START-UP CIRCUIT, SWITCH CONTROL CIRCUIT HAVING THE START-UP CIRCUIT AND POWER SUPPLY DEVICE HAVING THE SWITCH CONTROL CIRCUIT

摘要

A start-up circuit includes a first zener diode and a second zener diode coupled to each other, a first switch configured to perform a switching operation according to at least one of a first zener voltage of the first zener diode and a second zener voltage of the second zener diode, at least one second switch coupled to the first zener diode and the second zener diode, and a driving unit configured to drive the at least one second switch using a driving signal of a power switch which controls power supply.