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LM4811: Lm4811 volume Control method

Hanna Nabil
Prodigy 90 points
Part Number: LM4811

I don't have microprocessor in my circuit and I wanna use just tactile switches or any switch instead of mc to control volume, So i have been guided that this is the only IC that do that.

How the switches should be used  on clk and up/down pins !?? I mean Can I put both pins on one tactile switch ? As it will be hard to synchronize the clock and up/Dn if 2 tactile switches are used..

About the clock it isn't specified in the datasheet what is the Max the clk pin can handle ?  Can it handle 3.072MHZ ?

  • 0
    TI__Guru* 84915 points

    Hi, Hanna,

    Welcome to E2E and thank you for your interest in our products!

    The volume control of this device depends mainly of the clock rising edge. So, any pulse from an external controller or switch can work to either increase or decrease the volume. In case you are using a switch, it is important to suppress any bounce or additional pulse. Otherwise, it may cause additional volume increment/decrement.

    The logic state of the UP/DOWN pin and the clock edge will determine if the voltage increases or decreases.

    The 3.072MHz frequency can be supported by this device.

    Best regards,
    Luis Fernando Rodríguez S.

  • 0 in reply to Luis Fernando Rodriguez S.
    Prodigy 90 points

    Does this attached circuit from demo application in datasheet page 16 (attaching the clk pin 0.1uf & 2 100ohm resistor) will do the job and avoid the bouncing effect ?

    also in the schematic why there isn't also a bouncing capacitor on Up/DN pin ?should I put one if I attached this pin to a switch ?

  • 0 in reply to Hanna Nabil
    Prodigy 90 points

    or should I use this circuit at clk pin ? 

  • 0 in reply to Hanna Nabil
    Genius 3945 points

    Hanna Nabil said:

    Does this attached circuit from demo application in datasheet page 16 (attaching the clk pin 0.1uf & 2 100ohm resistor) will do the job and avoid the bouncing effect ?

    also in the schematic why there isn't also a bouncing capacitor on Up/DN pin ?should I put one if I attached this pin to a switch ?

    The intent is to both filter out bounces on the clock as well as delay the clock edge until after the Up/Down input has settled. If you press and hold Up/Down, or leave it unpressed, then it's static and settled before you press the clock switch. So there is no need for debounce on the Up/Down input.

    Of course two switches like this isn't a great user interface.

  • 0 in reply to Andy Peters
    Prodigy 90 points

    yes I got it, but what do you mean by it isn't a great user interface, and what can be an alternative for this excluding a micro-controller ? 

  • 0 in reply to Hanna Nabil
    Genius 3945 points

    Hanna Nabil said:

    yes I got it, but what do you mean by it isn't a great user interface, and what can be an alternative for this excluding a micro-controller ? 



    A user would likely expect an Up button and a Down button.  Look at any stereo or TV remote control. You don’t see a clock button and an Up/Down-select button, right?

    I‘m sure there’s a way to do something clever with 74xx-series logic and some passive parts, but I would just use a micro for this task.

  • 0 in reply to Andy Peters
    Prodigy 90 points

    Aha got that Thanks, 
    one last question , Shall this normal connection to CLOCK pin suppress bouncing ? 

  • 0 in reply to Hanna Nabil
    Prodigy 90 points

    the debouncing circuit is the same as the one in the datasheet by the way