A control circuit for controlling a power stage circuit of a switching converter, where the power stage circuit includes a magnetic component and a power switch, can include: the control circuit being configured to determine a turn-on trough of a current cycle by determining whether a time signal corresponding to a lock-on trough of the current cycle is within a threshold range, thereby controlling the power switch to be turned on at the determined turn-on trough; and whereby an ordinal number of the lock-on trough of the current cycle is the same as an ordinal number of the turn-on trough of the last cycle.