MTD20P06HDL di/dt = 300 A/µs Standard Cell Density trr High Cell Density trr tb ta , SOURCE CURRENT I S t, TIME Figure 11. Reverse Recovery Time (trr)SAFE OPERATING AREA The Forward Biased Safe Operating Area curves define able operation, the stored energy from circuit inductance dis- the maximum simultaneous drain–to–source voltage and sipated in the transistor while in avalanche must be less than drain current that a transistor can handle safely when it is for- the rated limit and must be adjusted for operating conditions ward biased. Curves are based upon maximum peak junc- differing from those specified. Although industry practice is to tion temperature and a case temperature (TC) of 25°C. Peak rate in terms of energy, avalanche energy capability is not a repetitive pulsed power limits are determined by using the constant. The energy rating decreases non–linearly with an thermal response data in conjunction with the procedures increase of peak current in avalanche and peak junction tem- discussed in AN569, “Transient Thermal Resistance – Gen- perature. eral Data and Its Use.” Although many E–FETs can withstand the stress of drain– Switching between the off–state and the on–state may tra- to–source avalanche at currents up to rated pulsed current verse any load line provided neither rated peak current (IDM) nor rated voltage (V (I DSS) is exceeded, and that the transition DM), the energy rating is specified at rated continuous cur- time (t rent (I r, tf) does not exceed 10 µs. In addition the total power D), in accordance with industry custom. The energy rat- averaged over a complete switching cycle must not exceed ing must be derated for temperature as shown in the (TJ(MAX) – TC)/(RθJC). accompanying graph (Figure 13). Maximum energy at cur- A power MOSFET designated E–FET can be safely used rents below rated continuous ID can safely be assumed to in switching circuits with unclamped inductive loads. For reli- equal the values indicated. 100 300 VGS = 20 V ID = 15 A SINGLE PULSE TC = 25°C 240 O–SOURCE (mJ) (AMPS) 10 100 µs 180 1 ms 10 ms 120 1.0 dc ALANCHE ENERGY V , DRAIN CURRENT A I D R 60 DS(on) LIMIT , SINGLE PULSE DRAIN–T THERMAL LIMIT AS PACKAGE LIMIT E 0.1 0 0.1 1.0 10 100 25 50 75 100 125 150 VDS, DRAIN–TO–SOURCE VOLTAGE (VOLTS) TJ, STARTING JUNCTION TEMPERATURE (°C) Figure 12. Maximum Rated Forward BiasedFigure 13. Maximum Avalanche Energy versusSafe Operating AreaStarting Junction Temperature 6 Motorola TMOS Power MOSFET Transistor Device Data