Switching power supply controller and control method

Discloses a switching power supply controller and control method. The switching power supply controller for controlling the switch on and off, the inductor current to generate an inductor in series with the switch, comprising: frequency jitter signal generation circuit for generating a time-varying jitter frequency signal; superposition circuit for the inductor current signal and the sampling frequency jitter signal and adds them together to generate a superimposed signal; a first comparator for comparing the superimposed signal is compared with a control voltage signal to generate a control switch OFF OFF. The use of switching power supply controller shaking inductor current sampling frequency control signal to improve the conductivity of the electromagnetic interference.