I’ve taken a look at the datasheet for the IC (a Toshiba TC78H660FTG). You don’t need to hook up a logic reference voltage to it, all it needs is the motor power supply. Any voltage below 0.7v is a logic low. Any voltage above 1.5v (up to 5.5V) is a logic high.
It has an internal voltage regulator, so you can power it on anything from 3V-16V (the IC is actually rated for 2.5V - 16V, but looks like Core have given themselves 0.5V headroom to account for the bit of loss between your input and the chip).
The schematic’s a little confusing because it doesn’t match up with the PCB labels. Instead it uses VCC and VDC instead of VM.
VM on the PCB = VDC on the schematic = whatever external power you supply. VCC is VDC, on the other side of the reverse polarity protection mosfet. On the schematic, VM is only used in one place - the pinout of the IC.
I probably should have tracked down the datasheet myself - It would be great if Core could provide a link to the chip datasets directly in the “Resources” list, much as Adafruit often do for their products .
I guess when all is said and done we are only writing → the logic pins and 3V3 is sufficient to flag a HIGH.
After you blow up a couple 3V3 pins with 5V0 is hard not to be just a little paranoid .
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