I need to use a SN754410 motor driver with a 4.5V microchip and 12V motor all running on batteries.
I want to power the microchip with 3x1.5v AAA batteries. The motor requires 12V and I want to use a larger 12V battery for this.
I'm reluctant to use a voltage regulator because testing the voltage drop from 12V to 4.5V I seem to use excessive current converting the voltage when the microchip is doing nothing.
Here's where I'm confused - do I need to connect the two ground (-ve) terminals of the 2 sets of batteries together?
Picture attached from the SN754410 data sheet.