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ADS7844: BUSY and DOUT are not output High

Satoshi
Guru 19595 points
Part Number: ADS7844

A few ADS7844 board are not output for BUSY and DOUT.

Waveform is attached below;

※Red: SCLK, Yellow: DIN, Write: BUSY, Blue: DOUT, 10μs/div

Please let me know about two points below;

・Is there any problem on above waveform?

　(Border specification for OK or NG by IC variation)

・Is ADS7844 have careful points for possibility to damage on BUSY (and DOUT)?

　For example, ESD, current, etc

By the way, waveform of OK board is below; 

Best regards,

Satoshi

  • 0
    TI__Mastermind 39985 points

    Hi Satoshi,

    I apologized for missing the post. Are the hardware and software of "good" board and "bad" board exactly same? Could the issue on the "bad" board be recovered by the cycling the power supply? Can you swap the ADC devices between "good" and "bad" board for test purpose (A-B B-A test). It's possible the device was damaged by ESD and other high transients or electrical overstress(EOS) if your system works in a harsh environment.

    Best regards,

    Dale

  • 0 in reply to Dale Li
    Guru 19595 points

    Hi Dale

    Thank you for reply,

    I checking to customer.

    Additional question, if there any detailed spec information for ESD rating, please let me know.

    I didn't find ESD specification on datasheet.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Mastermind 39985 points

    Hi Satoshi,

    I tried to find more information for this device, but I could not find it because this is a very old device.

    Regards,

    Dale

  • 0 in reply to Dale Li
    Guru 19595 points

    Hi Dale,

    Thank you for reply,

    I understood that ADS7844 is very old.

    Can you figure out the point of damage on ADS7844?

    Additional information, BUSY pin is connect to SN74LVC244 with pullup on store the customer's application box.

    I guess that BUSY pin is very unlikely to damage by ESD or EOL on above condition. 

    I looking for highly likely point for damage.

    If there need more detailed information, please let me know your e-mail.

    Best regards,

    Satoshi

  • 0 in reply to Satoshi
    TI__Mastermind 39985 points

    Hi Satoshi,

    I can not guess where and how the device was damaged. I suggest you to contact TI's local support team if you bought these devices from TI directly or an authorized distributor, they can do a failure analysis (FA) that will address the issue and answer your question. 

    Thanks&regards,

    Dale