AN 6161 Turn-off time, leakage current and reverse recovery current under conditions other than the datasheet Application Note AN6161 December 2014 LN32172 Authors: Colin Rout Introduction: Datasheets tend to give device characteristics at a set of standard conditions. These characteristics are, however, dependent upon those conditions and if precise values are required under operating or test conditions then the factory should be consulted. Several of these characteristics obey simple equations dependant on voltage and temperature such that values of the characteristics under different conditions can be estimated from normalised graphs such as those given below. Dependence of reverse recovery current on junction temperature Normalised Reverse recovery current 1.2 1.1 1 0.9 0.8 0.7 0.6 0 20 40 60 80 100 120 140 160 180 Junction temperature, T vj - (oC) Page 1 of 5 AN 6161 Dependence of forward & reverse leakage current on Voltage Normalised Forward/Reverse Leakage Current, ID/IR 1 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 0 10 20 30 40 50 60 70 80 90 100 Normalised applied voltage as % of rated voltage Dependence of Leakage current on Junction Temperature Normalised leakage current 3 2 1 0 0 10 20 30 40 50 60 70 80 90 Junction temperature Tj - ( °C) Page 2 of 5 100 110 120 130 140 AN 6161 Variation of Turn-off time with di/dt 1.5 1.4 1.3 1.2 1.1 1 0 10 20 30 40 50 60 70 80 90 100 Rate of decay of on-state current di/dt - (A/us) Variation of Turn-off time with dv/dt 1.6 1.4 Normalised turn-off time Normalised Turn-off time 1.6 1.2 1 0.8 0.6 0.4 0.2 0 0 50 100 150 200 250 300 350 400 Rate of change of re-applied forward voltage- dv/dt (V/us) Page 3 of 5 AN 6161 Variation of Turn-off time with temperature Normalised turn-off time 2.5 2 1.5 1 0.5 0 0 50 100 150 200 250 Junction temperature T VJ (oC) The graphs for the variation in turn-off time with temperature, re-applied voltage and di/dt can be combined into an EXCEL spreadsheet to estimate the turn-off time under conditions different to the datasheet conditions A Datasheet conditions data sheet tq di/dt dv/vt temp 200 50 20 125 us A/us V/us *C =0.0937*LN(B4)+0.7874 =0.178*LN(B5) + 0.4721 =0.2791*EXP(0.0102*B6) Required conditions di/dt dv/vt temp 5 20 125 A/us V/us *C =0.0937*LN(B10)+0.7874 =0.178*LN(B11) + 0.4721 =0.2791*EXP(0.0102*B12) resultant tq =B3*D10*D11*D12/(D4*D5*D6) µs Page 4 of 5 B C D AN 6161 IMPORTANT INFORMATION: This publication is provided for information only and not for resale. The products and information in this publication are intended for use by appropriately trained technical personnel. Due to the diversity of product applications, the information contained herein is provided as a general guide only and does n ot constitute any guarantee of suitability for use in a specific application.The user must evaluate the suitability of the product and the completeness of the product data for the application. The user is responsible for product selection and ensuring all safety and any warning requirements are met. Should additional product information be needed please contact Customer Service. Although we have endeavoured to carefully compile the information in this publication it may contain inaccuracies or typographical errors. The information is provided without any warranty or guarantee of any kind. This publication is an uncontrolled document and is subject to change without notice. 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