标签: slua042

slua042DN-43DesignNoteSimpleTechniquestoGenerateaNegativeVoltageBiasSupplyfromaPositiveInputVoltagebyBillAndreycakDevelopingalowpowernegativesupplyvoltagefromapositiveinputsupplycanbeaccomplishedusingsomeverycommonPWMcontrolICs.Typicalapplicationsincludegeneratinganegativefivethroughtwelvevolt(-5Vto-12V)supplyforanalogfunctionICs(OPamps),RS-232communicationcircuits,andMOSFETorIGBTgatedrivesatpowerlevelsbelowafewWatts.ManyPWMICscontainahighcurrenttotempoleoutputwhichgoeshighduringthedevice’sON-timeorpulsewidth.Theexactpulsewidthismodulatedtoregulateaconverter’soutputvoltageduringchangesininputvoltageandoutputcurrent.TheIC’stotempoleoutputcanalsobeusedasthemainswitchin……