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STSPIN820 setting current limit

I’m using your Nema 11 stepper motors with 3.8V and 0.67 A/phase. If I input these values in your current setting formula

current limit = VREF * 5 * A/V

with

0.67A = VREF * 5 * 0.67A / 3.8V

and so

VREF = 0,67A / 5 * 0.176A/V = 0,76V

That seems too high, as on the DRV8825 it is lower with only 0,335V (0,67A / 2). Where is my error?

Thanks!

Hello.

It looks like you are treating “A” and “V” as variables, but the “A/V” term is just indicating the units of “5” (5 amps per volt). The current limit setting only depends on the VREF voltage, and a VREF voltage of 0.134 V corresponds to a current limit of 0.67 A.

-Patrick

Thanks, Patrick, that “A/V” wasn’t present in your write-up for the DRV8825, so I did interpret it as variables for the STSPIN820 indeed.

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