Other Parts Discussed in Thread: UCC21732
Recently I have met several problems when using UCC21732 isolated gate driver IC in our 3-phase motor controller product(which has adopted SiC MOSFET).
FLT and RDY Falt:
1. FLT or RDY fault was often observed in motor drive production qualification test(occurred 5 times in the past 1000 products), and I think this could be a false alarm.
2. When I intentionally create short-circuit cases to test the de-sat protection functions, RDY fault was also sometimes observed.
So which conditions could possibly cause such phenomena? could it be caused by radiated EMI? since this chip has a very strong CMTI capability against conducted EMI.
De-sat blanking time setting:
I noticed there exists a deglitch filter of 150ns inside the chip. So for blanking time calculation, should I also take this extra 150ns for consideration? for example, if I set 100ns blanking time using the RC circuit, then the total real blanking time should be 250 ns...
Layout issue for high side SiC MOSFET:
In the datasheet, there you can find layout guidelines: " if the gate driver is used for the high side switch, which the COM pin is connected to the switch node, ground plane is not recommended". What was the reason behind this guideline? In addition to that, I find in the application note "SLUUBX2A", a ground plane was used...
Looking forward to your reply ：）
BTW, do you also have a local service person who could help us onsite? (in China). if yes, please contact me :)