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ADS1256: about Differential and Single-Ended input

Tsukui Yusuke
Guru 21930 points
Part Number: ADS1256


Hi,

I would like to discuss about differential and single ended input.
Customer want to use single ended input and differential input simultaneously.
(ex, AIN0/AIN1,AIN2/AIN3 : differential 　AIN4～AIN7 : single ended)
Can I use it like the above?

And If possible,
Please tell me what I should pay attention to AINx assignment.

Best Regards,
Yusuke/Japan Disty

  • 0
    TI__Mastermind 44680 points

    Hi Tsukui-san,

    Yes, this is possible and easy to implement on the ADS1256 since its input common-mode range allows for inputs to be grounded.

    The ADS1256 measures every signal differentially, meaning that you must always select which two pins to use in the voltage measurement. For single-ended signals, the ADC's negative input just needs to be connected to ground, typically AINCOM is used for this purpose...So for the differential measurements you would program the MUX register to measure the voltage between AIN0/AIN1 and AIN2/AIN3, and for the single-ended measurements you would program the MUX register to measure AIN4/AINCOM, AIN5/AINCOM, etc.

    Note that you do not have to use the AINCOM pin as the common ground if you find that selecting another pin is better for optimizing the PCB layout.

    Best regards,
    Chris