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CC2642R: how to adjust x-tal matching

robin Moon
Expert 1500 points
Part Number: CC2642R

We are using TI CC2642R1FRGZ.
For mass production, we did 48MHz crystal matching and got the same result as the below

The crystal matching company said that the paternal resistance value came out to -150 ohms, but it must be at least 1000 ohms to mass-produce.
So I have an inquiry as below.
1) I would like to know how to increase the value of the paternal resistance.
2) Although it is a similar inquiry to the number 1), I would like to ask if there is a way to increase the negative resistance value through S/W modification.

Please refer to the 48MHz crystal matching results, crystal DATASHEET in the attached data.


Please let me know if you need any additional design documents.

thanks

DSX321G_48M.pdfreview_x-tal.xlsx

  • 0
    TI__Expert 6450 points

    Hi Robin,

    1. Technically, you can adjust the negative resistance based on the equation below but the load capacitance is limited to the spec we recommend which is 6 - 9 pF. Please understand that this method merely changes the phase of the crystal which in turn changes the resistance and not the actual resistance.

    2. Not possible

    Best regards,

    Bun