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MSP430FR6047: Doubt about Resonator

Vinayak Potadar
Prodigy 200 points
Part Number: MSP430FR6047

Hello TI team,

We are using MSP430FRC6043 Ultasonic watermeter IC, we have some doubt about the recommended Resonator.

as in Datasheet TI has suggested to use Resonator of ( Fosc=8Mhz,Cl=18pF,Cs=4pF) but on Evaluvation Board TI has used Resonator of(Fosc=8Mh,Cl=22pF).

and also TI has used 12pF used across the resonator. 

I request you to assist on this issue.

Thank You in advance. 

  • 0
    TI__Mastermind 39125 points

    Hi,

    Usually, if the crystal Cl is 22pF, the C1 = C2 = 22pF * 2 - around 2pF PCB capacitance - around 1pF MCU pin capacitance = around 41pF.

    We choose 12pF in our EVM board, because we tested that with C1 = C2 = 12pF, the crystal is stable.

    Best regards,

    Cash Hao

  • 0 in reply to Cash Hao11
    Prodigy 200 points

    Hi Cash,

    thank you for your response.

    But in MSP430 data sheet the test conditions for Resonator is Fosc=8Mhz,Cl=18pF,Cs=4pF, and formula is CL=(C1*C2/(C1+C2))+Cstray. And after solving the formula we get C=32pF. 

    you are saying to use CL as 22pF but in Datasheet it mentioned CL as 18pF.

    can you please share related documents for the above query.

    thanks in advance.

  • 0 in reply to Cash Hao11
    Prodigy 200 points

    Hey cash,

    any update ?

    Regards,

    Vinayak

  • 0
    TI__Mastermind 39125 points

    Hi,

    Based on the datasheet of the resonator "AWSCR-8.00CV-T" we used on the EVM board. The CL is 22pF.

    Best regards,

    Cash Hao

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