Hello,
We have developed a product using a DRV8432, Using the reference circuit 8.2.3 in the datasheet (Document SLES242G)
We have noticed that during manufacture about 10% of our devices are not spinning the stepper motor consistently. The stepper motor sounds very scratchy and it jumps backwards every now and again. I have done some experimentation by reducing the bootstrap capacitors to 10nF from 100nF in the reference schematic. This seems to make everything run better and solve the problem.
Our system is running 24volts, OC_ADJ resistor is set to 68kohms. The PWM frequency is set to 5kHz
However when reading section 7.3.2.1, it sort of implies that I should be increasing the size of the boot strap capacitors. However when I fitted 200nF capacitors it didn't help, but reducing the caps to 10nF did help. I also notice that reducing the power supply voltage to 12 volts helps. Note that reducing the supply voltage to 12volts is not an option for application.
So can you please explain what is going on? as it my experimentation contradicts that which is in the datasheet, and I need to make a decision on the size of capacitors I tell manufacturing to fit.
Is there something else that I am missing?
Your help would be much appreciated.
Regards
Andrew Meek