I ran into a problem that the ESP32 couldn’t source enough current to reliably drive the LV8727; especially not two of them in parallel for the Y axis on my router. The LV8727 are common-positive, so I can’t just invert the signal and use n-MOSFETs to switch ground.
Even if I switch to opto-isolated TB6600 drivers and invert the logic signals, I still have to drive the opto-isolators, and that would require the enable GPIOs on my ESP32 to source about 70mA; just too much. The LV8727 will drive higher voltage to the steppers (45V) which gives me more headroom; one more reason to make a high-side swith.
I kept thinking there must be an inexpensive part to just buy to solve this problem, but I didn’t find it yet. (Yes, I know about typical MOSFET/resistor level shifters, as well as integrated level shifters like the TXB0104 and TXS0108E; they shift voltage, but won’t source much current. Already went down that path.)
Hopefully posting this project will cause someone to tell me what I’m missing, and I can give up and buy something simple and cheap that I didn’t figure out how to search for.
I haven’t tested this. Not even breadboarded it yet. But I rendered it!
I’d appreciate circuit review.
Edit: Now with PDF of schematic, I guess not everyone keeps kicad around to look at random circuits.