Thanks anyway mate, I am not committed to the MCP6044, can you recommend one
that would be suitable for my application or tell me what I should be
looking for?
Best regards
AJ
What is your application? If you are looking to use an op-amp as a
follower, you could look at the OPA333 from Texas Instruments. Not
that fast but really good spec's in terms of low power, low voltage,
and offset (rail to rail too!).
With any op-amp (just about anyway) you need to pay attention to the
data sheets absolute maximum ratings. Usually there will be a maximum
rating on the input voltage;i.e. Vcc + 0.3V using the OPA333 as an
example. If you go beyond this then you need to heed the maximum input
current rating. Again using the OPA333 as an example, it is listed as
+/-10mA and it is explicitly stated in the datasheet as well. A simple
series resistor can be used to do this. You can also use clamps on the
inputs too.
As far as I am aware, this limited input current is continuous and
would not damage the part and I would go as far as to say that it would
not cause worry in terms of degradation or reliability either. The
real fun is what happens when you are using a dual or a quad and one
channel experiences an electrical overstress event while the others are
driven normally. In your case if you are not going to have power
connected, the point is moot; however, through my discussions with
several colleagues and looking at test data it appears that you can
treat each channel as a separate block within the IC. It is true that
they will all ultimately share the same power rail and that there are
many paths for current to flow during an EOS event. I will have to
look at the test again to see how it was set up if you are interested.