This document discusses, among other things, methods for controlling a Rail-to-Rail enabling signal, including providing a first signal of an input signal of a control circuit to a level switching circuit, performing, by the level switching circuit, enabling control according to a high level and a low level of the first signal, and outputting, by the level switching circuit, a disabling signal in case of a failure of a power supply coupled to the level switching circuit. The document also discusses a circuit for controlling a Rail-to-Rail enabling signal and a level switching circuit configured to output a disabling signal properly to provide an accurate enabling control signal for equipment operated under control of an enabling control in case of the failure of the power supply.