Electrolytic Capacitor Ripple Current Derating Test Method and Life Time EvaluationFrom:郭雪松Date： Oct-27-04一.SPEC1.电解电容零件工程规格书中之Standard Rating表格，其中规定 了不同规格的电解电容Rated Ripple Current值，例如：Sharp机种 PWPC C904（滤波电容）67L215L-820-15N （CNN 公司 KXG Series）V VDCVCap.uFCase size争D*Lmmtan 8L.C.uARated RippleCurrentmA rms/105C1min5min120Hz100KHz4508218*35.50.24157676371517852.此电容用于电源输入端滤波，因此采用120Hz时的Rated RippleCurrent 规格 715mA。3.而用于评估电解电容Ripple Current之Spec要依据以下公式：SPEC=Spec （component） X频率系数（FM） X温度系数（TM）注：FM/TM取值方法见附表4.OTPV 评估电解电容 Ripple Current 的 Derating 规格为 85%, 因此 测试值SPECX85% 时判定OK。二.Test Method将电解电容接地端吸开串联一导线，直接用电流计探头测试该导线电流的有效值（rms），测试时要调整输入电压值（90V264V）达 到纹波电流最大。见图示：OIrms三.附表（FM&TM取值方法）：NCC公司产品为例l. Multiplying Factors on KMG Series (radial lead type)Frequency MultipliersRange50Hz120Hz300Hz1KHz10KHz100KHz3.3uF0.651.001.351.752.302.504.7uF 33uF0.751.001.251.501.751.8047uF 1000uF0.801.001.151.301.401.502200uF0.851.001.031.051.081.08Temperature MultipliersTemp (C)55657585105Multipliers2.232.2321.7312. Multiplying Factors on KY SeriesFrequency MultipliersRange120Hz1KHz10KHz100KHz180uF0.400.750.901.00220uF 560uF0.500.850.941.00680uF 1800uF0.600.870.951.002200uF0.750.900.951.003900uF4700uF0.850.950.981.00Temperature MultipliersTemp (C)55657585105Multipliers2.232.2321.7313. Multiplying Factors on KXG SeriesFrequency MultipliersRange120Hz1KHz10KHz100KHz100uF1.001.752.252.5120uF1.001.671.752.25Temperature MultipliersTemp (C)55657585105Multipliers2.232.2321.731Temperature multipliers shows the guide limits of the maximum available ripple current at each of the temperature,of which the life time at the rated maximum operating temperature is expected.四.电解电容寿命评估测试方法1. Calculation Formula:电容寿命 Life Time= Life(spec) X 2(Ts-Tt)/ioLife(spec):指spec中标明的寿命值Ts：电容最高使用温度值 Tt：电容本体温度测试值2. 判定方法：以上计算得出之寿命值与整机MTBF目标值比较， 若大于目标值则判定OK。3. 例如:SHARP 机种 C904 Life (spec) =10000Hrs, Ts=105C,Tt=52.6C,。SHARP MTBF 目标 50000Hrs。Life Time= 10000 X 2(io5-52.6)/io=377917Hrs5OOOOHrsOK