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User17668
Level 2
5 replies posted 10 questions asked 5 questions asked
Level 2
Hi Infineon,

several times I read about dV/dt induced turn-on? Can you please explain what it means?

Thanks and BR Melanie
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_Klaus
Moderator
Moderator 10 replies posted First comment on blog 10 sign-ins
Moderator
Dear Melanie,

this phenomenon can happen in bridge configurations and is sometimes referred to as "parasitic turn-on". I directly take out the explanation of this Bodo's Power article:

A scenario explaining this effect is shown in Figure 1. The body diode of the low-side switch S2 conducts the load current IL until the high-side switch S1 turns on. After the load current has commutated to S1, the drain-source voltage of S2 starts to increase. During this phase, the rising drain potential pulls up the gate voltage of S2 via the Miller capacitance Cgd. The turn-off gate resistor tries to counteract and pull the voltage down. If this resistor value is not low enough to pull the voltage down, the voltage might exceed the threshold level, leading to a shoot-through and an increase of switching losses.


4130.attach

Please note that while the text and the picture describes a MOSFET, the effect is the same for IGBTs.

Hope this helps!
Best regards,
Klaus

View solution in original post

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1 Reply
_Klaus
Moderator
Moderator 10 replies posted First comment on blog 10 sign-ins
Moderator
Dear Melanie,

this phenomenon can happen in bridge configurations and is sometimes referred to as "parasitic turn-on". I directly take out the explanation of this Bodo's Power article:

A scenario explaining this effect is shown in Figure 1. The body diode of the low-side switch S2 conducts the load current IL until the high-side switch S1 turns on. After the load current has commutated to S1, the drain-source voltage of S2 starts to increase. During this phase, the rising drain potential pulls up the gate voltage of S2 via the Miller capacitance Cgd. The turn-off gate resistor tries to counteract and pull the voltage down. If this resistor value is not low enough to pull the voltage down, the voltage might exceed the threshold level, leading to a shoot-through and an increase of switching losses.


4130.attach

Please note that while the text and the picture describes a MOSFET, the effect is the same for IGBTs.

Hope this helps!
Best regards,
Klaus
0 Likes