High efficiency constant current LED driver

a constant current led driver, high efficiency technology, applied in the direction of electroluminescent light sources, electric lighting sources, semiconductor lamp usage, etc., can solve the problems of narrow operating frequency range, limited modulation capability of the frequency for the gain, and insufficient frequency rang
US20110080102A1Inactive Publication Date: 2011-04-07INVENTRONICS HANGZHOU
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Patent Information

Authority / Receiving Office
US · United States
Patent Type
Applications(United States)
Current Assignee / Owner
INVENTRONICS HANGZHOU
Publication Date
2011-04-07
Estimated Expiration
Not applicable · inactive patent

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Abstract

The present invention discloses a high efficiency constant current LED driver, which comprises a rectification bridge, a PFC main circuit, an isolated DC / DC converter, a PFC controller and a PFC bus control circuit. Since the input voltage is an intermediate PFC bus voltage, which varies with the output voltage of the DC / DC converter. When the isolated DC / DC converter is an LLC resonant circuit, the operating frequency of the LLC circuit is close to the resonant frequency within a wide output voltage range. Thus, the gain range and the operating frequency is narrow, and can enable the constant current module to work with a high efficiency at a wide output voltage range. When the isolated DC / DC converter is a symmetric half bridge, or an asymmetric half bridge or a full bridge circuit, the duty cycle of DC / DC circuit is close to 50% within a wide output voltage range. Thus, the changing range of the duty cycle of the DC / DC converter will be narrow and can improve the efficiency dramatically.
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Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of Chinese Patent Application No. 200910153404.3 filed Oct. 1, 2009, which is incorporated herein by reference.BACKGROUND OF THE INVENTION

[0002] Exemplary embodiments of the present invention generally relate to a high efficiency constant current LED driver. More specifically, it relates to a kind of constant current circuit with active power factor correction (PFC), in which the intermediate bus voltage of power factor correction is adaptively changed with an output voltage, and it can get high efficiency during a wide output range.

[0003] A traditional method of a constant current driver for LED application is one active power factor correction (PFC) circuit plus one isolated DC / DC converter, and an output voltage of the PFC circuit is fixed. The topology of an isolated DC / DC converter is generally symmetric half bridge or asymmetric half bridge circuit, full bridge circuit, resonant circuit, which is usual...

Claims

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