IRFB/S/SL3806PbF

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5

Fig 13. Maximum Effective Transient Thermal Impedance, Junction-to-Case

Fig 14. Typical Avalanche Current vs.Pulsewidth

Fig 15. Maximum Avalanche Energy vs. Temperature

Notes on Repetitive Avalanche Curves , Figures 14, 15:

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

1. Avalanche failures assumption:

Purely a thermal phenomenon and failure occurs at a temperature far in

3. Equation below based on circuit and waveforms shown in Figures 16a, 16b.

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

during avalanche).

7.

25°C in Figure 14, 15).

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

Ri (°C/W)

τi (sec)

0.6086

0.00026

0.9926

0.001228

0.5203

0.00812

τ

J

τ

J

τ

1

τ

1

τ

2

τ

2

τ

3

τ

3

R

1

R

1

R

2

R

2

R

3

R

3

τ

τ

C

Ci

τi/Ri

Ci=

τi/Ri

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

0.05

Duty Cycle = Single Pulse

0.10

Allowed avalanche Current vs avalanche

pulsewidth, tav, assuming

∆Τj = 25°C and

Tstart = 150°C.

0.01

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

20

40

60

80

TOP

Single Pulse

BOTTOM 1.0% Duty Cycle

ID = 25A