IRF7484QPBF Datasheet, PDF (8/10 Pages) International Rectifier – AUTOMOTIVE MOSFET

IRF7484QPbF
100
Duty Cycle = Single Pulse
10
0.01
1
0.05
0.10
0.1
Allowed avalanche Current vs
avalanche pulsewidth, tav
assuming ∆ Tj = 25°C due to
avalanche losses
0.01
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
tav (sec)
1.0E+00
1.0E+01
Fig 19. Typical Avalanche Current Vs.Pulsewidth
1.0E+02
1.0E+03
Notes on Repetitive Avalanche Curves , Figures 15, 16:
250
225
TOP
Single Pulse
BOTTOM 10% Duty Cycle
(For further info, see AN-1005 at www.irf.com)
1. Avalanche failures assumption:
Purely a thermal phenomenon and failure occurs at a
200
ID = 14A
temperature far in excess of T_jmax. This is validated for
every part type.
175
2. Safe operation in Avalanche is allowed as long asT_jmax is
150
not exceeded.
3. Equation below based on circuit and waveforms shown in
125
Figures 12a, 12b.
100
4. P_{D (ave)} = Average power dissipation per single
avalanche pulse.
75
5. BV = Rated breakdown voltage (1.3 factor accounts for
voltage increase during avalanche).
50
25
0
25
50
75
100
125
Starting TJ , Junction Temperature (°C)
6. I_av = Allowable avalanche current.
7. ∆T = Allowable rise in junction temperature, not to exceed
T_jmax (assumed as 25°C in Figure 15, 16).
t_{av =} Average time in avalanche.
150 ^{D = Duty cycle in avalanche = tav ·f}
Z_thJC(D, t_av) = Transient thermal resistance, see figure 11)
Fig 20. Maximum Avalanche Energy
Vs. Temperature
P_{D (ave)} = 1/2 ( 1.3·BV·I_av) = DT/ Z_thJC
I_av = 2DT/ [1.3·BV·Z_th]
E_{AS (AR)} = P_{D (ave)}·t_av
8
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