DRV8434: Force to Constant Frequency Drive

Hi Jason,

The DRV8434 current regulation using all decay modes except smart tune ripple control STRC is based on fixed tOFF. However because tON can vary according to motor coil characteristics, supply voltage etc it cannot operate with a constant frequency. The STRC uses variable tOFF, so it will not be suitable as well. So there is no way to force the DRV8434 to a constant PWM frequency based current regulation.

Older stepper drivers such as the DRV8824 and DRV8825 use fixed PWM frequency based current regulation. 

Regards, Murugavel 

Hi Murugavel,

Thanks for your response here. I've let the customer know and will reach out again if needed.

Best,

Jason Maxwell

Hi Murugavel,

The customer has a couple more questions that I could use some help on:

"Does the DRV8824/25 use fixed frequency in all the decay modes? Would smart tune ripple on the DRV8434 result in smoother motor operation compared to decay modes on the older DRV8824/25?

Would there be another driver with similar pinout as DRV8434 that will do a constant frequency drive we can try?"

Please let me know what you think.

Best,

Jason Maxwell

Hi Jason,

Jason Maxwell said:

Does the DRV8824/25 use fixed frequency in all the decay modes?

Yes it does.

Jason Maxwell said:

Would smart tune ripple on the DRV8434 result in smoother motor operation compared to decay modes on the older DRV8824/25?

Definitely. The STRC or STDD automatically optimizes decay modes slow, fast used for optimum current regulation. 

Jason Maxwell said:

Would there be another driver with similar pinout as DRV8434 that will do a constant frequency drive we can try?"

The DRV8824 and 8825 are the only ones with fixed PWM. Thanks.

Regards, Murugavel 

Thank you Murugavel! These clarifications are super helpful for me and the customer.

I will let you know if there is anything else.

Best,

Jason Maxwell

Sure!