Announcements

Register now for the most anticipated Asia Pacific Power Seminar 2022

Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

MOSFET (Si/SiC) Forum Discussions

User16986
Level 1
First question asked
Level 1
Hi,

I'm using this transistor as an H-bridge (class D amplifier), driven by the DRV8702Q1 from TI. The voltage supply is 30 V and the output filter is composed of a 82 µH inductor and a 68 µF capacitor.

The voltage generation is made using two PWMs generated by an FPGA, bipolar switching. The problem I have is that when I increase the output voltage to 22 V, one of the top transistor burns (gate-source resistance goes to 0). I've tried everything I could come up with, but still haven't found the problem.
All the gate driving signals seem all right. I'm using a driving strength of ~250 mA, which would seem to be ok.

Do you have any insight?
Thanks,
Federico
0 Likes
1 Solution
Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @User16986 ,

In the H bridge configuration, how is the LC connected. Please provide the schematics for our further analysis.

As an initial analysis, assuming that you are driving the amplifier in BTL configuration, below is one possible reason for this failure. 

Gate wringing of potential higher than Vgs rating of the MOSFET could result in dielectric damage and G-S short, which could have resulted in damage of switch. 

Do you have clamping diodes on the Gate pin in your design? 

Following measurements across high side switch can be done to analyze this issue further. 

1. Drain to source voltage

2. Gate to source voltage

3. Drain current

Please share these measurements to analyze the root cause. 

 

Regards

Meghana 

 

View solution in original post

0 Likes
1 Reply
Meghana
Moderator
Moderator 50 solutions authored 5 likes given 100 replies posted
Moderator

Hello @User16986 ,

In the H bridge configuration, how is the LC connected. Please provide the schematics for our further analysis.

As an initial analysis, assuming that you are driving the amplifier in BTL configuration, below is one possible reason for this failure. 

Gate wringing of potential higher than Vgs rating of the MOSFET could result in dielectric damage and G-S short, which could have resulted in damage of switch. 

Do you have clamping diodes on the Gate pin in your design? 

Following measurements across high side switch can be done to analyze this issue further. 

1. Drain to source voltage

2. Gate to source voltage

3. Drain current

Please share these measurements to analyze the root cause. 

 

Regards

Meghana 

 

0 Likes