7
Motorola Bipolar Power Transistor Device Data
TYPICAL STATIC CHARACTERISTICS
Figure 18. Reverse Bias Switching Safe
Operating Area
10
2
01200400 VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)
6
600
IC, COLLECTOR CURRENT (AMPS)
0 V –1.5 V
–5 V
TC
≤
125
°
C
GAIN
≥
5
LC = 4 mH
800
8
4
1000
POWER DERATING FACTOR
Figure 19. Forward Bias Power Derating
TC, CASE TEMPERATURE (
°
C)
1.0
0.8
0.6
0.4
0.2
016014012010080604020
SECOND
BREAKDOWN
DERATING
THERMAL
DERATING
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 17 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 > 25°C. Second
breakdown limitations do not derate the same as thermal
limitations. Allowable current at the voltages shown on
Figure 17 may be found at any case temperature by using
the appropriate curve on Figure 19.
TJ(pk) may be calculated from the data in Figures 22 and
23. At any case temperatures, thermal limitations will reduce
the power that can be handled to values less than the
limitations imposed by second breakdown. For inductive
loads, high voltage and current must be sustained simulta-
neously during turn–off with the base–to–emitter junction
reverse biased. The safe level is specified as a reverse–
biased safe operating area (Figure 18). This rating is verified
under clamped conditions so that the device is never
subjected to an avalanche mode.
Figure 20. Dynamic Saturation