FunctionItemPreventionFreguencyAC/DC powersupplyThe converterconverts the ACmains(230VAC/50Hz) tothe 5VDC stabilitypower supply.1.The ripple wave of DCpower supply is large.2.The zener diode isbroken.3.The resistor of limitingcurrent burns in largecurrent situation.The controllerdoes not work.71.The AC mains are notstability.2. The rated power lossof the zener does notmeet up with therequirement.3.The smoothingcapacitor does notmatch with therequirement.4.The limiting currentresistor is not a windingresistor to havesufficient ability to passthe charge current.1.The engineer teststhe AC/DC powersupply according tothe mains.2. The rated power ofthe zener diodeshould be 0.5W ormore.3.There is a margindesign of thesmoothing capacitor.4.The limiting resistorshould be a windingresistor.3The EMCperformance ofHWThe controller willpass the EMC test.The controller dose notpass the EMC test.The controllerdoes not workas normalsometimes.71. The PCB layout doesnot match with therequirement.2.The VDD of the MCUis disturbed by somenoise. 3.TheI/Os of the MCU isdisturbed by somenoise.1. The mains inputshould cross the X2capacitor.2.The mains inputshould cross theZNR after the X2.3.A filter capacitorshould used toabsorb the noise ofthe VDD.4.A high frequencycapacitor shouldused to absorb thenoise of the VDD.5.The idel I/O of theMCU should bepulled up to VDD bya resistor.3Pre-requirementPotential Failure ModePotential FailureResultlevelclassFailure Root CauseCurrent DesigThe safetyperformance ofHWThe controller willpass the safty test.The controller dose notpass the safty test.The controllercan not protectthe product tobe safe when itis power onsometimes.81.The creepage of thePCB is not sufficient forthe requirement of thesafety. 2.The fuse doesnot protect the systemwhen ...
