STB Cool Stepper Driver
Version 1.10 is the final and tested version. It is available now.
STB Cool Stepper Driver V1.10 (8+8 pins) - http://youprintin3d.de/elektronik/open-source/240/drv8825-motortreiber-stb.html:
- Selectable current limit 1.8A/2.5A with solder jumper
- If the current is too high for the heat sinking, the motors will stop and the powersupply of the printer must be cycled.
STB Cool Stepper Driver V1.00 (8+8 pins):
- Initial release
- G3D driver
- SureStepr SD82B - http://www.panucatt.com/product_p/sd82b.htm
- DRV8825 Stepper driver (1.5 A max w/o heatsink! 2.2 with) - http://www.pololu.com/catalog/product/2132
Tuning motor current
From the TI DRV8825 datasheet [], the calculation for the maximum trip current is:
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.
Low means pin is connected to GND, high means connected to 3.3..5V.
Connections (top view)
|TOP Layer||BOT Layer|
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.