DRV8825 Motortreiber STB Edition

reprap.org/wiki

Tuning motor current

From the TI DRV8825 datasheet [[1]], the calculation for the maximum trip current is:

 I_CHOP= Vref/(5*Risense)

The sensing resistors are Rs=0.1 ohm, so a Vref of 1.25V should produce a maximum current of 2.5A. By default the STB Cool Stepper Driver is limited to 1.8A which is enough for most applications and no special heatsink is necessary. For the full 2.5A range SJ1 on the backside of the driver has to be shorted. The reference voltage can be measured direct on the center tab of the potentiometer R4.

Microstepping Settings

Low means pin is connected to GND, high means connected to 3.3..5V.

Connections (top view)

Schematics

Layout

TOP Layer	BOT Layer

Heat Consideration

Best cooling results are given if the heatsink is mounted on the area on the backside of the PCB where the soldermask ist cut out. Glueing the heatsink to the top of IC1 gives only limited improvements.