Telit Wireless Solutions GE863-QUAD, GE863-PY manual 1Power Supply Requirements

Page 15

GE863-QUAD

GE863-PY

1vv0300715 Rev. 1 - 19/09/06

4 Power Supply

The power supply circuitry and board layout are a very important part in the full product design and they strongly reflect on the product overall performances, hence read carefully the requirements and the guidelines that will follow for a proper design.

4.1Power Supply Requirements

The GE863-QUAD/PY power requirements are:

•	Nominal Supply Voltage:	3.8	V
•	Max Supply Voltage:	4.2	V
•	Supply voltage range:	3.4	V - 4.2 V
• Max Peak current consumption (impulsive):		1.9	A
• Max Average current consumption during GPRS transmission (rms):		500 mA
• Max Average current consumption during VOICE/CSD transmission (rms):		270 mA
• Average current during Power Saving:		≈ 4 mA
•	Average current during idle (Power Saving disabled)	≈ 19 mA

The GSM system is made in a way that the RF transmission is not continuous, else it is packed into bursts at a base frequency of about 216 Hz, the relative current peaks can be as high as about 2A. Therefore the power supply has to be designed in order to withstand with these current peaks without big voltage drops; this means that both the electrical design and the board layout must be designed for this current flow.

If the layout of the PCB is not well designed a strong noise floor is generated on the ground and the supply; this will reflect on all the audio paths producing an audible annoying noise at 216 Hz; if the voltage drop during the peak current absorption is too much, then the device may even shutdown as a consequence of the supply voltage drop.

TIP: The electrical design for the Power supply should be made ensuring it will be capable of a peak current output of at least 2 A.

Reproduction forbidden without Telit Communications S.p.A. written authorization - All Right reserved

page 15 of 79

Image 15

Contents GE863-QUAD GE863-PY Hardware User Guide Contents 10.4 10.110.2 10.312.1 13.113.2 This document is relating to the following products Overview PIN-OUT GE863 module connectionsPin Signal Function Internal Type Pull up Pin Signal Function Internal Type Pins Layout Turning on the GE863-QUAD/PY Hardware CommandsTurning off of the device can be done in two ways Turning OFF the GE863-QUAD/PYHardware shutdown Hardware Unconditional RebootGE863-QUAD Power Supply 1Power Supply RequirementsGE863-QUAD/PY power requirements are Electrical design Guidelines 2General Design RulesAn example of linear regulator with 5V input is 1.2 + 12V input Source Power Supply Design GuidelinesAn example of switching regulator with 12V input is Battery Source Power Supply Design GuidelinesBattery Charge control Circuitry Design Guidelines Thermal Design Guidelines Power Supply PCB layout Guidelines GSM Antenna Requirements AntennaGSM Antenna installation Guidelines Serial PortsGSM Antenna PCB line Guidelines Level Min Max Absolute Maximum Ratings -Not Functional Parameter Min MaxClear to Send Output from the GE863-QUAD/PY that Signals in the Uart connector on the EVK areNumber Pad Number 17-28-36 Ground 45-48-50-56It is available on the following pins 2MODEM Serial Port 2 Python Debug3RS232 level translation An example of level translation circuitry of this kind is 5V Uart level translation GE863-QUAD Audio Section Overview GM863-GPS + 20dB Microphone Paths Characteristic and RequirementsEcho canceller type Handset Echo canceller type Car kit hands-freeYou can set GA= +20dB to use standard resistor values That meansTIP environment consideration Other considerations General Design RulesBalanced Microphone Biasing Microphone BiasingUnbalanced Microphone Biasing GE863-QUAD Microphone Buffering Buffered Balanced MicSample circuit can be Buffer gain is given by the formula Gain = RR604605 = RR607606Buffered Unbalanced Single Ended Microphone Buffer bandwidth at -3dB shall be 4KHz Freq . = 2π * R719* C726 2π * R711* C727GE863-QUAD Short description Output Lines SpeakerSW volume level step Number of SW volume steps Output Lines CharacteristicsNoise Filtering Handset Earphone Design An example of internal Ear amplifier could be Hands-Free Earphone Low Power DesignCar Kit Speakerphone Design Short Description Evaluation Kit for Telit Modules EVK2@ 350mW 2 EVK2 Audio Lines CharacteristicsESD Data IntegritySIM Supply SchematicLayout Using a Gpio Pad as Input Using a Gpio Pad as OutputGeneral Purpose I/O Using the Buzzer Output GPIO7 10.3Using the Alarm Output GPIO6Min Max Units DAC and ADC section11.1DAC Converter DescriptionLow Pass Filter Example An AT command is available to use the DAC functionCommand is AT#DAC=enable,value Enabling DACUsing ADC Converter Input Voltage range AD conversion Bits Resolution11.2ADC Converter Sensitivity Lux Camera12.1Transchip Camera TypeCamera Interface Connectors Camera Physical Detail & Connector Camera Socket Connector Camera Board Module Main Block Diagram for supported cameras Schematic Diagrams for supported camera Camera setting shown here are the defaults ones Example usage script for cameraTaking an reading a photo 13.2Module Finishing & Dimensions Mounting the GE863-QUAD / PY on the Application Board13.1General Lead-free Alloy Surface finishing Ni/Au for all test padsRecommended foot print for the application Debug of the GE863 in Production StencilPCB pad Design Solder paste Following is the recommended solder reflow profile 13.2.6 GE863-QUAD / PY Solder ReflowGE863-QUAD Section A-A Packing SystemModules orientation on tray Moisture Sensibility Conformity Assessment Issues Safety Recommandations 19/09/06 Document Change LogRevision Date Changes 21/02/06