MCF8316A: Higher speed loop accuracy

Hi Yishan Chen,

MCF8316/5 or MCF8329 all mentions up to 3% speed accuracy with internal oscillator, this 3% accuracy is across temperature range.

Customer can use external oscillator and we expect upto 1% accuracy.

What is the application>

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

The application scenario is Lidar.

Could you please answer my question?

Yishan Chen said:

By the way, Is the speed loop accuracy in the datasheet means the accuracy of actual rotation speed? 3% in MCF8316 for example.

Yishan Chen said:

If we don't have any MCF devices can achieved that, Could we use DRV8311 to achieve that speed accuracy? What is the main obstacle to achieve this speed accuracy?

Thank you,

Yishan CHen

Hi Yishan Chen,

Speed Loop Accuracy: Yes this is the rotation speed accuracy.

Various factors influence the speed loop accuracy, signal chain accuracy, control loop bandwidth etc

In sensor less device relies on accuracy of BEMF sensing through phase current.

Even if you want to use DRV8311 you may need to try sensor or any high accuracy feed back method to minize errors.

There is also influence of temperature drift and hence we specify 3% means across temperature.

If you use external clock speed accuracy is less than 1%.

Thanks and Best Regards

Venkatadri S

Hi Venkatadri,

Thank you

Do we have any reference design or EVM can achieve high speed accuracy to satisfy customer requirements?

Do we have the suitable solution?

Best Regards,

Yishan Chen

Hi Yishan Chen,

Speed accuracy is due to device capability than EVM.

As mentioned before, by using external clock we get better speed accuracy .

Meanwhile I will check for some reference and share you.

Can you share motor data sheet?

Thanks and Best Regards

Venkatadri S

Hi VenKatadri,

Please check below motor data:

Pole pair：6
stator resistance：1Ω±8%
BEF Constant:Kt:14.6 mV/Hz
Stator inductance：700uH ± 10%( 5V 1KHz)
rate current：1A

Thank you,

Yishan Chen

Hi Yishan Chen,

I am traveling this week. I will respond by Friday.

Thanks and Best 

Venkatadri S 

HI Yishan Chen,

Motor parameters are good and as mentioned before we can achieve up to 1% speed accuracy by using external clock.

Thanks and Best Regards

Venkatadri S