2v capable motor driver chip... and power supply??

[RodSTAR]

Hello,
I need an advice about low voltaje stepper motors driving at fairly high amps.
I have several stepper motors rated at 2.1 volts @ 3A.
I have no idea how to drive them as the typical drivers like SN754410, L298, L293... (i own) and so on, only handle voltajes from about 4,5 volts.

What should I use to drive those steppers?

PD: And about power supply, how could I reach specific voltajes? some motors rate, 2.1v, 2.63v, 4.3v, 1,72v and so on...

thanks!

 

[alec_t]

My approach would be to use one of the driver chips you have, driving the motor via discrete transistor level converters.
The required voltage should be achievable with standard adjustable voltage regulator chips.

 

[RodSTAR]

alec_t
thanks for your response, let me confirm if understood correctly: You tell me to connect L298 outputs to discrete transistor level converters? any chip or schematic example please??
And in the power supply to use adjustable voltage regulator chips... you mean something like LM317?, they supply 1.5A, if I need for example 4A I would have to use 3 LM317's in parallel, or something....?

 

[Dragon Tamer]

I agree with alec_t, try using a MOSFET connected to the negative end of the stepper. If your stepper's power requirements are low enough, then you can have less than a 1V drop across the MOSFET. Another way is using an NPN connected to the negative end of the stepper coils, this will have about a 0.7V drop across the transistor but will be limited to the current that the transistor can handle.

 

[alec_t]

I'm not familiar with stepper-motor driver ICs but assume they have H-bridge outputs which switch more or less rail-to-rail? If so, then it should be possible to tap off from their outputs suitable voltages to drive, via series resistors, the bases of at least 5A-capable bipolar transistors working with a ~2V supply. As for the ~2V supply, using LM317s in parallel is not a good idea. Better to find a 4A-capable (or better) chip. I don't know of one off-hand, but Googling should hopefully come up with something suitable.
I've been assuming you need a ~2V supply, but IIRC from another thread on this forum stepper-motors are usually pulsed with a higher voltage initially, to get them moving, and then the voltage is reduced. You will need to research this subject before deciding on the power supply required.