BCW72LT1 データシートの表示（PDF） - Leshan Radio Company

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BCW72LT1

General Purpose Transistors

Leshan Radio Company 

LESHAN RADIO COMPANY, LTD.

BCW72LT1

1.0

0.7

0.5

D = 0.5

0.3

0.2

0.2

0.1

0.07

0.05

0.03

0.02

0.01

0.01

0.1

0.05

0.02

0.01

SINGLE PULSE

0.02 0.05 0.1 0.2

0.5 1.0 2.0

FIGURE 19A

P(pk)

t1

t2

DUTY CYCLE, D = t 1 / t 2

D CURVES APPLY FOR POWER

PULSE TRAIN SHOWN

READ TIME AT t (SEE AN–569)

1

Z θJA(t) = r(t) • RθJA

T J(pk) – T A = P (pk) Z θJA(t)

5.0 10 20

50 100 200 500 1.0k 2.0k

t, TIME (ms)

Figure 19. Thermal Response

5.0k 10k 20k

50k 100k

104

103

102

101

100

10–1

10–2

–4

V CC = 30 Vdc

I CEO

I

CBO

AND

I CEX @ V BE(off) = 3.0 Vdc

–2

0 +20 +40 +60 +80 +100 +120 +140 +160

T J , JUNCTION TEMPERATURE (°C)

Figure 19A.

DESIGN NOTE: USE OF THERMAL RESPONSE DATA

A train of periodical power pulses can be represented by the

model as shown in Figure 19A. Using the model and the device

thermal response the normalized effective transient thermal re-

sistance of Figure 19 was calculated for various duty cycles.

To find Z θJA(t) , multiply the value obtained from Figure 19 by

the steady state value R θJA .

Example:

The MPS3904 is dissipating 2.0 watts peak under the follow-

ing conditions:

t 1 = 1.0 ms, t 2 = 5.0 ms. (D = 0.2)

Using Figure 19 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 (pk) x R θJA = 0.22 x 2.0 x 200 = 88°C.

For more information, see AN–569.

400

200

100

60

40

20

10

6.0

4.0

2.0

1.0 ms 100µs

T C = 25°C

T A = 25°C

dc

10µs

1.0 s

dc

T J = 150°C

CURRENT LIMIT

THERMAL LIMIT

SECOND BREAKDOWN LIMIT

4.0

6.0 8.0 10

20

The safe operating area curves indicate I C –V CE limits of

the transistor that must be observed for reliable operation.

Collector load lines for specific circuits must fall below the

limits indicated by the applicable curve.

The data of Figure 20 is based upon T J(pk) = 150°C; T C or

T A is variable depending upon conditions. Pulse curves are

valid for duty cycles to 10% provided T J(pk) <150°C. T J(pk)

may be calculated from the data in Figure 19. At high case

or ambient temperatures, thermal limitations will reduce the

power that can be handled to values less than the limitations

imposed by second breakdown.

40

V CE , COLLECTOR–EMITTER VOLTAGE (VOLTS)

Figure 20.

M14–6/6

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