| 摘要 |
PROBLEM TO BE SOLVED: To commonalize a charging circuit for soft start with a charging and discharging circuit for protective operation. SOLUTION: A switching power supply device includes: an IC 101, input voltage detecting resistors R101, R102, a brown-out detecting (input low voltage detecting) circuit 103, a timer capacitor C101, switching elements Q101, Q102, a transformer T101 consisting of a primary winding Np and secondary windings Ns1, Ns2, a resonant capacitor C102, a current detecting resistor R103, rectification diodes D201, D202, a rectification capacitor C201, output voltage detecting resistors R201, R202, a shunt regulator IC201, and a photocoupler PC101. The timer capacitor C101 is connected to an SST terminal of the IC 101 so as to work as the soft start circuit as well as protection in abnormal conditions such as overcurrent, and the brown-out detecting circuit 103 is further connected to execute protecting operation. COPYRIGHT: (C)2011,JPO&INPIT |
