IRFR/U1010Z
1000
100
10
Duty Cycle = Single Pulse
Allowed avalanche Current vs
avalanche pulsewidth, tav
assuming ∆Tj = 25°C due to
avalanche losses
0.01
0.05
0.10
1
0.1
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
tav (sec)
Fig 15. Typical Avalanche Current vs.Pulsewidth
120
100
80
60
40
20
0
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
temperature far in excess of Tjmax. This is validated for
every part type.
2. Safe operation in Avalanche is allowed as long asTjmax is
not exceeded.
3. Equation below based on circuit and waveforms shown in
Figures 12a, 12b.
TOP
BOTTOM 1% Duty Cycle
= 42A
Single Pulse
I
D
4. PD (ave) = Average power dissipation per single
avalanche pulse.
5. BV = Rated breakdown voltage (1.3 factor accounts for
voltage increase during avalanche).
6. Iav = Allowable avalanche current.
7. ∆T = Allowable rise in junction temperature, not to exceed
Tjmax (assumed as 25°C in Figure 15, 16).
tav = Average time in avalanche.
25
50
75
100
125
150
175
D = Duty cycle in avalanche = tav ·f
ZthJC(D, tav) = Transient thermal resistance, see figure 11)
Starting T , Junction Temperature (°C)
J
PD (ave) = 1/2 ( 1.3·BV·Iav) = DT/ ZthJC
Iav = 2DT/ [1.3·BV·Zth]
Fig 16. Maximum Avalanche Energy
EAS (AR) = PD (ave)·tav
vs.Temperature
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KERSEMI [ Kersemi Electronic Co., Ltd. ]
