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ADS1115: About input pin (AIN0,AIN1,AIN2,AIN3)

Tsukui Yusuke
Guru 21930 points
Part Number: ADS1115

Hi,

I would like to ask about ADS1115 AIN0,AIN1,AIN2,AIN3.
Please tell me the input impedance of this pin.
Is it correct with understanding impedance value of Mohm order?

Best Regards,
Yusuke Tsukui / Japan disty

  • 0
    TI__Guru* 97835 points

    Tsukui-san,


    The input impedance is of the ADS1115 is listed in the Electrical Characteristics table on page 6 of the datasheet. The common-mode and differential impedance depend upon the input range setting. The larger input ranges show that impedances are larger than 1MΩ. The ±256mV range shows a differential input impedance of 710kΩ.

    On page 15 of the datasheet, there is a description of the common-mode and differential impedance. The impedance is caused by sampling and discharge of the input voltage at the modulator frequency of the ADC. Note that the modulator frequency is 250kHz.


    Joseph Wu

  • 0
    TI__Prodigy 330 points
    Hello Tsukui,

    The datasheet includes only the input impedance of AINp and AINn of the PGA. It is given in the table 7.5 "Electrical Characteristics"and shows the common-mode input impedance and differential input impedance depends of the gain.

    Best regards,
    Florian