supplies? I need ~1.4V headroom.
We will not provide guaranteed specs outside of those given in the datasheet.
The OP279 is generally spec'd for a 1k load. When driving a 500 ohm load from
10V supplies, the output can swing with 200mV of the positive rail and 150mV of
the negative rail - Guaranteed.
Driving a 120R using a +/-5 supply, you're getting real close to the output
current limit minimum of 45mA when you start going near the rail.
However, you are only for the output to swing to within 1.4V of the supply
which is quite a moderate requirement. Expecting a voltage headroom of around
1V when sourcing or sinking 30mA would be a reasonable expectation. The OP279
will probably meet your requirement, this can be confirmed by single part
testing in the lab but cannot be guaranteed because it is not production tested.
For guaranteed output swing, look at the AD8012.