Microstepping stepper motor drivers

Using with the 0.05Ω current sensing resistor, the reference voltage can be found using the formulae below: For DRV8825, the current limit (in amps)= 4 * Vref, For A4988, the current limit (in amps)= 2.5 * Vref. This current limit is 1.4 times the current in each coil in full step mode.

Using the formula, we get Vref of 0.525V for DRV8825 for a full step current of 1.5A in each coil. Also, we get Vref of 0.56V for A4988 for a full step current of 1A in each coil.

Note: these parts are similar in functionality but not drop-in-compatible. They have very similar interface and circuit requirements, however the package and performance characteristics are different.