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ADS1115: Power supply recommendation for ADS1115

Feng bin Su
Expert 7590 points
Part Number: ADS1115

Hi team, 

My customer is evaluating our ADS1115 for their design.

They would like to know whether there is a specific requirement for VDD quality. Can they use a buck converter to power up ADS1115? Or LDO only.

Does it will significance influence the performance of ADC? Thanks.

  • 0
    TI__Guru* 92715 points

    Feng,


    For best results I would use an LDO for the supply. Noise or ripple on the power supply can affect the measurement, but it's hard to know exactly how much. If you look in the datasheet, there are only a few specifications that can show the effect of the power supply.

    The datasheet doesn't list a power-supply rejection ratio, but on page 7 it does have a offset power-supply rejection of 1 LSB/V typical with the FSR=±2.048V, this is listed as a DC speccifaction. Also, there is a listing for gain power-supply rejection, showing that the supply voltage has a small effect on the gain error of typically 80ppm/V.

    Again, this does not necessarily show that power supply ripple will affect the measurement. However, DC changes did affect the measurement, and it's likely that power supply ripple from a buck converter would have as effect as well. Because of this, I would always use a lower noise power supply like an LDO and also use a 0.1uF decoupling capacitor near the VDD pin.


    Joseph Wu