Part Number:DRV8848
Hello,
I'm designing with the DRV8848 motor driver and I have a unique hookup that I wanted to run by you all before I commit to a prototype. I'm driving two motors, but only one will ever need to be on at any given time. Normally I would use both full bridges in the driver to control each motor individually. But other constraints in the design requires me to reduce the amount of control lines in a cable as much as possible.
Both motors will have one of their terminals connected together for a common line. Then the other two lines will be connected to the other pins individually. This allows full polarity control on both motors, but only one at a time.
So I want to control both motors with only 3 lines. Since there are 4 half bridges in the driver, I am going to put two of them in parallel and use that output for the common connection, and the other 2, one for each motor.
See the picture for a schematic.
In the datasheet, it says to float AIN1 and AIN2 in parallel mode. I'm assuming this is to prevent parallel bridges from shorting out by driven them opposite of each other. But it mentions that they must be floating on power up or coming out of sleep. So I didn't know if there is some special logic in there that puts it into parallel mode or something on startup.
I'm assuming that there are 4 input pins and AIN1 controls half bridge, AIN2 control half bridge 2, BIN1 controls half bridge 3 and BIN2 controls half bridge 4. And those go directly through the logic to the gate drivers. In order for my setup to work I need to use the AIN lines as well as the BIN lines, So the AIN lines will not be floating on startup.
Will parallel mode still work in this case?