Control device for DC-DC converter and control method controlling the same

A control device for a direct current-direct current (DC-DC) converter receiving an input power and generating an output voltage, comprising:

• a first error amplifier for comparing a reference voltage signal and the output voltage to generate a feedback signal;
• a sampling and holding control circuit coupled to the first error amplifier for generating a reference current signal according to the feedback signal and an input current associated with the input power;
• a filter for receiving the input current associated with the input power and generating an average current value according to the input current;
• a second error amplifier coupled to the sampling and holding and the filter for comparing the reference current signal and the average current value before generating a control signal;
• and
• a switching control circuit coupled to the second error amplifier for generating a switching signal according to the control signal from the second error amplifier, wherein the switching signal controls a conduction time of a switching element of the DC-DC converter.