I am trying to run a 12v motor (https://www.robotshop.com/uk/ghm-01-spur-gear-head-motor.html) with a stall current of 1.4A from a 5A lab power supply at 12v via a https://www.pololu.com/product/2961 (which uses the MAX14870 chip).
The motor just buzzes and a fault is indicated. I’m confident of the entire setup because it works for a much lighter motor. It also works if I limit the current from the supply to about 800mA.
It appears to me that these boards/chips can really only cope with a fraction of what it says on the datasheet, apparently around 800mA.