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DAC8801: Tolerance

Danilo A.
Mastermind 24705 points
Part Number: DAC8801

Hi Team,

According to the first page of the datasheet of DAC8801 the output current (at Vref = +10V) is specified as: 2 mA +/- 20%. A customer wants to confirm if the tolerance value is true.

Regards,

Danilo

  • 0
    TI__Guru 52663 points

    Hi Danilo,

    The current is dictated by the impedance of the R-2R ladder.  This device is specified as a 5kohm typical value.  Generally, these processes have a +/- 20% tolerance, which is probably where that range comes from.  That being said, we do not test the end-to-end impedance of the R-2R ladder, so I do not think it would be wise to assume they are guaranteed.  It is best to use MDACs ratiometrically. For example, the RFB resistor is matched to the ladder, so you can use it as a controlled gain.

    Thanks,

    Paul

  • 0 in reply to Paul_Frost
    Prodigy 40 points

    Hi Paul,

    Thanks a lot for your answer. It really makes sense to use the R-feedback, as it is also suggested in different application-notes. Then to evaluate the accuracy of the resulting DC level, one needs to know how well the value of the R-feedback is tracking the R-values of the R2R-ladder-network. Please advice !

    Best regards Ole.

  • 0 in reply to user3012780
    TI__Guru 52663 points

    They should match very closely.  These processes have very good resistor matching, but the absolute value can vary.  I would estimate <1%, but I do not have any characterization data for that.

    Thanks,
    Paul