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Original question:

DP83848K: About Load Capacitance of 25MHz Crystal

DP83848J: About Crystal selection.

teritama
Expert 1700 points
Part Number: DP83848J

Hi team,

We're selecting crystal for this device referencing from datasheet, SNLA079D and SNLA290.

we understand CL(load capacitance) is recommended 8pF to 20pF from SNLA290.

On the other hand, in datasheet says 25pF to 40pF and in SNLA079D says 15pF to 40pF. In this device , witch CL is recommended?

And, If our customer could check the matching with out value from recommended, Is it no problem to use the crystal?

best regards, 

teritama

  • 0
    TI__Mastermind 20676 points

    Hi Teritama,

    The value found in the datasheet is our recommendation, i.e. 25-40pF. However, the exact value is usually decided by the crystal vendor looking at all parasitics to achieve the required ppm accuracy. 

    Thanks,

    David

  • 0 in reply to David Creger
    Expert 1700 points

    Hi David,

    Thank you for your reply.

    I'll answer to the customer that 25-40pF is recommended. 

    > the exact value is usually decided by the crystal vendor looking at all parasitics to achieve the required ppm accuracy. 

    ⇒Does this mean that we should choose the CL1, CL2(in datasheet figure7-3) according the crystal exact CL value and not according recommend CL(25-40pF)?

    Best regards,

    teritama

  • +1 in reply to teritama
    TI__Mastermind 20676 points

    Hi Teritama,

    That is correct. The load capacitor values will vary with the crystal vendors. Check with the vendor for the recommended loads.

    Thanks,

    David