DRV8811 Not Working Properly

Thanks for your  reply..

When I power the device . Its working good..

after few seconds there no output in Bout_1,Bout_2..

So, is the device broken now or every time you power on, the issue will be the same?

Have you checked the output waveform, you can post it here if you have.

I still suspect the Rsense resistor. What is your current setting and power of the sense resistor?

And if your BOUTx failed, the motor should stop and vibrate, are you sure AOUTx is normal?

Thanks.

I also suggest checking your VREF voltage, and the associated ICHOP.  And like Wilson said, RCA/RCB components, and DECAY voltage.

Best regards,
RE

I Control the IC (DRV8811) with micro controller.

Decay Voltage is  2.5 V

Hi Mayilsamy

Have you checked the real value and connection of those components? Example, measure the resistance of both sense resistor on the issued board. check your motor's windings and the two phase resistors real value. Also could give the scope capture of your BOUTx when you said AOUT is normal.

A quick method is to swap the DRV8811 to a new one.

if the problem is just the same, then, we can say that there should be some hardware problems related to the PCB. Because there is almost no chance to met two broken parts with this kind of failure.

If the problem is gone, there should be some abnormal condition happened to the failure part and cause some damage to the parts.

Thanks,

Wilson Zuo

Wave Forms

Wave Forms.....

Hi..

Any body give your Email. Id  I sent motor running video..

Hi Mayilsamy

I have added you as my friend and give my email address.

from your waveform, there should be something wrong with BOUTx. I have never seen this before. So really need you to give more descriptions about your debuging process.

Thanks.

Wilson

Hi Mayilsamy,

Can you confirm the capacitor for RCA/RCB is 0.1uF? The datasheet does not specify a minimum or maximum, but it was intended to be much less than this.

The recommended Rx should be between 12kOhms and 100kOhms, and the recommended Cx should be between 470pF and 1500pF. The datasheet of a similar device, the DRV8818, shows these recommendations.

Please be sure to lower the Cx capacitor to be within this range, and let us know if BOUT begins working properly.

Thanks.

Hi.. All.

My motor running video uploaded in my profile...

So, Kindly watch it....

Hi Maylisamy

The motor looks running normally at first several seconds.

I think may be the cause is related PCB ground noise, and if the ground is not proper, noise on DIR and STEP inputs pin may affect the normal running sequense. Could you try to put a external pull down resistor such as 3k to ground of DIR pin and STEP pin and test again.

Could you show us the board or the PCB?

Thanks

Wilson Zuo

Hi Maylisamy

Just realized that you have RCA/RCB == 33k ,0.1uf.

That means Blanking time = 140us and OFF time = 3.3ms. It is too long for most steppers. That will cause running problems.

It is recommended to change the C value within 680p to 1500p so that the Blanking time is around 1~3us commonly used.

Thanks

Wilson Zuo

Thanks..  For your  reply at the earliest..

I changed the C value 1000p .. Motor starts to run..

Thank you..

And also motor making  hiss sound (ringing).

How to rectify it.

Mayilsamy.A 

Hi Mayilsamy

Glad to know it worked. The hiss sound is the currrent chopping noise. You can change the RC parameters to tune the mixed decay behavior. Please refer to datasheet Page9, 10 ,11 to optimize the fast decay and slow decay portion of the off time.

Usually the more fast decay time, the more current ripple and noise. But if fast decay time is too small, the current can't be regulated well as we want.

Also you can increase the PWM frequency by reduce the R*C value to lower the audio noise.

Thanks

Wilson

Hi.. Wilson.

I have one more doubt .  Whenever  I increase the  Vref  Voltage motor speed was automatically increased.

What is the step calculation?

How I control the  speed of the motor??

Thanks

Mayilsamy

Hi Mayilsamy,

VREF will control the torque and should not have an effect on speed unless the motor does not have enough torque to overcome the inertia of the load.

Since this is a STEP/DIR part, one pulse on the STEP pin will correspond to one step/microstep in the indexer. Speed is determined by the frequency of the step pulses.

Great Thread so far! 

-Frank

-Motion Marketplace

-www.motionmarketplace.com