Diagnose LEDs by Monitoring the Switch-Mode Duty Cycle

Abstract:Achangeintheforwardvoltage(VF)forastringofseries-connected,high-brightnessLEDs(HBLEDs)canindicatedeteriorationorcompletefailureofoneormoreoftheLEDs.Accordingly,thiscircuitassessestheLED'shealthbymonitoringVF.Maxim>AppNotes>AmplifierandComparatorCircuitsDisplayDriversLEDLightingKeywords:high-brightnessLEDs,HBLEDs,forwardvoltage,differentialmeasurments,LEDdrivers,comparatorsJul30,2010APPLICATIONNOTE4479DiagnoseLEDsbyMonitoringtheSwitch-ModeDutyCycleBy:FonsJanssen,SeniorMemberoftheTechnicalStaffAbstract:Achangeintheforwardvoltage(VF)forastringofseries-connected,high-brightnessLEDs(HBLEDs)canindicatedeteriorationorcompletefailureofoneormoreoftheLEDs.Accordingly,thiscircuitassessestheLED'shealthbymonitoringVF.AsimilarversionofthisarticleappearedintheApril4,2009issueofEDNmagazine.Theforwardvoltage(VF)ofhigh-brightnessLEDs(HBLEDs)isoftenmonitoredtoassessthehealthof