• State TI Thinks Resolved
  • Locked Locked
  • Replies 6 replies
  • Answers 2 answers
  • Subscribers 98 subscribers
  • Views 577 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

AM4379: AM437x Industrial EVM

Andrea Marson
Intellectual 800 points
Part Number: AM4379

According to the BOM, the 24 MHz crystal (ref. Y1) used in this board is

Suntsu Inc      SCM18B-24.000MHz TR

Is it possibile to have its datasheet?

Thanks in advance.

  • 0
    TI__Mastermind 42545 points
    Hi Andrea,
    I don't have a copy of the data sheet but I have requested it from Suntsu. Once it arrives, I will post it here.
    Regards, Bill
  • 0 in reply to Bill Taboada
    TI__Mastermind 42545 points

    Hi Andrea,

    According to Suntsu the part number in the BOM is a legacy part number. The data sheet for the new part number is attached.

    Regards, BillSUNTSU-SXT324.pdf

  • 0 in reply to Bill Taboada
    Intellectual 800 points

    Hi Bill,

    thanks a lot for your prompt response. The coding rules of the new crystal are different so I'm not sure about how to decode the old part number. Do you confirm that the old crystal's load capacitance is 18pF?

    If CL=18pF, I have two further questions:

    • I suppose that the board's designer assumed a total parasitic capacitance of 6pF (Cp) in order to match crystal's CL. Load capacitances are 24pF each (C35=C36=24pF). So (C35*C36)/(C35+C36)+Cp=12+6=18pF. Am I right?
    • These values seem to violate the maximum drive level of the crystal because the because the power dissipated is almost 600uW, while maximum drive level is 100uW (see Pxtal equation in AM437x datasheet).

    Thank you.

  • 0 in reply to Andrea Marson
    TI__Mastermind 42545 points

    Hi Andrea,

    Most likely the specification for the new crystal part number do not match the specification of the old part number. I don't have the original data sheet so I can't compare. We will have to find a new crystal the next time we need to build the board. You should find a crystal that matches the specification listed in the data manual. 

    Regards, Bill

  • 0 in reply to Bill Taboada
    Intellectual 800 points

    Hi Bill,

    what about Rbias?

    What criteria do you recommend in order to determine if it should be used or not?

  • 0 in reply to Andrea Marson
    TI__Mastermind 42545 points

    Hi Andrea,

    As stated, the bias resistor is generally not needed by crystals available today. If it is needed, that information us usually found in the crystal datasheet. Adding the footprint for the resistor will ensure that you have the option in case the crystal you choose needs the resistor. If the resistor is not needed, you can remove the pads in later revisions. 

    Regards, Bill