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ADS112U04: The accuracy of the ADS112U04 constant current excitation in the power supply range, the manual only describes the AVDD3.3~5V

andy lau
Prodigy 20 points
Part Number: ADS112U04

    The constant current excitation IDAC accuracy described in the manual is when the power supply is 3.3V~5.5V, but the power supply range of the ADC is 2.3V~5.5V. What is the accuracy of IDCA between 2.3V and 3.3V? 

    We need to use the power supply between 2.5V and 3.6V first. In this range, we need to ensure the accuracy. Therefore, we need to know the accuracy under low voltage. Is there any corresponding data and documentation?

  • 0
    TI__Guru** 112725 points
    Hi Andy,

    Welcome to the E2E forum! The characterization plots look very much the same at 2.3V and 3.3V for the IDAC accuracy, so you should be able to follow the same numbers as shown in the Electrical Characteristics table down to 2.3V. However, be very careful with your design. The IDAC compliance voltage is (AVDD - 0.9V), so at 2.5V AVDD, the maximum voltage drop to maintain accuracy would be 1.4V. If you are making a ratiometric measurement the minimum reference that can be applied is as the reference input is 0.75V. This leaves only a small voltage allowed for the connected sensor and gain that can be applied due to the common-mode input range. 2.5V may not be that practical in the end. Designs that I have seen are 3V or greater that use the IDACs for RTD ratiometric measurements. When using 2.5V, make sure you are very careful with your design to make sure that you will not have any issues.

    Best regards,
    Bob B
  • 0 in reply to Bob Benjamin
    Prodigy 20 points
    Thank you very much!!!