Multi PWM switch with mosfet
The IRF540 has a gate threshold voltage of 2-4 volts for a drain current of 250 uA, so depending on the part, you might not turn on the FET or might only turn it on partially.  There is no reason to divide the gate voltage down.  Look for a FET with "logic level" gate threshold voltage of less than 2 volts.  Then put a  2.5 volt zener in series with the gripper.







simulate this circuit &ndash; Schematic created using CircuitLab