DRV8818: Analog input pin

NAOKI AOYAMA

Guru 11215 points

Part Number: DRV8818
Other Parts Discussed in Thread: DRV8886AT

Hello,

Our customer use the DRV8818, have a question.

Is there any internal filter at analog input pin (VREF, DECAY)?

The customer are considering the noise impact on the device operation.

Best Regards,

Naoki Aoyama

over 7 years ago

0 James Lockridge19 over 7 years ago

TI__Genius 14487 points

Aoyama-san,

These pins do not have internal filtering. The datasheet recommends a 0.1-uF capacitor on DECAY. You can use that same value for VREF if you have noise concerns on that pin also.

0 NAOKI AOYAMA over 7 years ago in reply to James Lockridge19

Guru 11215 points

Hello James,

Thank you for your reply.

I see the DRV8818 has no internal filter at these pin.

I suggest the customer to connect a capacitor.

The device of the competitor have internal filter at all control pin.

datasheet_motor_driver_competitor.pdf

I hope the new devices like a DRV888x series have internal filter.

Thanks,

Naoki Aoyama

0 James Lockridge19 over 7 years ago in reply to NAOKI AOYAMA

TI__Genius 14487 points

Aoyama-san,

Thanks for your feedback. The DRV8886AT latches the DECAY pin setting at power-up like you describe. The VREF/RREF pin is an analog input, but since this sets the full-scale current level, the motor may not respond to noise/transient on this pin. I still recommend a capacitor on the VREF/REF pin, but if you are space- or cost-constrained, you may be able to remove it.

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DRV8818: Analog input pin