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DAC7311 output is 17.6 MV with 0 code written

Michael Schamberger
Prodigy 20 points
Other Parts Discussed in Thread: DAC7311

My colleague and I are using the DAC7311 in our board design. We are finding that on initial power up the DAC is outputting about 4 millivolts and when we write the 0 code to it the output it  is 17.6 millivolts. I set a break point in the software immediately before and after the call to the DAC write routine and I am measuring 17.6 millivolts coming out of the DAC. We see this on both of  our prototype boards. We’ve tried unloading the DAC and we’ve also tried placing a 2k resistor from the output to ground with the same result. The datasheet suggests that the 0 code output should be much closer to the rail. The VREF voltage to the DAC7311 is 2.621 Volts.

Aside from this zero code error, the results for other output values throughout the range are excellent. 

I can provide supporting documentation of the electronic circuitry and a logic analyzer screen capture of the zero code being written, separately.

  • 0
    TI__Genius 10615 points

    Hi Michael,

    This is very strange behavior for the device. Just to make sure, I took one of our devices to the lab and tested it myself. I could not replicate the issue. The datasheet specifies a typical zero-code error of 0.2 mV. In the lab I was able to obtain 0.26 mV right repeatable after power-up and after writing the code zero.

    I think I might need some more information to solve this issue.

    Is it possible for you to share the schematic of your prototype board? If you would rather share this privately, is it okay to contact you to your E2E registered email?

    If its okay to ask. Why does your application require very low zero code error?

  • 0 in reply to Eugenio Mejia
    Prodigy 20 points
    Hi Eugenio,

    I captured images of the relevant circuitry and a screen capture from a logic analyzer of the zero code DAC write to a Word Document that I can send you. If you need more information I can provide that. You can contact me at my registered email and I will respond with the attachment.

    Thanks,
    Mike Schamberger
  • 0 in reply to Michael Schamberger
    TI__Genius 10615 points
    This thread has been taken offline.
  • 0 in reply to Eugenio Mejia
    TI__Genius 10615 points
    Thread update:
    The problem seemed to arise when using DIO voltages above the Abs. Max. specification. In this case, AVDD = 2.6V and DIO = 5V.
    Keeping the DIO within the Abs. Max. specification solved the problem.