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Light-emitting diode (LED) backlight constant-current circuit

A technology of constant current circuit and backlight, applied in the direction of electric lamp circuit layout, light source, electric light source, etc., can solve the problems of high price and inability to be widely used, and achieve the effect of low cost, easy debugging and simple circuit.

Active Publication Date: 2013-11-06
GUANGZHOU SHIYUAN ELECTRONICS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The solution is mature and highly reliable, but the price is too expensive to be widely used

Method used

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  • Light-emitting diode (LED) backlight constant-current circuit
  • Light-emitting diode (LED) backlight constant-current circuit
  • Light-emitting diode (LED) backlight constant-current circuit

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Embodiment Construction

[0018] Embodiments of the present invention will now be described with reference to the accompanying drawings, in which like reference numerals represent like elements.

[0019] Please refer to figure 2 , which is a circuit diagram of the first embodiment of the LED backlight constant current circuit of the present invention. The LED backlight constant current circuit includes a timing control unit 10 and at least one constant current circuit unit 20 connected to the timing control unit 10 (eg, two in this embodiment, respectively connected to LED1 and LED2). The timing control unit 10 includes a first transistor Q1 and a second transistor Q2, and the emitter of the first transistor Q1 is connected to the power supply voltage input terminal VCC-Panel (connected to the previous stage AC-Panel) through a resistor R1. DC voltage regulator circuit, which outputs power supply voltage, such as 12V or 5V, the specific value of this voltage is set according to the power supply syste...

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PUM

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Abstract

The invention discloses a light-emitting diode (LED) backlight constant-current circuit which comprises a time sequence controlling unit and at least one constant-current circuit unit. The time sequence controlling unit comprises a first triode Q1 and a second triode Q2, an emitting electrode of the first triode Q1 is connected with the supply voltage input end through a resistor R1, and a base electrode of the first triode Q1 is connected to the supply voltage input end through a resistor R2 and is simultaneously connected to a collector electrode of the second triode Q2 through a resistor R3. A base electrode of the second triode Q2 is connected to the control end through a resistor R4, and an emitting electrode of the second triode Q2 is in ground connection. Every constant-current circuit unit comprises a third triode Q3 and a fourth triode Q4; a base electrode of the third triode Q3 is connected to a collector electrode of the first triode Q1 through a resistor R6, a collector electrode of the third triode Q3 is connected to a corresponding LED load and provides constant output current for the corresponding LED load, and an emitting electrode of the third triode Q3 is in ground connection through a resistor R7; a base electrode of the fourth triode Q4 is connected to an emitting electrode of the third triode Q3 through a resistor R8, a collector electrode of the fourth triode Q4 is connected to the collector electrode of the first triode Q1, and an emitting electrode of the fourth triode is in ground connection.

Description

technical field [0001] The invention relates to the field of switching power supply circuits, and more particularly to an LED backlight constant current circuit. Background technique [0002] At present, in the application industry of switching power supply, especially in the application field of LED backlight TV, the mainstream constant current solution is to mostly use BOOST boost circuit, that is, the front stage FLYBACK (or other architecture) outputs 12V (for power amplifier) ​​plus 24V (or other voltage levels), and then 24V again with the second-level BOOST constant current boosting method, the structure diagram is as follows figure 1 Shown: After the AC input is passed through the EMI filter circuit and bridge rectifier successively, the power supply voltage and 24V are output after passing through the front-stage AC-DC voltage regulator circuit, and then the output 24V is first boosted by a dedicated IC and then boosted to a constant current. The working mode is re...

Claims

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Application Information

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IPC IPC(8): H05B37/02
CPCY02B20/42Y02B20/40
Inventor 晁新库杨达富张碧原
Owner GUANGZHOU SHIYUAN ELECTRONICS CO LTD
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