AUIRL7766M2TR
7 2015-12-11
Notes on Repetitive Avalanche Curves , Figures 16, 17:
(For further info, see AN-1005 at www.infineon.com)
1. Avalanche failures assumption:
Purely a thermal phenomenon and failure occurs at a temperature far in
excess of T
jmax. This is validated for every part type.
2. Safe operation in Avalanche is allowed as long as T
jmax is not exceeded.
3. Equation below based on circuit and waveforms shown in Figures 18a, 18b.
4. P
D (ave) = Average power dissipation per single avalanche pulse.
5. BV = Rated breakdown voltage (1.3 factor accounts for voltage increase
during avalanche).
6. I
av = Allowable avalanche current.
7. T
= Allowable rise in junction temperature, not to exceed Tjmax (assumed as
25°C in Figure 16, 17).
t
av = Average time in avalanche.
D = Duty cycle in avalanche = t
av ·f
Z
thJC(D, tav) = Transient thermal resistance, see Figures 15)
P
D (ave)
= 1/2 ( 1.3·BV·I
av
) = T/ Z
thJC
I
av
= 2T/ [1.3·BV·Z
th
]
E
AS (AR)
= P
D (ave)
·t
av
Fig 17. Maximum Avalanche Energy vs. Temperature
Fig 18a. Unclamped Inductive Test Circuit
Fig 18b. Unclamped Inductive Waveforms
Fig 19a. Gate Charge Test Circuit
Fig 19b. Gate Charge Waveform
VDD
Fig 20a. Switching Time Test Circuit
Fig 20b. Switching Time Waveforms
25 50 75 100 125 150 175
Starting T
J
, Junction Temperature (°C)
0
10
20
30
40
50
60
70
E
A
R
,
A
v
a
l
a
n
c
h
e
E
n
e
r
g
y
(
m
J
)
TOP Single Pulse
BOTTOM 1.0% Duty Cycle
I
D
= 31A
