DRV8412 lowest frequency possible and corresponding bootstrap cap size?

We are using DRV8412 up to 10kHz.  Some applications are less than 100 Hz.  At 100 Hz what should the bootstrap cap be?  Is there a design equation?  The 5 ohm resistor on GVDD is already know, but for such a slow application we need to know how big the bootstrap cap should be. We are too far along to switch and picked this part because we are doing both stepper and BLDC applications.