I've used the DRV8303 several times in different boards. One layout is not working. It was mostly copied over from a different design.
The layout changes had little to do with the DRV8303's layout and nothing to do with its schematic. We added MLCC bulk capacitance, removed inductance on the motor phases, and went to a six layer board.
Conditions:
- PVDD is reading 15V.
- EN is pulled to 3.3V.
- VDD_SPI is 3.3V.
- REF is 3.3V via separate analog regulator
- AGND is connected to analog ground.
- CP1 and CP2 are connected to the typical capacitor.
Problem: It appears off. DVDD and AVDD are not outputting anything are at 0V. And we are not getting any replies on the SPI.
It has something to do with the board. I have removed a DRV8303 from the board in question, put it on a different board design, and it works. And I took a working DRV8303 and put it on the board in question and it does not work. Same power supplies, 95% same overall schematic, same regulators on both boards.
All testing was done without motors on or even connected.
My question is what are the primary conditions to power the DRV8303? I have gone pin by pin and most everything that I think is an input pin, I have met the conditions I can see in the data sheet. I would think its, PVDD, EN, REF, VDD_SPI.
And what kinds of faults can cause it to shut off and not respond to SPI? Keeping in mind this is a temporary fault that changes with the board design.
I'm trying to narrow down exactly what pins/conditions are causing this.
