Anyone use the Allegro A3967?

Bits

I have discovered that I have a fetish, stepper motors! I am using a sparkfun driver and it contains the allegro a3967 ic.

My question is the hold current; I cant seem to find on the data sheet where this is revealed? I was inclined to think that the hold current would be adjustable.

Phil Pilgrim (PhiPi)

Both running and hold current are set by the current sense resistor and by the voltage on the REF input. If you want the hold current to be different than the run current, you will have to change the REF input voltage while the motor is not running.

-Phil

Bits

Phil

I was afraid of this. Thank you.

Will half stepping create more heat in the motor vs. full stepping?

Phil Pilgrim (PhiPi)

Bits wrote:

Will half stepping create more heat in the motor vs. full stepping?

You can compute this yourself from the graphs given in the figures on pages 10 and 11 of the datasheet, which show the relative currents for each phase. The power dissipated via heat will be proportional to the square of the currents integrated over one complete cycle. Just remember, when doing your calculations that one step of full stepping equals two steps of half-stepping, so the full-step current needs to be counted twice in the integration.

You can also compute the heat dissipated during hold for any of the phases by squaring the currents in both windings and summing them.

-Phil

pedward

I just wanted to point out that your Avatar is a tease Bits! BTW, her name is Shay Maria.