LM4991: Feedback resistance

Atsuo Nakano

Prodigy 40 points

Part Number: LM4991

Tool/software:

Hi Ti,

I am planning to use a digital potentiometer for the feedback resistor (RF) of the LM4991.

I am thinking of using this to control the gain, but is this a problem?

Best regards,

3 months ago

0 Wenbin Li1 3 months ago

TI__Intellectual 2100 points

Hi Atsuo,

I think it's ok to use digipots for the feedback resistor.

But if you just only want to tune volume and the digipots need I2C control, you can check TPA2028/TPA2018, it is analog input AMP with I2C control to tune AGC which has the gain control settings.

Br,

Wenbin

0 Atsuo Nakano 3 months ago in reply to Wenbin Li1

Prodigy 40 points

Thank you for your prompt response.

Also, thank you for your suggestion.

Is it possible to use TPA2028 in single-ended?

Best regards,

0 Atsuo Nakano 3 months ago in reply to Atsuo Nakano

Prodigy 40 points

Hi Ti,

It is a single-ended input.

Best regards,

+1 Wenbin Li1 3 months ago in reply to Atsuo Nakano

TI__Intellectual 2100 points

Hi Atsuo,

regarding the single-ended input, you can refer to TPA2026 which is similar.

the page 32 of below link(TPA2026 datasheet.

https://www.ti.com/lit/gpn/TPA2026D2

Br,

Wenbin

0 Atsuo Nakano 3 months ago in reply to Wenbin Li1

Prodigy 40 points

Thank you for your answer.

I will consider it.

Best regards,

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LM4991: Feedback resistance