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A led drive circuit

A LED drive and circuit technology, applied in the direction of lamp circuit layout, electric light source, lighting device, etc., can solve the problems of long conduction time, low circuit operating frequency, human ear noise, etc., to improve efficiency, reduce switching loss, avoid noise effect

Active Publication Date: 2017-03-29
FREMONT MICRO DEVICES SHENZHEN LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] 3. The conduction time is very long when the input voltage is low, so the operating frequency of the circuit is very low, and it may even be lower than 20KHz, so there is the possibility of human ear noise

Method used

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Embodiment Construction

[0025] The present invention is aimed at the voltage drop in the prior art. The conduction loss of the high-voltage MOS is getting larger and larger; the minimum working voltage of the circuit is high and the working frequency of the circuit is too low when the input voltage is low, and there may even be the problem of human ear noise. An LED drive circuit that uses automatic selection mode to make the circuit work in BCM mode at high input voltage to reduce switching loss; and automatically enter CCM mode at low input voltage, which can effectively improve the efficiency of low voltage operation and reduce The minimum operating voltage is improved, and noise can be avoided at the same time.

[0026] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0027] figure 2 It is a functional bloc...

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Abstract

The invention provides an LED driving circuit. The LED driving circuit comprises an AC input switch (110), a rectifying filter module (120) of which the input end is connected with the AC input switch (110), a current regulating module (130) for providing constant current to a loaded LED, and a power supply module (140) of which the input end is connected with the rectifying filtering module (120); the output end of the rectifying filter module (120) is connected to the current regulating module (130). The LED driving circuit (100) further comprises a control module (150); the current regulating module (130) is used for sending a sampling signal to the control module (150); the power supply module (140) supplies working voltage to the control module (150). According to the LED driving circuit, the automatic selecting mode is adopted, thus the circuit can work in the BCM mode in case of high input voltage so as to reduce switch consumption, and the circuit automatically enters the CCM mode in case of low input voltage so as to effectively increase the efficiency of working at low voltage, and moreover, the minimum working voltage is reduced; meanwhile, noise can be avoided.

Description

Technical field [0001] The invention relates to the field of power electronics, and more specifically, to an LED drive circuit. Background technique [0002] The typical working principle of the Buck constant current LED drive circuit in the prior art is as follows figure 1 As shown, the source of the high-voltage MOS is connected to the current detection resistor Rcs, and the gate of the MOS is fixedly connected to the VCC terminal. When the low-voltage MOS is turned on by the driving module, the voltage of the node VS will be pulled down, so that the high-voltage MOS is turned on. The inductor current will increase with a fixed slope, and the VCS voltage will also increase accordingly. When the inductor current increases to make VCS equal to the internal comparison voltage Vref of the controller, the drive module will turn off the low voltage MOS and the node VS will rise rapidly. When VS rises to VCC-VS<Vth, the power switch M1 is turned off. At this time, the drain voltage...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H05B37/02
CPCY02B20/40
Inventor 许如柏黄裕泉
Owner FREMONT MICRO DEVICES SHENZHEN LTD
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