9S12DP512 - Suggest me which stepper motor dirver Ic can i use

[saravanan_TTL]

Hi,

Iam using mc9s12dp512 and i want to interface this with a stepper motor.Can any one tell me what stepper motor driver Ic can use.

Regards,

Saravanan.A

Alban clarified subject

Message Edited by Alban on 2007-03-02 10:31 PM

[rocco]

Hi, Saravanan:

There are probably hundreds that will work with the DP512, but there are probably only a half dozen that will be appropriate for your application.

We would really need to know more about what you are trying to do. The first questions that come to mind are:

How much voltage and current does your motor require? That will cut down the choices tremendously.

How much performance do you need to squeeze out of the motor? Control can be as simple as a switch for each phase, or as complex as a closed-loop transimpedance amplifier.

What kind of motion do you require? Constant velocity with linear ramps would be simpler that contoured motion. This is usually an issue for your firmware, but some driver chips might support some level of simple control.

How much circuit protection do you need? A motor embedded in a printer may not need over/under-voltage or short circuit protection, but an industrial application probably would.

What is your sensitivity to cost?

Once you determine the answers to these questions, you may find the choices to be more obvious. Hope that helps.

Message Edited by rocco on 2007-03-0202:49 PM

[peg]

Hi,

One thing rocco left out of his otherwise excellent answer:

If you already have the motor. What basic type is it? Five phase? Two? etc.

This would be the first step to narrow the field down.

[saravanan_TTL]

Hi,

Thanks for helping me.The stepper motor is used to pull the lever of fule injection pump in the wheel loader(one of the eaeth moving machine) .the specification of the stepper motor is as follows:-

1. The number of phases : 4

2. Resolution :1.8 degree

3. Angle error : <5 (less the 5%)

4. Rated winding current: 1.5A

5. Winding resistance : 5.7 ohms

6. Inductance: 19 mH/Phase

7. Rotor inertia: About 0.23 Kg.cm2

8. coil insulation class: class H

9. Insulation resistance: 500 M ohms

10. Effective working angle: 80 degree

The stepper motor is for industrial use with 24V.We have ULN2002A stepper motor driver Ic,but the current limit is 500mA.We need ic with 2A.

Regards,

Saravanan.A

Message Edited by saravanan_TTL on 2007-03-0305:36 AM

[bigmac]

Hello Saravananan,

From the data you have given, the stepper would appear to have only 44 steps between the limits of its travel.  What are the resolution requirements of the application - do you need to "fractional step" the motor?

The driver will also need to implement current limiting to 1.5A.  With 24 volts applied to a winding, the current can potentially reach a level of about 4.2A.  I assume this is to provide a more rapid initial build up of the winding current, for faster acceleration, but it does add some complication to the driver.  What maximum step rate do you need to achieve?

Regards,

Mac

[saravanan_TTL]

Dear Mac,

Thank you for your reply,As per my data I made a mistake regarding effective working angle(which i said 80 degree)which is worng. In our stepper motor between shaft and outter shaft there is a reduction gear ratio.The ratio is not known to us. The 80 deg. figure is the total movement after the reduction gearbox.

Plz consider our requirment 400 steps per second maximum step rate that we may need to reach.and we need to drive the motor from a voltage source varying from 16 to 28.5 volt. Maximum current per winding is between 1.5 to 2 amps in normal condition.

Kindly suggest any suitable driver IC fo r this purpose

the specification of the stepper motor is as follows:-

1. The number of phases : 4

2. Resolution :1.8 degree

3. Angle error : <5 (less the 5%)

4. Rated winding current: 1.5A

5. Winding resistance : 5.7 ohms

6. Inductance: 19 mH/Phase

7. Rotor inertia: About 0.23 Kg.cm2

8. coil insulation class: class H

9. Insulation resistance: 500 M ohms

Kindly treat this specification as the final one.Thanking you.

Regards,

Saravanan.A

[rocco]

Hi, Saravanan:

I usually don't use stepper motors with that current rating, but I have used motors both larger and smaller. The drivers that I use may not be ideal, but they will work.


The first is a high end unit that costs just over $100. It is a stand alone driver that does microstepping (10 microsteps per full-step, which is 2000 steps-per-revolution) and can handle up to 7 amps per phase. You can set it for 1.5 amps, and it will give you great performance, but at a high cost. It is a transimpedance amplifier, which means it will provide the correct current, regardless of the supply voltage. You can see it at:
http://www.geckodrive.com/product.cfm?pid=9


The second is an IC that is dirt cheap. It contains four half-bridge switches, which is just enough for one stepper motor. It can only supply 1 amp continuous and 2 amps peak, and it can only do full-stepping (200 steps-per-revolution) or half-stepping (400 steps-per-revolution). As Mac described, you would need to limit the current, which you can do with a 24 ohm, 20 watt (minimum) resistor in series with each phase. Some of the disadvantages of this approach are: current that will vary with voltage, excess heat generated by the resistors, and lower resolution. You can see it at:
http://focus.ti.com/docs/prod/folders/print/l293.html


I wish I could suggest something between these two extremes, but all of my experience is at the extremes.

[bigmac]

Hello Saravanan,

Another couple of possibilities - I have not used either device, and am not sure of their availability or price.

Allegro

A3977 with 2.5 A current rating.

Unitrode (now TI)

UC3770 with 2A rating.  A separate device would be needed for each of the two motor windings.

On another issue, I have done some calculations of the time required for the winding current to ramp from -1.5A to +1.5A, with 16V applied, using the inductance and resistance values you quoted.  If my calculations are correct, this will take about 2.5ms for each transition, for each phase.  So your desire to achieve a maximum (full?) step rate of 400 steps per second appears somewhat optimistic.  To go beyond 100 full steps per second would result in a reduction of available torque - whether it remains adequate as the step rate increases will depend on the applied mechanical load.  The situation may be further exacerbated with the mechanical inertia, of both the motor and the load, also taken into account.

Regards,

Mac

Message Edited by bigmac on 2007-03-0609:37 PM