| 摘要 |
The flyback converter receives power from a key telephone system (KTS) and provides VCC, -VCC and VDD to a key service unit (KSU). The flyback converter includes a controller (10) for generating PWM pulses, a voltage regulator (5) for regulating the voltage of power lines (1,2) and for providing starting voltage to the controller (10), a flyback transformer (15) having primary windings (A,B) and multiple secondary windings, a switching unit (20) for switching the current flowing through a winding (A) according to the PWM pulses, and a diode (D3) for providing VCC to the controller and cutting the starting voltage.
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