[sdiy] Taming things that run to the rails...

[David G Dixon]

Apparently, I stand corrected, and opamp saturation is defined as driving it
to the rail (according to Wikipedia, at least).

However, let's not confuse saturation with exceeding the common-mode voltage
range.  According to the datasheet, the common-mode voltage range for TL07x
(which is notorious for phase reversal problems) is, at minimum, +/-11V, and
typically -12 to +15V.  The typical open-loop gain is 200,000.  This means
that any differential voltage about 0.1 mV greater than the input voltage
offset (3 to 10mV, depending on the grade of the chip) will force it to the
rail in open-loop (i.e., comparator) mode.  However, phase reversal is only
a danger with very large differential voltages.