GUARANTEED SAFE OPERATING AREA LIMITS
20
5.0
Figure 15. Maximum Forward Bias
Safe Operating Area
VCE, COLLECTOR–EMITTER VOLTAGE (VOLTS)
5.0
2.0
1.0
0.50
0.02 10 20 30 45050
0.10
0.05
IC, COLLECTOR CURRENT (AMPS)
TC = 25
°
Cdc 1 ms
70 300200100
BONDING WIRE LIMIT
THERMAL LIMIT
SECOND BREAKDOWN LIMIT
10
µ
s
10
20
100
Figure 16. Maximum Reverse Bias
Safe Operating Area
VCE, PEAK COLLECTOR–EMITTER VOLTAGE (VOLTS)
14
10
0150 200 250 850350
6.0
2.0
IC(pk), PEAK COLLECTOR CURRENT (AMPS)
Bf
w
4
TC
v
100
°
C
450 700600
18
VBE(off) = 0 V
VBE(off) = 1 to 5 V
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 15 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
derate the same as thermal limitations. Allowable current at
the voltages shown on Figure 15 may be found at any case
temperature by using the appropriate curve on Figure 18.
TJ(pk) may be calculated from the data in Figure 17. 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 de-
vices is specified as Reverse Bias Safe Operating Area and
represents the voltage–current condition allowable 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 16 gives the RBSOA characteristics.