CN202085375U

CN202085375U - LED constant current switch power supply with output current adjustable

Info

Publication number: CN202085375U
Application number: CN2011202151046U
Authority: CN
Inventors: 李竹
Original assignee: Individual
Current assignee: Individual
Priority date: 2011-06-23
Filing date: 2011-06-23
Publication date: 2011-12-21
Anticipated expiration: 2021-06-23

Abstract

The utility model relates to an LED constant current switch power supply, in particular to an LED constant current switch power supply with output current adjustable. The LED constant current switch power supply with output current adjustable resolves the problem that the prior LED constant current switch power supply is liable to be influenced by extraneous factors, is bad in universality, can not meet the demand of harmonic waves and EMI conducting required by the CCC and CE, and has low power factors and efficiency. The LED constant current switch power supply with output current adjustable comprises an input EMI filtering and protection circuit, a rectification filtering circuit, an input over-voltage under-voltage protection circuit, a drain electrode over-voltage protection circuit, a pulse width modulation circuit, an output open circuit protection circuit, a pulse width modulation power supply circuit and an output rectification circuit. The LED constant current switch power supply with output current adjustable effectively resolves the problem that the prior LED constant current switch power supply is liable to be influenced by extraneous factors, is bad in universality, can not meet the demand of harmonic waves and EMI conducting required by the CCC and CE, and has low power factors and efficiency; and is suitable to the field of LED illuminating.

Description

The LED constant current switch power supply of adjustable output current

Technical field

The utility model relates to LED constant current switch power supply, specifically is a kind of LED constant current switch power supply of adjustable output current.

Background technology

Be applied to the following shortcoming of constant current switch power supply ubiquity of LED illumination at present: one,, disturbed by extraneous factors such as high pressure, thunderbolt, overcurrents easily owing to lack the safety circuit; Two, output current is single, and versatility is not strong, is not suitable for producing in batches; Three, can't satisfy harmonic wave and the Conducted EMI requirement that CCC and CE require; Four, power factor and efficient are lower.The problems referred to above at existing LED constant current switch power supply exists are necessary to invent a kind of novel constant current switch power supply.

Summary of the invention

The utility model requires and power factor and the lower problem of efficient in order to solve existing LED constant current switch power supply harmonic wave and Conducted EMI easily strong by extraneous factor interference, versatility, that can't satisfy CCC and CE requirement, and a kind of LED constant current switch power supply of adjustable output current is provided.

The utility model is to adopt following technical scheme to realize: the LED constant current switch power supply of adjustable output current comprises input EMI filtering and protective circuit, current rectifying and wave filtering circuit, input over-and under-voltage protective circuit, drain electrode overvoltage crowbar, pulse-width modulation circuit, output open circuit protective circuit, pulse-width modulation power supply circuits and output rectification circuit; Wherein, input EMI filtering and protective circuit are provided with two ac input ends; output rectification circuit is provided with two dc output ends; the output of input EMI filtering and protective circuit links to each other with the input of current rectifying and wave filtering circuit; the output of current rectifying and wave filtering circuit links to each other with the input of input over-and under-voltage protective circuit; the output of input over-and under-voltage protective circuit links to each other with the input of pulse-width modulation circuit; the output of pulse-width modulation circuit links to each other with the input of drain electrode overvoltage crowbar; the output of drain electrode overvoltage crowbar links to each other with the input of output rectification circuit; the input of pulse-width modulation power supply circuits links to each other with the output of output rectification circuit; the output of pulse-width modulation power supply circuits links to each other with the feeder ear of pulse-width modulation circuit; the input of output open circuit protective circuit with link to each other with the output of output rectification circuit, the output of output open circuit protective circuit links to each other with the feedback end of pulse-width modulation circuit.Described input EMI filtering and protective circuit, current rectifying and wave filtering circuit, input over-and under-voltage protective circuit, drain electrode overvoltage crowbar, pulse-width modulation circuit, output open circuit protective circuit, pulse-width modulation power supply circuits, output rectification circuit are the structure that those skilled in the art realize easily, and multiple malformation can be arranged.

During work, two ac input ends of input EMI filtering and protective circuit are connected power supply grid, and two dc output ends of output rectification circuit connect load (LED); Alternating current at first enters input EMI filtering and protective circuit; carry out rectifying and wave-filtering by current rectifying and wave filtering circuit then; direct current after the rectification is introduced into input over-and under-voltage protective circuit and carries out voltage detecting; enter pulse-width modulation circuit then; and by pulse-width modulation circuit generation pulse-width signal, pulse-width signal is given load (LED) power supply by output rectification circuit subsequently.When fluctuation takes place in load current, load voltage will fluctuate, input by the pulse-width modulation power supply circuits can feed back to pulse-width modulation circuit with fluctuation information, and sends pulse-width signal by pulse-width modulation circuit load current is adjusted, thereby makes load current keep stable; Input over-and under-voltage protective circuit circuit can prevent that extraneous factors such as high pressure, thunderbolt, overcurrent from causing interference to the constant current switch power supply; Can regulate load current by the pulse-width modulation power supply circuits.Compare with existing constant current switch power supply, the LED constant current switch power supply of adjustable output current described in the utility model has the following advantages: one, set up the safety circuit, can effectively prevent extraneous factors interference such as high pressure, thunderbolt, overcurrent; Two, output current is adjustable, and highly versatile is fit to produce in batches; Three, satisfy harmonic wave and the Conducted EMI requirement that CCC and CE require fully; Four, power factor and efficient are higher.

The utility model is rational in infrastructure, easy to use, efficiently solve existing LED constant current switch power supply harmonic wave and Conducted EMI easily strong, that can't satisfy CCC and CE requirement and require and power factor and the lower problem of efficient, be applicable to the fields such as illumination of LED by extraneous factor interference, versatility.

Description of drawings

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

Embodiment

The LED constant current switch power supply of adjustable output current comprises input EMI filtering and protective circuit, current rectifying and wave filtering circuit, input over-and under-voltage protective circuit, drain electrode overvoltage crowbar, pulse-width modulation circuit, output open circuit protective circuit, pulse-width modulation power supply circuits and output rectification circuit; Wherein, input EMI filtering and protective circuit are provided with two ac input ends, output rectification circuit is provided with two dc output ends, the output of input EMI filtering and protective circuit links to each other with the input of current rectifying and wave filtering circuit, the output of current rectifying and wave filtering circuit links to each other with the input of input over-and under-voltage protective circuit, the output of input over-and under-voltage protective circuit links to each other with the input of pulse-width modulation circuit, the output of pulse-width modulation circuit links to each other with the input of drain electrode overvoltage crowbar, the output of drain electrode overvoltage crowbar links to each other with the input of output rectification circuit, the input of pulse-width modulation power supply circuits links to each other with the output of output rectification circuit, the output of pulse-width modulation power supply circuits links to each other with the feeder ear of pulse-width modulation circuit, the input of output open circuit protective circuit with link to each other with the output of output rectification circuit, the output of output open circuit protective circuit links to each other with the feedback end of pulse-width modulation circuit;

Described input EMI filtering and protective circuit comprise piezo-resistance RV1, be connected with fuse F1 between piezo-resistance RV1 and the ac input end, piezo-resistance RV1 two ends also are connected to the series arm that is formed by first inductance-the 3rd inductance L 1-L3, first capacitor C, 1 serial connection; Described current rectifying and wave filtering circuit comprises the rectifier bridge that is made of first diode-the 4th diode D1-D4; Two inputs of rectifier bridge link to each other with first capacitor C, 1 two ends respectively, are connected with the series arm that is formed by the 4th inductance L 4 and second capacitor C, 2 serial connections between two outputs of rectifier bridge; Described input over-and under-voltage protective circuit comprises the series arm that is formed by the 5th diode D5 and the 3rd capacitor C 3 serial connections; Link to each other with second capacitor C, 2 two ends respectively with the series arm two ends that the 3rd capacitor C 3 serial connections form by the 5th diode D5; Described drain electrode overvoltage crowbar comprises the series arm that is formed by the 6th diode D6, the 7th diode D7, the 4th capacitor C 4 serial connections; Described pulse-width modulation circuit comprises pulse width modulating chip U1; The input of pulse width modulating chip U1 links to each other with the 3rd capacitor C 3, and the output of pulse width modulating chip U1 links to each other with the 7th diode D7; Described output open circuit protective circuit comprises triode Q1; The collector electrode of triode Q1 is connected with the series arm that is formed by the 11 diode D11 and the 12 diode D12 serial connection, and the collector electrode of triode Q1 links to each other with the feedback end of pulse width modulating chip U1; Described pulse-width modulation power supply circuits comprise the serial connection branch road that is formed by the 9th diode D9 and the tenth diode D10 serial connection; Described output rectification circuit comprises transformer T1; Two inputs of transformer T1 link to each other with the 6th diode D6 with the 4th capacitor C 4 respectively, are connected with by the 5th inductance L 5, the 8th diode D8, the 5th capacitor C 5, the 6th capacitor C 6 between two outputs of transformer T1 and connect the parallel branch that forms; The 9th diode D9 all links to each other with the output of transformer T1 with the 11 diode D11, is connected with the tenth capacitor C 10 between the output of transformer T1 and first capacitor C 1;

During work, piezo-resistance RV1 can protect back level element to exempt from the destruction of surge voltage, fuse F1 can form short-circuit protection to subsequent conditioning circuit, first inductance L, 1 filtering common-mode noise, second inductance L 2 and the 3rd inductance L 3 are in parallel with first resistance R 1 and second resistance R 2 respectively, the filtering differential mode noise, first capacitor C 1 is a differential mode safety electric capacity, be used for the filtering differential mode noise, the tenth capacitor C 10 is used for the filtering common-mode noise, and this part can be isolated the interference and the power supply grid of subsequent conditioning circuit; First diode-the 4th diode D1-D4 constitutes full-wave bridge rectifier circuit, and the 4th inductance L 4 and second capacitor C 2 constitute the LC filter circuit, can filter the High-frequency Interference in the direct current; The 4th resistance-the 7th resistance R 4-R7, the 5th diode D5 and the 3rd capacitor C 3 constitute input over-and under-voltage protective circuit, the voltage parameter is converted to the voltage detecting pin that current parameter is input to pulse-width modulation circuit, compare with the electric current of feedback, thereby modulating pulse width is provided with over-and under-voltage threshold value and stable output current; Pulse-width modulation circuit is provided with full power state by the tenth resistance R 10, and the feedback current value is adjusted in the change of the resistance value by 16 series connection of the 15 resistance R 15 and adjustable resistance the 16 resistance R again, constitutes the closed loop current feedback, makes outputting current steadily; The 4th capacitor C 4, the 8th resistance R 8, the 9th resistance R 9, the 6th diode D6 are with drain voltage clamp in addition, guarantee that drain voltage is in safe range, when the voltage at elementary winding two ends surpasses the voltage at C2 two ends and transient state AC when sinusoidal wave, need prevent to produce on the pulse width modulating chip reverse current by the 7th diode D7; The 6th diode D6, the 8th capacitor C the 8, the 12 resistance R 12 and the 13 resistance R 13 utilize the feedback winding of transformer to produce direct voltage, this voltage is supplied operating current by the tenth diode D10 and the 14 resistance R 14 to the bypass pin of pulse width modulating chip U1, the 5th capacitor C 5 and 6 pairs of bypass pins of the 6th capacitor C carry out local decoupling, between the starting period, the high-voltage constant current source that is connected internally to drain lead is to this electric capacity charging, after charging, the energy of storage is used to pulse width modulating chip U1 power supply, reaches stable state up to output; The 11 diode D11,17 resistance-the 19 resistance R 17-R19, the 11 capacitor C the 11, the 12 capacitor C the 12, the 12 diode D12 and triode Q1 provide the load open circuit protection function; If the disconnection output loading, output voltage will raise, and causes bias voltage to rise, and the voltage on the 12 capacitor C 12 also increases; In case the voltage on the 12 capacitor C 12 surpasses the voltage stabilizing threshold value of the 12 diode D12, triode Q1 will setover, and the electric current that enters feedback pin is dropped to reset automatically below the threshold value; In case enter the pattern of resetting automatically, switch will alternately stop and opening, and guarantees that output voltage was in the acceptable restriction before reconnecting load always; The damage that the too high voltages that may occur under the situation that can avoid when production test load to disconnect like this causes the 7th capacitor C 7 and the 8th capacitor C 8; The 8th diode D8 carries out rectification to secondary winding, and filtering is carried out in the 7th capacitor C 7 and 8 pairs of outputs of the 8th capacitor C; Can limit output voltage under the no-load condition as the 11 resistance R 11 of dummy load; The 5th inductance L 5 is used to reduce radiation EMI;

During concrete enforcement, pulse width modulating chip U1 disposes correspondent peripheral circuit, and the setting of peripheral circuit is known to those skilled in the art.

Claims

1. the LED constant current switch power supply of an adjustable output current is characterized in that: comprise input EMI filtering and protective circuit, current rectifying and wave filtering circuit, input over-and under-voltage protective circuit, drain electrode overvoltage crowbar, pulse-width modulation circuit, output open circuit protective circuit, pulse-width modulation power supply circuits and output rectification circuit; Wherein, input EMI filtering and protective circuit are provided with two ac input ends; output rectification circuit is provided with two dc output ends; the output of input EMI filtering and protective circuit links to each other with the input of current rectifying and wave filtering circuit; the output of current rectifying and wave filtering circuit links to each other with the input of input over-and under-voltage protective circuit; the output of input over-and under-voltage protective circuit links to each other with the input of pulse-width modulation circuit; the output of pulse-width modulation circuit links to each other with the input of drain electrode overvoltage crowbar; the output of drain electrode overvoltage crowbar links to each other with the input of output rectification circuit; the input of pulse-width modulation power supply circuits links to each other with the output of output rectification circuit; the output of pulse-width modulation power supply circuits links to each other with the feeder ear of pulse-width modulation circuit; the input of output open circuit protective circuit with link to each other with the output of output rectification circuit, the output of output open circuit protective circuit links to each other with the feedback end of pulse-width modulation circuit.

2. the LED constant current switch power supply of adjustable output current according to claim 1, it is characterized in that: described input EMI filtering and protective circuit comprise piezo-resistance (RV1), be connected with fuse (F1) between piezo-resistance (RV1) and the ac input end, piezo-resistance (RV1) two ends also are connected to the series arm that is formed by first inductance-the 3rd inductance (L1-L3), first electric capacity (C1) serial connection; Described current rectifying and wave filtering circuit comprises the rectifier bridge that is made of first diode-the 4th diode (D1-D4); Two inputs of rectifier bridge link to each other with first electric capacity (C1) two ends respectively, are connected with the series arm that is formed by the 4th inductance (L4) and second electric capacity (C2) serial connection between two outputs of rectifier bridge; Described input over-and under-voltage protective circuit comprises the series arm that is formed by the 5th diode (D5) and the 3rd electric capacity (C3) serial connection; Link to each other with second electric capacity (C2) two ends respectively with the series arm two ends that the 3rd electric capacity (C3) serial connection forms by the 5th diode (D5); Described drain electrode overvoltage crowbar comprises the series arm that is formed by the 6th diode (D6), the 7th diode (D7), the 4th electric capacity (C4) serial connection; Described pulse-width modulation circuit comprises pulse width modulating chip (U1); The input of pulse width modulating chip (U1) links to each other with the 3rd electric capacity (C3), and the output of pulse width modulating chip (U1) links to each other with the 7th diode (D7); Described output open circuit protective circuit comprises triode (Q1); The collector electrode of triode (Q1) is connected with the series arm that is formed by the 11 diode (D11) and the 12 diode (D12) serial connection, and the collector electrode of triode (Q1) links to each other with the feedback end of pulse width modulating chip (U1); Described pulse-width modulation power supply circuits comprise the serial connection branch road that is formed by the 9th diode (D9) and the tenth diode (D10) serial connection; Described output rectification circuit comprises transformer (T1); Two inputs of transformer (T1) link to each other with the 6th diode (D6) with the 4th electric capacity (C4) respectively, are connected with by the 5th inductance (L5), the 8th diode (D8), the 5th electric capacity (C5), the 6th electric capacity (C6) between two outputs of transformer (T1) and connect the parallel branch that forms; The 9th diode (D9) all links to each other with the output of transformer (T1) with the 11 diode (D11), is connected with the tenth electric capacity (C10) between the output of transformer (T1) and first electric capacity (C1).