Direct-current converter, and control circuit and method thereof

The application discloses a direct-current converter, and a control circuit and method thereof. The direct-current converter comprises a power switching circuit, a sample hold circuit, an error amplification circuit, a voltage current converter, a resistor, a comparison circuit and a logic control circuit. According to the invention, ZCD (zero current detection) can be accurately realized so as to control disconnection of a slave power tube.