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ADS131M08: DS shows it internal reference typ is 1.2V ,but curve shows is 1.18V

Haiwen Huang
Intellectual 2240 points
Part Number: ADS131M08


Dears:

Customer test ADS131M08 reference pin , it voltage is 1.18V, like the DS curve shows.

But in DS , typ is 1.2V, Custome want to know which reference they can use , 1.18V or 1.2 V to do calculation. Thanks .

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  • +1
    TI__Mastermind 47650 points

    Hello Haiwen,

    The typical internal voltage reference value when measured on the REFIN pin will be closer to 1.18V, as shown in Figure 6-29 data sheet plots.  However, there is internal scaling applied to the reference voltage, so that the full scale input range will be +/-1.2V/gain, and this corrected voltage will have an accuracy of +/-0.1% typical and temperature drift of 8ppm/C typical as shown in the datasheet specifications.

    When using the internal reference, the typical digital scaling factor applied is 1.2V/1.18V=1.017, but this value will vary slightly depending on the actual value of the internal reference for each device. 

    When using the external reference option, a fixed digital scaling factor of 0.96 is applied so that a standard 1.25V external reference voltage will still result in a full scale input range of +/-1.2V/gain.

    I hope this helps to clear up any confusion.

    Regards,
    Keith Nicholas
    Precision ADC Applications