BC618

5

Motorola Small–Signal Transistors, FETs and Diodes Device Data

Figure 12. Thermal Response

t, TIME (ms)

1.0

2.0

5.0

1.0

0.5

0.2

0.1

0.7

0.5

0.3

0.2

0.1

0.07

0.05

0.03

0.02

0.01

20

50

10

200

500

100

1.0 k

2.0 k

5.0 k

10 k

Figure 13. Active Region Safe Operating Area

VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)

1.0 k

0.4

700

500

300

200

100

70

50

30

20

10

0.6

1.0

2.0

4.0

6.0

10

20

40

TA = 25°C

D = 0.5

0.2

0.1

0.05

SINGLE PULSE

SINGLE PULSE

CURRENT LIMIT

THERMAL LIMIT

SECOND BREAKDOWN LIMIT

Z

θJC(t) = r(t) • RθJC TJ(pk) – TC = P(pk) ZθJC(t)

Z

θJA(t) = r(t) • RθJA TJ(pk) – TA = P(pk) ZθJA(t)

1.0 ms

100

µs

TC = 25°C

1.0 s

Design Note: Use of Transient Thermal Resistance Data

FIGURE A

tP

PP

PP

t1

1/f

DUTY CYCLE

+ t1 f +

t1

tP

PEAK PULSE POWER = PP