IRFR7446PBF Datasheet, PDF (6/10 Pages) International Rectifier – Brushed Motor drive applications

IRFR7446PbF
10
1
D = 0.50
0.20
0.10
0.1
0.05
0.01
0.001
1E-006
0.02
0.01
SINGLE PULSE
( THERMAL RESPONSE )
1E-005
0.0001
0.001
Notes:
1. Duty Factor D = t1/t2
2. Peak Tj = P dm x Zthjc + Tc
0.01
0.1
t1 , Rectangular Pulse Duration (sec)
Fig 14. Maximum Effective Transient Thermal Impedance, Junction-to-Case
100
Allowed avalanche Current vs avalanche
pulsewidth, tav, assuming ΔTj = 150°C and
Tstart =25°C (Single Pulse)
10
1
Allowed avalanche Current vs avalanche
pulsewidth, tav, assuming ΔΤ j = 25°C and
Tstart = 150°C.
0.1
1.0E-06
1.0E-05
1.0E-04
1.0E-03
tav (sec)
Fig 15. Typical Avalanche Current vs.Pulsewidth
1.0E-02
1.0E-01
140
Notes on Repetitive Avalanche Curves , Figures 14, 15:
TOP
Single Pulse
(For further info, see AN-1005 at www.irf.com)
120
BOTTOM 1.0% Duty Cycle
ID = 56A
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.
100
2. Safe operation in Avalanche is allowed as long asT_jmax is not exceeded.
3. Equation below based on circuit and waveforms shown in Figures 23a, 23b.
80
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).
60
6. I_av = Allowable avalanche current.
7. ΔT = Allowable rise in junction temperature, not to exceed T_jmax (assumed as
40
25°C in Figure 14, 15).
t_{av =} Average time in avalanche.
D = Duty cycle in avalanche = t_av ·f
20
Z_thJC(D, t_av) = Transient thermal resistance, see Figures 14)
0
25 50 75 100 125 150 175
Starting TJ , Junction Temperature (°C)
Fig 16. 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
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March 22, 2013