IRFS4020PBF datasheet(5/9 Pages) IRF

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Fig 13. Maximum Avalanche Energy vs. Drain Current

Fig 12. On-Resistance vs. Gate Voltage

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 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 17a, 17b.

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.

∆T = Allowable rise in junction temperature, not to exceed

Tjmax (assumed as 25°C in Figure 14, 15).

tav = Average time in avalanche.

D = Duty cycle in avalanche = tav ·f

ZthJC(D, tav) = Transient thermal resistance, see figure 11)

PD (ave) = 1/2 ( 1.3·BV·Iav) =

DT/ ZthJC

Iav = 2DT/ [1.3·BV·Zth]

EAS (AR) = PD (ave)·tav

9 10 11 12 13 14 15 16

VGS, Gate -to -Source Voltage (V)

100

125

150

175

200

225

250

275

300

ID = 11A

TJ = 25°C

TJ = 125°C

100

125

150

175

Starting TJ , Junction Temperature (°C)

100

200

300

400

TOP

1.6A

2.4A

BOTTOM 11A

1.0E-06

1.0E-05

1.0E-04

1.0E-03

1.0E-02

1.0E-01

tav (sec)

0.01

0.1

100

1000

0.05

Duty Cycle = Single Pulse

0.10

Allowed avalanche Current vs

avalanche

pulsewidth,

tav

assuming

∆ Tj = 25°C due to

avalanche losses

0.01

100

125

150

175

Starting TJ , Junction Temperature (°C)

100

TOP

Single Pulse

BOTTOM 1.0% Duty Cycle

ID = 11A

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