Adding a volume adjustment potentiometer to the LM4670 audio amplifier

Jameel Ahed

Prodigy 90 points

Other Parts Discussed in Thread: LM4670, LM4675

Can somebody help me add a volume adjustment potentiometer to the LM4670 amplifier?

The input is single ended. I will be following Figure 29 or Figure 30 on page 13, 14 of the datasheet.

What do you recommend I do?

over 10 years ago

0 Toyojiro Naokawa over 10 years ago

TI__Intellectual 1240 points

Hello Jameel-san,

I'll suggest you to use LM4675 instead of LM4670 because LM4670 has delta-sigma modurator and may have tone noise in audio freq range depending on inductance value of speaker. If your speaker inductance value is less than 13uH, then no tone noise. but larger than 13uH, I'll recommend to use LM4675 which take PWM modurator and no tone noise. LM4670 and LM4675 are functionally same and you can adjust the gain as fig-29 on LM4670 and fig-28 on LM4675 datasheet.

Best regards

T NAOKAWA

0 Jameel Ahed over 10 years ago in reply to Toyojiro Naokawa

Prodigy 90 points

Thank you very much for your help!

I will consider the LM4675 for my project instead.

I still do not see in Fig-28 of the LM4675 datasheet how to adjust the volume using a potentiometer. Can you draw me a simple schematic showing me how to implement this?

Thank you very much!

0 Toyojiro Naokawa over 10 years ago in reply to Jameel Ahed

TI__Intellectual 1240 points

Hello Jameel-san,

I up-loaded simple schematic about location of potentiometer.

Please visit the URL.

5751.LM4675 output adjustment.xlsx

I hope this help for you .

Best regards

T NAOKAWA

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Adding a volume adjustment potentiometer to the LM4670 audio amplifier