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CDCS502: Characteristics of Internal Capacitance & Tx-tal

Zeming Kong
Expert 3515 points
Part Number: CDCS502

Hi there,

My customer is evaluating CDCS502, and he needs to know the characteristics of internal 10pF load capacitance, like temp characteristics and tolerance.

Also, what does the Tx-tal mean? It is descripted as crystal power dissipation, so the crystal with power consumption > 50uW is recommended here?

Best,

Zeming

  • 0
    TI__Intellectual 770 points

    Hi Zeming,

                     Happy New Year. Since the first part of the question is related to an on-chip component, the internal 10 pF capacitance, i will need to discuss with my team to see if there is documentation of what the variation with PVT looks like. Please provide few days for me to get back to you with an answer.

  • 0 in reply to Badarish
    TI__Expert 3515 points

    Hi Badarish,

    Happy new year and thanks for your reply.

    Could you please tell me how long you may need to prepare for the question? The customer is fixing the design, so he wants a definite schedule. 

    And could you tell me if my consideration for the Tx-tal is correct at first?

    Very sorry for the sudden request and thanks for your support.

    Best,

    Zeming

  • 0 in reply to Zeming Kong
    TI__Guru* 81230 points

    Hi Zeming,

    Txtal is the drive level specification of a crystal. You are right, if you pick a crystal for this part, the drive level should be at least 50µW. 

  • 0 in reply to Zeming Kong
    TI__Intellectual 770 points

    Hi Zeming,

                      I was able to clarify with my team and based on the discussion, my recommendation is to assume a +-10% variation in the 10 pF capacitor specified in the datasheet across Process and Temperature. Note that this is not validated in production silicon and the datasheet only specifies nominal value. This variation is based on design feedback after considering the type of internal capacitor being used. 

    Noel has already answered the other question regarding power dissipation of the crystal.

    Hope this clarifies the customer questions.

    Thanks,

  • 0 in reply to Badarish
    TI__Expert 3515 points

    Hi Badarish,

    Thanks a lot for your timely support!

    Best,

    Zeming