Decrease voltage but keeping current

[benjaminpeere]

Hello everyone,

My problem is the next one :

I bought a Nema 17 stepper motor (this one : https://www.pololu.com/product/2267 ) and it’s driver (this one : https://www.pololu.com/product/2967), and I want to make them work with a nrf51822 BLE device, actually I can make it work with the nrf51dk from nordic semi conductors when I plug it in USB on my laptop but I would like to make it work with AAA batteries, that delivers 1.8A of current and 6V (I have 4 of them).
The problem is that the nrf51822 BLE device accepts 3.6V as maximum voltage, and the Nema17 2.6V, and I don’t want to break them both with a too high voltage, so I tried to reduce it with a voltage divider but it reduce the current to 0A, so nothing work after.
So I need to reduce the voltage to make everything safe but I also need to keep the current at it’s maximum level.

I was thinking to use a voltage regulator like this one : https://www.newark.com/rohm/ba33dd0t/fixed-ldo-voltage-regulator-3v/dp/08X1226

But I Wonder if the output current of 2A is not too high for my stepper motor.

I really hope that someone can help me,
Thank you very much!

[haakonsh]

I do not know how much current four AAA batteries in series can deliver. You'll find that information in the AAA battery's datasheet. 

You need a constant voltage source for the nRF51 and the stepper motor will create a lot of noise on the supply of the nRF51,  therefore you can not use the output of two of you AAA in series, half of your AAA stack. This means that you need to step down the voltage from 6V to the operating voltage of the nRF51, prefferably with an LDO due to the noisy supply.  

[benjaminpeere]

4 AAA batteries produce 1.8Amp of current, which is perfect for my motor, I know that I have to step down my voltage, I Don't know what is  LDO, is it preferable to use it instead of the voltage regulator that I showed in my previous post?

[haakonsh]

Ahh I did not catch that, yeah that's an LDO. However I suggest you use a variable instead of fixed voltage LDO as they are better at filtering noise. 

[benjaminpeere]

Oh ok, thank you very much for your answer!