Frequency modulation controller, switch mode power supply including the same, and switching operation frequency modulation method

摘要

Ripple of an input voltage is used to modulate a switching operation frequency of a switch mode power supply. A sensing voltage corresponding to the input voltage is received, a current ripple that is proportional to a difference between a peak value of the sensing voltage and the sensing voltage is generated, and a modulation control signal that is variable by the current ripple is generated. A switching frequency is modulated using an oscillator signal that is variable by the modulation control signal, and reduces the output voltage ripple.