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DAC108S085: usable SCLK frequency range

Shinichi Inoue
Guru 21566 points
Part Number: DAC108S085

Dear Specialists,

My customer is considering DAC108S085.

He'd like to know usable SCLK frequency.

Could you please advise?

(1) Could it possible to use SCLK 7MHz?

(2)How is the usable SCLK frequency ?

(3)What does this mean listed 

According to the AC and Timing Characteristics, fCLK typ is 40MHz, limit is 30MHz.

Typically, limit value is maximum frequency, this case is not.

it may be the lowest maximum frequency, is it correct? 

I appreciate your great help.

Best regards,

Shinichi

  • 0
    TI__Guru 53773 points

    Shinichi,

    The confusion stems from the top line conditions listed in the datasheet.  The PDS describes that the limits in Bold are limits across the devices functional temperature range.  What they are trying to make clear is that at room temperature you can operate the device at 40MHz, but across all temperatures you must operate at less than 30MHz.  This is the maximum frequency, there is not a minimum frequency, so 7MHz will not be a problem.  

    Let me know if you have any more questions.

    Thanks!

    Paul

  • 0 in reply to Paul_Frost
    Guru 21566 points
    Hi Paul,

    Thank you for your reply.

    I understand fSCLK:7MHz is no problem and difference between 40MHz and 30MHz.

    I'll send your comment to the customer.

    I would like to know lower spec of fSCLK, could you tell me.

    Is it possible to use quite low frequency like near DC?

    I appreciate your great help.

    Best regards,
    Shinichi
  • 0 in reply to Shinichi Inoue
    TI__Guru 53773 points

    Shinichi,

    Most DACs do not implement any kind of timeout for SPI, so there is not a minimum speed.  As long as the frame is valid, you could clock in data as slow as you would like.

    Let me know if you have any more questions.

    Paul

  • 0 in reply to Paul_Frost
    Guru 21566 points

    Hi Paul

    Thank you for your reply.

    I understand there ins no lower limit of SPI, of course DAC108S085.

    I'll also send this information to the customer.

    I appreciate your great help and cooperation.

    Best regards,

    Shinichi