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ADS1120: Alt suggestions for +/-2.0V input ADCs

Ue
Genius 16285 points
Part Number: ADS1120
Other Parts Discussed in Thread: ADS1119, ADS112C04, ADS122U04, ADS114S06B

Hi all

My customer is looking for a cost-effective 4-channel ADC, 16-Bit, 1ksps sufficient.

The ADS1120 seems to fit. Are there other options you can suggest ? The IDACs are not required.

Moreover they looked at the ADS1119, in the Datasheet section 6.1. Absolute Maximum Ratings they found:

AGND to DNGD min -2.8V max 0.3V.

I assume this is a typo, can you confirm this ?

Best regards

Ueli

  • +1
    TI__Guru** 112765 points

    Hi Ueli,

    Based on the title of the thread, it would appear that the customer wants to make 4 single-ended measurements relative to AGND and the voltages required are +/-2V relative to AGND.  Is my assumption correct?

    Is there a preferred communication protocol (I2C, SPI, UART)?  Similar to the ADS1120 (SPI) is the ADS112C04 (I2C) and the ADS122U04 (UART).

    If the measurement is to be a true measurement above and below AGND, then bipolar analog supplies are required for the analog supply for the ADC.  Otherwise an external level shifting is required to bring the input voltage within the measurement range of the ADC.

    The ADS1120 ( as well as the other devices mentioned above) allows for analog bipolar supplies, however the 4 single-ended measurement channels are with respect to AVSS and not AGND.  This means that one of the four input channels must be connected to AGND so the measurement can be referenced to AGND.

    Another possible option would be the ADS114S06B.  This device is 6 channels with an AINCOM pin that can be set to AGND.

    As to the question regarding the ADS1119, yes that is a typo.  The ADS1119 is a stripped down analog supply unipolar only version of the ADS112C04 and there was a cut and paste error when creating the ADS1119 datasheet.

    Best regards,

    Bob B

  • +1 in reply to Bob Benjamin
    TI__Genius 16285 points

    Hi Bob

    Thank you for the quick reply, I appreciate your detailed feedback.

    And correct, the customer has a +/-2.5V supply available and is therefore looking for ADCs where the analog supply can be +/-2.5V whereas the digital supply is 0/+2.5V.

    This makes the interface to the MCU much easier as no level-shifting of the SPI or I2C is required.

    For the interface there is no particular preference, SPI, I2C or UART would all work in the customer system.

    Best regards

    Ueli