CN202679750U

CN202679750U - Novel low-cost multi-group constant current output circuit of LED illumination power supply

Info

Publication number: CN202679750U
Application number: CN 201220334223
Authority: CN
Inventors: 刘全禄
Original assignee: ECU ELECTRONICS INDUSTRIAL Co Ltd
Current assignee: ECU ELECTRONICS INDUSTRIAL Co Ltd
Priority date: 2012-07-11
Filing date: 2012-07-11
Publication date: 2013-01-16
Anticipated expiration: 2022-07-11

Abstract

The present utility model relates to a novel low-cost multi-group constant current output circuit of an LED illumination power supply. The circuit comprises a switch power supply circuit, an input end is connected with alternating current, an output end is connected with an input end of a comparison circuit through a voltage-stabilizing circuit, the switch power supply circuit comprises a PWM controller and an optical coupler OC, the comparison circuit is composed of a plurality of comparators, a sampling resistor for collecting current output by each group is respectively connected with a reversal input end of the comparison circuit, an output end of the voltage-stabilizing circuit is connected with a positive input end of the comparison circuit, and an output end of the comparison circuit is connected with the PWM controller through the optical coupler OC. The switch power supply circuit, the voltage-stabilizing circuit, the comparison circuit and the sampling resistor are jointly adopted to form a control loop, through controlling duty ratio or switch frequency of a switch signal of the PWM controller of the switch power supply circuit, the output current can be stabilized, and constant current can be realized.

Description

A kind of novel low-cost of LED mains lighting supply is organized constant current output circuit more

Technical field

The utility model relates to LED mains lighting supply field, and especially a kind of novel low-cost of LED mains lighting supply is organized constant current output circuit more.

Background technology

In the LED solid-state illumination, the size of electric current determines the brightness (lumen) of LED lamp pearl, and electric current can not exceed the forward current rating of LED lamp pearl, otherwise can damage LED lamp pearl, thus usually require to come driving LED luminous with constant-current source, in order to lightness stabilized.Early stage LED solid-state illumination uses the constant voltage source power supply, and the every string LED in light fixture uses a driver, guarantees that constant current drives.Afterwards for cost and the too high consideration that affects the driver life-span of temperature rise, light fixture is cancelled constant-flow driver gradually, must be constant current output then all require the LED mains lighting supply, if light fixture is multi-string LED lamp pearl, correspondingly requiring power supply is multiple constant current output, the especially light fixture of higher-end.

The LED mains lighting supply of at present multiple constant current output mostly adopts the DC-DC circuit of many group BUCK (buck) to realize the constant current of many groups, but sort circuit has it self defective: line construction is complicated; Be again the secondary switch, so can increase EMI (electromagnetic interference), reduce the conversion efficiency of power supply, and cost be higher.

The utility model content

The purpose of this utility model is to provide a kind of low cost, need not the secondary switch, can realize that the novel low-cost of LED mains lighting supply of the multichannel output of accurate constant current organizes constant current output circuit more.

For achieving the above object, the utility model has adopted following technical scheme: a kind of novel low-cost of LED mains lighting supply is organized constant current output circuit more, comprise switching power circuit, its input termination alternating current, its output links to each other with the input of comparison circuit by voltage stabilizing circuit, switching power circuit comprises PWM controller and optocoupler OC, comparison circuit is comprised of a plurality of comparators, link to each other with the inverting input of comparison circuit respectively for the sample resistance that gathers every group of output current size, the output of voltage stabilizing circuit links to each other with the normal phase input end of comparison circuit, and the output of comparison circuit links to each other with the PWM controller by optocoupler OC.

As shown from the above technical solution, the utility model adopts switching power circuit, voltage stabilizing circuit, comparison circuit and sample resistance jointly to consist of control loop, duty ratio or the switching frequency of the switching signal by the PWM controller in the control switch power circuit, thereby the size of stabilizing output current realizes constant current.The utility model line construction is simple, and debugging is simple, and function easily realizes; Without secondary switch, rectification circuit, avoid producing extra EMI electromagnetic interference; The general common device of components and parts that adopts, cheap, reduced cost.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model.

Embodiment

A kind of novel low-cost of LED mains lighting supply is organized constant current output circuit more, comprise switching power circuit 1, its input termination alternating current, its output links to each other with the input of comparison circuit 3 by voltage stabilizing circuit 2, switching power circuit 1 comprises PWM controller and optocoupler OC, comparison circuit 3 is comprised of a plurality of comparators, link to each other with the inverting input of comparison circuit 3 respectively for the sample resistance that gathers every group of output current size, the output of voltage stabilizing circuit 2 links to each other with the normal phase input end of comparison circuit 3, the output of comparison circuit 3 links to each other with the PWM controller by optocoupler OC, as shown in Figure 1.The output of switching power circuit 1 is supplied with voltage stabilizing circuit and comparison circuit operating voltage.

As shown in Figure 1, described switching power circuit 1 also comprises rectification circuit, its input termination alternating current, its output links to each other with an end of switch transformer T primary coil by filter capacitor C2, the other end of switch transformer T primary coil links to each other with the drain electrode of field effect transistor Q1, the grid of field effect transistor Q1 links to each other with the output of PWM controller, the source electrode of field effect transistor Q1 is by current sense resistor ground connection, switch transformer T secondary coil is by diode D1 rectification, capacitor C 3 filtering, and supply voltage stabilizing circuit 2, optocoupler OC operating voltage, the output of optocoupler OC links to each other with the input of PWM controller.Described rectification circuit is full-wave rectifying circuit.

As shown in Figure 1, described voltage stabilizing circuit 2 comprises three terminal regulator IC1, its negative electrode is brought in power supply by the output that resistance R 9 connects switching power circuit 1, its plus earth, capacitor C 1 is in parallel with the output of three terminal regulator IC1, the end of resistance R 7, R8 links to each other with the two ends of capacitor C 1 respectively, links to each other with the input of comparison circuit 3 after resistance R 7, R8 dividing potential drop.Described comparison circuit 3 comprises first, two, three comparator IC2A, IC2B, IC2C, its normal phase input end all links to each other with the output of voltage stabilizing circuit 2, its inverting input respectively with resistance R 4, R5, the end of R6 links to each other, link to each other with the input of optocoupler OC in the switching power circuit 1 after its output parallel connection, resistance R 4, R5, the other end of R6 respectively with the sample resistance R1 that is used for gathering every group of output current size, R2, R3 links to each other, sample resistance R1, R2, the other end of R3 and connect rear respectively with the negative pole of filter capacitor C3, the secondary coil of switch transformer T links to each other.Resistance R 4, R5, R6 are used for impedance matching.First, second and third comparator IC2A, IC2B, IC2C are operational amplifier.

When work, alternating current AC is through changing into direct current DC after the rectification of process full-wave rectifying circuit, the filter capacitor C2 filtering first, duty ratio or the switching frequency (time of opening in the one-period) of PWM controller control field effect transistor Q1, namely control the energy that is sent to secondary coil by switch transformer T primary coil, secondary coil is through diode D1 rectification, pass through again 3 filtering of filtering capacitor C, output DC DC.

Three terminal regulator IC1 provides the normal phase input end of reference data voltage Vref to first, second and third comparator IC2A, IC2B, IC2C for generation of stable voltage after resistance R 7, R8 dividing potential drop; Sample resistance R1, R2, R3 detects respectively the size of every group of output current, change into voltage by resistance R 4, R5, R6 offers first, two, three comparator IC2A, IC2B, the inverting input of IC2C, compare with reference data voltage Vref respectively, by first, two, three comparator IC2A, IC2B, IC2C adjusts the electric current that optocoupler OC passes through, adjust duty ratio or the switching frequency of the switching signal of PWM controller, namely adjust the time that field effect transistor Q1 opens, if flow through resistance R 1, R2, the electric current of R3 increases (or reducing), effect through control loop, the shortening of the time of opening in the field effect transistor Q1 one-period (or growth), thereby stabilizing output current Io1, Io2, the size of Io3 realizes constant current.

In a word, line construction of the present utility model is simple, is comprised of general components and parts such as voltage stabilizing didoe, operational amplifier IC, resistance, and debugging is simple, and function easily realizes, and is cheap, reduced cost; Without secondary switch, rectification circuit, avoid producing extra EMI (electromagnetic interference).

Claims

1. the novel low-cost of a LED mains lighting supply is organized constant current output circuit more, it is characterized in that: comprise switching power circuit (1), its input termination alternating current, its output links to each other with the input of comparison circuit (3) by voltage stabilizing circuit (2), switching power circuit (1) comprises PWM controller and optocoupler OC, comparison circuit (3) is comprised of a plurality of comparators, link to each other with the inverting input of comparison circuit (3) respectively for the sample resistance that gathers every group of output current size, the output of voltage stabilizing circuit (2) links to each other with the normal phase input end of comparison circuit (3), and the output of comparison circuit (3) links to each other with the PWM controller by optocoupler OC.

2. the novel low-cost of LED mains lighting supply according to claim 1 is organized constant current output circuit more, it is characterized in that: described switching power circuit (1) also comprises rectification circuit, its input termination alternating current, its output links to each other with an end of switch transformer T primary coil by filter capacitor C2, the other end of switch transformer T primary coil links to each other with the drain electrode of field effect transistor Q1, the grid of field effect transistor Q1 links to each other with the output of PWM controller, the source electrode of field effect transistor Q1 is by current sense resistor ground connection, switch transformer T secondary coil is by diode D1 rectification, capacitor C 3 filtering, and supply voltage stabilizing circuit (2), optocoupler OC operating voltage, the output of optocoupler OC links to each other with the input of PWM controller.

3. the novel low-cost of LED mains lighting supply according to claim 1 is organized constant current output circuit more, it is characterized in that: described voltage stabilizing circuit (2) comprises three terminal regulator IC1, its negative electrode is brought in power supply by the output that resistance R 9 connects switching power circuit (1), its plus earth, capacitor C 1 is in parallel with the output of three terminal regulator IC1, the end of resistance R 7, R8 links to each other with the two ends of capacitor C 1 respectively, and the input with comparison circuit (3) after resistance R 7, R8 dividing potential drop links to each other.

4. the novel low-cost of LED mains lighting supply according to claim 1 is organized constant current output circuit more, it is characterized in that: described comparison circuit (3) comprises first, two, three comparator IC2A, IC2B, IC2C, its normal phase input end all links to each other with the output of voltage stabilizing circuit (2), its inverting input respectively with resistance R 4, R5, the end of R6 links to each other, link to each other with the input of optocoupler OC in the switching power circuit (1) after its output parallel connection, resistance R 4, R5, the other end of R6 respectively with the sample resistance R1 that is used for gathering every group of output current size, R2, R3 links to each other, sample resistance R1, R2, the other end of R3 and connect rear respectively with the negative pole of filter capacitor C3, the secondary coil of switch transformer T links to each other.

5. the novel low-cost of LED mains lighting supply according to claim 2 is organized constant current output circuit more, it is characterized in that: described rectification circuit is full-wave rectifying circuit.