Why do motor drivers require separate motor voltage and logic voltage?
I am looking to use a TM2209 stepper motor driver.
Below is a schematic of how I intend to power it. I'll also be using a MCU, currently an Arduino but might switch to a 3.3V Teensy, connected to the controls pins shown. I've only included the relevant pins.
From this extract from the watterot website it seems to me like VIO is not actually needed. I'm sure I'm missing something.
On power-down the logic supply voltage VIO should turned off at first and then the motor supply voltage VM, because the internal logic of the TMCxxxx driver is powered from VM. " https://learn.watterott.com/silentstepstick/faq/
Why would I need VIO at 5V or 3.3V if the internal logic is powered from VM? Can I run the driver with only 24V at VM?
If I wanted to power the MCU off the same 5V or 3.3V output of the voltage regulator (U3,) how would I protect the MCU from back EMF or if the motor is back driven?
Would it be better to have a separate voltage regulator coming of the 24V supply exclusive to the MCU?
simulate this circuit – Schematic created using CircuitLab