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ADS1158: Output Code for Single-ended

user5163865
Genius 3800 points
Part Number: ADS1158

Tool/software:

Hi,

Sorry for the basic question, but I would like to know about the following question from a customer.

"Is the full-scale range when used in single-ended half that when used differentially?"

Looking at Table 7 in the datasheet, INPUT SIGNAL VIN = ADCINP - ADCINN

In the single-ended case, I think the input range is AINx - AINCOM. I think this is essentially a pseudo-differential input, is that correct?

For example, in the following setting

+VREF=2.5V, -VREF=0V
AINx = 0 to 2.5V

1. When AINCOM = 0, the output code is 0 to 0x7FFF

2. When AINCOM = +VREF/2, the output code is 0x8000 to 0x7FFF

Is this correct?

Best regards,
Hiroshi

  • +1
    TI__Mastermind 45241 points

    Hi user5163865,

    user5163865 said:

    In the single-ended case, I think the input range is AINx - AINCOM. I think this is essentially a pseudo-differential input, is that correct?

    For example, in the following setting

    +VREF=2.5V, -VREF=0V
    AINx = 0 to 2.5V

    1. When AINCOM = 0, the output code is 0 to 0x7FFF

    2. When AINCOM = +VREF/2, the output code is 0x8000 to 0x7FFF

    These statements are correct. The ADS1158 differential input range extends from +1.066*VREF to -1.066*VREF, so if your input signals are single-ended you are only using the positive half of the ADC codes.

    -Bryan