Controlling stepper motors

[evergreen1]

Hi,

I´m planning to use two stepper motors for my project. And I´m thinking of controlling them with either the ULN2803 or the ULN2003 chip. Her's the specs for the stepper motors:

Current rating: 1A
Resistantace: 3,15Ω
Voltage: 3,15V

My question is if i'll be better of using two ULN2003 chips instead of the one ULN2803 since the motors will not be running symmetrically(simultanously)?? And will these stepper motors work fine with theese IC's?

Thanks in advance for comments!

 

[Diver300]

Neither of those would be in any good, as they are only rated to about 1/2 amp for each output.

Aside from that, there is no problem using one ULN2803 for two stepper motors, as it contains 8 separate drivers that can be driven completely independently.

Depending on how fast you want the stepper motors to run, you can get them to a larger maximum step rate if you use a higher supply voltage, and limit the current with resistors or with PWM.

 

[SABorn]

You dont say if they are bi-polar or uni-polar motors, and only uni-polar motors can be driven with uln2003 or uln2803, or you could just use 4 big transistors or mosfets.

Bi-polar you will need a H-bridge driver.

Pete.

 

[evergreen1]

It is unipolar stepper motors. I was i bit conserned about the fact that the motors is 1a, but i'm having some trouble finding 1a drivers for the stepper motors. Is there any way that I could connect two drivers in parallel to get the 1a current rating for the motors?

Again, thanks

 

[Boncuk]

Hi evergreen1,

one transistor of the array can sink 500mA. If you parallel 3 inputs and outputs they will sink 1.5A. per 3 transistors.

Driving two steppers you'll need 3 pcs. ULN2803 not to exceed the max allowed current.

The TI data sheet says nothing about the total power dissipation of one chip.

Since outputs are not active at the same time I'd give it a try.

Boncuk

 

[4pyros]

You can look at L297 and L298

 

[SABorn]

Why use a ULN2803 chip in the first place?
with a unipolar motor all you need is 1 transistor per coil and this could be easy done with a few BD-139 (1.5 amp) or BD-681 (4 amp) or even some mosfets, it is all very simple.

Pete.