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ADS8422: Questions related power supply

MESH
Intellectual 830 points
Part Number: ADS8422

Hello,

I considering AD conversion circuit that circuit is used ADS8422.

I have two questions related power supply for ADS8422.


1. I want to know how the + VAREG powered regulator works inside the ADS8422.

2. I want to check the existence of the power supply sequence when operating the ADS8422 with the following power supplies.
+VA: +5V power
+VAREG: +3.3V power or +5V power
+VBD: +3.3V power

Regards,

MESH

  • +1
    TI__Mastermind 36240 points

    Hello MESH,

    The +VAREG powers the internal logic for the conversion stage, +VBD powers the digital IO pins, and +VA powers the front-end acquisition.  Since the ADC inputs can range from -0.2V to Vref+0.2V, this circuitry must operate from a 5V supply.  The internal conversion logic operates at a lower internal voltage, which allows use of a 3V or 3.3V supply to reduce power dissipation.

    There are no power sequence requirements for ADS8422.  The only concern during power-up is to restrict the analog inputs and digital inputs to within the supply voltages, per the ABS Maximum Ratings.  For example, the analog input voltage should remain near 0V, and not exceed -0.4V to +0.1V before the +VA supply is powered on.

    Regards,
    Keith Nicholas
    Precision ADC Applications 

  • 0 in reply to Keith Nicholas
    Intellectual 830 points

    Hello, Keith Nicholas

    Thank you for your reply.

    Your reply is very helpful for me.

    Regards, MESH

  • +1 in reply to MESH
    TI__Mastermind 36240 points

    You are welcome.

    Regards,
    Keith