Post Go back to editing

Ask a question about ADA4945-1 specification

Category: Datasheet/Specs
Product Number: ADA4945-1

Hi,

As below picture, it says that the differential input voltage of ADA4945-1 is ±1V.In the same way,the differential input voltage of ADA4940-1 is 1.2V.How to understand it? For ADA4945-1,if the differential input voltage is more than ±1V,Can this device work correctly? Is it not a rail to rail input amplifier? For ADA4940-1,the differential input voltage is only positive rail, without negative rail,why?

 

Thanks!

Parents
  • Hi Jerry,

    In normal operation, an op amp has the feedback loop connected; therefore the differential input voltage is held at zero volts (neglecting the offset voltage). However under certain conditions, such as power-up, then the output can only slew to within a few millivolts of ground, the op amp may be subjected to a differential input voltage which is not zero. Certain input structures require limiting of differential input voltage to prevent damage. These op amps will generally have internal back-to-back diodes across the inputs. This will not always show up in the simplified schematics of the amps. It will show up, however, as a differential input voltage specification.

    Regarding the ADA4940 it should be both ways, it was just written as absolute there, it always depends on your reference.

    Regards,

    Goz

Reply
  • Hi Jerry,

    In normal operation, an op amp has the feedback loop connected; therefore the differential input voltage is held at zero volts (neglecting the offset voltage). However under certain conditions, such as power-up, then the output can only slew to within a few millivolts of ground, the op amp may be subjected to a differential input voltage which is not zero. Certain input structures require limiting of differential input voltage to prevent damage. These op amps will generally have internal back-to-back diodes across the inputs. This will not always show up in the simplified schematics of the amps. It will show up, however, as a differential input voltage specification.

    Regarding the ADA4940 it should be both ways, it was just written as absolute there, it always depends on your reference.

    Regards,

    Goz

Children
No Data