Circuits and devices related to switch controller. In some embodiments, a radio-frequency module can include a packaging substrate configured to receive a plurality of components, and a switching circuit implemented on the packaging substrate. The radio-frequency module can further include a control circuit configured to control operation of the switching circuit. The control circuit can include a regulator configured to generate a plurality of reference voltage levels for the operation of the switching circuit, or to be in a sleep mode, based on a control signal received through a common input node. The control circuit can further include a mode detector in communication with the regulator and configured to provide a first form of the control signal to the common input node to allow the plurality of reference levels to be generated by the regulator, or a second form of the control signal to the common input node to put the regulator in the sleep mode.