Motor driver for a handheld medical actuator where the board has to follow the enclosure contour and the motor mounts directly to the PCB assembly. No room for a separate driver module.
The Solution
Custom-shaped PCB built around the DRV8833 dual H-bridge. A magnetic Hall sensor on the board provides closed-loop speed feedback from the motor shaft. Board outline matches the enclosure geometry so it drops into the housing and the motor shaft aligns with the mechanical assembly.
Results
The Hall feedback loop maintains consistent actuation speed across varying load conditions and battery voltage. Smooth, repeatable motion with no stalling.
How the speed stays constant
The board measures what the motor actually does. A Hall sensor reads the shaft speed and closes the loop, so the actuator moves at the same pace whatever the load or the battery voltage.Why the loop is closed. Driven at a fixed duty, a small DC motor slows when the load rises and slows again as the battery sags, so the actuator would move differently at the end of a charge. Measuring the shaft speed with the on-board Hall sensor and correcting the duty in firmware holds the speed through both, and the duty trace shows the loop spending its headroom to do it.
Have a Similar Challenge?
Custom motor drivers with closed-loop control are a regular design task.
