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ADC128S102QML-SP: Confirmation

May
Genius 9880 points
Part Number: ADC128S102QML-SP

Hi Team,

Customer have specification questions regarding ADC128S102QML-SP. Below is the inquiry.

"

1. What is allowed analog input voltage range (IN0-IN7 inputs) with VA=5V and VD=3.3V?

  • There is a confusing Note (3) in the datasheet (SNAS411P) that says "When the input voltage at any pin exceeds the power supplies (that is, VIN less than AGND or VIN greater than VA or VD), the current at that pin should be limited to 10 mA".
  • We thought that the analog input range was 0 to VA and the input current would be quite small - unless the input exceeded VA (5V). Does something happen when the input exceeds VD (3.3V)?

2. some specific follow-up questions:

  • Are we operating in acceptable conditions with VA = 5V and VD = 3.3V?
    • We ensure that VD never exceeds VA
  • Can the analog inputs (IN0 – IN7) range from 0V to VA (5V) without causing any performance or accuracy problems?
    • This is specifically aimed at the case where IN[0:7] is in the range of 3.3V to 5V (above VD, but below VA)
    • We are expecting the input currents to remain normal in this range (as indicated in the datasheet)"

"

Thank you and looking forward for your kind response.

Regards,

Maynard

  • 0
    TI__Guru 63905 points

    Hi Maynard,

    1.)  The specified analog input (IN0-IN7) range with VA = 5V will be 0V to 5V.  The absolute maximum levels are -0.3V to +5.3V.  As you noted if the absolute maximum voltages are exceeded, immediate damage should not occur provided the input currents are limited <10mA.  Long-term reliability in this mode of operation is not characterized as the note below the table states. 

    To directly address your question, there will not be performance issues between analog inputs of +3.3V to 5V as these voltages are still within the +5V analog supply range.

    2.)  Yes, the system will work fine with analog inputs between 0V and VA, and VD always less than VA.  See above for the answer about the input range and input currents.  No performance impacts will occur between analog input voltages of +3.3V to 5V as long as VA is at least 5V.