The OPA6x7 have internal phase-reversal protection. Many FET-input op amps exhibit a phase reversal when the input is driven beyond the linear common-mode range. This issue is most often encountered in noninverting circuits when the input is driven below –12V, causing the output to reverse into the positive rail. The input circuitry of the OPA6x7 does not induce phase reversal with excessive common-mode voltage, so the output limits into the appropriate rail.