http://uphotos.eepw.com.cn/soothmusic/pics/03660905292735246c4839a728d83912.jpg

摘要：该电路从3.3V电源并联驱动多达四个白光LED，并调整总LED电流从1mA到106毫安在64个步骤，每一个为1dB。

Maxim/Dallas>AppNotes>AUTOMOTIVEDIGITALPOTENTIOMETERSDISPLAYDRIVERSKeywords:portablepower,whiteLEDs,logarithmicdimming,chargepump,digitalpotentiometerJul20,2004APPLICATIONNOTE3287White-LEDDriverProvides64-StepLogarithmicDimmingThiscircuitdrivesasmanyasfourwhiteLEDsinparallelfroma3.3Vsource,andadjuststhetotalLEDcurrentfrom1mAto106mA,in64stepsof1dBeach.ThecircuitofFigure1isdesignedforportable-powerapplicationsthatrequirewhiteLEDswithadjustable,logarithmicdimminglevels.ItdrivesasmanyasfourwhiteLEDsfroma3.3Vsource,andadjuststhetotalLEDcurrentfrom1mAto106mAin64stepsof1dBeach.ThedriverisachargepumpthatmirrorsthecurrentISET(sourcedfromU3'sSETterminal)