BUS98 BUS98A

6

Motorola Bipolar Power Transistor Device Data

The Safe Operating Area figures shown in Figures 12 and 13 are

specified for these devices under the test conditions shown.

30

Figure 12. Forward Bias Safe Operating Area

VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)

2

5

10

20

50

1000

10

1

0.5

0

Figure 13. Reverse Bias Safe Operating Area

VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)

200

400

600

40

20

100

0.2

TC = 25°C

80

60

20

1000

BUS98

VBE(off) = 5 V

TC = 100°C

IC/IB1 ≥ 5

0

Figure 14. Power Derating

TC, CASE TEMPERATURE (°C)

40

80

120

40

0

100

80

60

20

200

SECOND BREAKDOWN

DERATING

160

THERMAL

DERATING

800

BUS98A

100

200

500

5

2

0.1

0.05

0.02

tr = 0.7 µs

BUS98

BUS98A

LIMIT

ONLY FOR

TURN ON

DC

1 ms

SAFE OPERATING AREA INFORMATION

FORWARD BIAS

There are two limitations on the power handling ability of a

transistor: average junction temperature and second break-

down. Safe operating area curves indicate IC – VCE limits of

the transistor that must be observed for reliable operation,

i.e., the transistor must not be subjected to greater dissipa-

tion than the curves indicate.

The data of Figure 12 is based on TC = 25_C; TJ(pk) is

variable depending on power level. Second breakdown pulse

limits are valid for duty cycles to 10% but must be derated

when TC w 25_C. Second breakdown limitations do not der-

ate the same as thermal limitations. Allowable current at the

voltages shown on Figure 12 may be found at any case tem-

perature by using the appropriate curve on Figure 14.

TJ(pk) may be calculated from the data in Figure 11. At high

case temperatures, thermal limitations will reduce the power

that can be handled to values less than the limitations im-

posed by second breakdown.

REVERSE BIAS

For inductive loads, high voltage and high current must be

sustained simultaneously during turn–off, in most cases, with

the base to emitter junction reverse biased. Under these

conditions the collector voltage must be held to a safe level

at or below a specific value of collector current. This can be

accomplished by several means such as active clamping,

RC snubbing, load line shaping, etc. The safe level for these

devices is specified as Reverse Bias Safe Operating Area

and represents the voltage–current conditions during re-

verse biased turn–off. This rating is verified under clamped

conditions so that the device is never subjected to an ava-

lanche mode. Figure 13 gives RBSOA characteristics.