DRV8323: Using the INLC input pin to brake a BLDC motor

Alexander Frick

Part Number: DRV8323

Hello,

I am currently using the INLC pin on the DRV8323 as a hardwired brake for our BLDC motor.

A question has come up as we look into functional safety on our machine if the INLC pin is braking the motor directly, or if the INLC pin goes through the DRV software to brake the motor.

Can someone clarify how the INLC brake pin functionally brakes the motor? The block diagram for the DRV8323 does not show everything we need to determine how that signal gets from the INLC pin to brake the motor.

Thanks for the help!

over 3 years ago

0 Adam Sidelsky over 3 years ago

TI__Guru 61380 points

Alex,

Let me check with the team and see what we can provide. I may need until early next week.

Regards,

-Adam

0 Alexander Frick over 3 years ago in reply to Adam Sidelsky

Intellectual 645 points

Thanks Adam,

Let me know if you have any questions as the team looks into it!

Alex

0 Adam Sidelsky over 3 years ago in reply to Alexander Frick

TI__Guru 61380 points

Alex,

For the purposes of Functional Safety the INLC brake does not directly shut down the outputs.

The INLC goes to our normal digital inputs and then digital core which controls the output stage in 1x PWM.

Regards,

-Adam

0 Alexander Frick over 3 years ago in reply to Adam Sidelsky

Intellectual 645 points

Adam,

Thank you for the quick response!

What is the architecture of the digital core? It sounds like there is logic involved, but is it controlled with the same software as the main outputs?

If so, is there a similar driver chip that would give us a true hardware brake? Or would it be easier to design a circuit around the DRV chip to apply the motor brake?

Thanks for the help!

Alex

0 Adam Sidelsky over 3 years ago in reply to Alexander Frick

TI__Guru 61380 points

Alex,

Sorry for the delay.

The same digital core is used for both input parsing and sequencing the outputs.

If you need a functional safety device then we can discuss those needs.

It may be easier to add an external hardware brake which pulls the inputs low or the ENABLE pin low when needed.

Regards,

-Adam

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DRV8323: Using the INLC input pin to brake a BLDC motor