MTSF3N03HD

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7

t, TIME

Figure 13. Reverse Recovery Time (trr)

di/dt = 300 A/µs

Standard Cell Density

High Cell Density

tb

trr

ta

trr

SAFE OPERATING AREA

The Forward Biased Safe Operating Area curve (Figure

14) defines the maximum simultaneous drain–to–source

voltage and drain current that a transistor can handle safely

when it is forward biased. Curves are based upon maximum

peak junction temperature and a case temperature (TC) of

25

°C. Peak repetitive pulsed power limits are determined by

using the thermal response data in conjunction with the

procedures discussed in AN569, “Transient Thermal

Resistance – General Data and Its Use.”

Switching between the off–state and the on–state may

traverse any load line provided neither rated peak current

(IDM) nor rated voltage (VDSS) is exceeded, and that the

transition time (tr, tf) does not exceed 10 µs. In addition the

total power averaged over a complete switching cycle must

not exceed (TJ(MAX) – TC)/(R

θJC).

A power MOSFET designated E–FET can be safely used

in switching circuits with unclamped inductive loads. For

reliable operation, the stored energy from circuit inductance

dissipated in the transistor while in avalanche must be less

than the rated limit and must be adjusted for operating

conditions differing from those specified. Although industry

practice is to rate in terms of energy, avalanche energy

capability is not a constant. The energy rating decreases

non–linearly with an increase of peak current in avalanche

and peak junction temperature.

Although many E–FETs can withstand the stress of

drain–to–source avalanche at currents up to rated pulsed

current (IDM), the energy rating is specified at rated

continuous current (ID), in accordance with industry

custom. The energy rating must be derated for temperature

as shown in the accompanying graph (Figure 15). Maximum

energy at currents below rated continuous ID can safely be

assumed to equal the values indicated.

TJ, STARTING JUNCTION TEMPERATURE (°C)

Figure 14. Maximum Rated Forward Biased

Safe Operating Area

0

25

50

75

100

125

150

VDD = 30 V

VGS = 5 V

IL = 9 A

L = 5 mH

250

150

100

50

200

Figure 15. Maximum Avalanche Energy versus

Starting Junction Temperature

0.1

VDS, DRAIN-TO-SOURCE VOLTAGE (VOLTS)

1

10

RDS(on) LIMIT

THERMAL LIMIT

PACKAGE LIMIT

0.01

VGS = 20 V

SINGLE PULSE

TC = 25°C

10

0.1

dc

10 ms

1

100

100

1 ms

100 µs