I’m have made up a device that uses a half H-Bridge to control a motor. Of note, the “Run” mosfet is on PWM for speed control (the device will accelerate to a set speed, but will not vary from that speed), and the “Stop” mosfet is on / off only. Braking response and performance is important to the application.
The Arduino programming has a certain amount of freewheeling time between running and stopping to prevent shoot-through. I want to minimise the freewheeling time going from Run state to Stop state - which is currently 25ms. I am happy with the 50ms currently set for Stop to Run, but less downtime is desirable.
I’ve attached the circuit diagram I am using.
The motor pulls 20-30a stall current, so I have chosen some suitably rated P and N channel mosfets for the job. The P-channel is being driven by a smaller N-channel. I am using 100 ohm resistors from the arduino pins to the N-channel gates, and using 1k pull-up / down from the mosfet gates to whatever they are attached to.
I want to check the resistor values to see if they (particularly the pull up/down’s) are as tight as they could be. My feeling is that the 1k resistors are a little high and I could at least go to 470 or 220 ohms instead, and reduce the run to stop freewheeling time to 1 or 2ms…
But I would like some guidance from more knowledgeable people before I get too ambitious and fill the house with smoke.