© by SEMIKRON / 2020-05-25 / Technical Explanation / SKYPER
®
12 PV
PROMGT.1026/ Rev.7/ Template Technical Explanation
Page 30/37
Important Note
During the clamping process the IGBT is working in a typically not specified linear mode. The suitability of
the power semiconductor to operate under such linear conditions, the danger of creating oscillations
implying additional considerable loss must be considered and verified. In any case 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
®
12 PV 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 R
G(off)
. However, the proper
value has to be very carefully evaluated in the system in accordance with the individual application
parameters. The setup is a balance between staying within the maximum permitted short circuit time of
the IGBT and on the other hand reducing the overvoltage below the maximum collector-emitter voltage
of the IGBT. Please observe the individual SCSOA of your power semiconductor.
