I have a design based on the DRV8842 that drives a linear motor (a mechanical arm, like a solenoid, with a coil 1.2 mH, 5 Ohms). The mechanical arm have magnets that keep it stable at the two stops like a latch solenoid. In order to achieve a smooth transition from one stop to the other, the uC drives the H-bridge using a modulated PWM based on a calibrated S-curve (trapezoidal current) and we are having some issues with power supply sensitivity. The S-curve is cablibrated at 24.0VDC to produce a certain reponse in the load (travel time 20 ms, overshoot 10 mm, settling time 1 ms in both directions). When we vary the power supply within the specified range 21.6-26.4 (24VDC +-10%) the overshoot goes outside the calibrated range by more than 100% and the arm oscillates to much at the stops before it settles. Is there a way to make the DRV8842 control the current to the load over this voltage input range?
