 D372,701 D452,496 and other patents pending. 5,682,602 5,878,234 6,191,741 D367,062 D442,170 5,629,960 5,847,553 6,169,884 6,339,405 D416,857 This product includes technology licensed from:
2002 Sierra Wireless, Inc. All rights reserved. Printed in Canada. Heart of the Wireless Machine is a registered trademark of Sierra Wireless, Inc. Sierra Wireless, the Sierra Wireless logo, the red wave design, and Watcher are trademarks of Sierra Wireless, Inc. Windows is a registered trademark of Microsoft Corporation. Qualcomm is a registered trademark of Qualcomm Incorporated. Other trademarks are the property of the respective owners. Rev 1.0 Apr.02 Proprietary and Confidential 3 SB555 Hardware Integration Guide Contact Information Sales Desk:
Technical Support:
Phone: 1-604-232-1488 Hours: 8:00 AM to 5:00 PM Pacific Time e-mail: sales@sierrawireless.com Included with the purchase of the SB555 Development Kit you receive five hours of tier 3 engineering integration support. You will have received instructions by e-mail on how to access the OEM Customer Support web site. For more details, please contact your account manager, or the Sierra Wireless sales desk. Post: Sierra Wireless, Inc. 13811 Wireless Way, Richmond, BC Canada V6V 3A4 Fax: 1-604-231-1109 Web: www.sierrawireless.com Your comments and suggestions on improving this documentation are welcome and appre-
ciated. Please e-mail your feedback to documentation@sierrawireless.com. Thank you. Consult our website for up-to-date product descriptions, documentation, application notes, firmware upgrades, troubleshooting tips, and press releases:
www.sierrawireless.com 4 Proprietary and Confidential 2130075 Table of Contents About this Guide. 11 Introduction . 11 Document structure . 12 References . 13 Terminology and acronyms . 13 Conventions . 13 Mechanical Integration . 15 Introduction . 15 Physical dimensions . 16 Mounting the module . 17 Module weight . 18 Module shields . 18 Module connectors . 19 Host interface connector . 19 Location of pin 1 . 20 Antenna connector . 20 Assembly sequence . 21 Environmental issues . 21 Thermal dissipation . 22 Electrostatic discharge. 23 Shock and vibration . 24 Dust, dirt, and moisture . 24 Rev 1.0 Apr.02 Proprietary and Confidential 5 Hardware Integration Guide Electrical Integration . 25 Introduction . 25 Modem specifications . 25 Location of pin 1 . 26 General requirements . 27 Unused pins. 27 Preventing back-power when the modem is off. 27 Voltage regulation and buffering . 28 Electrostatic discharge . 29 Power . 29 Current consumption . 30 Sample power integration . 30 Power source . 30 MOSFET power switch. 32 Pins 1 and 2: Modem VCC . 32 Power regulator. 32 Pins 3, 4, 25, 30: Ground connection . 33 Requirements of the power interface. 34 Module shielding . 34 Power ramp-up . 34 Power-up timing . 35 Trace widths . 36 6 Proprietary and Confidential 2130075 Contents Serial Interfaces . 37 Introduction . 37 Serial port specifications . 37 External pullup and pulldown resistors . 38 ESD protection. 39 Primary port . 40 Pin 21: /DCD1. 41 Pin 22: RxD1. 41 Pin 23: TxD1 . 42 Pin 24: /DTR1 . 42 Pin 25: GND . 43 Pin 26: /DSR1. 43 Pin 27: /RTS1 . 43 Pin 28: /CTS1 . 44 Pin 29: /RI1 . 44 Pin 30: GND . 45 Port configuration . 45 Primary port sample integrations . 45 Sample 1: Internal host integration . 46 Sample 2: External serial connector. 47 Sample 3: Minimum integration . 49 Secondary port. 51 Pin 17: /CTS2 . 52 Pin 18: /RTS2 . 52 Pin 19: TxD2 . 52 Pin 20: RxD2. 53 Pin 25: GND . 53 Rev 1.0 Apr.02 Proprietary and Confidential 7 Hardware Integration Guide Port configuration. 53 Secondary port sample integration . 54 Minimum integration . 55 Voice Interface . 57 Introduction to voice features . 57 Audio block diagram . 57 Pinouts . 59 ESD protection . 59 Headset integration . 60 Headset interface specifications . 60 Microphone input (headset) . 62 Speaker output (headset) . 62 Sample headset integration . 62 Line level voice integration . 63 Microphone input (line level) . 65 Speaker output (line level). 65 Control Signals. 67 Introduction . 67 Control interface specifications . 67 External pullup and pulldown resistors. 68 ESD protection . 69 Status indicators . 69 Human interface (LEDs) . 70 Sample LED status interface. 70 8 Proprietary and Confidential 2130075 Contents Machine interface . 72 Sample machine interface to status outputs . 72 Shutdown and reset control. 73 Pin 37: /Shdn_Ack. 74 Pin 38: /ShutDown . 74 Pin 39: /Reset . 75 Sample shutdown interface integration . 76 Shutdown sequence . 77 Shutdown timing. 77 RF Integration. 79 Introduction . 79 RF connection . 80 Connector considerations . 80 Ground plane isolation . 81 ESD protection. 82 Antenna and cabling . 83 Matching antenna and cable. 83 Antenna options . 83 Cables . 84 Interference and sensitivity . 84 Power supply noise. 84 Device generated RF. 85 Modem generated RF switching noise . 87 Rev 1.0 Apr.02 Proprietary and Confidential 9 Hardware Integration Guide Appendix A:
Host Connector Pinouts . 89 Appendix B:Sample Integration . 93 Appendix C:
Electrostatic Discharge. 95 Introduction . 95 Charge creation . 95 Damage from ESD. 96 Types of damage . 97 Exposed interfaces . 97 Protection from ESD . 98 Requirements . 98 TVS diodes . 98 PCB design . 99 ESD integration considerations . 101 Return ground path . 101 Capacitance . 102 Selection guidelines . 103 10 Proprietary and Confidential 2130075 1: About this Guide 1 Introduction Document structure References Conventions Introduction This guide is one component of the SB555 Devel-
opment Kit. It covers the integration of the product from the hardware point of view. Other guides in the kit cover project planning, software integration, and product verification and config-
uration. For details on the features of the SB555 embedded modem, please consult the SB555 Embedded Modem Product Specification
(document #2130072). To aid you in making decisions on what aspects of the modem require integration in your project, and to determine what hardware is required to support particular features, please consult the SB555 Development Kit Design Guide
(document #2130179). This hardware guide covers the details of integrating each interface but does not discuss the reasons to include or exclude any particular element. Where configurable features are mentioned, the method of configuring or calibrating can be found in the Verification and Configuration Guide (document #2130078). Rev 1.0 Apr.02 Proprietary and Confidential 11 SB555 Hardware Integration Guide Document structure This document covers hardware integration issues in these main categories:
Mechanical Integration Mounting Connectors Environmental Issues Electrical Integration General Specifications General Considerations Power Supply Electrostatic Discharge (ESD) Serial Interface Primary Port (Serial 1) - Data Secondary Port (Serial 2) - Control Voice Interface Analog Voice Control Signals Status Signals Shutdown Control Reset RF integration RF Connections Antenna and Cabling Interference and Sensitivity Appendix APinouts Appendix BSample Integration, a typical MCU integration block diagram Appendix CElectrostatic Discharge (ESD) 12 Proprietary and Confidential 2130075 About This Guide References This guide covers only the hardware integration of the SB555 modem. It does not deal with specifics of product modem operation or use of the optional Embedded Modem Interface Kit. Please consult the other documents provided with the Development Kit or the Interface Kit User Guide for additional information on opera-
tions. You may also want to consult other documents available on our Internet site at www.sierrawireless.com. Terminology and acronyms This document makes wide use of acronyms that are in common use in data communications and cellular/PCS technology. Our Internet site provides a Glossary (document 2110032) that may be helpful in understanding some acronyms and terminology used in this guide. Conventions Numerics Numeric values are generally presented in decimal but may also be expressed in hexadecimal or binary. Hexadecimal values are shown with a prefix of 0x, i.e. in the form 0x3D. Binary values are shown with a prefix of 0b, i.e. in the form 0b00111101. Otherwise, values are presumed decimal. Rev 1.0 Apr.02 Proprietary and Confidential 13 SB555 Hardware Integration Guide Units Units of measure are given in metric. Where measure is provided in imperial units, they are shown in parenthesis after the metric units. Signal Names When signals are discussed by their function, the functional name is used in standard font (i.e. Reset, Shutdown Acknowledge). When the pin, wire, or trace carrying the signal is referenced, it will use the proper name in an alternate font:
/Reset
/Shdn_Ack Signals that are active low are named with a prefix slash / as shown in the sample above. Signal names without the slash are active high. Fonts Command and register syntax is noted using an alternate font:
AT~AUDMOD=1 Responses from the modem, or host system software prompts, are shown in this font:
CONNECT 14400 Character codes which are described with words or standard abbreviations are shown within angle brackets: such as <CR> for Carriage Return and <space> for a blank space character. 14 Proprietary and Confidential 2130075 2: Mechanical Integration 2 Introduction Physical dimensions Mounting Connectors Assembly sequence Environmental issues Introduction The SB555 CDMA2000 1X embedded modem form factor is the proprietary Sierra Wireless embedded module package. Physical dimen-
sions, mounting holes, and connectors are identical to other upcoming Sierra Wireless embedded modem products. This chapter covers the integration issues surrounding:
Mounting Connector fit Assembly sequence Environmental issues Rev 1.0 Apr.02 Proprietary and Confidential 15 SB555 Hardware Integration Guide Physical dimensions The SB555 comes in the Sierra Wireless propri-
etary standard module package. Dimensions in millimeters are shown in the figure below. Figure 2-1: Module dimensions (in mm) 16 Proprietary and Confidential 2130075 Mechanical Integration Mounting the module Sierra Wireless embedded modules have four (4) mounting holes of 2.5 mm (0.984) diameter, one located at each corner of the module (as seen in Figure 2-1). The mounting holes are sized to accommodate a metric M2 (#2 screw). The 40-pin host connector allows for either bottom or top entry, to permit mounting in any orientation. Sierra Wireless does not provide mounting hardware. The sample illustration does not show standoffs. Note: The integration should include standoffs of some kind to protect the modem shields from being crushed during assembly and from coming into contact with circuitry on the host device. Figure 2-2: Sample bottom entry mounting (mm) Rev 1.0 Apr.02 Proprietary and Confidential 17 SB555 Hardware Integration Guide Module weight The module has a total weight under 14 grams (0.49 ounces). Typical weight is 13.5 grams (0.48 ounces). Module shields The SB555 comes with shields on both top and bottom. These shields are attached to a fence surrounding the circuitry. Figure 2-3: Shield fence frame The internal webbing of the fence frame may be removed in some units to permit factory rework. This webbing is used for automated pick-and-
18 Proprietary and Confidential 2130075 Mechanical Integration place only. The product has been fully qualified mechanically and electrically with and without the webbing. Module connectors There are two connectors: a 40-pin header for the host interface, and an MMCX connector for the antenna. Both are mounted offset from the module centerline to prevent assembly orien-
tation errors. Host interface connector The host connector is a 40-pin, 1 mm pitch, 2-row, female header (Samtec part #CLM-120-02-
F-n-BE with bottom entry option). This host connector is capable of accepting either a top or bottom entry mating header connector. Suitable mating connectors are:
Samtec (www.samtec.com) MW, FTM or FTMH series Major League Electronics
(www.majorleagueelectronics.com) BSTCM-7 series The recommended exposed pin length is:
1.4 mm (0.055) for top entry 3.2 mm (0.125) for bottom entry The connector is not keyed. The connector is offset from the module centerline to prevent assembly orientation errors. Rev 1.0 Apr.02 Proprietary and Confidential 19 SB555 Hardware Integration Guide Location of pin 1 Pin 1 of the host connector is shown in Figure 2-4. When viewing the module with the connector facing up and the RF connector at the bottom, pin 1 is on the extreme right of the inside edge (lower row). Pin 40 Pin 2 Pin 39 Pin 19 Pin 1 Figure 2-4: Host connector pin locations Antenna connector The antenna connector is an MMCX female jack oriented in line with the module longitudinal axis. Mating plugs can be either straight or right-
angle. The detent on the connector is quite stiff to ensure the connection remains intact through vibration and shock. The connector is designed for 500 connection cycles, which may not be sufficient for some end-user applications. For this reason, and to allow for ESD protection, the modems MMCX connector should not be presented directly to the user for antenna attachment. The integration can include a host system built-in antennawithout presenting a connector to the useror any of a variety of RF connector types
(SMA, SMB, TNC, etc.) as suits the application. See Ground plane isolation on page 81 for additional information on insulating the RF connector ground. 20 Proprietary and Confidential 2130075 Mechanical Integration For mechanical integration, use a flexible 50 coaxial cable to allow attachment of the MMCX connector to the modem either before or after mounting the module on the host device. Assembly sequence Due to the strong detent in the MMCX antenna connector, Sierra Wireless recommends that you connect the antenna cable to the modem before connecting the modems 40-pin connector to the host device. This will avoid stress on the host connector. Your situation may vary; this is only a recommendation. Where host mounting is performed prior to antenna cable attachment, the module should be secured, with screws and standoffs, to the host device. Use suitable standoffs with screws or other mounts to hold the module securely in place, while preventing the modems shield from grounding to the host device. Environmental issues The SB555 embedded modem conforms to the specifications listed in Table 2-1 on the following page. Enhanced specifications may be achieved through appropriate mounting. Rev 1.0 Apr.02 Proprietary and Confidential 21 SB555 Hardware Integration Guide Table 2-1: Environmental specifications Temperature range Humidity Vibration
(random)**
Vibration
(sine wave)**
Shock**
Drop**
(unpackaged) Operating:
(modem ambient*)
-30 to +60C (-22 to +140F) Storage:
-40 to +85C (-40 to +185F) MIL-STD-202F 95% non-condensing @ 65C (149F) MIL-STD-810E 0.04 g2/Hz, 10 2000 Hz PC Card Standard 15 g (147 m/s2), 10 2000 Hz MIL-STD-202F 50 g (490 m/s2), 11 ms, 6 pulses/axis PC Card Standard 0.75 meter drop onto non-cushioned vinyl
(2 drops on each axis, 6 drops total)
* Modem ambient means in the immediate area of the modem, not the ambient temperature around the finished device. This is typically a temperature inside your device. A thermistor inside the modem (monitored by the modem CPU firmware) causes flow control to be activated should the internal temperature reach 75C (167F) as measured at the radio. Flow control is released when the temperature falls below 75C. Should the temperature of the radio reach 80C (176F), the modem terminates the connection in order to protect com-
ponents and avoid drifting outside radio specifications.
** Vibration, shock, and drop tests are performed for survivability. The modem is not in operation during the test. Cosmetic damage is ignored. Thermal dissipation Determination of thermal dissipation depends heavily on the usage model of the modem. The SB555 modem generates more heat when actively transmitting. However the transmitter is not on at all times, nor is the transmit power constant. 22 Proprietary and Confidential 2130075 Mechanical Integration Table 2-2 provides a guideline of the energy to be dissipated when the modem is in various states of activity. Table 2-2: Energy dissipation (typical) Current Mode consumption 3.3 V @ 0.7 mA 3.3 V @ 5 mA Energy to dissipate 2.3 mW 16.5 mW 3.3 V @ 40 mA 132 mW 3.3 V @ 160 mA 528 mW 3.3 V @ 370 mA 1219 mW 4.2 V @ 900 mA 3376 mW Shutdown Slotted sleep (SCI = 2)
(DTR deasserted) Slotted sleep (SCI = 2)
(DTR asserted) Receive Transmit
(typical at +3 dBm) Transmit (worst case)
(full power +23.5 dBm) Transmit cases are usually short duration bursts. Electrostatic discharge This is treated as an electrical integration issue. The SB555 does not provide a specified level of protection from electrostatic discharge (ESD). Exposed interfaces should be protected by your circuitry design. Details are covered in Chapter 3:Electrical Integration. Consult Electrostatic Discharge on page 95 for a general discussion of ESD. Rev 1.0 Apr.02 Proprietary and Confidential 23 SB555 Hardware Integration Guide Shock and vibration The specifications provided on shock and vibration are for the module free of integration hardware. A person rolling off a bed onto the floor is likely to emerge without injury; whereas one with a fire hydrant strapped to his back may not. Once integrated into your device, the surrounding hardware can have a significant impact on the modems survivability. Through the mounting and integration decisions you make, your design will need to meet your own products survivability specifications. Dust, dirt, and moisture The shields are not intended to provide the modem with protection from dust, dirt, or moisture. Your integration should provide reasonable insulation from these environmental factors as needed to meet your products specifi-
catons. 24 Proprietary and Confidential 2130075 3: Electrical Integration 3 Introduction Specifications General requirements Power supply Electrostatic discharge Introduction This chapter covers the integration requirements and issues related to the general electrical connection of the SB555 modem, and the power supply in particular. RF issues are covered in Chapter 7:RF Integration on page 79. The SB555 embedded modem presents all electrical interfaces on the single 40-pin host connector. This chapter covers:
The connector and the general electrical characteristics of the modem Power supply considerations Electrostatic Discharge (ESD) protection The elements of integrating each of the modem interfaces (serial, voice, and control signals) are covered in subsequent chapters. Modem specifications The SB555 embedded modem provides a single 40-pin (2x20) header. The connector pinouts are specified in Appendix A:Host Connector Pinouts on page 89. All signals are 3.0 V, HCMOS logic compatible. Rev 1.0 Apr.02 Proprietary and Confidential 25 SB555 Hardware Integration Guide Table 3-1: Host interface electrical characteristics Parameter Test Conditions Min Typical LO threshold HI threshold Power Vcc DC supply Digital Interface VIH VIL IIH IIL VOH VOL IOH LO output HI output Output current Input current Input current Max ripple 100 mVp-p 3 V applied to input 0 V applied to input IOH = 2.0 mA IOL = -2.0 mA VOH > 2.0 V 3.3 3.0 0 3.2 2.1 0 0 0 2.4 0 IOL Output current VOL < 1.0 V Max Units 4.2 3.3 0.8 120
-120 3.0 0.4 V V V A A V V 3.0 mA
-3.0 mA Location of pin 1 Pin 1 of the connector is shown in Figure 3-1. When viewing the module with the connector facing up and the RF connector at the bottom, pin 1 is on the extreme right of the inside edge
(lower row). Pin 40 Pin 2 Pin 39 Pin 19 Pin 1 Figure 3-1: Host connector pin locations 26 Proprietary and Confidential 2130075 Electrical Integration General requirements Unused pins Unused signals must be terminated properly. The pinout tables, both in the Appendix and in the interface sections, include a column for termi-
nation of unused pins. Preventing back-power when the modem is off Active low signals may be deasserted (driven high) by the host device when the modem is not needed. This applies 3.0 V to the modem on these pins and presents the risk of back-
powering. All connector inputs must be either high impedance (>20 k), or driven low, when the modem is powered off. This is required to prevent back-powering the modem. This is particularly important if the DTR signal is deasserted (high) when the modem is not in use. The sample integration shown in the appendix uses buffers. These provide both voltage conversion between 3.0 V of the modem and 3.3 V of the host MCU, and the required protection from back powering both the MCU and the modem. Note: Without proper input protection, the modem may draw sufficient current to remain powered, even when the normal supply power is removed. Rev 1.0 Apr.02 Proprietary and Confidential 27 SB555 Hardware Integration Guide Voltage regulation and buffering All logic signals at the SB555 host connector are referenced to 3.0 V. Logic signals at the host device may be referenced to 3.3 V, thus requiring the use of buffers between the devices. These buffers are discussed in the sections on the specific interfaces. See the Typical MCU Integration block diagram in the appendix. Note: The actual VCC of the logic internal to the SB555 is 3.0 V, not the 3.2 V4.2 V applied to the VCC pins of the SB555 module. The 74AHC series parts can tolerate 3.3 V applied to inputs while VCC = 0 V. This buffer is mainly to protect the SB555 when it is powered down while the host device remains powered up. Additionally, the modems input pins should not have a voltage applied to them that is more than 0.3 V above the internal VCC, which could happen when the modem is powered down. Although some of the SB555 output lines are configured as inputs by a reset, they all have weak internal pullup or pulldown devices
(approx. 50 k to 375 k), so no external resistors need to be added. If you decide to add external resistors:
Use pulldown resistors for:
/RI1
/DCD1 Use pullup resistors (to 3.0 V) for:
/DSR1
/CTS2 RxD2
/Shdn_Ack This is consistent with the internal devices. A suggested value is 100 k. 28 Proprietary and Confidential 2130075 Note: Floating signal lines can be noisy, and increase power consumption. Electrical Integration If a host reset configures any of its I/O pins
(controlling outputs to the modem: DTR1,
/RTS1, TxD1, /RTS2, TxD2, /ShutDown, MdmReset) as an input, and the pin does not have any internal pullup or pulldown device, use a pulldown resistor to prevent the line from floating. A suggested value is 100 k. Electrostatic discharge You are responsible for any ESD protection on digital circuits. Specific recommendations are provided as needed for each of the interfaces described in this guide. An appendix (page 95) also provides background on ESD. Power The SB555 CDMA2000 1X embedded modem requires 3.24.2 VDC (+3.3 V nominal); suitable for direct connection to a lithium-ion battery. The modem uses the following pins for the power interface:
Table 3-2: Power pinouts Pin Name Description Type Termination if not used 1, 2 Vcc 3, 4 GND 25 GND 30 GND 3.3 VDC power supply Ground Ground Ground Power Power Power Power Required Required Required Required Rev 1.0 Apr.02 Proprietary and Confidential 29 SB555 Hardware Integration Guide Pins 25 and 30 are included to provide a connection to ground near the pins for the two serial ports. The electrical characteristics of the power supply are:
Max ripple:
Minimum:
Typical:
Maximum:
100 mVp-p (1 Hz 100 kHz) 3.20 V 3.30 V 4.20 V Current consumption The current consumption of the modem varies considerably on the usage model of your device. Consult the Design Guide (document #2130179) for assistance in planning your requirements. Sample power integration The integration is discussed with reference to the sample block diagram in Figure 3-2: Power interface block diagram on page 31. All samples assume an MCU running at 3.3 V. If your host device uses internal logic at 3.0 V then the buffers discussed in this document may not be needed. Power source In the sample, the power source is a lithium-ion battery. Your power source may differ provided you stay within the 3.204.2 VDC requirement. The power is shown independent of the host device (MCU) power source, which may differ in your integration. 30 Proprietary and Confidential 2130075 Electrical Integration For the SB555 modem to maintain a clean RF signal, it is essential that the power supply also be clean. Ensure the supply power is as free of noise as possible. Figure 3-2: Power interface block diagram Rev 1.0 Apr.02 Proprietary and Confidential 31 SB555 Hardware Integration Guide Note: This mechanism is needed to follow the recommended shutdown sequence prior to removing power from the modem. MOSFET power switch The MOSFET power switch is recommended to provide the host device with software control of the power to the SB555 modem. A suggested part is SI2305DS from Siliconix (www.vishay.com/
brands/siliconix/). If an MCU reset configures the I/O pin that controls the MOSFET switch as an input, use a pullup or pulldown resistor to default the MOSFET control signal to the off state. Pins 1 and 2: Modem VCC To support a short burst power surge (current draw) when the modules transmitter is turned on, the power supply is filtered by a 100 F low-
ESR (Equivalent Series Resistance) capacitor between the supply (VBATT) and ground. Locate this as close as possible to the module connector. If a tantalum capacitor is used, it must have a sufficient surge current rating to handle a low-
impedance current source like a battery, otherwise it could fail. Power regulator This regulator is used to provide the appropriate voltage (3.0 V) for the LEDs and the digital signal input buffer. However, if the source power supply (VBATT) never exceeds 3.30 V, this voltage regulator can be omitted, the LED resistors can be connected directly to VBATT, and the buffer can also be powered directly by VBATT. 32 Proprietary and Confidential 2130075 Electrical Integration If the LEDs were connected directly to a VBATT of 4.2 V, the voltage at the /Status pins could exceed the limit of VCC + 0.3 V, possibly damaging the modem. There could also be constant leakage current, draining the battery. This will depend on the voltage drop across the selected LEDs. Similarly, if the buffer were powered by a VBATT greater than 3.30 V, the voltage at the input pins of the SB555 would also exceed the VCC + 0.3 V limit. Use a 3.0 V low-dropout (LDO) voltage regulator of sufficient output current to provide power to the I/O buffers (and LEDs if needed). A suggested part is the LP3985-3.0 from National Semiconductor. Pins 3, 4, 25, 30: Ground connection The ONLY ground connection to the modem must be through the 40-pin host connector. No ground connection to the modem shields must be made. This is to avoid degrading the RF perfor-
mance of the modem through ground loops. Also consult the section: Ground plane isolation on page 81. Rev 1.0 Apr.02 Proprietary and Confidential 33 SB555 Hardware Integration Guide Requirements of the power interface Module shielding The module is fully shielded to protect against EMI and to ensure FCC regulatory compliance. To maintain the shield effectiveness the modem shields must not be removed and must not be connected to the host ground. Ground loops must be avoided. See Ground plane isolation on page 81. Power ramp-up The SB555 modem will hold the circuitry in reset until stable power is established. When the voltage reaches 2.7 V nominal (2.552.925 V) and is held at or above that level for at least 10 s, a timer is started. The modem continues to hold in reset for 140560 ms to ensure power is stable. If power slips below 2.7 V for a few micro-seconds, the timer must restart. Figure 3-3: Power ramp-up timing 34 Proprietary and Confidential 2130075 Electrical Integration Power-up timing After release from reset, the modem performs a self test and initialization. It begins normal operation within 715 seconds. All serial port signals should be considered undefined or invalid until both /DSR1 and /CTS1 are asserted. Only at that time is the modem ready for use. Figure 3-4: Control signal timing t0Reset is released. t1After self test, initialization begins.
/DCD1 may change state based on its condition at the time of the reset. It should be ignored. t2/DSR1 asserts. Other signals should still be considered invalid. t3/CTS1 asserts, typically 156 s after /DSR1. At this time, the modem is ready. Signals other than /DSR1 and /CTS1 should be considered invalid or undefined until the process is complete. The final state of /DCD1 will depend on its configuration. Note: /DCD1 is shown in its factory default configuration. Rev 1.0 Apr.02 Proprietary and Confidential 35 SB555 Hardware Integration Guide Trace widths Ensure that the PCB trace widths to the SB555 VCC and GND pins are sufficient for a maximum current of 900 mA. Consult the Design Guide
(document #2130179) for details on current consumption in all modes. Do not connect the modem package shield to GND or AGND. 36 Proprietary and Confidential 2130075 4: Serial Interfaces 4 Introduction Primary port Secondary port Introduction The SB555 CDMA2000 1X embedded modem presents two serial port interfaces. Primary portthe basic modem interface offering AT command and user data I/O Secondary portfor modem management using a Sierra Wireless proprietary CnS (Control and Status) protocol This chapter deals with the electrical integration of each of these two serial ports. A full integration of both ports is recommended but a reduced integration is possible if you are prepared to sacrifice some features. Consult the Design Guide (document #2130179) for a discussion of the issues related to excluding connection of specific signals. Serial port specifications The serial ports operate at the same 3.0 V, HCMOS level as the rest of the modems digital interfaces, not +/-12 V RS-232C levels. If a modem serial port is to be presented to the user, appropriate level conversion and ESD circuitry is required. Rev 1.0 Apr.02 Proprietary and Confidential 37 SB555 Hardware Integration Guide Table 4-1: Serial interface electrical characteristics Parameter Conditions Typ. Min Max Units HI threshold LO threshold Digital Interface VIH VIL IIH IIL VOH VOL IOH LO output HI output Output current Input current 3 V applied input Input current 0 V applied input IOH = 1.0 mA IOL = -1.0 mA VOH > 2.0 V 2.1 10 0 2.0 IOL Output current VOL < 1.0 V 0 3.0 0 0 3.3 0.8 120
-120 3.0 0.4 V V A A V V 3.0 mA
-3.0 mA External pullup and pulldown resistors Although some of the SB555 output lines are configured as inputs by a reset, they all have weak internal pullup or pulldown devices
(approx. 50 K to 375 k), so no external resistors need to be added. If you decide to add external resistors (suggested value is 100 k), to be consistent with the internal devices:
Use pulldown resistors for:
/RI1
/DCD1 Use pullup resistors (to 3.0 V VBUF) for:
/DSR1
/CTS2 RxD2 38 Proprietary and Confidential 2130075 Serial Interfaces If integrating to an MCU, and its reset configures any of its I/O pins (controlling outputs to /DTR1,
/RTS1, or TxD1) as an input, and the pin does not have any internal pullup or pulldown device, use a pulldown resistor to prevent the line from floating. Floating signal lines can be noisy, and increase power consumption. A suggested value is 100 k. ESD protection You are responsible for any ESD protection on digital circuits. If you plan to extend one or both serial ports to the outside, choose a transceiver capable of 3.3 V logic and with built-in ESD protection. Suggested parts include:
SIPEX (www.sipex.com) SP3238E Maxim (www.maxim-ic.com) MAX3238E or MAX3222E Texas Instruments (www.ti.com) MAX3238 Rev 1.0 Apr.02 Proprietary and Confidential 39 SB555 Hardware Integration Guide Primary port The primary serial port pins (Serial 1) comprise a standard set of serial data and handshaking
(control) lines. Signals must be terminated properly if they are not used. Table 4-2: Primary Port (1) Connector Pinouts Pin Name Description Type 21 /DCD1 Serial 1 DCD 22 RxD1 23 TxD1 Serial 1 RX Serial 1 TX 24 /DTR1 Serial 1 DTR 25 GND 26 /DSR1 27 /RTS1 28 /CTS1 29 /RI1 30 GND Ground Serial 1 DSR Serial 1 RTS Serial 1 CTS Serial 1 RI Ground Output Output Input Input Power Output Input Output Output Power Termination if not used Not connected Required Required Ground Required Not connected Ground Not connected Not connected Required At a minimum, the integration requires RxD, TxD, and GND. The modem is not capable of ignoring RTS/CTS flow control. If these signals are not used in your integration, then /RTS1 must be forced active (low, grounded) when the modem is powered. 40 Proprietary and Confidential 2130075 Note: If your application intends to use Windows ACPI, then both DTR and RI are required signals. Serial Interfaces The remaining primary port control lines (DCD, DTR, DSR, and RI) are, strictly speaking, not needed; however they are desirable in most applications. The SB555 modem is designed to use all control signals of the serial interface. The recommended integration is to use the full family of controls to provide the greatest functionality. Pin 21: /DCD1 Data Carrier Detect normally asserts when the modem is on a traffic channel. It can be configured to:
Behave in a Unix-style wink modeon at all times and wink off (~1 s) when the traffic channel is lost Reflect the state of the connectionon when connected and off when disconnected Always assert The configuration method is discussed in the Verification and Configuration Guide (document
#2130078). Although not required, it is recommended to use DCD. If not used, the pin is left unconnected. Pin 22: RxD1 This is the data channel from the modem
(network) to the host. This is a required pin in all integrations. Rev 1.0 Apr.02 Proprietary and Confidential 41 SB555 Hardware Integration Guide Pin 23: TxD1 This is the data channel from the host to the modem (network). This is a required pin in all integrations. Pin 24: /DTR1 Data Terminal Ready is used extensively to control modem operations as discussed in the Design Guide. This pin is not strictly required, although it is required for Windows ACPI. If DTR is not used in your integration, /DTR1 must be tied active (low) by connecting to ground. The sample integration in the appendix (page 93) shows the /DTR1 line being driven by an open drain device (for example, a TMOS FET such as the 2N7000 or 2N7002), with a pulldown resistor on the input gate of the FET. The MCU I/O pin driving the /DTR1 signal should be high-impedance (or input), or an output driven to 0 V during and immediately after MCU reset. This allows the modem to remain in shutdown mode if the hosts DTR pin was deasserted to request the shutdown, and the MCU is subsequently powered down, then powered up again. This FET also protects the MCU when it is powered down while the modem remains powered up. The modems /DTR1 pin has a pullup resistor which could cause the voltage on the MCU pin to exceed VCC + 0.3 V, back-power the MCU, and increase the drain on the modems battery. This device prevents these problems. 42 Proprietary and Confidential 2130075 Serial Interfaces The SB555 is also protected by this FET when the modem is powered down while the MCU remains powered up. The modems input pins should not have a voltage applied to them that is more than 0.3 V above VCC, which could otherwise happen when the modem is powered down. Pin 25: GND This is a signal ground made available in proximity to the other serial port pins for conve-
nience. Pin 26: /DSR1 Data Set Ready is normally asserted following successful completion of a modems self-test and initialization. DSR is deasserted when the modem is in shutdown state, to advise the host that it is not available for use. DSR is optional but recommended. If not used, it can be left unconnected. Pin 27: /RTS1 Request To Send is asserted by the host when it is capable of receiving data from the modem, and deasserted to prevent overflow. The modem cannot ignore RTS, so if it is not used, it must be tied active (low) by connecting to ground; however doing this will risk data overflow at the host device. Rev 1.0 Apr.02 Proprietary and Confidential 43 SB555 Hardware Integration Guide Pin 28: /CTS1 Clear To Send is asserted by the modem when it is capable of receiving data from the host, and deasserted when the modems buffers are full (or the modem is not ready to receive commands from the host). This pin is also the final signal to the host indicating that the modem has completed its initialization and is ready for use. Only if the application can tolerate data loss due to transmission overruns, should this pin can be left unconnected. Pin 29: /RI1 Ring Indicator is used to advise the host of one of the following conditions:
An incoming call (telephone is ringing) An incoming SMS message A return to network coverage Windows ACPI requires use of this signal. Otherwise, the signal is optional. If not used, it can be left unconnected. RI is strongly recommended for any integration using the voice feature of the modem. The RI signal can be used to wake a sleeping host when an incoming call arrives, allowing the device to perform much like a standard cellular telephone. If RI is used for wakeup, you must connect it to an appropriate circuit to detect it and manage the host wakeup operation.
/RI1 is an active low signal that asserts with a duty cycle of 200 ms on and 200 ms off. Incoming calls will trigger the RI to cycle until 44 Proprietary and Confidential 2130075 Serial Interfaces the connection attempt is either answered or dropped. The other event triggers (SMS messages and return to coverage) will assert /RI1 three times for each triggering event. Your implementation must handle the detection of events and ignore any additional cycles that are not needed. Pin 30: GND This is a signal ground made available in proximity to the other serial port pins for conve-
nience. Port configuration The primary serial port is configured for 8-data bits, no parity bits, and 1-stop bit. The DTE host data-rate on the primary serial port can be from 9600 bps to 230.4 kbps, configured by software command. The factory default setting is 115.2 kbps. The modem does not support autobaud detection. Primary port sample integrations Three integration options are discussed below:
Internal host integration connects to a serial port of an MCU External serial connector exposing a standard RS-232 connection Minimum integration, the minimal connection (to an MCU in this sample). Rev 1.0 Apr.02 Proprietary and Confidential 45 SB555 Hardware Integration Guide Sample 1: Internal host integration This sample integrates all signals of the serial port to an MCU. Buffers are used to manage the level conversions between 3.0 V at the modem and 3.3 V at the MCU. SN74AHC541 (or equivalent) octal buffers powered by a 3.0 V (VBUF) rail will serve on the inputs to the modem. Connect the /OE1 and
/OE2 buffer pins to GND. Connect the inputs of any unused buffers to GND and leave the outputs unconnected. Another SN74AHC541 (or equivalent) octal buffer, this time powered by the host's 3.3 V
(VCC) rail, is used to protect the output lines from the modem. The source of the 3.0 V VBUF power used by the input buffer is discussed in the section: Power regulator on page 32. The output buffer is powered by the hosts supply. Figure 4-1: Primary serial port integrationMCU Sample 46 Proprietary and Confidential 2130075 Serial Interfaces This sample uses an open drain on /DTR1, which is discussed in the description of Pin 24: /DTR1 on page 42. If the host will be using partial system shutdown to conserve powerrelying on the modem to wake up the host via the ring indicatorthen the
/RI pin at the MCU will have to be an interrupt-
capable input to trigger the host wakeup. Sample 2: External serial connector If you are going to present the primary serial port as an external RS-232 interface, you must include appropriate level conversion and ESD protection. Typically a MAX3238 is used, as shown in Figure 4-2. The supply power to the chip must be the same 3.0 V (VBUF) level supported by the digital logic of the SB555. This ensures the output signals from the RS-232 conversion do not over drive the SB555. If the host system logic is used to enable the conversion chip (as shown in the sample), the same logic should control the power to the SB555
(although not shown in the sample). This prevents a situation where the conversion chip might back-power the SB555 through /DTR1 and
/RTS1. Conversely, if the SB555 is powered while the MAX3238 is not, there can be a current drain through the SB555 serial outputs. Values for the capacitors are not shown. Consult the data sheet for the chip you use for values. Rev 1.0 Apr.02 Proprietary and Confidential 47 SB555 Hardware Integration Guide Figure 4-2: Primary serial port integrationexternal RS-232 connector Depending on the capabilities of the selected chip, the ring indicator may still be used to control host power. Provided the 3.0 V supply is active and the software switch is off, the chip may still pass the /RI1 signal to another pin (not shown) that can be used to wake the local host. 48 Proprietary and Confidential 2130075 Serial Interfaces Sample 3: Minimum integration At a minimum, data receive (RxD1) and transmit (TxD1), and ground (GND) are required. This sample integration does not enforce flow control so data overruns and lost data are possible; your application must be tolerant of this. The minimum required integration is described in Table 4-3 and the block diagram in Figure 4-3:
Table 4-3: Primary port minimum integration Signal Pin Requirement
/DCD1 RxD1 TxD1
/DTR1 GND
/DSR1
/RTS1
/CTS1
/RI1 GND 21 22 23 24 25 26 27 28 29 30 Optional (unconnected) Required Required GND GND Optional (unconnected) GND Optional (unconnected) Optional (unconnected) GND Rev 1.0 Apr.02 Proprietary and Confidential 49 SB555 Hardware Integration Guide Note: The modem is not capable of ignoring RTS/
CTS flow control. If these signals are not used in your integration, then RTS must be forced active (low) when the modem is powered. Figure 4-3: Primary serial port integrationminimum sample The modem firmware always respects hardware handshaking. This means that if RTS/CTS are not used, the /RTS1 signal input to the modem must be forced active (low) by connecting it to ground. The CTS signal is optional and can be left uncon-
nected if not used. The modem will assert and deassert it regardless of the hardware integration. DTR can be configured for a variety of control applications in the modem. To prevent accidental recognition of transitions and avoid any flow control problems, the required integration of an unused /DTR1 signal is to tie it active (low) by connecting to ground. All other control lines are outputs from the modem and can be safely left unconnected if not needed. 50 Proprietary and Confidential 2130075 Note: This port is required for operation with Watcher, the Sierra Wireless enabling software. Serial Interfaces Secondary port The secondary port of the SB555 embedded modem is used to exchange control and status information while a data connection is in progress on the primary port. The secondary port can also support CAITa diagnostics tool used during CDG3 testing. The port is, strictly speaking, optional, but without it, the host device is very limited in its ability to control or monitor the modem while connected. See the Design Guide (document
#2130179) for a full discussion. This port provides only the basic TX and RX lines along with flow controlRTS and CTS. Other control signals are not provided. Table 4-4: Secondary port connector pinouts Pin Name Description Type Termination if not used 17 /CTS2 18 /RTS2 19 TxD2 20 RxD2 25 GND Serial 2 CTS Serial 2 RTS Serial 2 TX Serial 2 RX Ground Output Not connected Input Input Output Power Ground Ground Not connected Required Rev 1.0 Apr.02 Proprietary and Confidential 51 SB555 Hardware Integration Guide Pin 17: /CTS2 The Clear To Send signal is optional and can be left unconnected if not used. The modem will assert and deassert it regardless of the hardware integration. Clear To Send is asserted by the modem when it is capable of receiving CnS commands from the host, and deasserted when the modems buffer is full (or the modem is not ready to receive CnS commands from the host). Only if the application can tolerate loss of CnS commands due to transmission overruns, should this pin be left unconnected. Pin 18: /RTS2 Request To Send is asserted by the host when it is capable of receiving CnS responses and notifica-
tions from the modem, and deasserted to prevent overflow. The modem cannot ignore RTS, so if it is not used, it must be tied active (low) by connecting to ground. Pin 19: TxD2 Note: See the Design Guide for details of the consequences of not including the secondary port in your integration. This is the data channel from the host to the modem for CnS messages. This is a required pin in all integrations using Watcher; otherwise the pin is optional. 52 Proprietary and Confidential 2130075 Serial Interfaces Pin 20: RxD2 This is the data channel from the modem to the host for CnS messages and notifications. This is a required pin in all integrations using Watcher;
otherwise it is optional. Pin 25: GND This is a signal ground made available in proximity to the other serial port pins for conve-
nience. Port configuration The secondary serial port is configured for 8-data bits, no parity bits, and 1-stop bit. The DTE host data-rate on the secondary serial port can be from 9600 bps to 115.2 kbps, configured by software command. The factory default setting is 115.2 kbps. The modem does not support autobaud detection. Rev 1.0 Apr.02 Proprietary and Confidential 53 SB555 Hardware Integration Guide Secondary port sample integration Note: The secondary port is typically not extended to an outside RS-232 connector, although this can be done in a completely standalone modem productone not using built-in host application software. This sample integrates all signals of the serial port to an MCU. Buffers are used to manage the level conversions between 3.0 V at the modem and 3.3 V at the MCU. This element of the integration is the same as that described on page 46 for the primary port. The source of the 3.0 V (VBUF) power used by the input buffer is discussed in the section: Power regulator on page 32. The output buffer is powered by the hosts supply. Figure 4-4: Secondary serial port sample integration 54 Proprietary and Confidential 2130075 Serial Interfaces Minimum integration To use the port, the minimum integration is described in the following table:
Table 4-5: Secondary port minimum integration Signal Pin Requirement
/CTS2
/RTS2 TxD2 RxD2 GND 17 18 19 20 25 Optional GND Required Required Required Figure 4-5: Secondary serial port minimum integration At a minimum, receive (RxD2) and transmit (TxD2) data, along with ground (GND) are required. This integration does not enforce flow control so data overruns and lost data are possible; your application must be tolerant of this. Rev 1.0 Apr.02 Proprietary and Confidential 55 SB555 Hardware Integration Guide 56 Proprietary and Confidential 2130075 5: Voice Interface 5 Introduction Headset Line level Introduction to voice features The SB555 CDMA2000 1X embedded modem supports voice operation similar to a cellular telephone. Integration of the modem to use the voice features requires a microphone input and speaker output. These can be either directly to a standard cellular headset or to your custom audio circuit (at line level). The modems analog voice capability is configured at the factory to use a direct connection to a standard cellular headset. Software commands are used to make configu-
ration and calibration changes. This chapter has sections describing each of the two configurations of the voice interface. Audio block diagram The simplified block diagram on the following page is intended to provide you with some understanding of how the various configuration, calibration, and user controls affect the circuit. The AT commands used to control the audio circuit are all prefixed with the tilde (~) character. There are two areas where a loopback can be configured for testing (not shown), that are described in the Verification and Configuration Guide. Rev 1.0 Apr.02 Proprietary and Confidential 57 SB555 Hardware Integration Guide Figure 5-1: Simplified audio block diagram Setting line level (~AUDMOD) primarily affects the amount of microphone gain. There is also some associated filtering, used to compensate for the headset microphone, that will be switched out (flat response) when using the line level configuration. Calibration of the microphone and speaker levels is handled on the digital side of the Codec. Use of ~MICLVL and ~SPKLVL is described in the Configuration and Verification Guide. The users volume control (~SPKVOL) is prior to the echo cancellation circuitry. It is also included in the sidetone return, along with a separate control of sidetone gain (~STGLVL). 58 Proprietary and Confidential 2130075 Pinouts Table 5-1: Analog voice interface pinouts Pin Name Description Type Voice Interface Termination if not used 13 MIC+
Voice Mic+
Input (Diff.) AGND 14 SPKR+
Voice Speaker Output Not connected 15 MIC-
16 AGND Voice Mic-
Input (Diff.) AGND Audio Common Ground
(AGND) Not connected Note: The Audio Common Ground is independent of the systems signal ground. If the audio circuitry is not used, the inputs (pins 13 and 15) should be connected to AGND (pin 16). Under normal operation, the modem only turns on the audio circuit when needed for a voice connection. Note that if the audio circuit is enabled, there is a bias current of just under 1 mA on the MIC pins that will cause some current drain. ESD protection You are responsible for any ESD protection required. An appendix (page 95) provides background on ESD. Rev 1.0 Apr.02 Proprietary and Confidential 59 SB555 Hardware Integration Guide Headset integration This is the default configuration from the factory. Level calibration is described in the Verification and Configuration Guide (document #2130078). Headset interface specifications The modems analog voice interface configured for direct use with a standard cellular headset has the following electrical specifications:
Table 5-2: Headset interface electrical characteristics Parameter Conditions Typ. Min Max Units Microphone Input ZIN Input impedance VI Input level 0dBm0 Reference level AV Gain error Differential 4 4.2 4.5 k mic sens. =
-58 dBV / Bar 1 kHz sine wave Amp Gain =
26 dB
-30 dBm0 to
+3 dBm0 input
-44 88 45.5
-21.8 110.2 dBV dB SPL mVRMS
-1.5 0
+1.5 dB Transmit noise C-message weighted 10 VRMS SINAD S:(THD+N)
-45 dBm0 to
+3 dBm0 input 25 45 dB 60 Proprietary and Confidential 2130075 Table 5-2: Headset interface electrical characteristics (cont.) Parameter Conditions Typ. Max Min Units Voice Interface IMIC Mic DC current Speaker Output ZL Load impedance PO THD Speaker output power Total harmonic distortion MUTE AV Gain error Receive noise SINAD S:(THD+N) IMD VO Intermod. distortion DC on speaker out Electret condenser Source =
1.8 VDC
@ 2200 Single-ended 32 32 load digital input = +3 dBm0
@ 1020 Hz Maximum output level into 32
@ 498 Hz Digital input =
+3 dBm0
@ 1020 Hz
-30 dBm0 to
+3 dBm0 input Digital input =
0x0000 A-weighted
-45 dBm0 to
+3 dBm0 input 498 Hz &
2020 Hz equal level AC-coupled 220 500 A 8.8 mW 5
-80 dB
-1.5 0
+1.5 dB 200 VRMS 25 50 42 0 dB dB VDC Rev 1.0 Apr.02 Proprietary and Confidential 61 SB555 Hardware Integration Guide Note: Single-ended drive will reduce input impedance by 50% to 2.1 k typical. Microphone input (headset) The microphone input is a capacitively connected differential input, with input impedance greater than 4 k. Microphone signals should be -44 dBV (18 mVp-p) nominal. If a single-ended drive is desired, the MIC- input must be connected to the Audio Common ground (pin 16) as close to the microphone, or its connector, as possible. Do not use a general system ground, but rather the Audio Common (AGND) provided by the module. The modem provides a microphone DC bias of just under 1 mA of current for a standard micro-
phone. Speaker output (headset) The speaker output is a single-ended signal used to interface to a headset. The output signal is AC-coupled -21 dBV (250 mVp-p) nominal into a 32 load. If additional amplification is needed, it is the responsibility of the integrator. Sample headset integration Note: The Audio Common Ground is independent of the system ground used for other operations. The simplest integration of the modems voice service uses the conventional analog micro-
phone and speaker pins (1316). These can be connected directly to a standard 3-wire cellular headset. 62 Proprietary and Confidential 2130075 Voice Interface 1 2 3 4 13 MIC+
14 SPKR+
15 MIC -
16 AGND SJ - 2504N Figure 5-2: Sample headset integration A preferred integration would use both MIC+
and MIC- as a differential pair (with ground on either side) to reduce noise. Note: This sample does not include ESD protection. You are responsible for all ESD protection circuitry. Line level voice integration The modems analog voice interface is configured at the factory for direct use with a standard cellular headset. The interface can be configured for line level by using:
AT command: AT~AUDMOD=1 CnS command KST_AUDMOD (5006) When this is done, the microphone gain is reduced by 28 dB and the frequency response is flat (a filter is switched out). The speaker circuitry is unchanged. Rev 1.0 Apr.02 Proprietary and Confidential 63 SB555 Hardware Integration Guide The interface has the following electrical specifi-
cations:
Table 5-3: Line level interface electrical characteristics Parameter Conditions Typ. Min Max Units Line Input ZIN Input impedance Differential 4 4.2 4.5 k VI Maximum input level MIC+ or MIC-
single-ended 0dBm0 Reference level AV Gain error SINAD S:(THD+N) Line Output ZL Load impedance VO Reference signal level VOmax Maximum output level THD Total harmonic distortion MUTE Amp Gain =
-2 dB
-30 dBm0 to
+3 dBm0 input
-45 dBm0 to
+3 dBm0 input Single-ended Digital input 0 dBm0
@ 1020 Hz Digital input
+3 dBm0
@ 1020 Hz Maximum output level into 600
@ 498 Hz Digital input =
+3 dBm0
@ 1020 Hz 2.28 VP-P 1.14 VRMS
-1.5 25 0 45 600 375
+1.5 dB dB mVRMS 1.5 VP-P 5
-80 dB 64 Proprietary and Confidential 2130075 Voice Interface Table 5-3: Line level interface electrical characteristics (cont.) Parameter AV Conditions Gain error Typ. Max
+1.5 Min
-1.5 0 dB Units
-30 dBm0 to
+3 dBm0 input Receive noise SINAD S:(THD+N) IMD VO Intermod. distortion DC on speaker out Digital input =
0x0000 A-weighted
-45 dBm0 to
+3 dBm0 input 498 Hz &
2020 Hz equal level AC-coupled 200 VRMS 25 50 42 0 dB dB VDC Microphone input (line level) When using line level differential drive, both pins must be AC-coupled via 100 nF capacitors. The input signal is -21 dBV (250 mVp-p) nominal from a 600 source. Speaker output (line level) The output signal is AC-coupled -21 dBV
(250 mVp-p) nominal into a 600 load. If additional amplification is needed, it is the responsibility of the integrator. Rev 1.0 Apr.02 Proprietary and Confidential 65 SB555 Hardware Integration Guide 66 Proprietary and Confidential 2130075 6: Control Signals 6 Introduction Status indicators Shutdown control Reset Introduction The SB555 embedded modem makes use of several control signals to indicate connection state, control the shutdown process, and reset the modem. This chapter deals with the hardware integration of these control interfaces:
Status outputs Shutdown request and acknowledge Reset Control interface specifications All signals are 3.0 V, HCMOS logic compatible. These signals must be terminated properly if they are not used. Table 6-1: Control interface electrical characteristics Parameter Conditions Typ. Min Max Units HI threshold Digital interface VIH VIL IIH LO threshold Input current 3 V applied to input 2.1 0 3.0 0 3.3 0.8 120 V V A Rev 1.0 Apr.02 Proprietary and Confidential 67 SB555 Hardware Integration Guide Table 6-1: Control interface electrical characteristics (Continued) Parameter Units Conditions Typ. Max Min IIL VOH VOL IOH IOL Input current 0 V applied to input IOH = 2.0 mA IOL = -2.0 mA VOH > 2.0 V VOL < 1.0 V HI output LO output Output current Output current 0 2.4 0
-120 A 3.0 0.4 V V 3.0 mA
-3.0 mA External pullup and pulldown resistors Although some of the SB555 output lines are configured as inputs by a reset, they all have weak internal pullup or pulldown devices
(approx. 50 K to 375 k), so no external resistors need to be added. If you decide to add external resistors, to be consistent with the internal devices:
Use pullup resistors (to 3.0 V VBUF) for:
/Shdn_Ack A suggested value is 100 k. If integrating to an MCU, and its reset configures any of the I/O pins (controlling outputs to
/ShutDown, or /Reset) as an input, and the pin does not have any internal pullup or pulldown device, use a pulldown resistor to prevent the line from floating. Floating signal lines can be noisy, and increase power consumption. A suggested value is 100 k. 68 Proprietary and Confidential 2130075 Control Signals ESD protection You are responsible for any ESD protection required. An appendix (page 95) provides background on ESD. Status indicators Four status output indicators are provided on the SB555 modem. Table 6-2: Status Indicator Pinouts Description Name Pin 3, 4 Ground
5 /Status1 7 /Status2 9 /Status3 11 /Status4 Status 1 Status 2 Status 3 Status 4 Type Termination if not used Power Output Output Output Output Required Not connected Not connected Not connected Not connected These indicators can be configured by software to work in one of two ways:
Human interfacetypically driving LEDs
(Blinking patterns are used that are not suitable as inputs to a microcontroller.) Machine interfaceproviding two-state operation for polling, or edge-detection inter-
rupts for events. The configurationhuman or machineapplies to all signals. You cannot mix and match configurations. Rev 1.0 Apr.02 Proprietary and Confidential 69 SB555 Hardware Integration Guide You can implement as few or as many of these signals as suits your project. See the Design Guide (document #2130179) for a discussion of the specific applications. Human interface (LEDs) By default from the factory, these outputs are defined for a human interface presuming connection to LED indicators (blinking patterns are used). All four signals are active low. They are capable of directly driving LEDs with up to 2 mA sinking or sourcing. Up to 3 mA is supported if 3.0 V does not need to be maintained. There is a damping applied to Status 3 and Status 4 (pins 9 and 11). When triggered active
(on) they will remain on for a minimum of 50 ms. This is to provide a definite visual signal on an LED. Sample LED status interface A typical LED human interface is shown in Figure 6-1 on the following page. The LEDs are connected in such a way that when power to the SB555 VCC pins is removed, power to the LEDs is also removed. This prevents back-powering the modem through the LEDs and status pins when the modem is powered down. The requirement for this will depend on the type of LEDs selected and the voltage drop across the part. Use a regulator of sufficient output current, such as the LP3985-3.0 from National Semiconductor. 70 Proprietary and Confidential 2130075 Control Signals Figure 6-1: Sample LED integration The 3.0 V low-dropout (LDO) voltage regulator is used to provide the appropriate voltage for the LEDs. However, if the supply power (VBATT) never exceeds 3.30 V, or the LEDs provide suffi-
cient voltage drop to prevent back-powering, this voltage regulator can be omitted; the LED resistors can be connected directly to VBATT. If the LEDs were connected directly to a VBATT of 4.2 V, the voltage at the /Status pins could exceed the limit of VCC + 0.3 V, possibly damaging the modem. There could also be constant leakage current, draining the battery. Rev 1.0 Apr.02 Proprietary and Confidential 71 SB555 Hardware Integration Guide Machine interface To configure the modem to use the machine interface use one of these techniques:
AT command AT~SOMOD=1 CnS command KST_SOMOD (5003) All four signals are active low. Depending on the application, there may be a need to trigger interrupts on falling or rising edges, or both. There is a damping applied to Status 3 and Status 4 (pins 9 and 11). When triggered active
(on, low) they will remain on for a minimum of 50 ms. This is to prevent unduly frequent triggering of interrupts on the machine interface. Buffers should be used to protect the modem from back-power, and adjust for 3.0 V to 3.3 V logic differences, if required by the MCU. Sample machine interface to status outputs Figure 6-2: Sample status interface to machine integration Buffers are used to manage the level conversions between 3.0 V at the modem and 3.3 V at a host MCU. An SN74AHC541 (or equivalent) octal 72 Proprietary and Confidential 2130075 Control Signals buffer powered by the MCU's 3.3 V VCC rail is suggested. Connect the /OE1 and /OE2 pins to GND. This buffer is there mainly to protect the host MCU if it is ever powered down while the SB555 remains powered up. Only omit this buffer if all MCU input pins can tolerate 3.0 V applied to them while the MCU is powered down (MCU VCC = 0 V) without back-powering the MCU, and if the MCU input pins dont have pullups which could back-power the modem when it is powered down. Shutdown and reset control To correctly shutdown the modem prior to powering it off or resetting it, the host device must implement a shutdown request and acknowledge handshake. This can be done in software or hardware. See the Design Guide for details. The hardware mechanism to handshake a shutdown requires the implementation of the Shutdown Request (/ShutDown) and Shutdown Acknowledge (/Shdn_Ack) signals. Table 6-3: Shutdown control pinouts Pin Name Description Type Termination if not used 37 /Shdn_Ack Shutdown Acknowledge Output Not connected 38 /ShutDown Shutdown Request 39 /Reset Reset Input Input 3.0 V 3.0 V Rev 1.0 Apr.02 Proprietary and Confidential 73 SB555 Hardware Integration Guide Buffers should be used to protect the modem from back-power, overpower, and to adjust for 3.0 V to 3.3 V logic differences. Pin 37: /Shdn_Ack Shutdown Acknowledge is asserted (low) by the modem when the shutdown process is complete and the modem may be reset or powered off. Use of a buffer is recommended for hosts not using 3.0 V logic. It is also required if the host cannot handle cases where the modem is active
(the pin is deasserted high) while the host is powered down. If not implemented, leave this pin unconnected. Pin 38: /ShutDown This is a level sensitive signal that must be held asserted until the shutdown is acknowledged. It is detected by the modem firmware in a polling cycle for signal state, not by edge detection interrupt. Detection by the modem takes from 500 s to 10 ms depending on the state of the modem (active or sleeping) at the time. It may be necessary to buffer this input pin to protect against back-powering the modem if the SB555 is switched off while the host is kept on. A buffer will also protect against over driving the 3.0 V level of the modem by hosts using higher voltage logic. If Shutdown Request is not implemented, tie
/ShutDown to 3.0 V (VBUF). This prevents false detection of a shutdown request should the modem not be configured to ignore the signal. 74 Proprietary and Confidential 2130075 Control Signals Pin 39: /Reset The modem can be reset using a hardware control signal on pin 39, /Reset. The signal is active low and must be asserted for a minimum of 40 s. The /Reset pin of the SB555 should be driven by an open drain device (for example, a TMOS FET such as the 2N7000 or 2N7002), with a pulldown resistor on the input gate of the FET. The hosts MCU I/O pin driving the modems reset signal should be high-impedance (or input), or an output driven to 0 V during and immediately after MCU reset. This avoids accidentally resetting the modem during MCU powerup or powerdown. This FET also protects the MCU when it is powered down while the modem remains powered up. The modems /Reset pin has a pullup resistor which could back-power the MCU, and increase the drain on the modems battery, if this device is omitted. This FET also protects the SB555 when it is powered down while the MCU remains powered up. The modems input pins should not have a voltage applied to them that is more than 0.3 V above the modems VCC, which could otherwise happen when the modem is powered down. If the hardware reset is not to be used, the signal must be tied to 3.0 V (VBUF), providing a logic high to prevent holding the modem in reset. Rev 1.0 Apr.02 Proprietary and Confidential 75 SB555 Hardware Integration Guide Sample shutdown interface integration This sample shows the shutdown handshaking pins buffered to protect both the modem and the host MCU from back-power situations, and to handle logic level conversion. The manual on/off switch to the modem is shown for consistency with other samples but can be omitted. Figure 6-3: Sample shutdown and reset integration Buffers are used to manage the level conversions between 3.0 V at the modem and 3.3 V at a host MCU. SN74AHC541 (or equivalent) octal buffers 76 Proprietary and Confidential 2130075 Control Signals powered by the MCU's 3.3 V VCC rail for the modem output, and powered by the modems 3.0 V VBUF for the modem input, are suggested. Connect the /OE1 and /OE2 pins to GND. The host in this sample has control of the power to the modem. Following assertion of /Shdn_Ack, the host can switch off the modem via the MOSFET. Shutdown sequence The suggested shutdown sequence is described below:
1. The user switches off the host using the soft on/off switch. 2. The host MCU detects the user request to power down and asserts /ShutDown. 3. The modem performs a graceful shutdown and asserts /Shdn_Ack. 4. The host detects the modem has shutdown and issues the control signal to the MOSFET to turn off the modem, or asserts /Reset. 5. The host completes any other internal shutoff processes. Shutdown timing Entering Shutdown The shutdown process requires varying amounts of time, depending on the state of the modem at the time of the shutdown request. Detection of the request can take from 500 s
(active) to 10 ms (sleeping). Once detected, the time needed to shutdown gracefully depends on the activity of the modem at the time the Rev 1.0 Apr.02 Proprietary and Confidential 77 SB555 Hardware Integration Guide shutdown request is issued. It the modem must disconnect a call or deregister from the network, more time is needed. Typical shutdown time, measured from the assertion of the request to the acknowledgement from the modem is given the table below. Table 6-4: Shutdown timing Modem activity Voice call connected Data call connected Registered but no call active (must contact the network to deregister) Modem in process of registering Modem is not registered Modem in deep sleep (no coverage) Typical time to shutdown (seconds) 3.25 2.3 2.9 1.45 1.3 0.75 Leaving Shutdown The modem can be restored to normal operation by deasserting the Shutdown Request (without a power cycle). The modem will perform a full reset in this case, taking from 715 seconds. See Reset timing on page 55 for details. 78 Proprietary and Confidential 2130075 7: RF Integration 7 Introduction RF connection Antenna and cabling Interference and sensitivity Introduction This chapter covers issues related to the Radio Frequency (RF) integration of the SB555 embedded modem. The modems RF specifica-
tions are noted in the table below. Table 7-1: Radio specifications Transmitter power Maximum 224 mW into 50 (+23.5 dBm) Closed loop frequency stability PCS band 150 Hz Receiver sensitivity
-104 dBm Transmit band 18501910 MHz Receive band 19301990 MHz Channel spacing Cellular band 1.25 MHz Receiver sensitivity
-104 dBm Transmit band Receive band 824849 MHz 869894 MHz Channel spacing 1.25 MHz Rev 1.0 Apr.02 Proprietary and Confidential 79 SB555 Hardware Integration Guide RF connection The antenna connector is an MMCX connector jack oriented in line with the module longitu-
dinal axis. Mating connectors can be either straight or right-angle plugs. The RF connector of the SB555 can be connected directly to test equipment. Connection to an antenna requires the antenna type to be correctly matched to the modem, using a 50 cable. Connector considerations Varying integrations have different require-
ments for the antenna type and method of connection. Is the antenna permanently attached to the host device or removableattached by a user-acces-
sible connector? Permanent attachment (like that in a cellular handset) means the cabling from the antenna to the modem is internal to the device. If there is a user-accessible connector, how frequently is the antenna likely to be attached and detached? A PC Card application is an example where the user may attach and detach the antenna fairly often; whereas a telemetry device using a cable to reach an antenna mounted externally is rarely detached. Is the antenna connection prone to stress or vibration that might loosen it? Vehicle mounted devices are subject to vibration that can loosen or detach an antenna cable unless an appropriate connector is used. 80 Proprietary and Confidential 2130075 RF Integration The modules MMCX antenna connector is designed for high reliability (stiff detent) but few connection cycles (500 cycles). Depending on your application, this may not support end-user demands. You may need to consider presenting an alternate connector (SMA, SMB, TNC, etc.) to the user. Ground plane isolation Ground loops must be avoided between the host connector and the antenna. Figure 7-1: Ground plane RF Isolation Rev 1.0 Apr.02 Proprietary and Confidential 81 SB555 Hardware Integration Guide The coaxial cable connecting the module to the antenna carries the ground connection. There must be an electrical isolation between the ground plane at the antenna and the ground plane used by the modem. If these two ground planes were not isolated, there would be a ground loop from the modem through the coaxial cable and back through the ground plane to the modems own ground. This must be avoided. If your integration uses the devices case as part of a ground connection, then the external antenna connection must be isolated from the case to avoid creating a ground loop. However, in vehicle integrations, it is acceptable to have a remote antenna ground connection to the vehicle chassis. Figure 7-2: Connector ground isolation ESD protection You are responsible for all ESD protection. This is usually made a part of the antenna matching circuitry. This is not lightning strike protection. The appendix (page 95) provides some general information on ESD protection. 82 Proprietary and Confidential 2130075 RF Integration Antenna and cabling After determining the connection method
(integral or user-accessible connector) the selection of an antenna and cable must be made. Matching antenna and cable Matching the antenna gain with cable loss is critical to effective RF performance. For proper matching, the antenna should be 50 ohms with a return loss || -10 dB between 824 894 MHz and 1850 1990 MHz. Overall system antenna gain, with cable loss, should be -2 dBi and +2 dBi. Keep in mind that your achieved value will have an impact on radiated power and the FCC SAR test results. The VSWR (Voltage Standing Wave Ratio) must be less than 2 over the entire band. This will ensure correct modem control of output power. Antenna options There are several antenna manufacturers producing dual-band products that will work well with the SB555. Custom antenna design is possible but requires a skilled RF engineer to ensure that RF performance is maintained. The antenna requirements can be taken from Table 7-1, Radio specifications, on page 79. Location of the antenna can have an impact on the RF performance of the SB555 modem. The modem is self-shielded to prevent interference in Rev 1.0 Apr.02 Proprietary and Confidential 83 SB555 Hardware Integration Guide most applications, but this does not mean that you can ignore antenna placement. See Inter-
ference and sensitivity on page 84. Cables All connecting cables between the modem and the antenna must be 50 . Mismatching the impedance will result in a significant reduction in RF performance. Interference and sensitivity There are several sources of interference that could impact the SB555 modems RF perfor-
mance. Some of those that relate to how you manage your design are discussed here. Sierra Wireless offers desensitivity screening required by some carriers and recommended by most others. Power supply noise Noise in the power supply can lead to noise in the RF signal. The specification for power supply ripple is no more than 100 mVp-p 1 Hz 100 kHz. 84 Proprietary and Confidential 2130075 RF Integration Device generated RF All electronic computing devices generate radio frequency (RF) interference. You should pay particular attention to RF noise as it can impact the sensitivity of the SB555 modems radio receiver. The proximity of the hosts electronics to the antenna and radio have an effect on the radio sensitivity. There are many high-speed devices
(in particular the processor itself) running at frequencies of 10s of MHz. Higher order harmonics of these frequencies caused by the rapid rise and fall times, often fall within the operating frequency band of the radio. For example, if we have a sub-system running at 40 MHz, the 22nd harmonic falls at 880 MHz, which is within the cellular forward channel frequency band. In practice there is more than one interfering frequency harmonic, and the net effect is a series of desensitized communication channels. This energy leaks out of the computer, and is received by the antenna, masking the desired signal. Most device designers are familiar with having to pay attention to radiated emissions in order to meet the FCC part 15 rules. The major culprits in causing RF desensitivity have been found to be the microprocessor and memory, display panel and display drivers, and switching mode power supplies. Some or all of the following techniques may be followed to mitigate RF desensitivity:
Keep the antenna as remote as possible. By moving the antenna further away from the cause of the interference, the effect of the Rev 1.0 Apr.02 Proprietary and Confidential 85 SB555 Hardware Integration Guide interference may be reduced. The drawback of this approach is that the modem may be less convenient to use. Shield the host device. The SB555 itself is well shielded to avoid interference, however it is not practical to shield the antenna for obvious reasons. It may be practical to employ shielding over the worst radiating elements of the host device (e.g. the main processor) to reduce the emissions. A better, but often less practical approach is to build RF shielding into the device packaging. Feed-through capacitors or discrete filtering may be used on high frequency lines to filter out unwanted energy. Board layout with attention to these issues. Use multi-layer PCBs to form shielding layers around high-speed clock traces. It must be cautioned at this point that the tradi-
tional 80/20 rule does not hold for RF shielding. A single (non-conducting) wire passing through the most perfect shielded enclosure can cause 10s of dB of lost sensitivity. Ideally a perfect Faraday cage is created around the noise source, and every signal passing through this shield wall is filtered using a feed-through capacitor. Since this level of perfection is typically difficult to achieve, RF shielding becomes a learned art, viewed as black magic. Effective integrators of wireless communication devices inside computing devices are likely to make use of good design practices coupled with investigative techniques to locate and isolate sources of interference. It is important to carry out these investigations as early as possible in the design cycle. 86 Proprietary and Confidential 2130075 RF Integration The SB555 radio circuits use a number of Inter-
mediate Frequency (IF) stages. The following specific frequencies should be avoided or suppressed in the host device to maintain the best sensitivity performance:
183.6 MHz 228.6 MHz 263.6 MHz Modem generated RF switching noise In addition to outside frequencies interfering with the modems sensitivity, the modem itself can cause noise in hearing aids due to the keying of the transmitter. Most digital wireless technologies do not transmit radio frequencies (RF) continuously. They transmit in bursts, usually of a specific duration, which are often described in terms of RF switching frequencies. Unfortunately, most hearing aids are not immune to RF; they try to rectify the switching frequencies into audio. This causes unpleasant noise for hearing aid users in close proximity to transmitters, as is the case with digital wireless phones. Although we do not imagine there will be any problems or complaints related to wireless computer applications, it still may be useful to know the switching frequencies and the output power levels of the Sierra Wireless SB555. The SB555 uses an RF switching frequency of 37.5 Hz. In data connections, the duty cycle is variable from a minimum of 0 to a maximum of Rev 1.0 Apr.02 Proprietary and Confidential 87 SB555 Hardware Integration Guide 75%. The duty cycle may hit the maximum 75%
during large file transfers when the system has allocated the maximum bandwidth to the user. Otherwise, the duty cycle will be lower. Power per transmission is infinitely variable over a 73.5 dB range from -50 dBm to +23.5 dBm. Power varies up or down over this range during the transmission and is adjusted every 1.25 ms. Variations follow a time constant, so large steps are not instantaneous, and variation in magnitude is entirely dependent on path loss between the modem and the base station, which in turn varies depending on a variety of fading mechanisms. During voice operation, the duty cycle of the transmitter varies depending on the energy content of the user's voice. The frame rate of 37.5 Hz remains the same. 88 Proprietary and Confidential 2130075 Appendix A:
Host Connector Pinouts A The following table lists the pinouts of the 40-pin host connector of the SB555 embedded modem. Those pins shown as Reserved are to be termi-
nated as noted in the rightmost column. Signal type indicates if the signal is an input to the modem or output from the modem. The column marked U/D drv indicates any modem internal pullup or pulldown resistor on inputs, or the drive capability in mA for outputs. Table 7-2: Host connector pinouts Pin Description Name Signal type U/D drv Termination if not used 1, 2 Vcc 3.3 VDC power supply 3, 4 GND 5 /Status1 6 Ground Status 1 Reserved 7 /Status2 Status 2 8 Reserved 9 /Status3 Status 3 10 Reserved 11 /Status4 Status 4 12 Reserved Power Power Output Input Output Input Output Input Output Input
3 D 3 D 3 D 3 D Required Required Not connected Not connected Not connected Not connected Not connected Not connected Not connected Not connected Rev 1.0 Apr.02 Proprietary and Confidential 89 SB555 Hardware Integration Guide Table 7-2: Host connector pinouts (cont.) Pin Description Name Signal type U/D drv Termination if not used 13 MIC+
Voice Mic+
Input (Diff.) U AGND 14 SPKR+
Voice Speaker Output
Not connected Voice Mic-
Input (Diff.) D AGND 15 MIC-
16 AGND 17 /CTS2 18 /RTS2 19 TxD2 20 RxD2 Audio Common Ground (AGND) Serial 2 CTS Output Serial 2 RTS Serial 2 TX Serial 2 RX 21 /DCD1 Serial 1 DCD 22 RxD1 23 TxD1 Serial 1 RX Serial 1 TX 24 /DTR1 Serial 1 DTR 25 GND 26 /DSR1 27 /RTS1 28 /CTS1 29 /RI1 30 GND 31 32 Ground Serial 1 DSR Serial 1 RTS Serial 1 CTS Serial 1 RI Ground Reserved Reserved
3 D D 3 3 3 D U
3 D 3 3
3 3 Not connected Not connected Ground Ground Not connected Not connected Required Required Ground Required Not connected Ground Not connected Not connected Required Not connected Not connected Input Input Output Output Output Input Input Power Output Input Output Output Power Output Output 90 Proprietary and Confidential 2130075 Appendix A: Host Connector Pinouts Table 7-2: Host connector pinouts (cont.) Pin Description Name Signal type 33 34 35 36 Reserved Reserved Reserved Reserved 37 /Shdn_Ack Shutdown Acknowledge 38 /ShutDown Shutdown Request 39 /Reset Reset 40 Reserved Input Output Output Input Input U/D drv Termination if not used D 3
2 D U
Ground Not connected Not connected Not connected Not connected 3.0 V 3.0 V Not connected Rev 1.0 Apr.02 Proprietary and Confidential 91 SB555 Hardware Integration Guide 92 Proprietary and Confidential 2130075 Appendix B: Sample Integration B Rev 1.0 Apr.02 Proprietary and Confidential 93 SB555 Hardware Integration Guide 94 Proprietary and Confidential 2130075 Appendix C:
Electrostatic Discharge C Introduction Creation Damage Protection Considerations Introduction ESD (Electrostatic Discharge) is commonly experienced as the static shock that might occur when reaching for a door handle. It is caused by a difference in electrical potential between you and the door handle, and can be in excess of 3500 volts. Such a sudden discharge of high voltage can cause severe damage to electronic circuits and must be protected against. To provide that protection, you should have an understanding of where these charges come from, what they can do in the circuit, and how they can be managed. Charge creation People are one of the most common generators of ESD. Normal movement constantly rubs electrons onto and off of various substances we encounter. As electrons transfer, there can be an accumulation in the body of a substantial potential differential. The magnitude of the charge may be only a few micro Coulombs, but the voltage potential between two objects can be in the thousands of Rev 1.0 Apr.02 Proprietary and Confidential 95 SB555 Hardware Integration Guide volts. When two objects of different potential get close enough, an electrostatic discharge takes place. The movement of an electronic device in and out of a persons pocket or a carrying case can cause a charge to develop. When the charged object encounters another object with a sufficient difference in potential (like a persons finger), there will be a discharge to equalize the charges in the two objects. When the discharge takes place, the voltage involved can be damaging (and painful). Damage from ESD Electronic circuits contain semiconductors and components that can be sensitive to the high voltages involved in ESD. They can be damaged or destroyed. MOS (Metal Oxide Semiconductor) and field effect devices are among the most sensitive to ESD. Power diodes and power transistors are less affected. VMOS devices can be damaged by a shock as small as 30 volts. EPROMs, OP-AMPS, and CMOS circuits are also very sensitive to ESD. The damage can result from a single event with a high voltage, but there can also be damage resulting from the cumulative effect of several small discharges. The damage may be a fatal failure of the part, but could also appear as changes in the electrical characteristics of semiconductors. This means 96 Proprietary and Confidential 2130075 Appendix C: Electrostatic Discharge the device may still appear to function normally in most respects, but display abnormal behavior in certain circumstances. Quite often there is no observed spark involved in the discharge. The user of a device may not be aware that there was a damaging discharge. Types of damage The damage resulting from ESD can take one of three forms:
Fatal The device is permanently damaged due to junction shorting, oxide punch-through, or melting. Latch-up There is a temporary fault (perhaps a loss of data) but the device is not permanently damaged. Latent The device experiences a slow degra-
dation of performance, eventually leading to a fatal fault. Exposed interfaces Any product that exposes an interface to the outside world can be susceptible to ESD damage. Shielding of cases and cables only prevents exter-
nally radiated ESD emissions. Some external component is needed to absorb transient energy to protect against conducting the energy to sensitive internal parts. In the Sierra Wireless modems, the serial ports
(via transceivers), RF connector, and voice inter-
faces can all be exposed to the outside world. It is up to the integrator to provide protection. Rev 1.0 Apr.02 Proprietary and Confidential 97 SB555 Hardware Integration Guide Protection from ESD There are several types of suppression devices on the market. Many are specifically designed to provide ESD protection. Requirements Any ESD protection must limit the voltage reaching the device to a non-destructive level. This may be above the normal operating voltage of the device. It must also respond extremely quickly to an event. The discharge happens very rapidly. The device must be able to handle a high peak transient, and itself survive multiple and repet-
itive discharges. Reverse leakage of current must be minimal. TVS diodes Transient-voltage-suppression (TVS) diodes are solid-state parts designed to meet the require-
ments to protect semiconductors from damaging ESD. They can protect devices of these types:
MOS (metal-oxide semiconductor) CMOS (complimentary-MOS) bipolar TTL (transistor-transistor logic) GaAs (gallium-arsenide) The strategy is to divert the transient energy away from sensitive parts. They are shunt-
connected across the protected line. The TVS diode forms a low-impedance path when a 98 Proprietary and Confidential 2130075 Appendix C: Electrostatic Discharge voltage exceeds the nominal voltage of the device. This diverts the energy away from the protected circuit, limiting it to the clamping voltage of the TVS diode. After the high-voltage event passes, the TVS diode returns to its high-
impedance state. Zin External Interface ESD Current TVS Diode Protected Circuit Figure 7-3: Simple TVS diode protection The TVS diode should be rated at the level of ESD protection desired. A typical rating is 8 kV (contact) and 15 kV (air discharge). Devices on the market are often designed for particular interfaces (such as RS-232 and USB). They are commonly available as an array of TVS diodes in a single package. PCB design Layout of a PCB plays a part in the protection of the circuit. Use of TVS diodes suppresses the damage of direct ESD surges but the impact of the electromagnetic field generated by the discharge is another matter. Parasitic induc-
tance in the protection path can result in signif-
icant voltage overshoot, leading to damage. Rev 1.0 Apr.02 Proprietary and Confidential 99 SB555 Hardware Integration Guide ESD Pulse Overshoot s t l o V Failure Voltage Clamp Voltage Vcc Time Figure 7-4: Possible inductance voltage overshoot The voltage developed across an inducted load is proportional to the rate of change in the current
(V = L di/dt). The rise time of ESD events is typically very fast, in the order of 1 ns to reach its peak. Making the shunt paths as short as possible reduces the effects of parasitic inductance. All inductive paths must be optimized, including:
from TVS diode to protected circuit connector to TVS diode ground return The ESD protection device should also be as close as possible to the connector to reduce transient coupling into nearby traces. Secondary effects of ESD can cause disruption to other areas of circuitry even if there is no direct path between the connector and the circuit. A long trace can act like antenna, receiving energy from the electromagnetic field generated by the ESD. Short traces reduce this effect. 100 Proprietary and Confidential 2130075 Appendix C: Electrostatic Discharge Routing critical signals near the edge of a board or near protected lines can increase the risk of inducing damage. The following points summarize the guidelines for designing a PCB to reduce ESD damage:
Transient return path to ground as short as possible Avoid shared transient return paths Minimize board loop areas, power and ground loops Critical signal paths as isolated as possible from board edge and protected lines Provide effective resistance between the ground plane of sensitive components and that used for ESD protection ESD integration considerations Return ground path The route taken to divert the ESD energy is critical to successful protection. Usually the protection device is placed immediately adjacent to the point of entry of ESD (connector) with a well-defined route to ground the transient energy out of the device. This route must also avoid inducing energy in adjacent traces and components. Rev 1.0 Apr.02 Proprietary and Confidential 101 SB555 Hardware Integration Guide Capacitance Generally, the lower the clamping voltage of the TVS diode, the higher the capacitance. This extra capacitance might attenuate signals in high-
speed digital circuitry. Selecting the right protection device also involves protecting the functionality of the circuit. This problem is even more apparent with the RF antenna interface, where attenuation can be costly. Care must be taken to keep insertion loss low while maintaining adequate protection. Some devices on the market for RF protection claim losses below 0.2 dB with less than 1 pF capacitance. Mitigating the problem of capacitance is commonly managed by linking multiple diodes in series, reducing overall capacitance. An alter-
native is to use a high voltage rectifier with low capacitance in series, and in opposite polarity, with the TVS diode. C2 = 5 pF C1 = 200 pF Ct =
1 1/C1 + 1/C2
= 4.9 pF Figure 7-5: Reducing capacitance with rectifier 102 Proprietary and Confidential 2130075 Appendix C: Electrostatic Discharge Selection guidelines The parameters related to protection specifica-
tions you need to consider are:
Reverse Standoff Voltage (VRWM) The normal operating voltage of the device. At this voltage, the protection device will appear as high impedance to the modem. Reverse Breakdown Voltage (VBR) This is the voltage at which the protection device begins to conduct and becomes the low impedance path. Peak Pulse Current (Ipp) The highest surge current that the protection can withstand without being damaged itself. Clamping Voltage (Vc) The maximum voltage drop across the protection device for a given peak pulse current. Select a device that has:
VRWM >= the normal operating voltage of the modem Ipp >= the expected peak of the transient pulse current (typically 30 A at 8 kV contact) Vc <= the maximum voltage handling capability of the modem Cj < the maximum loading capacitance to maintain signal integrity Additional specifics are available in the main text of this document. Rev 1.0 Apr.02 Proprietary and Confidential 103 SB555 Hardware Integration Guide 104 Proprietary and Confidential 2130075
frequency | equipment class | purpose | ||
---|---|---|---|---|
1 | 2002-11-25 | 1850 ~ 1910 | PCB - PCS Licensed Transmitter | Original Equipment |
app s | Applicant Information | |||||
---|---|---|---|---|---|---|
1 | Effective |
2002-11-25
|
||||
1 | Applicant's complete, legal business name |
Sierra Wireless Inc.
|
||||
1 | FCC Registration Number (FRN) |
0005810874
|
||||
1 | Physical Address |
13811 Wireless Way
|
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1 |
Richmond, BC, N/A V6V 3A4
|
|||||
1 |
Canada
|
|||||
app s | TCB Information | |||||
1 | TCB Application Email Address |
m******@ccsemc.com
|
||||
1 | TCB Scope |
B1: Commercial mobile radio services equipment in the following 47 CFR Parts 20, 22 (cellular), 24,25 (below 3 GHz) & 27
|
||||
app s | FCC ID | |||||
1 | Grantee Code |
N7N
|
||||
1 | Equipment Product Code |
SB555
|
||||
app s | Person at the applicant's address to receive grant or for contact | |||||
1 | Name |
Y**** W********
|
||||
1 | Title |
Sr. Manager, Regulatory Compliance
|
||||
1 | Telephone Number |
604-2********
|
||||
1 | Fax Number |
604-2********
|
||||
1 |
y******@SierraWireless.com
|
|||||
app s | Technical Contact | |||||
n/a | ||||||
app s | Non Technical Contact | |||||
n/a | ||||||
app s | Confidentiality (long or short term) | |||||
1 | Does this application include a request for confidentiality for any portion(s) of the data contained in this application pursuant to 47 CFR § 0.459 of the Commission Rules?: | Yes | ||||
1 | Long-Term Confidentiality Does this application include a request for confidentiality for any portion(s) of the data contained in this application pursuant to 47 CFR § 0.459 of the Commission Rules?: | No | ||||
if no date is supplied, the release date will be set to 45 calendar days past the date of grant. | ||||||
app s | Cognitive Radio & Software Defined Radio, Class, etc | |||||
1 | Is this application for software defined/cognitive radio authorization? | No | ||||
1 | Equipment Class | PCB - PCS Licensed Transmitter | ||||
1 | Description of product as it is marketed: (NOTE: This text will appear below the equipment class on the grant) | SB555 Embedded Modem Module for Mobile Application | ||||
1 | Related OET KnowledgeDataBase Inquiry: Is there a KDB inquiry associated with this application? | No | ||||
1 | Modular Equipment Type | Does not apply | ||||
1 | Purpose / Application is for | Original Equipment | ||||
1 | Composite Equipment: Is the equipment in this application a composite device subject to an additional equipment authorization? | No | ||||
1 | Related Equipment: Is the equipment in this application part of a system that operates with, or is marketed with, another device that requires an equipment authorization? | No | ||||
1 | Grant Comments | Power is conducted. This device is to be used only for mobile and fixed applications. The antenna(s) used for this transmitter must be installed to provide a separation distance of at least 20 cm from all persons and must not be co-located or operating in conjunction with any other antenna or transmitter. Users and installers must be provided with antenna installation instructions and transmitter operating conditions for satisfying RF exposure compliance. Antennas used for this module must not exceed 10 dBi gain in Cellular band and 9 dBi for PCS band for mobile and fixed operating configurations. This device is approved as a module to be installed in other devices. | ||||
1 | Is there an equipment authorization waiver associated with this application? | No | ||||
1 | If there is an equipment authorization waiver associated with this application, has the associated waiver been approved and all information uploaded? | No | ||||
app s | Test Firm Name and Contact Information | |||||
1 | Firm Name |
Compliance Certification Services Inc
|
||||
1 | Name |
S****** C******
|
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1 | Telephone Number |
408-4******** Extension:
|
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1 | Fax Number |
408-4********
|
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1 |
s******@ccsemc.com
|
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Equipment Specifications | |||||||||||||||||||||||||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Line | Rule Parts | Grant Notes | Lower Frequency | Upper Frequency | Power Output | Tolerance | Emission Designator | Microprocessor Number | |||||||||||||||||||||||||||||||||
1 | 1 | 22.901(d) | 824 | 849 | 0.224 | 2.5 ppm | 1M25F9W | ||||||||||||||||||||||||||||||||||
1 | 2 | 24E | 1850 | 1910 | 0.224 | 2.5 ppm | 1M25F9W |
some individual PII (Personally Identifiable Information) available on the public forms may be redacted, original source may include additional details
This product uses the FCC Data API but is not endorsed or certified by the FCC