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DAC7821 reference voltage powering requirement

Singamareddy Ayyappareddy
Intellectual 270 points
Other Parts Discussed in Thread: DAC7821

Hi All,

Query 1)

We want to use DAC7821 in my design.Due to some other components in the board we want to give power to DAC7821 like this:

1st  VDD(3.3V), and then after few seconds Vref.Until Vref generated externally Vref pin of  DAC will be floating.

Can anybody confirms the floating Vref pin for some time and giving power to vref pin after some time won't be a issue?

Query 2)

Can we change run time DAC 7821 reference voltage?

Noted thank you for your suggestion,

  • 0
    TI__Genius 11750 points

    Hello Singamareddy,

    This shouldn't be an issue.  If Vref is truly floating no current will flow in the R-2R structure of the DAC.  A good rule of thumb is to verify any conditions in the 'absolute maximum ratings' table.  This table usually shows supply restrictions, as there may be ESD diodes between one supply to another.  In this particular case, there are no ESD diodes from reference to any signals/supplies.

    Best Regards,

    Matt