Hi team,
My customer uses DRV8350 in ride-on mower, and they want to know the maximum transient High-side gate drive pin voltage with respect to SHx (GHx) within 200ns? The datasheet only tells continuous High-side gate drive pin voltage with respect to SHx (GHx).
My second question is, now they find really large ringring between GHx and SHx, can you help to analyze this issue and give me some idea to fix it?
Thank you!
Gary
Gary,
Thanks for posting on the MD forum!
I think it is easier to understand the ABS max specifications if I explain their reasoning.
Specs (1) and (2) above are for the GHx voltage with respect to VCP. The reason for this is that the output is separated from the VCP generation by a few diodes and ESD structures. Our main care about here is that the VCP node doesn't get pumped up by the GHx node and violate it's specs which would cause those diodes and ESD structures to conduct unnecessarily. This unwanted conduction can cause extra heating and damage to the part internally.
Spec (3) is for the internal clamping diode between GHx and SHx which is there to make sure that the FET Vgs is not exceeded. This diode will clamp the Vgs voltage to ~15V but obviously it needs some time to turn on so likely your short voltage event is not long enough to turn it on.
To analyze their waveform we need a few more details:
Which FET is used?
Is there a series gate resistor?
Which IDRIVE setting is used?
What is their desired SHx rise/fall time?
The information above will help us analyze if their gate drive solution is configured correctly.
We would also like to review their schematic and layout if it can be shared (privately is okay).
Regards,
-Adam
