CN202143271U - High accuracy multipath LED current sharing circuit - Google Patents
High accuracy multipath LED current sharing circuit Download PDFInfo
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- CN202143271U CN202143271U CN201120276772U CN201120276772U CN202143271U CN 202143271 U CN202143271 U CN 202143271U CN 201120276772 U CN201120276772 U CN 201120276772U CN 201120276772 U CN201120276772 U CN 201120276772U CN 202143271 U CN202143271 U CN 202143271U
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Abstract
The utility model relates to a high accuracy multipath LED current sharing circuit, comprising multiple paths of light emitting branches parallelly connected, wherein the LED anode of each path of LED light emitting branch is connected with the anode output end of an externally connected power supply. The high accuracy multipath LED current sharing circuit is characterized in that the LED cathode of any branch in the multipath LED current sharing circuit is connected with a first resistor, then a second resistor, and thereafter an externally connected cathode output end of the externally connected power supply; the LED cathodes of other LED braches in the multipath LED current sharing circuit are connected with the collectors of triodes, each of the emitters of the triodes is connected with a sample resistor, and then the cathode output end of the externally connected power supply, and the sampling resistors and the second resistor have the same resistance value; and the bases of the triodes are connected with the output ends of operational amplifiers, the same-phase input ends of the operational amplifier are connected with the second end of the first resistor respectively, and the anti-phase input ends of the operational amplifiers are connected with the emitters of the triodes correspondingly. The high accuracy multipath LED current sharing circuit can realize multipath LED high accuracy current sharing, and the circuit structure is simple.
Description
Technical field
The utility model relates to a kind of high accuracy LED multi-path flow equalizing circuit.
Background technology
As everyone knows, LED needs constant-current driving, and for high-power LED, because the inconsistency of its forward voltage drop causes its directly parallel connection use.But in some application scenario, because a maximum number of the LED that the restriction of safety extra low voltage makes series connection is restricted.
The flow equalizing circuit of existing parallel connection LED is realized through mirror current source usually; Its circuit theory is as shown in Figure 1; Through the flow equalizing circuit that this form realizes, its current-sharing precision receives the Vbe influence of triode, and the electric current of two-way is also variant when the Vbe of different triodes is variant.Owing to the negative temperature characteristic of triode Vbe, Vbe will produce bigger deviation along with the difference of temperature when two triode temperature are inconsistent, influence the current-sharing precision equally simultaneously.The effect of R2～R (n+1) is to reduce because the difference of the two-way electric current that Vbe pressure reduction causes; Usually can to get the pressure reduction at R2～R (n+1) two ends consistent with Vbe or approaching in order to reach good effect; But, will cause the loss on R2～R (n+1) to increase like this, reduce the whole efficiency of system.In addition, because the deviation of LED forward voltage drop VF, when deviation is excessive, can make the system can't operate as normal.Illustrate; As shown in Figure 1; When the VF sum of all LED on this road of I2 series connection is above less than the VF sum 0.7V of all LED series connection on this road of I1, triode Q2 this moment saturation conduction, the pressure reduction that can't reduce Vce again makes system balancing; This will cause system's cisco unity malfunction, just can't realize the effect of two-way current-sharing.
The utility model content
The utility model technical problem to be solved is to above-mentioned prior art the high accuracy LED multi-path flow equalizing circuit that a kind of circuit structure is simple, can realize high-precision current-sharing effect to be provided.
The utility model solves the problems of the technologies described above the technical scheme that is adopted: this high accuracy LED multi-path flow equalizing circuit; The luminous branch road of LED multi-path that comprises connection parallel with one another; LED is anodal in the luminous branch road of each paths of LEDs all is connected with the external power supply cathode output end; It is characterized in that: the LED negative pole of any branch road connects first end of first resistance in the luminous branch road of said LED multi-path; Second end of first resistance connects first end of second resistance, and second end of second resistance is connected with the external power supply cathode output end; The LED negative pole of other branch roads all connects the collector electrode of a triode in the luminous branch road of said LED multi-path; The emitter of this triode is connected with the external power supply cathode output end after all connecting a sampling resistor, and the resistance of all sampling resistors is all identical with said second resistance; In addition; The base stage of all triodes links to each other with the output of an operational amplifier respectively; The in-phase input end of all operational amplifiers all links to each other with second end of said first resistance, and the emitter of the triode on the inverting input of all operational amplifiers and the luminous branch road of corresponding LED links to each other.
As improvement, between the base stage of all triodes and ground, be connected an electric capacity respectively.
Compared with prior art, the advantage of the utility model is: can realize the sampling of low-voltage, reduce the loss on sampling resistor.Simultaneously, use amplifier can realize high-precision current-sharing effect, and do not have temperature to float.In addition through regulating the resistance of R1, can well adapt to LED pressure drop between each road and difference, the utility model is a kind of current-sharing scheme of high-efficiency high-accuracy.
Description of drawings
Fig. 1 is the circuit theory diagrams of LED flow equalizing circuit in the prior art.
Fig. 2 is the circuit theory diagrams of the utility model embodiment one.
Fig. 3 is the circuit theory diagrams of the utility model embodiment two.
Fig. 4 is the circuit theory diagrams of the utility model embodiment three.
Embodiment
Embodiment describes in further detail the utility model below in conjunction with accompanying drawing.
Embodiment one
Referring to LED flow equalizing circuit shown in Figure 2; The luminous branch road of two paths of LED that comprises connection parallel with one another; In the luminous branch road of this two paths of LED; Be composed in series LED electroluminescent lamp string by plurality of LEDs, wherein the anodal of LED electroluminescent lamp string all is connected with the external power supply cathode output end, and wherein the negative pole of LED electroluminescent lamp string connects first end of first resistance R 1 in the luminous branch road of first paths of LEDs; Second end of first resistance R 1 connects first end of second resistance R 2, and second end of second resistance R 2 is connected with the external power supply cathode output end; The negative pole of LED electroluminescent lamp string connects the collector electrode of a triode Q1 in the luminous branch road of second paths of LEDs, and the emitter of this triode Q1 connects one and adopts resistance R 3 backs to be connected with the external power supply cathode output end, and the resistance of sampling resistor R3 is identical with said second resistance R 2; In addition, the base stage of triode Q1 links to each other with the output of an operational amplifier N1, and the in-phase input end of operational amplifier N1 links to each other with second end of said first resistance R 1, and the inverting input of operational amplifier N1 links to each other with the emitter of triode Q1.Between the base stage of said triode and ground, be connected a capacitor C 1.
When flowing through second resistance R 2, the circuit I 1 in the luminous branch road of first paths of LEDs produces a la tension de reference Uref est; Realize closed-loop control through operational amplifier in the luminous branch road of second paths of LEDs; This closed-loop control is electric current series connection negative feedback, and triode Q1 emitter links to each other with the inverting input of operational amplifier, no matter is in DC channel; Still in alternating current path, feedback all exists.As Uref during greater than Uf1, the voltage U 1 at transistor base place is for just, and circuit I 2 electric currents in the luminous branch road of second paths of LEDs increase, and Uf1 increases, and causes Δ U=(Uref-Uf1) to reduce, and forms the negative feedback of circuit.Vice versa.Final in system stability, Uref=Uf1, at this moment, because R2=R3 can realize I1=I2.
The current error of following this circuit two-way of surface analysis; The steady-state error of general dc current stabilized power supply can be divided into two types: the first kind is static receiver error (an abbreviation static difference); Relevant with the type and the input signal of power-supply system, comprise given static difference and disturbance static difference, static difference can overcome through the adjusting of system; Second type is systematic error, mainly by the temperature of current sampling unit, adjuster, device float, in time, floats and causes, is the error that power-supply system can't overcome.The negative-feedback circuit that present embodiment adopts operational amplifier to realize can effectively be eliminated static difference.And its systematic error mainly contains that the adjusting deviation of resistance and the amplifier of sampling resistor causes, resistance can select for use the F shelves to get Chip-R, and the adjusting deviation of amplifier can be ignored itself, finally realizes the precise current-equalizing of two-way.Between transistor base and ground, increase the variation that capacitor C 1 can be slowed down the voltage U 1 at transistor base place, increase the stability of system.
Embodiment two
Different with embodiment one is; Comprise the luminous branch road of three paths of LEDs, referring to shown in Figure 3, wherein in the luminous branch road of Third Road LED; Also be composed in series LED electroluminescent lamp string by plurality of LEDs; The anodal of Third Road LED electroluminescent lamp string is connected with the external power supply cathode output end equally, and the negative pole of Third Road LED electroluminescent lamp string connects the collector electrode of triode Q2 equally, and triode Q2 emitter is connected with the external power supply cathode output end after connecting sampling resistor R4; The base stage of triode Q2 also connects the output of an operational amplifier N2; The in-phase input end of operational amplifier N2 links to each other with second end of first resistance R 1, and the inverting input of operational amplifier N2 links to each other with the emitter of triode Q2, also is connected with a capacitor C 2 between the base stage of triode Q2 and the ground.
Produce a la tension de reference Uref est when equally, the circuit I 1 in the luminous branch road of first paths of LEDs flows through second resistance R 2; The luminous branch road of two paths of LED is all realized closed-loop control through amplifier in addition, and this closed-loop control is electric current series connection negative feedback.The emitter of triode Q1 links to each other with the inverting input of operational amplifier N1, no matter is in DC channel, and still in alternating current path, feedback all exists.As Uref during greater than Uf1, U1 is for just, and the I2 electric current increases, and Uf1 increases, and causes Δ U=(Uref-Uf1) to reduce, and forms the negative feedback of circuit.Vice versa.Final in system stability, Uref=Uf is because R2=R3 can realize I1=I2.In like manner, triode Q2 emitter links to each other with the inverting input of operational amplifier N2, and as Uref during greater than Uf2, U2 is for just, and the I3 electric current increases, and Uf2 increases, and causes Δ U=(Uref-Uf2) to reduce, and forms the negative feedback of circuit.Vice versa.Final in system stability, Uref=Uf2 is because R2=R4 can realize I1=I3.Finally, i.e. I1=I2=I3.Realize 3 tunnel current-sharings.
Embodiment three
Narration through embodiment one and two; We can extend to the thought of the utility model the LED multi-path flow equalizing circuit more than three tunnel; Referring to shown in Figure 4; As long as the LED negative pole of other branch roads is all connected the collector electrode of a triode Q2, Q3, Q (n-1); The emitter of all triode Q2, Q3, Q (n-1) connects one respectively and adopts resistance R 3, R4, R (n+1) back to be connected with the external power supply cathode output end, and the resistance of all sampling resistor R3, R4, R (n+1) is all identical with said second resistance R 2; And; The base stage of all triode Q2, Q3, Q (n-1) is linked to each other with the output of an operational amplifier N2, N3, N (n-1) respectively; The in-phase input end of all operational amplifier N2, N3, N (n-1) all links to each other with second end of said first resistance R 1; The emitter of triode Q2 on the inverting input of all operational amplifier N2, N3, N (n-1) and the luminous branch road of corresponding LED, Q3, Q (n-1) links to each other, and can realize the LED multi-path current-sharing.
Claims (2)
1. high accuracy LED multi-path flow equalizing circuit; The luminous branch road of LED multi-path that comprises connection parallel with one another; LED is anodal in the luminous branch road of each paths of LEDs all is connected with the external power supply cathode output end; It is characterized in that: the LED negative pole of any branch road connects first end of first resistance (R1) in the luminous branch road of said LED multi-path, and second end of first resistance (R1) connects first end of second resistance (R2), and second end of second resistance (R2) is connected with the external power supply cathode output end; The LED negative pole of other branch roads all connects the collector electrode of a triode in the luminous branch road of said LED multi-path; The emitter of this triode is connected with the external power supply cathode output end after all connecting a sampling resistor, and the resistance of all sampling resistors is all identical with said second resistance (R2); In addition; The base stage of all triodes links to each other with the output of an operational amplifier respectively; The in-phase input end of all operational amplifiers all links to each other with second end of said first resistance (R1), and the emitter of the triode on the inverting input of all operational amplifiers and the luminous branch road of corresponding LED links to each other.
2. high accuracy LED multi-path flow equalizing circuit according to claim 1 is characterized in that: between the base stage of said triode and ground, be connected an electric capacity.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120276772U CN202143271U (en) | 2011-07-28 | 2011-07-28 | High accuracy multipath LED current sharing circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201120276772U CN202143271U (en) | 2011-07-28 | 2011-07-28 | High accuracy multipath LED current sharing circuit |
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| CN202143271U true CN202143271U (en) | 2012-02-08 |
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| CN201120276772U Expired - Lifetime CN202143271U (en) | 2011-07-28 | 2011-07-28 | High accuracy multipath LED current sharing circuit |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103596322A (en) * | 2012-08-16 | 2014-02-19 | 深圳市海洋王照明工程有限公司 | Constant current comparison circuit for LED driving circuit |
-
2011
- 2011-07-28 CN CN201120276772U patent/CN202143271U/en not_active Expired - Lifetime
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103596322A (en) * | 2012-08-16 | 2014-02-19 | 深圳市海洋王照明工程有限公司 | Constant current comparison circuit for LED driving circuit |
| CN103596322B (en) * | 2012-08-16 | 2017-07-14 | 深圳市海洋王照明工程有限公司 | A kind of constant current comparison circuit for LED drive circuit |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| EE01 | Entry into force of recordation of patent licensing contract |
Assignee: SELF ELECTRONICS CO.,LTD. Assignor: Lin Wanjiong Contract record no.: 2012330000180 Denomination of utility model: High-precision multipath LED (light-emitting diode) current-equalizing circuit Granted publication date: 20120208 License type: Exclusive License Record date: 20120416 |
|
| ASS | Succession or assignment of patent right |
Owner name: NINGBO HI. TECH. PARK SELF ELECTRONICS CO., LTD. Free format text: FORMER OWNER: LIN WANJIONG Effective date: 20141222 |
|
| C41 | Transfer of patent application or patent right or utility model | ||
| TR01 | Transfer of patent right |
Effective date of registration: 20141222 Address after: The national high tech Zone Juxian 315103 Ningbo Road, Zhejiang province No. 1345 Patentee after: SELF ELECTRONICS CO.,LTD. Address before: 315103 Zhejiang city of Ningbo province high tech Zone Juxian Road No. 1345 Ningbo Purcell Electronics Ltd. Patentee before: Lin Wanjiong |
|
| C56 | Change in the name or address of the patentee | ||
| CP01 | Change in the name or title of a patent holder |
Address after: The national high tech Zone Juxian 315103 Ningbo Road, Zhejiang province No. 1345 Patentee after: SELF ELECTRONICS CO., LTD. Address before: The national high tech Zone Juxian 315103 Ningbo Road, Zhejiang province No. 1345 Patentee before: SELF ELECTRONICS CO.,LTD. |
|
| CX01 | Expiry of patent term |
Granted publication date: 20120208 |
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| CX01 | Expiry of patent term |