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ADS1018 VRef?

Sima Mitra
Prodigy 30 points

Other Parts Discussed in Thread: ADS1018

Hi All,

What is the internal reference voltage on the ADS1018? I can't find it in the data sheet.

I'm wondering if this part could be used to measure a li-po battery's voltage while being powered more-or-less directly off of the battery. Would the chip operate if the PGA was set to 2/3 to accommodate the full range of the battery's voltage but the VDD can drop as low as 2.3V? 

(I know a Li-Po battery should generally be above 3.3V and a stand-alone fuel gauge would be a better option).

Thanks!

Sima

  • 0
    TI__Guru** 100225 points
    Sima,


    The short answer is that yes, the device would operate if the PGA was set to 2/3 (with a full-scale of +/-6.144V) and the VDD drops to 2.3V. However AIN should not go above a voltage of VDD. At that point the input voltage would read 2.3V max and you'd never be able to reach the full scale.

    You can think of the reference as a voltage of 4.096V. The ADC reference is really a virtual reference so that it operates even with a supply lower than the reference. We say that the PGA=1 gives a full scale of +/-4.096V just for ease of explanation.

    I'd note that the reference specifications are rolled up into the specification for the PGA gain. Gain error is similar to the reference error and the gain drift is the equivalent to the reference drift.

    For further information read the section on Full-Scale Input on page 12 of the datasheet.


    Joseph Wu