Telit Wireless Solutions GE863-QUAD, GE863-PY manual Power Supply PCB layout Guidelines

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GE863-QUAD

GE863-PY

1vv0300715 Rev. 1 - 19/09/06

4.2.3Power Supply PCB layout Guidelines

As seen on the electrical design guidelines the power supply shall have a low ESR capacitor on the output to cut the current peaks and a protection diode on the input to protect the supply from spikes and polarity inversion. The placement of these components is crucial for the correct working of the circuitry. A misplaced component can be useless or can even decrease the power supply performances.

•The Bypass low ESR capacitor must be placed close to the Telit GE863-QUAD/PY power input pads or in the case the power supply is a switching type it can be placed close to the inductor to cut the ripple provided the PCB trace from the capacitor to the GE863-QUAD/PY is wide enough to ensure a dropless connection even during the 2A current peaks.

•The protection diode must be placed close to the input connector where the power source is drained.

•The PCB traces from the input connector to the power regulator IC must be wide enough to ensure no voltage drops occur when the 2A current peaks are absorbed. Note that this is not made in order to save power loss but especially to avoid the voltage drops on the power line at the current peaks frequency of 216 Hz that will reflect on all the components connected to that supply, introducing the noise floor at the burst base frequency. For this reason while a voltage drop of 300- 400 mV may be acceptable from the power loss point of view, the same voltage drop may not be acceptable from the noise point of view. If your application doesn't have audio interface but only uses the data feature of the Telit GE863-QUAD/PY, then this noise is not so disturbing and power supply layout design can be more forgiving.

•The PCB traces to the GE863-QUAD/PY and the Bypass capacitor must be wide enough to ensure no significant voltage drops occur when the 2A current peaks are absorbed. This is for the same reason as previous point. Try to keep this trace as short as possible.

•The PCB traces connecting the Switching output to the inductor and the switching diode must be kept as short as possible by placing the inductor and the diode very close to the power switching IC (only for switching power supply). This is done in order to reduce the radiated field (noise) at the switching frequency (100-500 kHz usually).

•The use of a good common ground plane is suggested.

•The placement of the power supply on the board should be done in such a way to guarantee that the high current return paths in the ground plane are not overlapped to any noise sensitive circuitry as the microphone amplifier/buffer or earphone amplifier.

•The power supply input cables should be kept separate from noise sensitive lines such as microphone/earphone cables.

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Contents GE863-QUAD GE863-PY Hardware User Guide Contents 10.2 10.110.3 10.412.1 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 Guidelines An 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 MaxNumber Pad Number Signals in the Uart connector on the EVK are17-28-36 Ground 45-48-50-56 Clear to Send Output from the GE863-QUAD/PY thatIt 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 Echo canceller type Handset Microphone Paths Characteristic and RequirementsEcho canceller type Car kit hands-free + 20dBYou 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 GPIO611.1DAC Converter DAC and ADC sectionDescription Min Max UnitsCommand is AT#DAC=enable,value An AT command is available to use the DAC functionEnabling DAC Low Pass Filter ExampleUsing ADC Converter Input Voltage range AD conversion Bits Resolution11.2ADC Converter 12.1Transchip Camera CameraType Sensitivity LuxCamera 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 Revision Date Changes Document Change Log21/02/06 19/09/06
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