降压型高功率LED驱动器

Thecircuitandfirmwaredescribedinthisapplication

notedemonstratesaminimalpartscountdriver/control-

lerforahigh-power(1Worgreater)LED.Thecircuitis

basedonabucktopologyswitchingpowersupply

usingtheon-chipcomparatorperipheralwithinthe

PIC12F675PIC

®

microcontroller.Theswitchingpower

supplydesignensuresefficientpowertransferbetween

thesystembatteryandtheoutputLED.

TheFlashPICmicrocontrollerisusedtoimplement

intensitycontrol,automatedintensitycompensationfor

lowbatteryconditions,andtheabilitytoplaybackpre-

programmedFlashsequences.TheFlashPICmicro-

controlleralsoallowsthecreationofacustomPC-

basedgraphicaluserinterface,usingthePICkit™1

FlashStarterKitforprogrammingthepre-programmed

Flashsequences.Thecombinationoftheswitching

powersupplydesignandthemicrocontrollerresultsin

anefficientcircuitwithadvancedautomatedfeatures

whilekeepingthecircuitsimpleandinexpensive.AN874BuckConfigurationHigh-PowerLEDDriverVoltageandCurrentAuthor:KeithCurtisMicrochipTechnologyInc.The1wattchosenmodulerequiresatypicaldriveof3.4Vat350mAtoproduceitsfulloutputbrightness.Themaximumcurrentdrivefortheunitis500mA.INTRODUCTIONExceedingthemaximumcurrentspecificationforthemodule,evenbyshortdurati