AD8054 absolute maximum input voltage

Hello,

I am using the AD8054 opamp as a comparator.

I have a scenario in which I apply 3V to the positive input terminal of the AD8054, while the VCC may still be powered off. I didn't see that the AD8054 has input clamping diodes, so I guess it should be o.k in this scenario, but I am not sure. I also have a 100 ohm protection resistor in series with the positive input of the AD8054.

Please advice if this design is o.k.

Best regards,

Vadim.

  • +1
    •  Analog Employees 
    on Jun 4, 2020 2:42 AM 9 months ago

    Hello,

    It is best to have proper power-up sequencing to avoid damage on the part.
    In the event of Input Over Voltage, a series resistor in the input pin would help to limit the current.
    It is recommended to limit the current to +/- 5mA unless/otherwise specified.
    To get your required R series, you may use this formula.

    You are using the AD8054 as comparator and the input voltage is 3V? If this is correct, then you may violate Abs Max Rating.
    The Differential Input Voltage of AD8054 is only +/- 2.5V.
    I suggest that you pick a comparator part.

    Here is a selection table for our available comparators.

    Also, in this link is a good article to read regarding using op-amp vs. comparator.

    Thanks and regards.

  • Thanks! 

    It is actually an old design, that we have to update and change as little as possible. So I will increase the protection resistor to meet the input current.

    I am not worried about the differential input voltage because we connect the negative input of the opamp to 1.5V.

    Thanks and best regards,

    Vadim.