Hi all,
I currently have a design that is powered by a 12V adapter .
With a foot pedal the user is controlling the motor which is done by a STM32G4 controller with EEPROM emulation.
We get a lot of devices back, sometimes the 12V adapter is broken or sometimes the firmware is bricked but unbricked when reflashed.
Probably the flash gets corrupted when the flash erase controller is unlocked.
What I noticed is very large spikes on the 12V rail which is motorcontroller VM
Also the 12v to 3.3V LDO is passing the spikes:
I started with floating the SR pin to reduces slew rate a bit.
That didn't help much.
Then I noticed there is zero bulk capacitance on the VM pin.
I started with 240uF cap all the way up to 2700uF
It is a lot better now, but a larger cap will become an issue with the casing.
What are some options I can try?
Lowering or increasing PWM frequency?
