Patent ID: 8873251
Filing Date: 2014-10-28
Classification: H02M

Abstract:
1. An output adjustment circuit, comprising: a rectifier and filter circuit configured to receive an alternative current (AC) voltage and convert the AC voltage into a square wave signal; a voltage drop circuit comprising a primary coil and a secondary coil, the primary coil connected to the rectifier and filter circuit, the primary coil configured to receive the square wave signal; a voltage output circuit connected to the secondary coil; a pulse-width modulation (PWM) regulator connected to the primary coil, and the PWM regulator configured to generate a pulse signal to turn on and turn off the primary coil periodically; and a feedback circuit connected to the PWM regulator, the feedback circuit configured to control a duty cycle of the pulse signal to adjust a during time of the primary coil being on in a cycle, and the primary coil configured to transmit corresponding energy to the secondary coil according the during time; wherein the feedback circuit comprises a light-emitting diode, the PWM regulator comprises an opto-electronic coupler and a pulse generator configured to generate the pulse signal, the opto-electronic coupler connected to the pulse generator, the opto-electronic coupler located adjacent to the light-emitting diode to sense light emitted by the light-emitting diode, and a first current flowing through the opto-electronic coupler being adjusted by the brightness of the light emitted by the light-emitting diode, and the duty cycle of the pulse signal being adjusted by the first current; wherein the feedback circuit comprises a three-terminal adjustable regulator comprising a regulator anode, a regulator cathode, and a reference end, the light-emitting diode comprises a diode anode and a diode cathode, the regulator cathode connected to the diode cathode, the regulator anode connected to ground, and a voltage value on the reference end being configured to adjust a second current flowing through the regulator anode and the regulator cathode.