MJE5850_06 Datasheet, PDF (6/8 Pages) ON Semiconductor – 8 AMPERE PCP SILICON POWER TRANSISTORS 300 - 350 - 400 VOLTS 80 WATTS

MJE5850, MJE5851, MJE5852
SWITCHING TIMES NOTE
In resistive switching circuits, rise, fall, and storage times
have been defined and apply to both current and voltage
waveforms since they are in phase. However, for inductive
loads which are common to SWITCHMODE power
supplies and hammer drivers, current and voltage
waveforms are not in phase. Therefore, separate
measurements must be made on each waveform to
determine the total switching time. For this reason, the
following new terms have been defined.
t_sv = Voltage Storage Time, 90% I_B1 to 10% V_CEM
t_rv = Voltage Rise Time, 10−90% V_CEM
t_fi = Current Fall Time, 90−10% I_CM
t_ti = Current Tail, 10−2% I_CM
t_c = Crossover Time,10% V_CEM to 10% I_CM
An enlarged portion of the inductive switching waveform
is shown in Figure 7 to aid on the visual identity of these
terms.
For the designer, there is minimal switching loss during
storage time and the predominant switching power losses
occur during the crossover interval and can be obtained
using the standard equation from AN−222A:
P_SWT = 1/2 V_CCI_C(t_c)f
In general, t_rv + t_fi ] t_c. However, at lower test currents
this relationship may not be valid.
As is common with most switching transistors, resistive
switching is specified at 25°C and has become a benchmark
for designers. However, for designers of high frequency
converter circuits, the user oriented specifications which
make this a “SWITCHMODE” transistor are the inductive
switching speeds (t_c and t_sv) which are guaranteed at 100_C.
1.0
0.7
0.5
0.3
0.2
0.1
0.07
0.05
0.03
0.02
0.01
0.1
V_CC = 250 V
I_C/I_B = 4
T_J = 25°C
t_r
t_d
0.2 0.3 0.5 0.7 1.0
2.0 3.0 5.0 7.0 10
I_C, COLLECTOR CURRENT (AMPS)
Figure 9. Turn−On Switching Times
10
0.7
0.4
0.3
0.2
0.1
0.1
t_s
V_CC = 250 V
I_C/I_B = 4
V_BE(off) = 5 V
T_J = 25°C
t_f
0.3 0.5 0.7 1.0
2.0
4.0 7.0 10
I_C, COLLECTOR CURRENT (AMPS)
Figure 10. Turn−Off Switching Time
1
0.7
D = 0.5
0.5
0.3
0.2
0.1
0.07
0.05
0.03
0.02
0.01
0.01
0.2
0.1
0.05
0.02
0.01
SINGLE PULSE
0.02
0.05 0.1 0.2
0.5 1
Z_qJC(t) = r(t) R_qJC
R_qJC = 1.25°C/W MAX
D CURVES APPLY FOR POWER
PULSE TRAIN SHOWN
READ TIME AT t₁
T_J(pk) − T_C = P_(pk) Z_qJC(t)
2
5 10 20
50
t, TIME (ms)
Figure 11. Typical Thermal Response [Z_qJC(t)]
P_(pk)
t₁
t₂
DUTY CYCLE, D = t₁/t₂
100 200
500 1 k
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