MMBT6521LT1G_16 Datasheet, PDF (6/7 Pages) ON Semiconductor – Amplifier Transistor

MMBT6521LT1G, SMMBT6521LT1G
1.0
0.7
0.5
D = 0.5
0.3
0.2
0.2
0.1
0.1
0.07
0.05
0.05
0.02
0.03
0.02
0.01
SINGLE PULSE
0.01
0.01 0.02 0.05 0.1 0.2 0.5 1.0 2.0
P_(pk)
FIGURE 21
t₁
t₂
DUTY CYCLE, D = t₁/t₂
D CURVES APPLY FOR POWER
PULSE TRAIN SHOWN
READ TIME AT t₁ (SEE AN−569)
Zq_JA(t) = r(t) w Rq_JA
T_J(pk) − T_A = P_(pk) Zq_JA(t)
5.0 10 20 50 100 200
t, TIME (ms)
500 1.0 k 2.0 k 5.0 k 10 k 20 k 50 k 100 k
Figure 20. Thermal Response
10⁴
DESIGN NOTE: USE OF THERMAL RESPONSE DATA
V_CC = 30 Vdc
10³
A train of periodical power pulses can be represented by
the model as shown in Figure 21. Using the model and the de-
10²
I_CEO
vice thermal response the normalized effective transient ther-
mal resistance of Figure 20 was calculated for various duty
10¹
cycles.
To find Z_qJA(t), multiply the value obtained from Figure 20
10⁰
I_CBO
by the steady state value R_qJA.
AND
Example:
10^-1
I_CEX @ V_BE(off) = 3.0 Vdc
The MPS6521 is dissipating 2.0 watts peak under the follow-
ing conditions:
10^-2
-4 -2
00
t₁ = 1.0 ms, t₂ = 5.0 ms. (D = 0.2)
0 + 20 + 40 + 60 + 80 + 100 + 120 + 140 + 160 _{Using Figure 20 at a pulse width of 1.0 ms and D = 0.2, the}
T_J, JUNCTION TEMPERATURE (°C)
reading of r(t) is 0.22.
Figure 21.
The peak rise in junction temperature is therefore
DT = r(t) x P_(pk) x R_qJA = 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.
400
200
100
60
40
20
10
6.0
4.0
2.0
1.0 ms ^{100 ms}
T_C = 25°C
T_A = 25°C
dc
10 ms
1.0 s
dc
T_J = 150°C
CURRENT LIMIT
THERMAL LIMIT
SECOND BREAKDOWN LIMIT
4.0 6.0 8.0 10
20
V_CE, COLLECTOR-EMITTER VOLTAGE (VOLTS)
Figure 22.
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 22 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 20. At high case or
ambient temperatures, thermal limitations will reduce the
power that can be handled to values less than the limitations
imposed by second breakdown.
40
www.onsemi.com
6