Stepper motor drivers ?

[Clyde Crashkop]

I am designing a circuit board to control 4 unipolar stepper motors. I planned on using the Allegro 5804 but they are obsolete. I have looked into some of their newer chips but can’t find much info or application notes. I want this board to drive any motor from 9 volts to 24 volts or more and at least 1 amp. What unipolar stepper motor driver chips do you guys like and where can I find info and application notes for them?
Meanwhile I am looking into a couple chips mentioned on this forum.

[Edison4]

The Allegro SLA7062M is a nice unipolar driver chip that I have used.

The datasheet can be found here: www.techkits.com/SLA7062M.pdf

Page 11 of the datasheet shows applications information. The chip can drive up to 3 Amps and will operate in half-step, quarter-step, eigth-step or sixteenth-step (microstepping) modes. It accepts simple step & direction signals so it will work fine with any parallel port breakout board.

-Ed

[Clyde Crashkop]

Thanks Ed
Do you know where I can find any sample application circuits that I can use as a starting point?
That sense circuit wants an 0.1 to 2 ohm resistor. The only resistors I see at Digikey in that range are 5 watt. ???? It's only a sense input and 4 5 watt resistors take up a lot of real estate.
I am a digital kind of guy and not an engineer.
If I could find example circuits, I could adjust them to fit my needs.

[ninefinger]

Check out www.hobbycnc.com website - his "old" design uses the SLA7062M chip.

I bought one of the 4 motor controllers and it works well for me (a mechanical guy - definitely not electronically oriented!)

[Clyde Crashkop]

Thanks ninefinger
I saved that one for future reference. His prices are great but he didn’t divulge any secrets.

[Edison4]

Clyde,

The sense resistors carry the motor current which can be a maximum of 3 Amps.
I use 0.3 Ohm, 3 Watt resistors. (Power dissipation = I*I*R) 3 x 3 x 0.3 = 2.7 Watts. So 3 Watt resistors are minimum, 5 Watt resistors will be even better.

Mouser Electronics carries 0.3 Ohm, 3 Watt resistors.

I understand the real estate issue, so I mount my resistors vertically.
You can see a photo of my board here: http://www.techkits.com/industrial/index.htm

-Ed

[Clyde Crashkop]

Thanks Ed
That helps a lot. Somehow I didn't think they would do that. I assumed (hehehe) that the sense pins would just be a reference.
Nice board!

[pminmo]

Might find some help at my website: