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November 19, 2014

 

IRFB7446GPbF

Fig 14. Maximum Effective Transient Thermal Impedance, Junction-to-Case

Fig 16. Maximum Avalanche Energy vs. Temperature

Notes on Repetitive Avalanche Curves , Figures 15, 16:

(For further info, see AN-1005 at www.irf.com)

1.Avalanche failures assumption:

Purely a thermal phenomenon and failure occurs at a

part type.

exceeded.

3. Equation below based on circuit and waveforms shown in Figures

23a, 23b.

5. BV = Rated breakdown voltage (1.3 factor accounts for voltage

increase during avalanche).

7.

(assumed as 25°C in Figure 14, 15).

D = Duty cycle in avalanche = tav ·f

Fig 15. Avalanche Current vs. Pulse Width

1E-006

1E-005

0.0001

0.001

0.01

0.1

t1 , Rectangular Pulse Duration (sec)

0.001

0.01

0.1

1

10

0.20

0.10

D = 0.50

0.02

0.01

0.05

SINGLE PULSE

( THERMAL RESPONSE )

Notes:

1. Duty Factor D = t1/t2

2. Peak Tj = P dm x Zthjc + Tc

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

tav (sec)

0.1

1

10

100

1000

Allowed avalanche Current vs avalanche

pulsewidth, tav, assuming  j = 25°C and

Tstart = 150°C.

Allowed avalanche Current vs avalanche

pulsewidth, tav, assuming Tj = 150°C and

Tstart = 25°C (Single Pulse)

25

50

75

100

125

150

175

Starting TJ , Junction Temperature (°C)

0

40

80

120

TOP

Single Pulse

BOTTOM 1.0% Duty Cycle

ID = 70A