Sierra Wireless SL8084T Wireless Module User Manual Hardware Integration Guide for AirPrime SL8084T

Sierra Wireless Inc. Wireless Module Hardware Integration Guide for AirPrime SL8084T

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4112719 2.1 January 07, 2013 AirPrime SL8084T Hardware Integration Guide

4112719 Rev 2.1 January 07, 2013 2 Hardware Integration Guide Important Notice Due to the nature of wireless communications, 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 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. Safety and Hazards Do not operate the Sierra Wireless modem in areas where cellular modems are not advised without proper device certifications. These areas include environments where cellular radio can interfere such as explosive atmospheres, medical equipment, or any other equipment which may be susceptible to any form of radio interference. 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. 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 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. Limitations of Liability This manual is provided “as is”. Sierra Wireless makes no warranties of any kind, either expressed or implied, including any implied warranties of merchantability, fitness for a particular purpose, or noninfringement. The recipient of the manual shall endorse all risks arising from its use. The information in this manual is subject to change without notice and does not represent a commitment on the part of Sierra Wireless. SIERRA WIRELESS AND ITS AFFILIATES SPECIFICALLY DISCLAIM 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 PRODUCT, EVEN IF SIERRA WIRELESS AND/OR ITS AFFILIATES HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES OR THEY ARE FORESEEABLE OR FOR CLAIMS BY ANY THIRD PARTY. Notwithstanding the foregoing, in no event shall Sierra Wireless and/or its affiliates aggregate liability arising under or in connection with the Sierra Wireless product, regardless of the number of events, occurrences, or claims giving rise to liability, be in excess of the price paid by the purchaser for the Sierra Wireless product. Customer understands that Sierra Wireless is not providing cellular or GPS (including A-GPS) services. These services are provided by a third party and should be purchased directly by the Customer.

4112719 Rev 2.1 January 07, 2013 4 Hardware Integration Guide Document History Version Date Updates 1.0 October 17, 2012 Document creation 1.1 October 17, 2012 Updated Table 6 RF Bands 2.0 January 07, 2013 Added sections:  4 RF Circuit Routing Constraints  6.3 Important Compliance Information for North American Users Updated section 2.1 Power Supply 2.1 Updated Table 2 Averaged Call Mode Data DC Power Consumption

4112719 Rev 2.1 January 07, 2013 5 Contents 1. INTRODUCTION .................................................................................................. 8 1.1. Hardware Development Components ............................................................................... 8 2. POWER INTERFACE ........................................................................................... 9 2.1. Power Supply .................................................................................................................... 9 2.2. Electrostatic Discharge (ESD) ......................................................................................... 10 2.3. Power States ................................................................................................................... 11 3. RF INTEGRATION ............................................................................................. 12 3.1. Supported RF Bands ....................................................................................................... 12 3.1.1. Ground Connection Guidelines ................................................................................ 12 3.1.2. Shielding Guidelines ................................................................................................ 12 3.2. Antenna Guidelines ......................................................................................................... 12 3.2.1. Choosing the Correct Antenna and Cabling ............................................................ 12 3.2.2. Determining the Antenna’s Location ........................................................................ 13 3.3. RF Desense Sources ...................................................................................................... 13 4. RF CIRCUIT ROUTING CONSTRAINTS ........................................................... 14 5. AUDIO INTERFACE ........................................................................................... 16 5.1. Audio Function Codec Responsibilities ........................................................................... 16 6. REGULATORY INFORMATION......................................................................... 18 6.1. Important Notice .............................................................................................................. 18 6.2. Safety and Hazards ......................................................................................................... 18 6.3. Important Compliance Information for North American Users ........................................ 18 6.3.1. EU Regulatory Conformity ....................................................................................... 19 7. REFERENCES ................................................................................................... 20 7.1. Reference Documents ..................................................................................................... 20 7.2. Acronyms and Definitions ................................................................................................ 20

4112719 Rev 2.1 January 07, 2013 6 List of Figures Figure 1. AppCAD Screenshot for MicroStrip Design Power Mode Diagram ................................ 14 Figure 2. RF Routing Example with Lead Type RF Connectors .................................................... 14 Figure 3. RF Routing Example with SMT Type RF Connectors ..................................................... 15 Figure 4. Coplanar Clearance Example ......................................................................................... 15 Figure 5. Antenna Microstrip Routing Example .............................................................................. 15

4112719 Rev 2.1 January 07, 2013 7 List of Tables Table 1. Power and Ground Specifications ..................................................................................... 9 Table 2. Averaged Call Mode Data DC Power Consumption ......................................................... 9 Table 3. Power Supply Requirements ........................................................................................... 10 Table 4. ESD Specifications .......................................................................................................... 10 Table 5. Supported SL8084T Power States .................................................................................. 11 Table 6. RF Bands ......................................................................................................................... 12 Table 7. Audio Interface Features ................................................................................................. 16 Table 8. Audio Pin Description ...................................................................................................... 16 Table 9. Codec Responsible for Special Functions ...................................................................... 16

4112719 Rev 2.1 January 07, 2013 8 1. Introduction The Sierra Wireless AirPrime SL8084T soldered-down module forms the radio component for the products in which it is embedded. Module-specific performance and physical characteristics are described in document [2] AirPrime SL808x Product Technical Specification and Customer Design Guidelines. Note: An understanding of network technology, and experience in integrating hardware components into electronic equipment is assumed. 1.1. Hardware Development Components Sierra Wireless manufactures two hardware development components to facilitate the hardware integration process:  AirPrime SL Socket Board – Adapter board into which an SL module is embedded. This board may be used as a stand-alone platform for basic hardware development.  AirPrime SL Development Kit – Hardware development platform that integrates with the socket-up board. The development kit provides access to all of the interfaces supported by the SL module. For instructions on using the SL Development Kit, see document [1] Universal AirPrime SL Series Development Kit User Guide.

4112719 Rev 2.1 January 07, 2013 9 2. Power Interface 2.1. Power Supply Power is provided to the SL8084T through power and ground pins as detailed in the following table. Table 1. Power and Ground Specifications Signal/Pin Name Pins Type Specification Parameter Min Typ Max Units VCC_3V6a 42, 44 V Voltage range VCC 3.30 3.60 4.30 V Ripple voltage (Uripp) 100 mVpp VREF_1V8 10 V Maximum supply current = 1 mA 1.62 1.80 1.98 V GND 19, 20, 21, 23, 28, 30, 35, 37, 38, 39, 52 V - 0 - V a. Host-provided input voltage should provide 3A instantaneous (lasting 5ms) current. See the table below for band-specific continuous current requirements. Table 2. Averaged Call Mode Data DC Power Consumptiona Mode Band Tx Power Current (at 3.6V) Conditions Peak (mA)b Average (mA) WCDMAc Band 1 +23 550 500 0 190 190 Band 5 or 6 +23 550 500 0 180 180 HSDPAc Band 1 +23 570 520 0 210 210 Band 5 +23 570 520 0 200 200 GSM / GPRSd 1 slot 2 slots 3 slots 4 slots 850 +32 1320 220 360 - -  Class 10  50Ω 900 +32 1610 260 425 - - 1800 +30 1000 180 285 - - 1900 +30 860 165 260 - - or 6

4112719 Rev 2.1 January 07, 2013 10 Hardware Integration Guide Power Interface Mode Band Tx Power Current (at 3.6V) Conditions Peak (mA)b Average (mA) EDGE 850 +27 860 170 260 340 400  Class 12  50Ω 900 +27 960 180 280 360 430 1800 +26 740 150 230 290 340 1900 +26 660 150 220 270 300 a. Includes USB bus current. b. Peak consumption averaged over 100µs. c. Current consumption increases by 50mA with a 6dB return loss-based load-pull. d. GSM mode peak current increases to 2.2A (from nominal 1.6–1.7A) with 6dB return loss-based load-pull. The host device must provide power to the AirPrime soldered-down module over pins 42 and 44 (VCC_3V6) as detailed in the following table. Table 3. Power Supply Requirements Requirement Type Value Power Supply 3.6V (nominal) Voltage Range (VMIN – VMAX) 3.3V – 4.3V Current (instantaneous (≤5ms)) 3A Current (continuous) 700mA Note: The host must provide safe and continuous power to the module; the module does NOT have protection circuits to guard against electrical overstress. 2.2. Electrostatic Discharge (ESD) The host device must provide adequate ESD protection on digital circuits and antenna ports as detailed in the following table. Note: The level of protection required depends on the application. Table 4. ESD Specifications Category Connection Specification Operational RF port (antenna launch and RF connector) IEC-61000-4-2 — Level (Electrostatic Discharge Immunity Test) Non-operational Host connector interface Unless otherwise specified:  JESD22-A114-B +/- 2kV Human Body Model  JESD22-C101 +/- 300V Charged Device Signals USIM connector ESD protection is highly recommended at the point where the USIM contacts are exposed, and for any other signals that would be subjected to ESD by the user. Other host signals

4112719 Rev 2.1 January 07, 2013 11 Hardware Integration Guide Power Interface 2.3. Power States The SL8084T module has five power states as detailed in the following table. Table 5. Supported SL8084T Power States State Description Host Powered Module Powered USB Interface Active RF Enabled Normal (Default state)  Capable of placing / receiving calls or establishing data connections on network  USB interface is fully active  Current consumption in a call or data connection is affected by:  Radio band in use  Tx power  Receive gain settings  Data rate  Number of active Tx time slots     Low Power  ‘Airplane’ mode — Rx / Tx are disabled; USB interface is active  State entered automatically when critical voltage / temperature thresholds are exceeded. Host should consider powering off module to prevent damage to unit.     Sleep  Normal state of module between calls or data connections.  Module cycles between wake (polling the network) and sleep, at network provider-determined interval.     Off  Host power is connected  Module is powered down (drawing minimal current from host power supply)     Disconnected  Host power is disconnected from module  All module-related voltages are at 0V    

4112719 Rev 2.1 January 07, 2013 12 3. RF Integration 3.1. Supported RF Bands Table 6. RF Bands Technology Band Tx Frequency (MHz) Rx Frequency (MHz) GSM GSM 850 824 – 849 869 – 894 EGSM 900 880 – 915 925 – 960 DCS 1800 1710 – 1785 1805 – 1880 PCS 1900 1850 – 1910 1930 – 1990 WCDMA1 Band I (WCDMA 2100) 1920–1980 2110–2170 Band V (WCDMA 850) 824 – 849 869 – 894 Band VI (WCDMA 800) 830–840 875–885 1 WCDMA channel spacing is 5 MHz, but this can be adjusted to optimize performance in a particular deployment scenario. 3.1.1. Ground Connection Guidelines When connecting the module to system ground:  Prevent noise leakage by establishing a very good ground connection to the module through the host connector.  Minimize ground noise leakage into the RF. Depending on the host board design, noise could potentially be coupled to the module from the host board. This is mainly an issue for host designs that have signals traveling along the length of the module, or circuitry operating at both ends of the module interconnects. 3.1.2. Shielding Guidelines The module is fully shielded to protect against EMI and to ensure compliance with FCC Part 15 - “Radio Frequency Devices” (or equivalent regulations in other jurisdictions). Note: This shielding must NOT be removed. 3.2. Antenna Guidelines 3.2.1. Choosing the Correct Antenna and Cabling Consider the following points for appropriate antenna selection:  The antenna (and associated circuitry) should have a nominal impedance of 50Ω with a return loss of better than 10 dB across each frequency band of operation.  The system gain value affects both radiated power and regulatory (FCC, IC, CE, etc.) test results.

4112719 Rev 2.1 January 07, 2013 13 Hardware Integration Guide RF Integration 3.2.2. Determining the Antenna’s Location Consider the following points when deciding where to place the antenna:  Antenna location may affect RF performance. Although the module is shielded to prevent interference in most applications, the placement of the antenna is still very important—if the host device is insufficiently shielded, high levels of broadband or spurious noise can degrade the module’s performance.  Connecting cables between the module and the antenna must have 50Ω impedance. If the impedance of the module is mismatched, RF performance is reduced significantly.  Antenna cables should be routed, if possible, away from noise sources (switching power supplies, LCD assemblies, etc.). If the cables are near the noise sources, the noise may be coupled into the RF cable and into the antenna. 3.3. RF Desense Sources Common sources of interference that may affect the module’s RF performance (RF desense) include  Power supply noise  Can lead to noise in the RF signal  Module power supply ripple limit <= 100 mVp-p 1 Hz–100 kHz  Interference from other embedded wireless devices  Any harmonics, sub-harmonics, or cross-products of signals that fall in the module’s Rx range may cause spurious response, resulting in decreased Rx performance.  Tx power and corresponding broadband noise may overload or increase the noise floor of the module’s receiver, resulting in RF desense.  Severity of interference depends on proximity of other antennas to the module’s antennas.  Host electronic device-generated RF  Proximity of host electronics to the module’s antenna can contribute to decreased Rx performance.  Some devices include microprocessor and memory, display panel and display drivers, and switching mode power supplies. Note: In practice, there are usually numerous interfering frequencies and harmonics. The net effect can be a series of desensitized receive channels.

4112719 Rev 2.1 January 07, 2013 14 4. RF Circuit Routing Constraints To route the RF antenna signals, the following recommendations must be observed for PCB layout: The RF signals must be routed using traces with a 50 characteristic impedance. Basically, the characteristic impedance depends on the dielectric constant (εr) of the material used, trace width (W), trace thickness (T), and height (H) between the trace and the reference ground plane. In order to respect this constraint, Sierra Wireless recommends that a MicroStrip structure be used and trace width be computed with a simulation tool (such as AppCAD, shown in the figure below and available free of charge at http://www.avagotech.com). Figure 1. AppCAD Screenshot for MicroStrip Design Power Mode Diagram The trace width should be wide enough to maintain reasonable insertion loss and manufacturing reliability. Cutting out inner layers of ground under the trace will increase the effective substrate height; therefore, increasing the width of the RF trace. Caution: It is critical that no other signals (digital, analog, or supply) cross under the RF path. The figures below show generic examples of good routing techniques. Figure 2. RF Routing Example with Lead Type RF Connectors

4112719 Rev 2.1 January 07, 2013 15 Hardware Integration Guide RF Circuit Routing Constraints Figure 3. RF Routing Example with SMT Type RF Connectors  Fill the area around the RF traces with ground and ground vias to connect inner ground layers for isolation.  Cut out ground fill under RF signal pads to reduce stray capacitance losses.  Avoid routing RF traces with sharp corners. A smooth radius is recommended.  The ground reference plane should be a solid continuous plane under the trace.  The coplanar clearance (G, below) from the trace to the ground should be at least the trace width (W) and at least twice the height (H). This reduces the parasitic capacitance, which potentially alters the trace impedance and increases the losses. Note the figure below shows several internal ground layers cutout, which may not be necessary for every application. Figure 4. Coplanar Clearance Example Figure 5. Antenna Microstrip Routing Example

4112719 Rev 2.1 January 07, 2013 16 5. Audio Interface The AirPrime SL8084T embedded module supports analog and PCM audio as summarized in the following tables. Refer to document [2] AirPrime SL808x Product Technical Specification and Customer Design Guidelines for detailed information about the audio interfaces. Table 7. Audio Interface Features Audio Type Feature Details Analog Implementation  Supports analog audio processing  Does not provide on-board filtering (except for blocking capacitors on microphone lines)  Host must provide bias and signal filters  Host should terminate unused audio lines with pull-down resistors Digital (PCM) Implementation Primary PCM supported to interface with external codec Power 1.8V (use VREG_MSME_1V8 as logic reference) Table 8. Audio Pin Description Audio Type Signal Name Pin # Description Notes Analog MIC_P 53 Microphone positive terminal In series with 0.1 μF DC blocking capacitor MIC_N 54 Microphone negative terminal In series with 0.1 μF DC blocking capacitor SPK_N 56 Speaker negative terminal SPK_P 57 Speaker positive terminal Digital PCM_SYNC 64 PCM synchronization bit 8 kHz PCM_DOUT 65 PCM output PCM_DIN 66 PCM input PCM_CLK 67 PCM clock 2 MHz for primary PCM mode 5.1. Audio Function Codec Responsibilities The responsibilities of the module codec and host codec for special functions are detailed in the following table. Table 9. Codec Responsible for Special Functions Function Responsible Codec FIR filtering Tx and Rx paths Module Noise suppression Required due to high sensitivity and gain in Tx path Module Echo cancellation Different for each audio path and environment (handset, headset, car kit, speakerphone) Module High pass filtering/slope filtering functions Required per phone acoustic requirements Module

4112719 Rev 2.1 January 07, 2013 17 Hardware Integration Guide Audio Interface Function Responsible Codec AGC (Automatic Gain Control) Normalizes audio volumes in varying acoustic environments Module DTMF tones Generation and detection of DTMF tones is required in both directions of the phone Interface Module Comfort noise Low level noise injected into Rx path for user ‘connection’ experience Module Simple ringers Digital and analog tones, melody ringers, MIDI with limited memory storage Module Voice memo Performed by host if significant memory storage is required Host Polyphonic ringtones Host often supports WAV, MIDI formats with significant memory storage Host Path switching Turn on audio path depending on user interface selection, or headset detection Host Path mixing Required for voice memo recording and playback via multiple audio paths Host Transducer interfaces Host provides acoustic drivers. Must occur outside of path switching and mixing Host Adjustable gain/volume settings Based on user interface selections Host/Module DTMF/ringer tone generation Host/Module

4112719 Rev 2.1 January 07, 2013 18 6. Regulatory Information 6.1. Important Notice Because of the nature of wireless communications, 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 and its affiliates accept 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. 6.2. Safety and Hazards Do not operate your AirPrime SL8084T modem:  In areas where blasting is in progress  Where explosive atmospheres may be present including refueling points, fuel depots, and chemical plants  Near medical equipment, life support equipment, or any equipment which may be susceptible to any form of radio interference. In such areas, the SL8084T modem MUST BE POWERED OFF. Otherwise, the SL8084T modem can transmit signals that could interfere with this equipment. In an aircraft, the SL8084T modem MUST BE POWERED OFF. Otherwise, the SL8084T modem can transmit signals that could interfere with various onboard systems and may be dangerous to the operation of the aircraft or disrupt the cellular network. Use of a cellular phone in an aircraft is illegal in some jurisdictions. Failure to observe this instruction may lead to suspension or denial of cellular telephone services to the offender, or legal action or both. Some airlines may permit the use of cellular phones while the aircraft is on the ground and the door is open. The SL8084T modem may be used normally at this time. 6.3. Important Compliance Information for North American Users The SL8084T modem has been granted modular approval for mobile applications. Integrators may use the SL8084T modem in their final products without additional FCC/IC (Industry Canada) certification if they meet the following conditions. Otherwise, additional FCC/IC approvals must be obtained. 1. At least 20 cm separation distance between the antenna and the user’s body must be maintained at all times. 2. To comply with FCC/IC regulations limiting both maximum RF output power and human exposure to RF radiation, the maximum antenna gain including cable loss in a mobile-only exposure condition must not exceed 6 dBi in the cellular band and 3.5 dBi in the PCS band. 3. The SL8084T modem and its antenna must not be co-located or operating in conjunction with any other transmitter or antenna within a host device.

4112719 Rev 2.1 January 07, 2013 19 Hardware Integration Guide Regulatory Information 4. Refer to section 4 RF Circuit Routing Constraints for RF signal conditions. 5. A label must be affixed to the outside of the end product into which the SL8084T modem is incorporated, with a statement similar to the following: This device contains FCC ID: N7NSL8084T This equipment contains equipment certified under IC: 2417C-SL8084T 6. A user manual with the end product must clearly indicate the operating requirements and conditions that must be observed to ensure compliance with current FCC/IC RF exposure guidelines. The end product with an embedded SL8084T modem may also need to pass the FCC Part 15 unintentional emission testing requirements and be properly authorized per FCC Part 15. Note: If this module is intended for use in a portable device, you are responsible for separate approval to satisfy the SAR requirements of FCC Part 2.1093 and IC RSS-102. 6.3.1. EU Regulatory Conformity Sierra Wireless hereby declares that the SL8084T modem conforms with all essential requirements of Directive 1999/5/EC. The Declaration of Conformity made under Directive 1999/5/EC is available for viewing at the following location in the EU community: Sierra Wireless (UK) Limited Suite 5, The Hub Fowler Avenue Farnborough Business Park Farnborough, United Kingdom GU14 7JP

4112719 Rev 2.1 January 07, 2013 20 7. References 7.1. Reference Documents [1] Universal AirPrime SL Series Development Kit User Guide Reference: WA_DEV_LG_UGD_003 [2] AirPrime SL808x Product Technical Specification and Customer Design Guidelines Reference: 4111992 7.2. Acronyms and Definitions Acronym or Term Definition AGC Automatic Gain Control BER Bit Error Rate - a measure of receive sensitivity BLER Block Error Rate Call Box Base Station Simulator - Agilent E8285A or 8960, Rohde & Schwarz CMU200 CDMA Code Division Multiple Access dB Decibel = 10 x log10 (P1/P2) P1 is calculated power; P2 is reference power Decibel = 20 x log10 (V1/V2) V1 is calculated voltage, V2 is reference voltage dBm Decibels, relative to 1 mW - Decibel(mW) = 10 x log10 (Pwr (mW)/1mW) DUT Device Under Test EDGE Enhanced Data rates for GSM Evolution EM Embedded Module ESD ElectroStatic Discharge FER Frame Error Rate - a measure of receive sensitivity GPRS General Packet Radio Services GPS Global Positioning System GSM Global System for Mobile communications Hz Hertz = 1 cycle/second inrush current Peak current drawn when a device is connected or powered on IS-2000 3G radio standards for voice and data (CDMA only) IS-95 2G radio standards targeted for voice (cdmaONE) LDO Low Drop Out - refers to linear regulator MHz MegaHertz = 10E6 Hertz (Hertz = 1 cycle/second) MIO Module Input/Output MPE Maximum Permissible Exposure—the level of radiation to which a person may be exposed without hazardous effect or adverse biological changes OTA Over-The-Air or Radiated through the antenna PCS Personal Communication System - PCS spans the 1.9 GHz radio spectrum

4112719 Rev 2.1 January 07, 2013 21 Hardware Integration Guide References Acronym or Term Definition RF Radio Frequency RMS Root Mean Square SA Selective Availability Sensitivity (Audio) Measure of lowest power signal that the receiver can measure Sensitivity (RF) Measure of lowest power signal at the receiver input that can provide a prescribed BER/BLER/SNR value at the receiver output. SIM Subscriber Identity Module SL8084T Sierra Wireless AirPrime soldered-down module used on GSM/UMTS networks SNR Signal to Noise Ratio SOF Start of Frame - a USB function UART Universal Asynchronous Receiver Transmitter UMTS Universal Mobile Telecommunications System USB Universal Serial Bus USIM Universal Subscriber Identity Module VCC Supply voltage WCDMA Wideband Code Division Multiple Access—In this document, the term “UMTS” is used instead of “WCDMA”. XIM In this document, XIM is used as part of the contact identifiers for the USIM interface (XIM_VCC, XIM_CLK, etc.).