I am seeing an intermittent stop of the switching output on our gate driver board. Our use case is pretty much "9.2.2 Design 2: PSR Flyback Converter With Dual Outputs of 15 V and –7.7 V at 200 mA" from the datasheet.
The schematics is as follow (input voltage is 24V, coming from a Traco 24V DC-DC, I've scoped Vin and it is fairly steady and noise free):
We are seeing the following intermittent behaviour when the gate are switching:
(Green = SW output from LM5180, Red/blue = Low/High side gate Vgs)
You can see on the zoomed out plot at the top of the pictures the interruption is quite severe.
We've somehow managed to reduce/remove the behaviour by adding a Y cap between the isolation barrier, but we do not think this is a "proper" fix and would like to understand what is causing the PSU to stop regulating.
The main problem is that we think this has in time caused some IGBT failures (after only 1h of running!). The Vgs voltage not being high enough (potentially 10-12V instead of 15V) is causing the switches not to turn on fully, increasing dissipation and ultimately making the switch fail. Some times, the regulation stops long enough for the gate driver UVLO protection to trigger.
Thanks for your help,