Telit Wireless Solutions UC864 manual General Design Rules, Electrical Design Guidelines

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UC864-E Hardware User Guide

1vv0300766a Rev.1 - 31/01/08

5.2General Design Rules

The principal guidelines for the Power Supply Design embrace three different design steps:

•The electrical design

•The thermal design

•The PCB layout.

5.2.1 Electrical Design Guidelines

The electrical design of the power supply depends strongly from the power source where this power is drained. We will distinguish them into three categories:

•+5V input (typically PC internal regulator output)

•+12V input (typically automotive)

•Battery

5.2.1.1 + 5V input Source Power Supply Design Guidelines

•The desired output for the power supply is 3.8V, hence there's not a big difference between the input source and the desired output and a linear regulator can be used. A switching power supply will not be suited because of the low drop out requirements.

•When using a linear regulator, a proper heat sink shall be provided in order to dissipate the power generated.

•A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks close to UC864-E, a 100μF tantalum capacitor is usually suited.

•Make sure the low ESR capacitor on the power supply output (usually a tantalum one) is rated at least 10V.

•A protection diode should be inserted close to the power input, in order to save the electrical circuit from power polarity inversion.

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Contents UC864 Hardware User Guide This document is relating to the following products UC864-E Hardware User GuideContents 11.2 10.310.4 11.1Disclaimer Overview Length 36.2 mm Width 30 mm Thickness 8mm Mechanical DimensionsPIN-OUT UC864-E module connectionsCmos Reserved Pin Signal Function 1 UC864-E Antenna connectorTurning on the UC864-E Hardware Commands10k Hardware shutdown Turning OFF the UC864-EHardware Unconditional Restart 10k +1.8 Power Supply Requirements Power SupplyUC864-E Hardware User Guide Electrical Design Guidelines General Design Rules1.2 + 12V input Source Power Supply Design Guidelines UC864-E Hardware User Guide Battery Source Power Supply Design Guidelines UC864-E Hardware User Guide Thermal Design Guidelines Power Supply PCB layout Guidelines Antenna Requirements AntennaAntenna Installation Guidelines Operating Range Interface levels 1.8V Cmos Logic level specificationsAbsolute Maximum Ratings -Not Functional Operating Range Interface levelsReset signal Absolute Maximum Ratings Not Functional Serial PortsSignals of the UC864-E serial port are RS232 level translation UC864-E Hardware User Guide UC864-E Hardware User Guide 5V Uart level translation UC864-E Hardware User Guide Communication ports combinations USB PortSelection Audio Section OverviewGenerality DefinitionsInput lines microphone Electrical CharacteristicsEarMT Buffers Output lines speakerNot General Purpose I/OLogic level specifications Using a Gpio Pad as Output Using a Gpio Pad as InputUsing the Alarm Output GPIO6 Using the Buzzer Output GPIO7 LED status Device Status Indication of network service availabilityOperating Range VAUX1 power supply VAUX1 power outputRTC Bypass out Mounting UC864-E on your board USB Vbus Usbid Debug of the UC864-E in productionConformity Assessment Issues Safety Recommandations Revision Date Changes Document Change Log