Abstract: A multifunctional LED device and multifunctional speaker system are disclosed. A multifunctional LED device consistent with the present disclosure includes a power supply unit configured to supply power; a control unit configured to process audio signals and control commands; an audio power amplifier configured to drive a speaker, a speaker configured to play audio signals, a first wireless transceiver configured to communicate with a smart terminal, a second wireless transceiver configured to communicate with other LED devices, and an LED light source. The multifunctional speaker system includes several multifunctional wireless LED devices configured to works as wireless speakers, and a smart terminal to control the system remotely. The smart terminal may communicate with and control all the multifunctional LED devices. The multifunctional LED devices may communicate with each other as well. Two of the multifunctional LED devices may be configured as a 2.0-channel speaker system.

Abstract: Multifunctional LED devices and multifunctional LED wireless conference systems are provided. A multifunctional LED device includes LED light source assembly, LED drive and power supply unit, controller unit, audio power amplifier unit, microphone module, wireless transceiver module, speaker unit, and/or audio codec unit. The wireless transceiver module is configured to communicate with each of a smart terminal and a second multifunctional LED device. A multifunctional LED wireless conference system includes at least two multifunctional LED devices and at least one smart terminal to read status of and to remotely control the at least two multifunctional LED devices. The smart terminal communicates with outside terminal(s) to send audio signals from the outside terminal(s) to the multifunctional LED device(s) for broadcasting.

Abstract: A power supply system includes a transformer having a primary winding on its primary side for coupling to a power source and one or more secondary windings on its secondary side. A first control circuit is disposed on the primary side of the transformer for controlling a current flow in the primary winding. A second control circuit disposed on the secondary side of the transformer, and the second control circuit is configured to provide a regulated output voltage. In the power supply system, the first control circuit is configured to generate a control signal for controlling the current flow in the primary winding without using a feedback control signal from the secondary side of the transformer.

Abstract: A power supply system includes a transformer having a primary winding on its primary side for coupling to a power source and one or more secondary windings on its secondary side. A first control circuit is disposed on the primary side of the transformer for controlling a current flow in the primary winding. A second control circuit disposed on the secondary side of the transformer, and the second control circuit is configured to provide a regulated output voltage. In the power supply system, the first control circuit is configured to generate a control signal for controlling the current flow in the primary winding without using a feedback control signal from the secondary side of the transformer.

Abstract: A time delay synchronous control scheme for a power supply, which has multiple outputs and tight output regulations, is provided. The switching mode power supply includes (1) a front-end DC/DC converter with current mode output, which can be a LLC Series Resonant converter (SRC) or a flyback converter; (2) one or several post buck converters directly cascaded from the output capacitor of the front-end DC/DC converter; (3) a new scheme of time delay synchronous control used to make the post buck synchronize and modulate from the front-end LLC-SRC or flyback converter. The proposed time delay synchronous control circuit can eliminate the conventional input filter of the post buck converters, as well as reduce the ripple current on the output capacitor of the front-end DC/DC converter, as a result of which, a high efficiency for the overall architecture can be obtained.

Abstract: An LLC series resonant converter and a driving method for the synchronous rectification power switches thereof are provided. The LLC series resonant converter includes a bridge circuit, a resonant network, a transformer, a rectification circuit, and a frequency adjustment controller. The bridge circuit includes at least one pair of power switches. The power switches drive the resonant network. The rectification circuit includes at least one pair of synchronous rectification power switches. The synchronous rectification power switches and the power switches have a mapping relation between them. The frequency adjustment controller provides driving signals to the synchronous rectification power switches in response to the operating frequency of the LLC series resonant converter and the series resonant frequency of the resonant network, to implement synchronous rectification in the LLC series resonant converter.

Abstract: An LLC series resonant converter and a driving method for the synchronous rectification power switches thereof are provided. The LLC series resonant converter includes a bridge circuit, a resonant network, a transformer, a rectification circuit, and a frequency adjustment controller. The bridge circuit includes at least one pair of power switches. The power switches drive the resonant network. The rectification circuit includes at least one pair of synchronous rectification power switches. The synchronous rectification power switches and the power switches have a mapping relation between them. The frequency adjustment controller provides driving signals to the synchronous rectification power switches in response to the operating frequency of the LLC series resonant converter and the series resonant frequency of the resonant network, to implement synchronous rectification in the LLC series resonant converter.

Abstract: The proposed architecture includes a Dual Boost PFC circuit for receiving the AC input voltage and generating the DC bus voltage, at least one inverter coupled to the Dual Boost PFC circuit for driving at least one CCFL to offer a backlight of a LCD panel, and a DC/DC converter coupled to the Dual Boost PFC circuit for offering power to the LCD apparatus. Since neither the input bridge rectifier nor the DC/DC converter between the PFC circuit and the backlight inverter is included in the presented architecture, relatively the simpler configuration and the higher conversion efficiency than those of the prior art are achieved.

Abstract: A constant voltage reset circuit used in a forward converter for the holdup time requirement or the wide input voltage range is disclosed. In one embodiment, the constant voltage reset circuit comprises a reset capacitor, a parallel-coupled switch, and a diode coupled in series with the reset capacitor which is configured to cooperate therewith to reset an energy from the transformer. The forward converter employing the reset circuit or the method achieves a higher efficiency with a larger turn ratio and without the 50% limitation of maximum duty cycle.

Abstract: A constant voltage reset circuit used in a forward converter for holdup time requirement or wide input voltage range is disclosed. In one embodiment, the constant voltage reset circuit comprises (1) a reset capacitor, and (2) a parallel-coupled switch and a diode coupled in series with the reset capacitor which is configured to cooperate therewith to reset an energy from the transformer. The forward converter employing the reset circuit or the method achieves high efficiency with large turn ratio and without 50% limitation of maximum duty cycle.