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ADS131M02: positive or negative issue with the input values of AINxN and AINxP?

Chu Allen
Intellectual 370 points
Part Number: ADS131M02

Tool/software:

Hello,
May I ask if ADS131M02, powered by a single power supply, can have negative values for AINxN and AINxP inputs? Used for current detection, it is positive when discharging and negative when charging in the opposite direction.
The specification sheet lists the absolute value range of AINxN and AINxP inputs. What is the actual input range? For example, can AINxP input a -2V analog value?

  • 0
    TI__Mastermind 39545 points

    Hello chu Allen,

    AINxP and AINxN pin of ADS131M02 can support a bipolar input between AGND – 1.3 (negative voltage -1.3V under the ground) and AVDD for Gain=1/2/4 or AVDD-1.8 for Gain>4.

    ADS131M02 ADC actually measures the voltage difference between AINxP and AINxN pins, so Vin = VAINxP  –  VAINxN between -Vref/Gain and +Vref/Gain. 

    • Single-ended input:  AINxN is shorted to the ground (AGND), the signal on the AINxP can sweep between -Vref/Gain and +Vref/Gain (-1.2V ~ 1.2V for gain=1).
    • Differential input: Vin = VAINxP - VAINxN between -Vref/Gain and +Vref/Gain (-1.2V ~ 1.2V for gain=1). If there is a high common-mode voltage, you will have to use an amplifier or INA to handle it in front of the ADC.

    You can use one of these configurations for your current measurement.

    Based on these information, this ADC can not directly support -2V analog signal, you will have to scale -2V signal down to meet the input requirement of the ADC. I hope my explanation can help you understand this ADC.

    BR,

    Dale