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Original question:

ADS1120: Design help of Vref

ADS1120: Output code for single end application

Tess Chen
Intellectual 2675 points
Part Number: ADS1120

Hi,

Application is to use ADS1120 measure 4-22mA signal with 130ohm resistor.  The application is single-end application with external 4.096V reference. 

The datasheet table 13 shown below indicate the output code for difference input. I want to confirm for single end application, what's the output code range? 8000h to 7FFFh as below or 0 to FFFFh? I assume that at the FS(4.096V), output code is 65535(2^16)? Thanks.

Best Regards,

Tess Chen

  • 0
    TI__Guru** 113765 points

    Hi Tess,

    The ADS1120 actually always measures differentially with AINP in respect to AINN.  If AINN is tied low or is connected to AVSS in the mux settings this means that only the positive range can be measured.  So with single-ended measurements you can measure 0 to +FS where the code range is 0 to 0x7FFF (2^15).

    Best regards,

    Bob B