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PCM1781 power up and down

Other Parts Discussed in Thread: PCM1781, CC8520, PCM5101A, PCM5102EVM-U

Hello All,


I am using a PCM1781 in a consumer audio application that has a standby requirement.

The design pulls power from a 5V regulator I have running the 1781 and I will hear an audible pop through my amplifier.  I think I'm looking for a solution that soft starts, soft powers down the 1781.

Has anyone dealt with a similar problem?

What was the solution.

Details- the input from the PCM1781 is from a PurePath wireless CC8520.

I don't think that the CC8520 is the problem.  I have successfully been able to delay the PurePath turn on, but the problem still persists.   I have also independently cut power to the wireless section (disable 3.3V supply) and the problem still persists.  


This setup has been great- and I have used it on a couple of other products without having to go to standby. 

Thanks,

Justin

  • Hi, Justin,

    The PCM1781 is about ten years old, so we have made great advances in the performance for our newer devices. I suggest you look at the PCM5101A which is one of our newer products and I think you will find it is a nice upgrade to the older PCM1781.

    If you are driving a final amplifier stage with the PCM1781, you might try muting the amplifier while the PCM1781 is powering up and down.

    -d2

  • Don,

    I know it's been a while since this conversation started, but I'm beginning a new project and intend to use upgrade from the PCM1781 to the PCM5101A. The PCM5101A will be fed by a PurePath CC8520. From what I can see the I2S bus is the same, is there anything I need to consider in the setup of the PCM5101A when connecting the the CC8520?

    Thanks,

    Justin
  • Hi, Justin,

    I don't think so. The PCM5101A is a hardware-controlled device, so you don't need to program it or anything.

    -d2
  • Don,

    Thanks for the reply, I figured out the hardware setup.


    I'm down laying out the PCB.  I found in the data sheet that it suggest putting the power supply and charge pump caps as close to the PCM5101A as possible.

    The example layout shows the 0.1uF caps as 0605 or 0402 parts, but does not show the 10uF parts.

    My question is do only the 0.1uF caps need to be close and can the 10uF caps be more remotely located?

    Thanks,

    Justin

  • Hi, Justin,

    Great!

    For layout recommendations, please check our EVM design: PCM5102EVM-U

    -d2