The Pololu DRV8835 Dual Motor Driver Carrier website suggests 1.5A peak. I’m looking to drive two of the Pololu HP gearmotors which have a stall current of 1.6A, slightly higher than the recommended DRV8835 peak. I’ll try to avoid stalling but they may both stall at the same time (which should be detected via encoders and stopped quickly). The motors will be driven with PWM across a range of duty cycles, and changing direction frequently.
It seems the DRV8835 can in fact handle two of these motors since that has been suggested in other posts by Pololu staff.
I actually have two DRV8835s ** and could use one on each motor with inputs and outputs paralleled, giving 3.0A peak capability on each.
Would this actually offer benefits or is it simply unnecessary? Any disadvantages other than cost and a bit more wiring?
Many thanks in advance,
Dan
** As background, I chose two DRV8835s over two DRV8838s since was interested to experiment with forward/brake PWM vs forward/coast PWM, which I understand is only supported by the former. (I edited my post to move this note away from the main questions).
Whether the DRV8835 will work in your setup depends on many factors (e.g. load on the motors and how they are run). For instance changing directions from full speed in one direction to full speed in the other direction can briefly draw twice the stall current through your motor driver. You could probably use a single DRV8835 with those motors if you avoid stalling the motors and implement acceleration and deceleration limiting. However, you might be pushing the limits of your driver and could damage it. If you want to be safer, you could parallel the outputs of the driver like you mentioned.
I think Derrill’s reply is overly conservative. I generally expect the DRV8835 to work fine with a pair of high-power micro metal gearmotors (assuming you are powering them at close to 6 V) since it has built-in protections against over-current. We use a single DRV8835 in our Zumo Robot for Arduino to control a pair of those motors, and I have never heard of an instance of driver failure.
Thanks Ben. I may be using a higher voltage, e.g. 8.5V mostly with PWM bringing average back to approx 6V average but will be bursts at 8.5V. Though I must admit I’m impressed at how powerful the motors are even at 4.8V (have got one plugged into 4 x 1.2V AA NiMH at the moment), so perhaps won’t need to go higher than 6V! I’ll bear both your advice in mind.
Regards,
Dan
