Design Help

I have built a motor driver using the A3941 controller, but am having some strange issues (runs faster one direction than the other). Could you let me know what values you are using for the gate resistors, charge pump cap and vreg cap?

Les Hildenbrandt


It doesn’t look like there’s anything inherently asymmetric about that chip, and parts like the caps and resistors you mention also shouldn’t make a difference (assuming you’re using the caps recommended in the datasheet and the same resistors on all MOSFETs). The main thing that could add some asymmetry is your layout, though motors also don’t necessarily turn the same in both directions. You could verify that by flipping the motor leads and then seeing if the speed difference follows which MOSFETs the current is going through as opposed to which direction the current is going.

- Jan