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PCM1774: Request for review of schematic of PCM1774

Grady Lee
Genius 3825 points
Part Number: PCM1774

Tool/software:

Hi, TI expert

A customer has requested a schematic review of the PCM1774.

- Application: Industrial and vehicle driving record type AI BOX.

Please review whether there are any parts to be modified or added.

Thank you.

  • 0
    TI__Mastermind 40215 points

    Hi,

    Today is a holiday for our team in the U.S. Please expect a 24 hour delay in our response.

    Thank you for your patience,
    Jeff McPherson

  • 0 in reply to Jeff McPherson
    Genius 3825 points

    Hi, Jeff McPherson

    In addition, please confirm one more thing.

    Regarding the CAPACITOR value of the POWER SUPPLY PIN, I applied it by referring to the EVM board reference.

    Since it is applied relatively simply in the data sheet, I would like to reduce the CAPACITOR if possible because the space is narrow.

    Please check this part as well.

  • 0 in reply to Grady Lee
    TI__Mastermind 26641 points

    I will review it by the end of Wednesday. Thanks for your patience.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    TI__Mastermind 26641 points

    Hello Grady,

    Here are few recommendations:

    1- You don't need the series 22 ohm resistor for all digital pins, for I2S pins keep them

    2- For I2C pins use pull up resistors ( you can refer to this  application note  for more information: SLVA704–June 2015 Understanding the I2C Bus)

    3- For MODE pin remove 22-ohm , you can use a pull down/up resistor based on your need.

    4- The  capacitors you have at the moment are preferable and I would use them but at the end of the day you can always differ from recommendation and still the part would work fine. So if you really have to reduce them, then that is what needs to be done.

    Regards,

    Arash

  • 0 in reply to Arash Loloee
    Genius 3825 points

    Hi, Arash

    Thank for response.

    Customer have additional questions.

    Q1) 1- You don't need the series 22 ohm resistor for all digital pins, for I2S pins keep them
    → You said 22ohm is not necessary, if I use it, will it be a problem?

    Q2) Regarding the VDD (DIGITAL CORE) voltage, there is no explanation in the spec sheet about how the characteristics are different at 1.8V and 3.3V.
    Please explain this part.

    Please check. Thank you.

  • 0 in reply to Grady Lee
    TI__Mastermind 26641 points

    Hi Grady,

    The  22 to 100 Ohm resistors are used to avoid reflection and ringing on I2S  lines.  We do not use those resistors for other pins .  Removing/shorting an unnecessary component should be easy and i suggest to do so even do I don't think it will be an issue. 

    Whatever is provided in the datasheet,  is the data set that we have available. If there was a change/shift  in the characteristic for 1.8V vs 3.3V,  it would have been mentioned in datasheet and plots and numbers would have been provided.

    Regards,

    Arash