| 摘要 |
PROBLEM TO BE SOLVED: To enable driving after stoppage of the circuit operation, without the addition of signal line in the power supply circuit for completely suspending supply of power in waiting condition. SOLUTION: The output of an oscillation circuit, configured with a transistor TR1, resistors R1, R2, a capacitor C4 and a transformer TR, is smoothed with a diode D1 to provide a DC voltage from an output terminal Vout. In a waiting condition, a current detection circuit 22 detects the voltage drop of the resistor R4, sets a latching circuit 21, makes the transistor TR2 conductive and stops oscillation to stop an output from the output terminal Vout. In this case, when a drive signal turns on a switch SW, a Zener diode ZD2 is turned on, a current flows into a photocoupler 4, the latching circuit 21 is reset, the transistor TR2 is turned off, the oscillation circuit starts the oscillation, and thereby a DC voltage can be obtained from the output terminal Vout. |
