MJE13003
http://onsemi.com
5
t
rv
TIME
I
C
V
CE
90% I
B1
t
sv
I
CPK
V
clamp
90% V
clamp
90% I
C
10% V
clamp
10%
I
CPK
2% I
C
I
B
t
fi
t
ti
t
c
Figure 7. Inductive Switching Measurements
Table 2. Typical Inductive Switching Performance
I
C
AMP
T
C
_C
t
sv
ms
t
rv
ms
t
fi
ms
t
ti
ms
t
c
ms
0.5 25
100
1.3
1.6
0.23
0.26
0.30
0.30
0.35
0.40
0.30
0.36
1 25
100
1.5
1.7
0.10
0.13
0.14
0.26
0.05
0.06
0.16
0.29
1.5 25
100
1.8
3
0.07
0.08
0.10
0.22
0.05
0.08
0.16
0.28
NOTE: All Data Recorded in the Inductive Switching Circuit in Table 1
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
clamp
t
rv
= Voltage Rise Time, 10−90% V
clamp
t
fi
= Current Fall Time, 90−10% I
C
t
ti
= Current Tail, 10−2% I
C
t
c
= Crossover Time, 10% V
clamp
to 10% I
C
An enlarged portion of the inductive switching
waveforms is shown in Figure 7 to aid in 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−222:
P
SWT
= 1/2 V
CC
I
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.
