3.3v/5v掌上电脑及lcd电源稳压器电池或墙上适配器供电系统，为逻辑电路及lcd供电概述the max722 and max723 cmospower-supply ics create dual regulated dc outputs for small,battery-operated microprocessor systems. each device generates amain output (3v or 5v, selectable) and a negative auxiliary outputthat is adjustable for lcds. each device accepts two inputvoltages. power can come from a main battery (two or three alkalineor nicad), or an unregulated dc source such as an ac-dc walladapter.
the max722/max723 provide three improvements over prior-artdevices. physical size is reduced; the high switching frequencies(up to 0.5mhz), made possible by mosfet power transistors, allowfor tiny (
the max722 and max723 differ only in the lower fixed output voltageof the main regulator, with a 3.3v output for the max722 and a 3.0voutput for the max723.
for flash memory or pcmcia applications that require a +12v outputvoltage, refer to the max717–721 data sheet.关键特性low 0.9v to 5.5v battery inputrangeunregulated 7v to 20v dc inputrangedual regulated outputsmain output: 3.3v/5vauxiliary output: 0v to -100v87% efficiency at 200maefficient pram keep-alive: 80% at1ma8w/in³ power density60µa quiescent current20µa shutdown mode with vrefalive500khz maximum switchingfrequency±1.5% vref tolerance (overtemp.)detect output powerfailures16-pin narrow so packages应用/使用条码扫描仪lcd对比度调节医疗仪表掌上电脑便携式数据通信便携式数据收集设备

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