Chapter 161

DC/DC converters for portable computers

Steve Pietkiewicz and Jim Williams

Abstract

DC/DC converters for portable computers are discussed.

Keywords

DC/DC converter

LT1073

LT1173

LT1072

Portable computers require simple and efficient converters for 5V power and display driving. A regulated 5V supply can be generated from two AA cells using the circuit shown in Figure 161.1. U1, an LT1073-5 micropower DC/DC converter, is arranged as a step-up, or “boost” converter. The 5V output, monitored by U1’s SENSE pin, is internally divided down and compared to a 212mV reference voltage inside the device. U1’s oscillator turns on when the output drops below 5V, cycling the switch on and off at a 19kHz rate. This action alternately causes ...

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