CN103687208A

CN103687208A - LED overcurrent protection circuit

Info

Publication number: CN103687208A
Application number: CN201310620369.8A
Authority: CN
Inventors: 孙爱玲
Original assignee: Individual
Current assignee: Individual
Priority date: 2013-11-29
Filing date: 2013-11-29
Publication date: 2014-03-26

Abstract

The invention discloses an LED overcurrent protection circuit comprising a rectifier module, a transformer and an output end. The output end of the rectifier module is connected with the transformer. The transformer is connected to the output end. An overcurrent protection module is connected between the rectifier module and the transformer. A photoelectric coupler can be connected between the rectifier module and the output end. The LED overcurrent protection circuit is reasonable in design, simple in structure, high in protective capability, high in reliability, safer, and more reliable, and the functions of the circuit are effectively protected.

Description

LED current foldback circuit

Technical field

The present invention relates to a kind of LED protective circuit, especially a kind of LED current foldback circuit.

Background technology

Along with social progress, LED industry has had larger development, and the equipment of LED industry is also had higher requirement; At present; in the electronic information epoch of high speed development; the stability of circuit design has caused people's great attention more and more; function due to current protection; more can guarantee that circuit safety moves reliably; but some traditional protection control units do not drop into overcurrent protection control unit; to such an extent as to when electric current excessive; or in the situation of circuit wrong; the large electric current of moment can burn out monoblock circuit; cause circuit working abnormal, make relevant LED damaged by large electric current, cause reduce its useful life.

Summary of the invention

A kind of LED of preventing that the object of the invention is to design in order to solve the deficiency of above-mentioned technology damages, and improves the LED current foldback circuit in useful life.

For above-mentioned purpose, the LED current foldback circuit that the present invention is designed, comprises AC power, rectification module, transformer and output, and the output of described rectification module is connected with transformer, transformer is connected with output, between rectification module and transformer, is connected with overcurrent protection module, described overcurrent protection module comprises the first voltage-stabiliser tube, the second voltage-stabiliser tube, the first triode, the second triode and protector, wherein the first voltage-stabiliser tube is connected with the positive pole of the second voltage-stabiliser tube, between the negative pole of the first voltage-stabiliser tube and the electrode input end of rectification module, be connected with electric capacity, the negative pole of the second voltage-stabiliser tube is connected with the collector electrode of the first triode and the grid of protector respectively, the base stage of the collector electrode of the first triode and the second triode is connected with resistance, between the emitter of the second triode and the source electrode of protector, be connected with resistance, the collector electrode of the second triode is connected with the base stage of the first triode, between the two ends of the first former limit inductance coil of described transformer, be connected with drain source drive circuit, and one end of the first former limit inductance coil of transformer is also connected with the drain electrode of protector, between the base stage of the first triode and the electrode input end of rectification module, be connected with mutual resistance of connecting and resistance, second one end of former limit inductance coil and the base stage of the first triode of transformer are in series with RC series circuit, and and the emitter of the first triode between be connected in series with diode and resistance.

By the design of said structure, make that circuit global design is reasonable, protective capability is strong, reliability is high.

As preferably: be also connected with photoelectrical coupler between described rectification module and output; The present invention can play the effect of feedback in circuit.

As preferably: secondary inductance coil one end of described transformer is connected with diode, and described diode cathode is connected with secondary inductance coil, negative pole is connected with the positive pole of output, between the described secondary inductance coil other end and the positive pole of output, is connected with filter capacitor; The present invention utilizes diode to make electric current unilateal conduction, plays the effect of rectification.

The LED current foldback circuit that the present invention is designed, its beneficial effect is: the invention enables that circuit global design is reasonable, protective capability is strong, reliability is high; And by preferred version, safer, reliable, the effective function of protective circuit.

Accompanying drawing explanation

Fig. 1 is the integrated circuit structural representation of embodiment 1.

In figure: rectification module 1, transformer 2, output 3, overcurrent protection module 4, drain source drive circuit 5, RC series circuit 6, the first voltage-stabiliser tube Z1, the second voltage-stabiliser tube Z2, the first triode Q1, the second triode Q2, protector Q4, capacitor C 0, photoelectrical coupler U1, resistance R 3), resistance R 4, resistance R 5, resistance R 6, resistance R 7, resistance R 8, resistance R 12, filter capacitor C4, diode D3.

Embodiment

Below by embodiment, the invention will be further described by reference to the accompanying drawings.

Embodiment 1:

As shown in Figure 1; the described LED current foldback circuit of the present embodiment; comprise AC power, rectification module 1, transformer 2 and output 3; the output of described rectification module 1 is connected with transformer 2; transformer 2 is connected with output 3, between rectification module 1 and transformer 2, is connected with overcurrent protection module 4.

Described overcurrent protection module 4 comprises the first voltage-stabiliser tube Z1, the second voltage-stabiliser tube Z2, the first triode Q1, the second triode Q2 and protector Q4, wherein the first voltage-stabiliser tube Z1 is connected with the positive pole of the second voltage-stabiliser tube Z2, between the electrode input end of the negative pole of the first voltage-stabiliser tube Z1 and rectification module 1, be connected with capacitor C 0, the negative pole of the second voltage-stabiliser tube Z2 is connected with the collector electrode of the first triode Q1 and the grid of protector Q4 respectively, the base stage of the collector electrode of the first triode Q1 and the second triode Q2 is connected with resistance R 6, between the source electrode of the emitter of the second triode Q2 and protector Q4, be connected with resistance R 12, the collector electrode of the second triode Q2 is connected with the base stage of the first triode Q1, between the two ends of the first former limit inductance coil of described transformer 2, be connected with drain source drive circuit 5, and one end of the first former limit inductance coil of transformer 2 is also connected with the drain electrode of protector Q4, between the electrode input end of the base stage of the first triode Q1 and rectification module 1, be connected with the mutual resistance R of connecting 3 and resistance R 4, second one end of former limit inductance coil and the base stage of the first triode Q1 of transformer 2 are in series with RC series circuit 6, and and the emitter of the first triode Q1 between be connected in series with diode D2 and resistance R 8, between described rectification module 1 and output 3, be also connected with photoelectrical coupler U1, secondary inductance coil one end of described transformer 2 is connected with diode D3, and described diode D3 is anodal to be connected with secondary inductance coil, negative pole is connected with the positive pole of output 3, between the described secondary inductance coil other end and the positive pole of output 3, is connected with filter capacitor C4.

During work, by the first voltage-stabiliser tube Z1, the second voltage-stabiliser tube Z2, the first triode Q1 and the second triode Q2, protect protector Q4; In normal work, the first voltage-stabiliser tube Z1 and the second voltage-stabiliser tube Z2 do not play any effect in circuit; Now, AC alternating voltage is from L, N input is through rectification module 1 rectification supply rear class, resistance R 3, resistance R 4, resistance R 5, resistance R 6, resistance R 7, resistance R 8 provide the circuit of normal work for the first triode Q1 and the second triode Q2, now, the first base stage of triode Q1 and the Current rise of emitter, rise to the voltage being greater than in resistance R 6, when the first triode Q2 connects, the current driving ability of the first triode Q1 reduces base voltage will be partially anti-, the current stops of the first triode Q1 base stage and emitter rises, the first triode Q1 cut-off; When not shaking at circuit, when output open circuit or output short-circuit (output current is now very large); can cause the grid potential of protector Q4 to raise; make the electric current on protector Q4 sharply increase; when voltage reaches the voltage of the second voltage-stabiliser tube Z2 setting; the second voltage-stabiliser tube Z2 is not damaged by the pipe of protection protector Q4, thereby reaches the object of protective circuit.

The described LED current foldback circuit of the present embodiment benefit is compared with prior art: the present embodiment makes circuit global design reasonable, and simple in structure, protective capability is strong, reliability is high; More safe, reliable, effectively protected the function of circuit.

Claims

1. a LED current foldback circuit, comprise rectification module (1), transformer (2) and output (3), the output of described rectification module (1) is connected with transformer (2), transformer (2) is connected with output (3), it is characterized in that: between rectification module (1) and transformer (2), be connected with overcurrent protection module (4), described overcurrent protection module (4) comprises the first voltage-stabiliser tube (Z1), the second voltage-stabiliser tube (Z2), the first triode (Q1), the second triode (Q2) and protector (Q4), wherein the first voltage-stabiliser tube (Z1) is connected with the positive pole of the second voltage-stabiliser tube (Z2), between the electrode input end of the negative pole of the first voltage-stabiliser tube (Z1) and rectification module (1), be connected with electric capacity (C0), the negative pole of the second voltage-stabiliser tube (Z2) is connected with the collector electrode of the first triode (Q1) and the grid of protector (Q4) respectively, the base stage of the collector electrode of the first triode (Q1) and the second triode (Q2) is connected with resistance (R6), between the source electrode of the emitter of the second triode (Q2) and protector (Q4), be connected with resistance (R12), the collector electrode of the second triode (Q2) is connected with the base stage of the first triode (Q1), between the two ends of the first former limit inductance coil of described transformer (2), be connected with drain source drive circuit (5), and one end of the first former limit inductance coil of transformer (2) is also connected with the drain electrode of protector (Q4), between the base stage of the first triode (Q1) and the electrode input end of rectification module (1), be connected with mutual resistance of connecting (R3) and resistance (R4), one end of the second former limit inductance coil of transformer (2) and the base stage of the first triode (Q1) are in series with RC series circuit (6), and and the emitter of the first triode (Q1) between be connected in series with diode (D2) and resistance (R8).

2. LED current foldback circuit according to claim 1, is characterized in that: between described rectification module (1) and output (3), be connected with photoelectrical coupler (U1).

3. LED current foldback circuit according to claim 1 and 2; it is characterized in that: secondary inductance coil one end of described transformer (2) is connected with diode (D3); and described diode (D3) is anodal to be connected with secondary inductance coil; negative pole is connected with the positive pole of output (3), between the described secondary inductance coil other end and the positive pole of output (3), is connected with filter capacitor (C4).