
© by SEMIKRON / 2019-07-23 / Technical Explanation / SKYPER
®
42 LJ R
PROMGT.1026/ Rev.7/ Template Technical Explanation
Page 28/35
Figure 21: SKYPER
42 LJ R | Application example for active clamping
Important Note
During the clamping process the IGBT is working in linear mode and generates additional considerable loss.
Hence, active clamping must not be operated during standard switching to avoid thermal overstress and
reduced IGBT lifetime.
Parameter
Min
Typ
Max
Threshold high CLMP-input
-
-
13 V
Threshold low CLMP-input
2 V
-
-
5.7
Soft Off
The SKYPER
42 LJ R provides a separate turn-off path TOP_SOFTOFF/BOT_SOFTOFF activated by the
driver, if an error event is detected on the secondary side, as described in chapter 5.1. Switching-off a
semiconductor via the soft-off path aims to reduce the switching speed of the semiconductor and, hence,
the over voltage caused by the di/dt through the system’s stray inductances is decreased.
Recommendation
Usually the Soft Off resistor is roughly 10 times as high as the standard off resistor. However the proper
value has to be very carefully evaluated in the system in accordance with the individual application
parameters. Target is to stay within the short circuit proofed time of the IGBT but at the same time
reduce the overvoltage below the maximum collector-emitter voltage of the IGBT.
SKYPER
®
42 LJ R
R
1
CLMP_IN_TOP X100:07
PWR_GND_TOP X100:08
TOP_OFF X100:06
V
Z
en
er
DC+
T1
R
G(off)_TOP
R
CLMP_TOP
R
G
_
C
L
M
P
AC
1
TOP_IN
D
C
L
M
P
PWR_VS_N_TOP X100:10
D
G
_
C
L
M
P