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DP83822H: Crystal Circuit Question

PY (Pengyu) Song
Expert 5860 points
Part Number: DP83822H

Hi team,

  1. Just to be clear, the total load capacitance = C1*C2/(C1+C2) + Cstray? If C1 = 12pF & C2 = 12pF, the total load cap = 6pF + Cstray ==> correct? 
  2. For 25-MHz Crystal, datasheet specifies load capacitance between 10pF to 40pF, so should we recommend customer to increase C1 & C2 to at least 20pF each to meet 10pF minimum spec? 
  3. How to determine R1? 

  • +1
    TI__Mastermind 25955 points

    Hi Pengyu,

    1.  Yes, the calculation you did is correct.
    2. We recommend using 20pF for the recommendation. Please let the customer confirm with the vender for the 20pF load capacitors because different crystals might have a different recommendation from ender.
    3. R1 is the current limit resistor. It generally used to limit the power dissipation within the crystal. For the detail value of R1, we need to ask the crystal vender about it.

    --

    Regards,

    Hillman Lin