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ADS8509 serial interface

Kevin Halloran
Expert 1345 points
Other Parts Discussed in Thread: ADS8509, SN74AHC1G125

Doing a new design with ADS8509 and need to know if the DATA output line, used with serial interface, goes tristate when /CS is disabled. Want to connect other SPI device data lines to a common data line. Documentation waveforms make it look like maintains last bit state, H or L after /CS goes high but want to verify before create PCB.

Thanks,

Kev

 

  • 0
    TI__Expert 3260 points

    Hi Kev,

     

    The DATA output line does not go tristate when /CS is disabled. (Additional verification can be found in the datasheet, page 6: "...between conversions DATA stays at the level of the TAG input when the conversion was started.")

     

    To be able to share the data bus, a simple solution might be for you to use a single bus buffer gate with tristate output (like the SN74AHC1G125, for example), and use the /CS for the /OE line. Hope this helps.

     

    Regards,

    Michael

  • 0 in reply to Michael W
    Expert 1345 points

    Hi Michael.

    Thanks for the response.  I had already put in a 125 buffer while waiting for the response as I figured that was the way it was but just wanted to make sure.

    Thanks again,

     

    Kev