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Original question:

ADS125H02： how to use

ADS125H02: how to use

YUKIO YAMAMOTO
Prodigy 60 points
Part Number: ADS125H02

Hi Bryan-san

If AIN0 = 0V, 1V, and 2V are applied with the following settings, what is the correct answer for the converted values of each voltage?

H VDD = + 15V, HVSS = -15V, AIN0 / 1 = 0-10V, AINCOM = GND
Connect to and set MUX [2..0] = 011b and GAIN [3..0] = 0010b.

-yamamoto

  • 0
    TI__Mastermind 35161 points

    Hi Yamamoto-san,

    Table 15 in the ADS125H02 datasheet provides the conversion equations from input signal in volts to output code.

    First you need to calculate the full-scale input signal for your system, which for this ADC is VREF/GAIN. Assuming VREF = 2.5V and GAIN = 0.25, then this value is 10 V. Therefore, a 10V signal equals a positive full-scale code (7FFFFFh) and -10V signal equals a negative full-scale code (800000h)

    For your specific signals:

    • If AIN0 = 0V and AINCOM = 0V, then VIN = 0V and the ideal output code = 000000h
    • If AIN0 = 1V and AINCOM = 0V, then VIN = 1V, and the ideal output code = (1V / 10V) * 7FFFFFh = 0CCCCDh
    • If AIN0 = 2V and AINCOM = 0V, then VIN = 2V, and the ideal output code = (2V / 10V) * 7FFFFFh = 19999Ah

    These codes are ideal, such that they do not include noise, offset or gain errors. Therefore, the real codes might be slightly different.

    You can also reference our ADS125H02 calculator tool to help you convert voltage to code. This is what I used to perform the conversions above: https://www.ti.com/lit/zip/sbac234

    -Bryan