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ADS114S08: Question on using Vref for other application

Yuanchen Zhu
Intellectual 340 points
Part Number: ADS114S08

Dear TI Expert,

  We have an application of detecting 4~20mA signal.  So far, we've designed to use a resistor of high precision and a non-inverting opamp to amplify the signal. which is then fed into ADS114S08's analog input.  Because our application has high priority on low current consumption, we wonder if we want to use internal 2.5V reference (REFOUT) for opamp's bias voltage (since REFOUT can be configured power down when ADC is in power down mode), is that ok? Or should this 2.5V reference be left alone, never be used for other purpose?  Or it can be used, only some care needs to be taken care of?

Hope someone can shed some light on this.

Yuanchen Zhu

  • +1
    TI__Guru** 112705 points

    Hi Yuanchen Zhu,

    Yes, it is possible to use the ADS114S08 REFOUT to bias other parts of your system as long as the required output current does not exceed the total available listed in the Electrical Characteristics as shown below:

    When turning on/off the internal reference, there will be a startup and settling time that needs to be considered.  The time will depend on the value of capacitance attached to REFOUT.  There are some example times shown in Table 10 of the datasheet and as shown below:

    Best regards,

    Bob B

  • 0 in reply to Bob Benjamin
    Intellectual 340 points

    Thanks for your analysis.