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PCM1795 VcomL, VcomR

KANJI SHIBATANI
Mastermind 6205 points

Other Parts Discussed in Thread: PCM1795

 

Hello,

My customer intend to design their product using PCM1795

They want to reduce the PCM1795 VcomL, VcomR set up time as attached ( .tiff ) file.

Q1  VcomL( VcomR also)  terminal voltage is 2.5V  ? in the  schematic in  d/s page 37.Fig 52 ?

Q2 Customer's schematic as attached is Okay?  ( I think input impadance is high enough, its Okay, but no description in d/s)

Please advise.

 

Thank you for your support.

Best Regards

 

 

PCM1795_Vom.TIF

 

 

 

 

 

 

 

  • 0
    TI__Guru 57800 points

    Hi Shibatani-San,

    I have asked Justin-San to take a look to your questions, as he is out of the office due to holiday, he will get back to you in one or two days. 

    Best Regards,

      -Diego Meléndez López
       Audio Applications Engineer

  • 0 in reply to Diego Melendez
    TI__Mastermind 28110 points
    Hi Shibatani-San,

    Q1: Yes the Vcom output is always 2.5V, this is created internall from a constant curent source, and therefore will not change.

    Q2: The input impedance of the Vcom pins is 20k Ohms, this means that the external voltage divider the customer is proposing will be largely driven by the external circuit, but this voltage directly feeds the internal current segments, so if there is any issue with the voltage divider, it will directly couple into the output. We recommend that you try the smaller capacitor without the external divider.

    Justin
  • 0
    Mastermind 6205 points
    Dear Justin-san,

    Thank you for your quick answer !
    I will talk to customer.

    Best Regards