2N5087
http://onsemi.com
6
Figure 17. Thermal Response
t, TIME (ms)
1.0
0.01
r(t) TRANSIENT THERMAL RESISTANCE
(NORMALIZED)
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 1.0k 2.0k 5.0k 10k 20k
50k
100k
D = 0.5
0.2
0.1
0.05
0.02
0.01
SINGLE PULSE
DUTY CYCLE, D = t
1
/t
2
D CURVES APPLY FOR POWER
PULSE TRAIN SHOWN
READ TIME AT t
1
(SEE AN569)
Z
q
JA(t)
= r(t) w R
q
JA
T
J(pk)
- T
A
= P
(pk)
Z
q
JA(t)
t
1
t
2
P
(pk)
FIGURE 19
Figure 18. Active−Region Safe Operating Area
T
J
, JUNCTION TEMPERATURE (°C)
10
4
-40
I
C
, COLLECTOR CURRENT (nA)
Figure 19. Typical Collector Leakage Current
V
CE
, COLLECTOR-EMITTER VOLTAGE (VOLTS)
400
2.0
I
C
, COLLECTOR CURRENT (mA)
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
q
JA(t)
, multiply the value obtained from Figure
17 by the steady state value R
q
JA
.
Example:
The 2N5087 is dissipating 2.0 watts peak under the follow-
ing conditions:
t
1
= 1.0 ms, t
2
= 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
DT = r(t) x P
(pk)
x R
q
JA
= 0.22 x 2.0 x 200 = 88°C.
For more information, see ON Semiconductor Application
Note AN569/D, available from the Literature Distribution
Center or on our website at www.onsemi.com.
The safe operating area curves indicate I
C
−V
CE
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 T
J(pk)
= 150°C; T
C
or
T
A
is variable depending upon conditions. Pulse curves are
valid for duty cycles to 10% provided T
J(pk)
≤ 150°C. T
J(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
10
0
10
1
10
2
10
3
- 20 0 + 20 + 40 + 60 + 80 + 100 + 120 + 140 +160
V
CC
= 30 V
I
CEO
I
CBO
AND
I
CEX
@ V
BE(off)
= 3.0 V
T
A
= 25°C
CURRENT LIMIT
THERMAL LIMIT
SECOND BREAKDOWN LIMIT
1.0 ms
10 ms
T
C
= 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
T
J
= 150°C
100 ms
