Question
We are using ADA4004 OP-Amp in an application with high differential input
voltage. (0...10V). It is supplied with +-15V. Do the inputs of this Opamp draw
higher input currents, with this differential input voltages?
Will there any other problems arise?
Answer
Unfortunately there is an error in the datasheet Rev. G of the ADA4004
(http://www.analog.com/ADA4004) in the Absolute Maximum Ratings on page 5 of
the datasheet. The Maximum Differential Input Voltage of the ADA4004 is ±600mV
and not ±Vsy. There are back-to-back diodes connected between the input pins of
the amplifier limiting the Maximum Differential Input Voltage to a diode drop.
This will be corrected in future revisions of the datasheet.
Having said that, a 10V Differential Input Voltage to the amplifier would
damage the part. If this is unavoidable, limit the input current to less than
5mA, by placing input series resistors at both input pins. Note that this
however would introduce thermal noise.