DRV8301 PWM Output

Jordda

Other Parts Discussed in Thread: DRV8301, DRV8302

Hi,

I make a DRV8301 board which schematic follows the EVM board design. Now this board can output 5V from its buck converter. But it cannot output PWM with PWM input into DRV8301. Could you advice me how to debug this issue? Thanks!

over 12 years ago

0 Jordda over 12 years ago

Intellectual 665 points

More information for my condition ....

I run DRV8301 EVM board to produce PWM from its control card. When DRV8301's PWM into my board, I found FAULT is LOW and OTW is HIGH. If no PWM into my board, FAULT and OTW are kept HIGH. I do not send any command to DRV8301 via SPI interface.

0 Nicholas Oborny over 12 years ago in reply to Jordda

TI__Mastermind 21320 points

Hi Jackson,

The buck will still be enabled even when the DRV8301 is in a FAULT condition which sounds like the issue that you are having. The FAULT condition will disable the drive side, hence your problem. There are four main reasons that a FAULT could be occuring, over-current, over-temp, over-voltage, or under-voltage. This is all in the datasheet. What kind of motor are you driving, what kind of power supply are you using?

-Nick

0 Jordda over 12 years ago in reply to Nicholas Oborny

Intellectual 665 points

Thank you. I will try to debug this issue based on your advice.

0 Jordda over 12 years ago in reply to Jordda

Intellectual 665 points

I've checked GVDD pin voltage and found it's 0.01V only. So I guess that's why FAULT error happened. Besides one capacitor 2.2uF/25V connected between GVDD and GND, what should I take care of ?? If we cannot do anything for GVDD, it ,does it mean this DRV8301 is broken ??

0 Wilson Zuo over 12 years ago in reply to Jordda

TI__Mastermind 26065 points

Hi Jordda

May be a superfluous reminding here, have you make sure the PowerPAD firmly soldered to the GND Plane? For DRV8301, the PowerPAD is not only for thermal dissipation. It is also the GND connection.

Thanks.

Wilson

Motor Application Team

0 Jordda over 12 years ago in reply to Wilson Zuo

Intellectual 665 points

Hi Wilson,

Really appreciate your advice. Indeed, we coat the paste between PCB ground pad and DRV8301 (Pin57) power pad. If this paste is not conductive, is it a problem?

0 Wilson Zuo over 12 years ago in reply to Jordda

TI__Mastermind 26065 points

Hi Jordda

So, you mean the PowerPAD is not connected to you ground?

That will cause problem as the PowerPAD is acturally the GND PIN of DRV8301. It must be well soldered to ground for DRV8301 or DRV8302, which is unlike other DRV8x parts that the PowerPAD is only for thermal function.

You can test it again quickly with some handly craft to connect the pad to ground.

Also, Powerpad is really needed for cool it even its a pre driver.

Thanks.

Wilson

0 Jordda over 12 years ago in reply to Wilson Zuo

Intellectual 665 points

I will try it again based on the guideline. Thank you !!

Just a curious question here... I've connected Pin-28 AGND with PCB ground pad. Also 5V from bulk converter is okay. So Pin-28 AGND cannot fully cover Pin-57 grounding function for electrical part ??

0 Wilson Zuo over 12 years ago in reply to Jordda

TI__Mastermind 26065 points

Hi Jordda

Yes. AGND is usually for logic section. Here the PowerPAD is like PGND which is for power stage.

Thanks.

Wilson

0 Jordda over 12 years ago in reply to Wilson Zuo

Intellectual 665 points

Very clear and useful comments. Wilson, Thanks !!

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DRV8301 PWM Output