| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a switching power supply device capable of preventing the increase of power loss and the breakage of a load even when a power supply voltage of switching control means decreases. <P>SOLUTION: A switching power supply device 1 has: switching means Q<SB POS="POST">1</SB>that carries out switching of a primary side DC voltage to generate a switching voltage; switching control means 4 that controls the switching means Q<SB POS="POST">1</SB>; power supply voltage generation means 5 that rectifies and smooths an induction voltage of a first auxiliary coil T<SB POS="POST">3</SB>wound so as to have the same polarity as a primary coil T<SB POS="POST">1</SB>, and generates a power supply voltage to be supplied to the switching control means 4; and stop means 6 that makes the switching control means 4 stop the control to the switching means Q<SB POS="POST">1</SB>when the power supply voltage becomes less than a predetermined threshold voltage. <P>COPYRIGHT: (C)2012,JPO&INPIT |
