> I have an LMC662 dual CMOS rail-to-rail op-amp hooked up so that one of
the
> two amps is in a non-inverting buffer config and then other has both
inputs
> tied to Vdd (5v in this case). Vss is 0 volts.
>
> When I apply a voltage to the non-inverting input,the output follows it
> perfectly until I get to  3.7v,at which the output suddently swings up to
> 5v. If I decrease the non-inv input,the output stays at 5v until I get
> below 3.7v at the input at which time it begins to follow the input again.
> I also have a scope hooked up to the output and I detect no oscillation or
> other strange behavior throughout the entire input range from 0 to 5v.


With the - input tied directly to the output, the output should track the
input within maybe 0.5V or so of the rails (I don't have the spec handy)
One thing, is that amp stable at unity gain, and are you within the minimum
supply?  Either could cause oddball output.