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.
1
Figure 12. Forward Bias Safe Operating Area
VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)
550
0.01
30
10
2
1
5
0.5
100010 100
0
FIgure 13. Reverse Bias Safe Operating Area
VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)
0200 400
40
20
50
600
TC = 25
°
C
TC = 100
°
C
IC/IB
≥
5
IC, COLLECTOR CURRENT (AMPS)
0.1
200
DC
1 ms
IC, COLLECTOR CURRENT (AMPS)
tr
≤
0.7
µ
s
LIMIT ONLY
FOR TURN ON
2 20 500
30
10
0.2
0.05
0.02
800 1000
VBE(off) = 5 V
BUV48 BUV48A
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
v
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 1 1. 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 reverse
biased turn–off. This rating is verified under clamped condi-
tions so that the device is never subjected to an avalanche
mode. Figure 13 gives RBSOA characteristics.
0
Figure 14. Power Derating
TC, CASE TEMPERATURE (
°
C)
040 80
80
40
100
120
POWER DERATING F ACT OR (%)
160 200
60
20
SECOND BREAKDOWN
DERATING
THERMAL DERATING