A4988 VREF setting

Support Motor controllers/drivers and motors
1

Is the VREF setting dependent on the input VCC voltage to the A4988?

My carrier board is mounted in a difficult place and I would like to set the VREF on the A4988 before they are installed. The boards are logic powered by a 3.3V supply generated on my CPU board and use a 24V supply to power the driver stage. I would like to setup the A4988 on a breadboard using a 5V power supply to provide VCC (I assume I don’t need to power the driver stage to set the VREF).

Will this work or do I need to power the boards with the same voltage that they will be used at?

Is is possible to just set the VREF by measuring the resistance of the pot from the VREF test point to ground?

Thanks

2

Hello,

You can set the VREF voltage with only VDD and GND connected to your A4988. The voltage at VDD should be the same as the logic level of your controller. So if your controller is 3.3V, you should supply 3.3V to VDD when setting the current limit.

Since the current limit is dependent on the VREF, just setting the same resistance on the pot would not help.

-Derrill