| 摘要 |
PURPOSE:To prevent an element from damaging in a simple circuit configuration by limiting a current at an overcurrent generating time by utilizing a transistor switch and a time constant circuit in a controller. CONSTITUTION:A main transistor 7 is coupled with a transformer T in a self-excited oscillator 2 to self-excite by ON/OFF operations, a DC voltage applied to an input voltage terminal 1 is converted into an AC voltage, and power is supplied through a transformer T to an output circuit 4. A controller 3 has an output voltage control function and an overcurrent limiting function. When the output voltage rises, the collector current of a control transistor 9 is increased, the voltage of a time constant circuit 10 is decreased, the transistor 8 is turned ON early to shorten the ON period of the transistor 7. The transistor 9 is turned ON during the OFF period of the transistor 7 in an overcurrent state, the discharge of the circuit 10 is further accelerated to abruptly shorten the ON period on the transistor 7, thereby limiting a load current. |
