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Constant-current LED drive circuit, LED drive device and control method thereof

A technology of LED driving and constant current, which is used in the layout of electric lamp circuits, lighting devices, electric light sources, etc.

Active Publication Date: 2012-04-25
HANGZHOU SILAN MICROELECTRONICS
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] and figure 1 The disadvantage of the topology structure of the shown constant current LED drive circuit and its external LED circuit is: comparing the reference voltage VREF with the voltage VCS on the sampling resistor 106, the voltage VCS on the sampling resistor 106 does not exceed the reference voltage VREF at the highest, thus The peak current of the output current of the load LED light string is a constant value, but the average current of the output current is not controlled, so when the input voltage VIN, the output voltage (voltage drop of the load LED) and the value of the inductance change, the output current The average IAVG of will change

Method used

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  • Constant-current LED drive circuit, LED drive device and control method thereof
  • Constant-current LED drive circuit, LED drive device and control method thereof
  • Constant-current LED drive circuit, LED drive device and control method thereof

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Embodiment Construction

[0049] The content of the present invention will be further described below in conjunction with the accompanying drawings.

[0050] Figure 4 A schematic diagram of an LED drive device composed of the constant current LED drive circuit and its external LED circuit proposed by the present invention, including:

[0051] The selector 310, the selector 310 inputs the first resistance sampling voltage VCS and the reference voltage VREF through the voltage sampling terminal CS, the first resistance sampling voltage VCS is controlled by the gate control signal GATE of the NMOS power transistor, and the reference voltage VREF is controlled by the gate control signal GATE of the NMOS power transistor The reverse signal GATE_N of the gate control signal of the NMOS power tube is controlled. When the NMOS power tube is turned on, the gate control signal GATE of the NMOS power tube is at a high level, and the output signal VSN of the selector 310 is the first resistor sampling voltage VC...

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Abstract

The invention discloses a constant-current LED drive circuit which comprises a selector, an error amplifier, an oscillator, a slope compensation module, a comparer, a trigger and a driver. Because the average value of output voltages (VSN) of the selector is equal to a reference voltage (VREF), when an NMOS (N-channel metal oxide semiconductor) power transistor is conducted, a sampling voltage (VCS) is equal to the output voltage (VSN) of the selector, in the whole working period of the LED drive circuit, no influence of changes of the input voltage, the output voltage and a peripheral inductance to the average current of the LED is ensured, and the output current is facilitated to be set.

Description

technical field [0001] The invention relates to LED driving technology, in particular to constant current LED driving technology. Background technique [0002] figure 1 It is a traditional constant current LED drive circuit and its external LED circuit, including oscillator 101, RS flip-flop 102, comparator 103, drive circuit 104, power tube 105, resistor 106, inductor 107, Schottky diode 108 and LED string lights109. Wherein, the output of the oscillator 101 is connected to the S terminal of the RS flip-flop 102, the negative input terminal of the comparator inputs the reference voltage VREF, and the positive input terminal of the comparator is connected to one end of the resistor 106 and the source end of the power transistor 105; One end is grounded, the output of the comparator 103 is connected to the R terminal of the RS flip-flop 102, the output terminal Q of the RS flip-flop 102 is connected to the input of the driving circuit 104, the output of the driving circuit ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H05B37/02
Inventor 王栋
Owner HANGZHOU SILAN MICROELECTRONICS