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LM4875: LM4875 Volume Control

Rachel Zhou
Prodigy 70 points
Part Number: LM4875

Dear Engineers，

LM4875 can change the gain by controlling the voltage of DC Vol foot.According to the datasheet, DC Vol pins a sliding rheostat to control the voltage.

What should I do if I control the volume with two volume buttons?

Is there any other way to do it than by using a potentiometer?

How do I connect my buttons?

Thank you very much！

  • 0
    TI__Guru* 84915 points

    Hi, Rachel,

    The gain can be controlled by the DC Vol pin as you mentioned. However, in order to increase the gain, the DC Vol pin requires of a voltage from GND to VDD. The gain variation is described in Figure 26 ( http://www.ti.com/lit/ds/symlink/lm4875.pdf#page=10 ).

    If you could modify the voltage level with the two volume buttons, you would be able to modify the gain. Otherwise, you would need to use a potentiometer connected to VDD. Or another voltage source from GND to VDD.

    Please let me know if you have additional questions or comments.

    Best regards,
    Luis Fernando Rodríguez S.