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ADA4000 comparator

Hi AD,

is the ADA4000-1 can be used as a comparator instead of amplifier and is it a dedicated op-amp to work for this kind of use (e.g comparator)

It seems that ADA4000 is highly sensitive working as a comparator and it doesn't like this non linear mode.

Moreover with a transistor on the output which could create high DV/DT for example.

thanks for your help,

  • If I understand correctly, that will be an electrical over-stress condition. The device is not designed to operate without power, so if you're driving that much of a signal into the device, you may be damaging the inputs possibly either by damaging the JFET input stage, or possibly through the ESD protection.

    I'll need to refer you to the textbook I liked earlier for information on designing around such circumstances.

  • 'the inputs possibly either by damaging the JFET input stage, or possibly through the ESD protection.'


    there is no internal schematic of ADA4000 within the datasheet so I cannot assess/calculate if these input voltage values could lead to an internal damage.

    Could you provide me with an analysis/calcultation taking into account internal design of this op-amp regarding input voltages (attached above) seen by each input, please ?

    Thx in advance,

  • Correct, and unfortunately I do not have the information on the internal design as well (I cover a different set of parts).

    The best I can offer is to measure the voltage across the resistors and infer currents from that. Further, I would recommend replacing the part, start with no external signals (so input to your Gain of -2 amplifier is grounded) and power up the device. Does the output position itself around ground? Then, if you apply a small input of 0-1V, does the output respond with 0-(-2) v? Since there is no schematic, I have run out of suggestions past these, so the best bet is to make sure the design is within the absolute max ratings and the design guidelines from the book above.



  • Quite funny since it seems that roles are reversed now...ADA4000 is a black box for me !

    Please provide a schematic of internal circuit of ADA4000 and components characteristic, so I could assess if my system is well designed for your AD's device.

    No one at AD facilities could provide me with these information please ?

  • This question has been assumed as answered either offline via email or with a multi-part answer. This question has now been closed out. If you have an inquiry related to this topic please post a new question in the applicable product forum.

    Thank you,
    EZ Admin