Stepper motor drivers ?

[ClydeCrashKop]

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?

 

[Papabravo]

This is the classic that can be used with various other types of chips
https://www.st.com/stonline/books/pdf/docs/1334.pdf

 

[arunb]

I have used the L297/L298 driver ICs before for my projects.

They are OK for most applications but unfortunately they occupy quite a lot of PCB space as the translator and the control ICs are seperate, and so may not be an ideal choice for a microcontroller based project.

A better alternative is the SLA 7062 driver ICs from Sanken Electronics, Only one single driver IC is required, the basic operations like motion selection (1/2 step, 1/4 or 1/8 step) , clockwise/anticlockwise rotation are all very easily implemented. The best feature is that the translator and the control ICs are all integrated in one IC, unlike the L297/L298.

 

[philba]

the 7060/7061/7062 is a pretty hard chip to find, especially in small quantities. I got in on a group buy a year ago, min order was something like 60 units. It's a pretty nice chip but cost me around $10 each.

Using a small micro to drive 2 hbridges isn't that hard to do and may well be cheaper.

have you considered driving the steppers as bipolar motors? if they are 6 or 8 wire motors, you should be ok. there are a number of decent solutions like the A3977. The advantage is that they implement current limiting which allows you to drive the motors at a higher voltage and you don't have to use limiting resistors.

 

[arunb]

Quite right these ICs are expensive compared to other solutions. The H bridge is quite a simple one, and also effective. But the advantages of a driver IC (having current chopping control) cannot be ignored. The problem with a H bridge drive is that some current always flows through the motor, thus causing wastage. But for driver ICs this is not a problem as motor current is reduced after the end of motion.

I used H bridge drivers before and I found that the motor and the transistors always became hot even when there is no motion, we had to correct the problem by adding a relay that switched ON or OFF the motor supply when required. With the SLA 7062 or L297/L298 drivers this is not required.

 

[ClydeCrashKop]

Thanks guys
I asked an Allegro Engineer about the SLA 7050 and he suggested the .75 amp A3967 and sent me an application note on how to apply it to a unipolar stepper motor with no resistors or capacitors. If I knew for sure that I could do that with the 2.5 amp A3977, I would. The bipolar option would be an asset. The problem is that I am a digital kind of guy and not an engineer. They give a formula like this toff =Rt*Ct but they don’t tell what units they are working with. I did figure that one out with this spec.:Fixed Off Time Rt =56 k ,Ct =680 pF, toff = 38 µs
And this calculator **broken link removed**

This is the kind thing that hangs me up:
The maximum value of current limiting is set by the selection of Rs and the voltage at the V REF input with a transconductance function approximated by:
Itrip max =Vref /8Rs
The DAC output reduces the Vref output to the current-sense comparator in precise steps (see table 2 for (%I TRIP max at each step).
I TRIP =(%I TRIP max/100)x I TRIP max
It is critical to ensure that the maximum rating 0.5 on the SENSE terminal is not exceeded.
Current Sensing: Rs =0.5/ITRIP max
If I could find example circuits, I could adjust them to fit my needs.
I think I searched for SLA 7062 circuits but got no results. Maybe I am not looking in the right place.

PS: RC Time Calculator
**broken link removed**
others
**broken link removed**
better
**broken link removed**
everything
http://www.csgnetwork.com/electronicsconverters.html

 

[ClydeCrashKop]

In the SLA 7062 data sheet 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 four 5 watt resistors take up a lot of real estate.
Do you know where I can find any sample application circuits that I can use as a starting point?