标签: tc682

CreatinganegativeDCbiasvoltagefromapositiveDCsupplyoftenisrequiredinbattery-powered,portable,hand-heldinstrumentsthatuseaLiquidCrystalDisplay(LCD).ManyLCDsrequirearelativelylargenegativebias(ontheorderof-10V).Sincemanyportablesystems(suchascellularsubscriberunits)oftenhavearegulated+5VDCbiasavailable,thecriticaldesigntaskinvolvesconvertingthissupplyvoltagetoanegativeDCbiasfortheLCD.Thisapplicationnotediscussestheadvantagesanddisadvantagesofseveralalternativesforimplementingthe-10VbiasrequiredbytheLCD.MAN804DesignAlternativesToTheTC682ForPerformingInvertingVoltageDoublerFunctionsAuthor:PatMarescaTRADITIONALTC682MicrochipTechnologyInc.IMPLEMENTATIONFigure1showsacircuitimplementationusingINTRODUCTIONMicrochipTechnology'sTC682togeneratethe-10VLCDbiasfromaregulated+5Vinput.AssumingthataCreatinganegativeDCbiasvoltagefromapositiveDC……