Hi
Is there a way to calculate the minimum VDD capacitor in a stepper and BLDC motor control system?
Are there a difference in these calculation for driving a stepper or a BLDC?
Are there any suggestion how to find the smallest capacitor value for a drive system? I could I measure if the choosen capacitor is to small?
Thanks for you answer in advance an kind regards
René
Hi René,
There are two primary constraints for determining the capacitor.
1) Please note section 8.2.1.2.2 of the datasheet
2) Please note the absolute maximum voltage on VDD and GVDD (13.2V)
Voltage spikes should be minimized by having a capacitor large enough to handle current surges based on 10% of the load current
One option is to use the DRV8412EVM and modify the capacitors for your needs. At lower currents, you may not need the 330uF and the 47uF. If doing this, be careful of the absolute maximum voltage, and note the VDD also supplies a 5V and 3.3V regulator.
The DRV8412EVM User's guide contains a schematic for maximum current. The link is: 
