Hi
I have bought the EVM and I have made some changes in order to use it in 1x PWM mode, with Hall sensors feedback. To do that, I have removed R23 and mounted 0 Ohm resistors in R48, R50 and R52. The Brake (INLC) has been connected to 3.3V, the ENABLE was connected to 3.3V as well, the PWM was provided by the board that I normally use to drive another BLDC driver. As a first attempt to see the motor running I have used a 20 kHz PWM with a duty cycle ramp up from 25% to 40%.
Unfortunately, the initial PWM was 25% and not 0%; anyway the EVM board was able to drive the motor, apparently without issues. But looking at the gates with the oscilloscope I have observed a strange signal at the high sides: each time a GHx was involved (in its turn) the first PWM pulse was clean but all the subsequent ones were something like a 2 MHz frequency.
In the photo you can see GHA (blue) and GLA (yellow). PWM duty now is 40% @ 20 kHz, V motor is around 54V (48V batteries, fully charged). Here below you can see an elarged detail:
and a more enlarged one of GHA only (you can see the 500 ns period):
As i said, the motor was running but the MOSFETS were becoming quite hot in around 10 seconds. So I decided to adopt a smoother PWM ramp up, from 0% to 40% and I believe the board was behaving properly. I say "I believe" because after 3-4 seconds it stopped working and I did not have enough time to record some scope traces: now the motor does not turn, the DRV8353RH is hot and the FAULT LED is always ON (never seen it before).
Could you please help me understand what was the cause of the 50 ns oscillation? And what could be the cause that broke the driver?
Many thanks in advance
Andrea
