Telit Wireless Solutions UC864 manual 1.2 + 12V input Source Power Supply Design Guidelines

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UC864-E Hardware User Guide

1vv0300766a Rev.1 - 31/01/08

An example of linear regulator with 5V input is:

5.2.1.2 + 12V input Source Power Supply Design Guidelines

•The desired output for the power supply is 3.8V; hence due to the big difference between the input source and the desired output, a linear regulator is not suited and shall not be used. A switching power supply will be preferable because of its better efficiency especially with the 2A peak current load represented by UC864-E.

•When using a switching regulator, a 500kHz or more switching frequency regulator is preferable because of its smaller inductor size and its faster transient response. This allows the regulator to respond quickly to the current peaks absorption.

•For car Pb battery the input voltage can rise up to 15.8V and this should be kept in mind when choosing components: all components in the power supply must withstand this voltage. The same consideration has to be applied to the voltage peaks that in a Car Application could rise to 100V.

•A Bypass low ESR capacitor of adequate capacity must be provided in order to cut the current absorption peaks, 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 spike protection diode should be inserted close to the power input for Car applications, in order to clean the supply from spikes.

•A protection diode should be inserted close to the power input, in order to save UC864-E from power polarity inversion. This can be the same diode as for spike protection.

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Contents UC864 Hardware User Guide UC864-E Hardware User Guide This document is relating to the following productsContents 10.3 10.411.1 11.2Disclaimer Overview Mechanical Dimensions Length 36.2 mm Width 30 mm Thickness 8mmUC864-E module connections PIN-OUTCmos Reserved 1 UC864-E Antenna connector Pin Signal FunctionHardware Commands Turning on the UC864-E10k Turning OFF the UC864-E Hardware shutdownHardware Unconditional Restart 10k +1.8 Power Supply Power Supply RequirementsUC864-E Hardware User Guide General Design Rules Electrical Design Guidelines1.2 + 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 Antenna RequirementsAntenna Installation Guidelines Logic level specifications Absolute Maximum Ratings -Not FunctionalOperating Range Interface levels Operating Range Interface levels 1.8V CmosReset signal Serial Ports Absolute Maximum Ratings Not FunctionalSignals 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 USB Port Communication ports combinationsAudio Section Overview GeneralityDefinitions SelectionElectrical Characteristics Input lines microphoneOutput lines speaker EarMT BuffersGeneral Purpose I/O NotLogic level specifications Using the Alarm Output GPIO6 Using a Gpio Pad as InputUsing a Gpio Pad as Output Using the Buzzer Output GPIO7 Indication of network service availability LED status Device StatusRTC Bypass out VAUX1 power outputOperating Range VAUX1 power supply Mounting UC864-E on your board Debug of the UC864-E in production USB Vbus UsbidConformity Assessment Issues Safety Recommandations Document Change Log Revision Date Changes