Joulwatt Technology Co., Ltd.

Joulwatt Technology (hangzhou) Co., Ltd.

Yingyan He

Guoqiang Liu

Yuancheng Ren

Xunwei Zhou

Pitleong Wong

Hao Long

Zhongwu Wu

A power supply circuit and a light-emitting diode (LED) driving system using the power supply circuit are provided. The power supply circuit includes a linear conversion circuit, a first capacitor, and a direct current-direct current (DC-DC) conversion circuit, where an alternating current input signal is rectified to form a first rectified voltage. The linear conversion circuit receives the first rectified voltage and has an output terminal connected to the first capacitor. After the power supply circuit is started, the linear conversion circuit controls the first rectified voltage to charge the first capacitor in a time period when the first rectified voltage is near a trough. The DC-DC conversion circuit receives a first capacitor voltage and performs power conversion to output a supply voltage. At least part of the linear conversion circuit and at least part of the DC-DC conversion circuit can be integrated with an LED driving circuit.

Power supply circuit and light-emitting diode (LED) driving system using power supply circuit

A flyback converter, a constant-current control method, and a lighting system are provided. The constant-current control method includes: sampling a loop current in a resonant loop to obtain a first sampling signal; obtaining zero crossing time of an excitation current in the resonant loop; and turning off a first switch tube when the first sampling signal reaches a reference value, and turning off a second switch tube after the zero crossing time of the excitation current in the resonant loop to control an average value of the excitation current to keep constant. The present disclosure can achieve a constant average value of an excitation current in each switching cycle based on a loop current in a resonant loop on the primary side of the converter, thereby realizing constant-current control of an output current of the converter.

Flyback converter, constant-current control method, and lighting system

Disclosed a control circuit for a lighting circuit. In the control circuit, an AC input signal provided at an AC input terminal is rectified to obtain a rectified voltage, a low potential end of the rectified voltage is used as a reference ground, a load of the lighting circuit is composed of N strings connected in series, and N is a natural number greater than or equal to 2, when the control circuit detects that the AC input terminal is connected to a dimmer, the control circuit controls the N strings to be simultaneously turned on, when the control circuit detects that the AC input terminal is not connected to the dimmer, the control circuit controls the N strings to be individually turned on in accordance with the rectified voltage. According to the present disclosure, the lighting circuit can obtain a high power factor and is compatible with the dimmer, and the scheme is simple and easy to implement.

Control circuit and control method for lighting circuit, and lighting circuit

There is provided a dimming circuit, a dimming method and a LED driving circuit. On the basis of the dimming of a dimmer, the circuit according to the disclosure generates a plurality of current reference signals corresponding to a plurality of loads in accordance with a dimming signal, to change a ratio of load currents of the plurality of loads, so that, the adjustment of color temperature is implemented, wherein the dimming signal represents the changes of switching operation or dimming speed of the dimmer, and the ratio of current load currents of the plurality of loads is latched or a predetermined ratio of load currents is latched. According to the disclosure, the dimmer can be used for directly adjusting color temperature, without the need for a MCU, so that, the system compatibility is improved and the cost is decreased.

Growing community of inventors

Hangzhou, China

Yingyan He