Question about DRV8840

Jose Balderas

Other Parts Discussed in Thread: DRV8840

I have a problem with DRV8840.

When I enable the circuit rhrought the enable terminal , the motor is work but only a few secons, I review my circuit and can not find a problem, Someone know what is the problem?

Best Regards, Alberto.

over 11 years ago

0 Ryan Kehr over 11 years ago

TI__Guru 55605 points

Alberto,

Are you using an EVM? If not, can you please post your circuit and layout?

Also, do you have a spec for your motor and any information about your application/load conditions/etc, would be helpful.

Is the nFAULT pin going LOW?

0 Jose Balderas over 11 years ago in reply to Ryan Kehr

Prodigy 50 points

I design my owm board,

I attach the files.8360.Pcbs.pdf 3201.Esquematico.pdf

0 Jose Balderas over 11 years ago in reply to Ryan Kehr

Prodigy 50 points

The state of nFULT pin is LOW.

0 Ryan Kehr over 11 years ago in reply to Jose Balderas

TI__Guru 55605 points

Thanks for posting your schematic and layout.

Couple of points to check to ensure chip is working:

1). The nFAULT pin is an open-drain output. You will need a pull-up to 3.3V to see the proper operation of that pin.

2). I don't see any bulk capacitance (100uf or larger) on your VCC node. This will be necessary to avoid an under voltage condition when the motor is loaded or over-voltage under deceleration or sudden stop. Use a scope to check your supply at startup and see if it is within the operating range.

3). Check V3p3out pin to ensure the regulator is working. I think we also recommend a 0.47uf cap on that pin.

4). Is the PowerPad on the bottom of the chip soldered to your PCB? Thermal protection could be turning on.

0 Jose Balderas over 11 years ago in reply to Ryan Kehr

Prodigy 50 points

Thanks Ryan for your support,

I solve the problem with the motor.

Best Regards,

Alberto.

0 Ryan Kehr over 11 years ago in reply to Jose Balderas

TI__Guru 55605 points

Alberto,

Great! I will go ahead and close this out.

0 Matthew Krenik over 11 years ago in reply to Ryan Kehr

Intellectual 675 points

Hello, I am having problems with the DRV8840 as well. The nFault is high, and there is a large capacitor on Vm and everything seems to be hooked up correctly (I copied the design on the evaluation module, and put it on a breadboard). The one problem I have is that the regulator doesn't seem to be working V3P3OUT pin is at 0V.

How can I fix this issue? Is it because the chip is not functioning properly, maybe an issue with soldering, or is it something regarding the circuitry?

Best,

Matthew

0 Wilson Zuo over 11 years ago in reply to Matthew Krenik

TI__Mastermind 26065 points

Hi Matthew

Could you open a new post of your issue?

And better with your schematic and the picture or layout of the breadboard.

And if the problem is not found on TI EVM, there should be layout or schematic problems.

Thanks.

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Question about DRV8840