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6

REV.02 20120403

BCW70

T

Figure 15. Typical Collector Leakage Current

V

CC

= 30 V

–4

–2

0

+20

+40

+60

+80

+100

+120

+140

+160

I

CBO

AND

I

I

CEO

DESIGN NOTE: USE OF THERMAL RESPONSE DATA

A train of periodical power pulses can be represented by the

model as shown in Figure 16. Using the model and the device

thermal response the normalized effective transient thermal resis-

tance of Figure 14 was calculated for various duty cycles.

To find Z

Example:

Dissipating 2.0 watts peak under the following conditions:

t

Using Figure 14 at a pulse width of 1.0 ms and D = 0.2, the reading

of r(t) is 0.22.

The peak rise in junction temperature is therefore

∆T = r(t) x P

For more information, see AN–569.

DEVICE CHARACTERISTICS