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LP5907-Q1: Which parameter should see , if my system ( DAC ) would work at 50MHz

Julio Cesar Molina Saqui
Prodigy 40 points
Part Number: LP5907-Q1

Hi,

I would like to get the best performance in the power supply for my DAC (PCM5252) .

what is the effect of the clock system (in my case 50MHz ) on the power supply?

which parameters should always take into account when I'm working with powering noise sensitive systems? only output noise? 

Could you suggest a list of techniques in order to improve the output noise?

thanks a lot for  your support.

  • 0
    TI__Mastermind 29260 points

    Hi Julio,

    Please review these application notes and let me know if you have further questions.

    http://www.ti.com/lit/an/slyt201/slyt201.pdf

    http://www.ti.com/lit/an/slyt489/slyt489.pdf

    http://www.ti.com/lit/an/slyt504/slyt504.pdf

    http://www.ti.com/lit/wp/slyy076/slyy076.pdf

    These application notes are from an LDO perspective.

    Section 11 of the DAC datasheet provides additional details on best practices.
    You will want to incorporate a ground plane to protect noise sensitive devices from capacitively coupled EMI (one of the four EMI coupling mechanisms).
    The LDO circuitry should have GND of the LDO directly underneath it on layer 2.  The same for the DAC.  This will act as an effective EMI shield against capacitively coupled transients, such as those from the 50MHz clock. 

    Conductive EMI is another one of the 4 EMI coupling mechanisms.  By adding decoupling capacitors, you are protecting the DAC from this EMI mechanism.  The thinner the dielectric between the top layer and the layer 2 (which should be GND), the better, as this reduces the inductance and increases the board capacitance, which improves your decoupling. 

    I hope this helps.

    Thanks,

    - Stephen