We have up until now tried to use two L293B h-bridge chips “in-parallel” to distribute the current.
We have burned up a few so we bought the Dual MC33926 Motor Driver Carrier(Pololu item #: 1213) in hopes that it will work for us.
The event the bot is built for is in one week… I want to make absolutly sure i connect everything correct before i power it.
if i understand correctly the in1 and in2 determine the direction. L H = F, H L = R(or vice versa).
Q1: on some h-bridges you can toast the chip if both are high or low, will that happen on this board?
Q2: when the SF’ is latched due to over current, does a PWM signal on in1 or in2 clear the latch - does PWMing the PWM/D basicly continuously clear the SF’ latch?
Q3: is there anything else is should prepaire for?
A1: No. Have you seen the motor driver truth table on page 16 of the MC33926 datasheet?
A2: Note 31 on that same page of the datasheet says:
So a PWM signal on D1 or D2 will clear the latch, but a PWM signal on in1 or in2 will not.
A3: I suggest you read through the datasheet so you better understand how the driver works. One thing to consider is whether you want drive-brake operation (requires two PWM lines per motor channel: one for in1 and one for in2) or drive-coast operation (requires one PWM line per motor channel connected to either D1 or D2). The disable lines are capable of higher switching speeds than the in1 and in2 lines (8 us vs 18 us), but drive-brake operation typically leads to a more linear relationship between PWM and motor speed, it tends to work better at slow speeds, and it will potentially draw less power.
Also, for the health of your motors and your driver, I suggest you avoid going directly from full-speed forward to full-speed reverse and vice versa. You should insert a braking period between such operations and/or implement acceleration limiting in your code.
