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DS90UB940N-Q1: Need advice for external components selection

Atsushi Hirai
Expert 4960 points
Part Number: DS90UB940N-Q1

Hi team,

My customer want to reduce the BOM or use usual cheap components as much as possible.

Please give me your advice.

- Customer do not use I2S. Can they remove the capacitor at CAP_I2S and leave it open?

- Customer do not use CSI1 output. Can they remove VDD12_CSI1 power supply, bypass capacitor and leave it open?

- They want to use E24 resistor for MODE_SEL0/1.

For MODE_SEL0, they use setting No.2. is 68kohm/20kohm combination works fine?

For MODE_SEL1, they use setting No.1. is 75kohm/15kohm combination works fine?

Best Regards,

  • 0
    TI__Guru** 103215 points

    Hello Atsushi,

    Can you share the resistor tolerances for the MODE pins you mentioned? We will also check the remaining questions next week.

    Best Regards,

    Casey

  • 0 in reply to Casey McCrea
    TI__Expert 4960 points

    Hi Casey-san,

    The tolerance is 1% or 5%.

    Thank you for your support.

  • 0 in reply to Atsushi Hirai
    TI__Intellectual 2930 points

    1.CAP_I2S needs to be there and cannot be removed . It is a compensation cap for an internal regulator. Removing it may create regulator instability that may create significant noise inside the silicon

    2. Bypass cap on VDD12_CS1 can be removed if you are not using that port

    3. I would suggest not to change the tolerance values of the resistors as the MODE_SEL are validated using specific values and specific tolerances

    Thanks

    Vijay

  • 0 in reply to Vijaya Ceekala
    TI__Expert 4960 points

    Vijay-san,

    I have questions to your answer. Please give me your advice again.

    1.CAP_I2S needs to be there and cannot be removed . It is a compensation cap for an internal regulator. Removing it may create regulator instability that may create significant noise inside the silicon

    -> I heard the purpose of the capacitor is I2S PLL loop filter. If so, I though it can be removed. Could you double check it?

    2. Bypass cap on VDD12_CS1 can be removed if you are not using that port

    -> My question is not only the capacitor but also the connection. Is it okay that VDD12_CS1 leave floating?

    3. I would suggest not to change the tolerance values of the resistors as the MODE_SEL are validated using specific values and specific tolerances

    -> Do you mean 68kohm/20kohm +/-1% E24 resistor has a risk of misconfiguration?

    Regards,

  • 0 in reply to Atsushi Hirai
    TI__Intellectual 2930 points

    Both regulator cap and I2s PLL cap are important and cannot be removed. It is not OK to keep VDD12_CS1 floating.

    Yes any values that are not recommended in Datasheet can lead to a risk of misconfiguration. These are parts meant for Automotive applications and are qualified with a specific set of components with specific tolerances. We cannot change it as it may lead to risk of misconfiguration

    Thanks

    Vijay