NPN MPS6521 PNP MPS6523

11

Motorola Small–Signal Transistors, FETs and Diodes Device Data

PNP

MPS6523

TYPICAL DYNAMIC CHARACTERISTICS

Figure 37. Thermal Response

t, TIME (ms)

1.0

0.01

0.01

0.02

0.03

0.05

0.07

0.1

0.2

0.3

0.5

0.7

0.02

0.05

0.1

0.2

0.5

1.0

2.0

5.0

10

20

50

100

200

500

1.0 k 2.0 k

5.0 k 10 k

20 k

50 k 100 k

D = 0.5

0.2

0.1

0.05

0.02

0.01

SINGLE PULSE

DUTY CYCLE, D = t1/t2

D CURVES APPLY FOR POWER

PULSE TRAIN SHOWN

READ TIME AT t1 (SEE AN–569)

Z

θJA(t) = r(t) • RθJA

TJ(pk) – TA = P(pk) Z

θJA(t)

t1

t2

P(pk)

FIGURE 19

Figure 38. Active–Region Safe Operating Area

TJ, JUNCTION TEMPERATURE (°C)

104

–4

0

Figure 39. Typical Collector Leakage Current

VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)

400

2.0

DESIGN NOTE: USE OF THERMAL RESPONSE DATA

A train of periodical power pulses can be represented by the model

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

response the normalized effective transient thermal resistance of

Figure 17 was calculated for various duty cycles.

To find Z

θJA(t), multiply the value obtained from Figure 17 by the

steady state value R

θJA.

Example:

The MPS6523 is dissipating 2.0 watts peak under the following

conditions:

t1 = 1.0 ms, t2 = 5.0 ms (D = 0.2)

Using Figure 17 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 RθJA = 0.22 x 2.0 x 200 = 88°C.

For more information, see AN–569.

The safe operating area curves indicate IC–VCE 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 18 is based upon TJ(pk) = 150°C; TC or TA is

variable depending upon conditions. Pulse curves are valid for duty

cycles to 10% provided TJ(pk) ≤ 150°C. TJ(pk) may be calculated from

the data in Figure 17. At high case or ambient temperatures, thermal

limitations will reduce the power than can be handled to values less

than the limitations imposed by second breakdown.

10–2

10–1

100

101

102

103

–2

0

0

+ 20

+ 40

+ 60

+ 80 + 100 + 120 + 140 + 160

VCC = 30 V

ICEO

ICBO

AND

ICEX @ VBE(off) = 3.0 V

TA = 25°C

CURRENT LIMIT

THERMAL LIMIT

SECOND BREAKDOWN LIMIT

1.0 ms

10

µs

TC = 25°C

1.0 s

dc

dc

4.0

6.0

10

20

40

60

100

200

4.0

6.0

8.0 10

20

40

TJ = 150°C

100

µs