1ED34 driver RDYC problem

[User22510]

Hi all,
I am using 1ED3491MU12MXUMA1. Supply voltage LOW side= 5V, Supply voltage fo HIGH side = +/- 15V (+/- 3%).
Drivers are used with IGBT FS200R06KE3.
There are 6 drivers on the board.

Everything works fine, but driver "freezes" sometime and gives only RDYC = L. LOW and HIGH side supply is correct (acc. datasheet).
It is not possible to reset this failure or get drivers into normal functional state (except switch OFF/ON).
This failure happens during normal function, not after switching LOW side supply on.
All RDYC signals from drivers are connected to one net and is not possible to decide which driver is holding RDYC in L state.

Does somebody know some reason for stated behaviour?

Thanks for reaction.

J.S.

[Pablo_EG · Accepted solution]

Hello J.S.,

Thank you for posting on Infineon Forums.

I understand that the RDYC signal goes low, signifying a gate driver internal status fault.
Besides supply voltage, there are more reasons why RDYC can go low:

Ready sources
• the input side is properly supplied, VCC1 supply above UVLO1 threshold
• the output side is properly supplied with a positive voltage, VCC2 supply above UVLO2 threshold
• no VEE2 over GND2 failure
• Internal signal transmission is operating nominal
• the ON pin monitoring of the gate driver is below VEE2 + 2 V, IGBT has to be off at start-up

It would be helpful if you could take oscilloscope shots of VCC2, VEE2, and GND2 when the switching happens.
The FS200R06KE3 IGBT has a considerable gate capacitance.
Because of this, the gate driver output side power supply (VCC2/GND2/VEE2) should be decoupled very well.
If the gate driver is insufficiently decoupled, the positive supply rail (VCC2-GND2) voltage could drop bellow the UVLO value, and turn-off the gate driver. This will then trigger a RDYC=low event.
Please let us know what the value of the decoupling capacitors is.
A snippet of your schematic would be of great help.

Best regards,
Pablo