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AMC1035-Q1: Operating range for analog inputs AINP and AINN

Saraswathy G
Prodigy 100 points
Part Number: AMC1035-Q1
Other Parts Discussed in Thread: AMC1035

Tool/software:

Hello, 

I understand from the datasheet that when the maximum common mode input voltage for the range highlighted is 2.7V

I would also like to understand what would happen if this voltage is exceeded. What would be the behavior of the delta-sigma modulator in such a scenario ?

Will it be possible also share a more detailed block diagram?

Thanks in advance !

  • 0
    Prodigy 100 points

    Also, how is "Absolute common-mode input voltage(1)" and "Operating common-mode input voltage(2)" defined ? What is the difference ?

    Suppose I have a scenario where AINP is 3V and AINN is 2V, which condition under the "Operating common-mode input voltage(2)" should I consider ?

  • 0 in reply to Saraswathy G
    TI__Guru**** 175201 points

    Hi Saraswathy,

    Please review the datasheet section 7.4.2 regarding what happens if you exceed the common mode voltage levels.  The Absolute common mode voltage refers to the ABS MAX voltage shown in section 6.1 - these are levels which can cause permanent damage to the device. Please review Figures 38 and 39 for the operating common-mode range.

  • 0 in reply to Tom Hendrick
    Prodigy 100 points

    Hello, thank you for the information. But I would like to understand one more point- according to my understanding Fig 38 and 39, show the relationship of common mode voltage with respect to the supply with 2 cases - Vainp-Vainn=1.25V and Vainp=Vainn.

    Figure 38 refers to the case when |Vaip-Vainn|=1.25V and Fig 39 refers to the case when Vainp=Vainn. How would the common mode voltage be if |Vainp-Vainn| is less than 1.25V , say around 0.8V ? How do we then derive the relationship ?

  • 0 in reply to Saraswathy G
    TI__Guru**** 175201 points

    The shaded area of Figure 38 would still be your guide.  You are going to be in the 5.0V band and your allowable CM range is -0.8 to 2.1V.  The AINN pin of the AMC1035 is meant to be grounded and the input signal on AINP can then swing +/-1V around ground.