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DAC81416: Error bit and shut-down

laurent lefevre
Prodigy 120 points
Part Number: DAC81416

HI,

With somes electromagnetics perturbations the DAC81416EVM fall in shut-down mode and when I read the status register (0x02) bit 0 (TEMP-ALM) and bit 3 (RESERVED ???) are set to "1".
What does mean the bit 3?
Why an error temperature when the Vtempout=1,25V?
How can I reset this error? The set to "1" of ALM-RESET bit in the TRIGGER register  works well for the TEMP-ALM but not for the bit 3.

Regards,
Laurent Lefevre.

  • 0
    TI__Genius 14220 points

    Hi Laurent,

    Thank you for your query. Are you putting the EVM to any EMI/EMC test? Do you see any other malfunction other than the RESERVED bit toggle? You can ignore the status of the RESERVED bits. They are for internal functions and should be treated as "don't care".

    Hope that answers your question.

    Regards,

    Uttam Sahu

    Applications Engineer, Precision DAC

  • 0 in reply to Uttam Sahu
    Prodigy 120 points

    Hi Uttam,

    No, it is not an EMI/EMC test, it is just an on/off on my soldering iron.
    Ok for the bit 3, I will ignore it but why the bit 0 (TEMP-ALM) is set to "1" which results in a shutdown of the DAC?

    Regards,
    Laurent Lefevre

  • 0 in reply to laurent lefevre
    TI__Genius 14220 points

    Hi Laurent,

    The TEMP-ALM bit is a safety feature so that the die temperature doesn't exceed beyond 140 oC in normal conditions (see section 9.3.4.2 of the datasheet). Looks like the soldering iron is causing a temperature rise in the die beyond the specified limit.

    Hope that explains the alarm condition you're observing.

    Regards,

    Uttam

  • 0 in reply to Uttam Sahu
    Prodigy 120 points

    Hi Uttam,

    That doesn't explain the alarm condition, because the soldering iron is just turned on or turned off,  but not used near the DAC.

    Regards,
    Laurent.

  • 0 in reply to laurent lefevre
    TI__Genius 14220 points

    Hi Laurent,

    I am not able to understand the connection between the soldering iron and the DAC. Could you please explain? Is it creating any power supply glitch etc?

    Regards,

    Uttam

  • 0 in reply to Uttam Sahu
    Prodigy 120 points

    Hi Uttam,

    It is not an EMI/EMC test but when the soldering iron turns on or turns off, that produces some electromagnetics perturbations and that set to "1" the TEMP-ALM bit and put the DAC in shutdown mode, why?

    I was monitoring the temperature at this time, with the VTEMPOUT in DAC output, and the value was normal (1,22V).

    Regards,
    Laurent.

  • 0 in reply to laurent lefevre
    TI__Genius 14220 points

    Hi Laurent,

    Apologies for the late response due to the local holidays. The DAC81416EVM is mainly designed for functional evaluation. We haven't put any EMI/EMC protection circuits. Hence, it is possible that there might be some impact on the DAC when there is a power surge causing a glitch on the DAC power supply or ground.

    You can monitor the power supplies and reference using a scope and check if there is any glitch when you switch on/off the soldering iron. On a system, the power supply needs to be filtered for common-mode noise for minimizing such disturbances.

    Regards,

    Uttam

  • 0 in reply to Uttam Sahu
    Prodigy 120 points

    Hi Uttam,

    Thank you for your reply.

    Regards,
    Laurent.