Stepper motor driver chip

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I'm looking at a project where a couple of "beefy" bipolar stepper motors are being used.

Motor info (all I can get at the momnet):
Current rating 2.8A
Phase resistance 0.9 Ohms
Phase inductance 2.5 mH

The motors are being driven at the moment by a controller which can supply 2.2A (1.6A RMS) but it is just enough and needs a little more.

I'm looking at the L6208 which SEEMS to be somewhat better than the L298 but the L298 LOOKS a lot beefier. :roll:

Also the L298 seems to have been around for ever, it's even in my 1992 SGS-Thompson PAPER databook. :shock:

So advice on anything newer/better/cheaper would be appreciated.

The usual "URGENT", hold my hand, do all the work for me apply of course. :lol:

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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You can have a less-beefy looking driver for more current if the forward switch drop is smaller. So, I would not let the appearance deter you if the specs look good.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Agree. The L6208 uses DMOS fets with Rds_on of 0.3 Ohm. Whereas the L298 uses "ordinary" bipolar transistors which have a saturation voltage of 1.7 resp 2V @ 2A. And that leads to a lot higher power dissipation.
You can now let my hand go ......
... yes, and Jim's hand too :lol:

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You said controller, but my Engineer Sensory Perception read that as Chip. There are Beaucoup boards for robots in every conceivable current rating at DFrobot.

Imagecraft compiler user

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Hand holding MAY still be required... :-)

Quote:
There are Beaucoup boards
The whole point of the exercise is NOT to have any other boards but a brand spanking new Mega1280 or 2560 based controller module with the lot, the 2 motors being only part of the overall project. Do DFrobot show their diagrams? :shock:

edit they do but the largest seems to be a 2A L298 based board.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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js wrote:
I'm looking at a project where a couple of "beefy" bipolar stepper motors are being used.

Motor info (all I can get at the momnet):
Current rating 2.8A
Phase resistance 0.9 Ohms
Phase inductance 2.5 mH

How about the ST L6470: "dSPIN fully integrated microstepping motor driver with motion engine and SPI"
â–  Operating voltage: 8 - 45 V
â–  7.0 A output peak current (3.0 A r.m.s.)

Datasheet: www.st.com/internet/com/TECHNICA...

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That seems to be a very nice IC.

Back in the previous century Elektor magazine had a board that basically provided all these functions; it only took a double eurocard sized PCB... modern technology can stuff all of that inside a tiny chip :)

One possible problem I see is that the package has a big thermal pad on the underside; this might make prototyping or hand soldered small runs more difficult.

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Imagecraft compiler user

Last Edited: Fri. May 18, 2012 - 03:36 PM
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Now, you sparkies will surely correct the old bit-pusher, but isn't L298 and similar just a "driver"?

We've had success on a couple of production apps using Allegro parts http://www.allegromicro.com/en/P... With the current control and choppers and whatnot built-in it seemed to make the job striaghtforward.

You can put lipstick on a pig, but it is still a pig.

I've never met a pig I didn't like, as long as you have some salt and pepper.

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I had looked at the ST L6470 but it is SPI driven, I rather the L6208 because it is closer to what is being used now software wise, trying to minimise changes as much as possible.

Both chips have the same current rating and all the built in goodies that the L298 doesn't have.

The Allegro A3979 seems a good candidate also. Unfortunately I seem to get this feeling when using Allegro parts that they will be discontinued and sure enough the 1st chip I looked at was not recommended for new designs.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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John -

I don't see those 2 chips as being equivalent. The L298 is a generic full-H dual bridge and can be used to drive motors, solenoids, steppers, and such. The L6208 is designed specifically for steppers with current control and the whole shebang. Then, again, I see that there are really two L6208s. There is L6208Q which seems to be just the dual full-H bridge and L6208D which is the stepper controller.

If you really are driving a stepper, then something with the goodies specifically for steppers can be a huge help. I have used the NJR chips and they work very well.

Jim

Jim Wagner Oregon Research Electronics, Consulting Div. Tangent, OR, USA http://www.orelectronics.net

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Quote:
I don't see those 2 chips as being equivalent
They are not of course, it's just that many seem to be using the L298, then I realised that either one needs to use the L297 or control the L298 in software (+ diode etc.) so the L6208N (the PDIP seems to have better dissipation) becomes very attractive.

It can just be driven with 2 pins for step and direction (similar to what the current system does with external controller boxes) so the code changes are insignificant.

Quote:
I have used the NJR chips
Any particular part number? It needs to supply about 2A-3A RMS like the L6208N.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly