CN202364429U

CN202364429U - Led control circuit

Info

Publication number: CN202364429U
Application number: CN2011204439043U
Authority: CN
Inventors: 谭伟; 廖武强; 卢卡·博尔汀; 陈玉立
Original assignee: Osram Co Ltd
Current assignee: Osram GmbH; Osram Co Ltd
Priority date: 2011-11-10
Filing date: 2011-11-10
Publication date: 2012-08-01
Anticipated expiration: 2021-11-10

Abstract

The utility model relates to a LED control circuit, comprising a rectification unit (1), a load set branch circuit with a plurality of serially connected load sets (LED string -1,...LED string -N) and switches (Q1, ...QN) in parallel connection with respective load sets (LED string -1, ...LED string -N), characterized in that the LED circuit also comprises a light modulation control circuit which receives a light modulation signal (S1) representing light modulation states and a temperature signal (S2) representing temperatures of the load set branch circuit, and outputs control signals (S31, ...S3N) to each of the switches (Q1, ...QN). The LED control circuit of the utility model possesses the advantages of a simple structure, low costs and strong compatibility and is easy to integrate.

Description

The LED control circuit

Technical field

The utility model relates to a kind of LED control circuit.

Background technology

At present, the design of blend of colors has been widely used with the CCT (colour temperature) that is used to obtain to have expection and the white light of CRI (color rendering index).Usually for example use yellow light LED and blue-ray LED simultaneously and carry out mixed light and obtain white light.The compatibility of dimmer is a very important performance parameter for the LED product.Therefore press for a kind of LED control device of taking into account light modulation and control LED mixed light.Usually when design utilizes the LED control device of PWM light modulation, consider the reaction speed of led driver to pwm control signal.Therefore need use the DC-DC transducer, be that step-down controller provides the fast reaction to pwm control signal.

The problem that exists in the prior art is, when in lighting device, comprising a plurality of LED lamp string, need be equipped with a DC-DC step-down controller accordingly for each LED lamp string.The LED control device that designs like this is in cost and the too much resource of space requirement, and also very difficult light modulation and the mixed light process of controlling the LED lamp string of different colours simultaneously.

The utility model content

The purpose of the utility model is to provide a kind of LED control circuit, and said LED control circuit can overcome shortcoming of the prior art, have simple in structure, with low cost, be easy to integrated and compatible strong advantage.

Purpose according to the utility model realizes through a kind of like this LED control circuit: this LED control circuit comprises rectification unit and load group branch road and a plurality of switch parallelly connected with load group separately with a plurality of load group that are cascaded; It is characterized in that; The LED control circuit also comprises adjusting control circuit, and this adjusting control circuit receives the dim signal that characterizes dimming state and characterizes the temperature signal of load group branch road temperature and export control signal to each switch.

At length say to have electric current supply part and brightness adjustment control part according to the LED control circuit of the utility model.It is constant to carry out light modulation and mixed light and maintenance CCT according to demand in order to ensure the whole LED control circuit; Need obtain with each load group, be the relevant dim signal and the temperature signal of operating state of the different LED lamp string of color through the dimming control part branch; The control signal that is fit to through the switch output to each load group is thus regulated the brightness of each load group, so that realize light modulation and mixed light simultaneously.In addition, this LED control circuit simple in structure, with low cost has favorable compatibility, can be widely used in the majority of illumination environment.

Proposing in preferred embodiment according to one of the utility model; Adjusting control circuit comprises micro-control unit, signal converter and Temperature Detector; Micro-control unit receives dim signal and by the detected temperature signal of Temperature Detector; And sending pulse-width signal corresponding to each load group to signal converter, signal converter sends control signal corresponding to each switch respectively according to pulse-width signal.Dim signal for example can be the signal relevant with the angle of flow of dimmer; Temperature signal for example can be in the whole LED control circuit, to detect the temperature signal that obtains.Micro-control unit is handled dim signal that is received and temperature signal, produces the pulse-width signal that is respectively applied for each switch of control.Signal converter becomes to be applicable to that with pulse width modulated signal conversion the signal of switch is so that realize the control to switch.

Proposing in preferred embodiment according to one of the utility model, micro-control unit receives the signal of the dimmer output after the rectification unit rectification as dim signal.That is to say that micro-control unit can directly obtain dim signal from LED control circuit inside.

Proposing in preferred embodiment according to one of the utility model, micro-control unit receives directly signal by dimmer output as dim signal.In the case, micro-control unit can be obtained the dim signal of dimmer through being used for and the outside port that carries out exchanges data by the outside.

According to one of the utility model preferred embodiment in; Micro-control unit comprises signal processor, central processing unit and analog to digital converter; Wherein dim signal is input to central processing unit through signal processor, and temperature signal is input to central processing unit through analog to digital converter.

According to one of the utility model preferred embodiment in; The LED control circuit also comprises the ratio module; Be connected to rectification unit behind one end of ratio module, and other end connection signal processor, dim signal is input to central processing unit through ratio module, signal processor.Especially, signal processor is the real-time waveform analyzer.Can directly obtain to characterize the voltage signal of dimming state thus, and through being transfused in the real-time waveform analyzer after the ratio conversion.

According to one of the utility model preferred embodiment in, signal processor is to be connected directly to dimmer to obtain the decoding signals of dim signal.Can directly decode thus, so that central processing unit can read to the dim signal that obtains through outside port.

According to one of the utility model preferred embodiment in, between rectification unit and load group branch road, be connected with a unique two-stage step-down converting unit.Owing in LED control circuit, have the adjusting control circuit that to regulate and control each load group respectively, therefore only need the function that a two-stage step-down converting unit just can be implemented in needs a plurality of step-down controllers to realize in the prior art according to the utility model.

According to one of the utility model preferred embodiment in, first step-down controller that two-stage step-down converting unit comprises correcting power factors and the second ring step-down controller that stagnates that carries out the DC-to-dc conversion.Through two step-down controllers being used as together the step-down controller of two-stage type, can guarantee also can be by the constant electric current of two-stage step-down converting unit output when the voltage dynamic change of load group.

Preferably, the LED control circuit also comprises power factor correction controller that is connected with first step-down controller and the stagnant ring buck controller that is connected with the second stagnant ring step-down controller.

One preferred embodiment in, power factor correction controller is integrated on the same chip with stagnate ring buck controller and micro-control unit and signal converter.Can reduce structure space thus, embody the compactedness and the integration of whole LED control circuit.

According to one of the utility model preferred embodiment in; Temperature Detector comprises first resistance and thermistor; Wherein an end of first resistance connects DC power supply; The other end connects an end of thermistor, the other end ground connection of thermistor, and micro-control unit is connected between first resistance and the thermistor.The temperature signal that exists with voltage form that can obtain through thermistor thus.

According to one of the utility model preferred embodiment in; Switch is MOSFET; Wherein the grid of MOSFET is connected to signal converter to obtain control signal corresponding; Each load group is connected between the drain electrode and source electrode of corresponding MOSFET, also comprises the drain electrode that be connected MOSFET parallelly connected with each load group and the filter capacitor between the source electrode.

According to one of the utility model preferred embodiment in, rectification unit comprises electromagnetic interface filter and rectifier bridge, wherein be connected to behind the electromagnetic interface filter dimmer and before be connected to rectifier bridge, be connected to two-stage step-down converting unit before the rectifier bridge.

Description of drawings

In the accompanying drawing, in different views, similar reference number is often referred to identical part.In description, with reference to attached drawings, the various embodiment of the utility model have been described, wherein:

Fig. 1 shows first execution mode according to the LED control circuit of the utility model;

Fig. 2 shows second execution mode according to the LED control circuit of the utility model;

Fig. 3 shows the 3rd execution mode according to the LED control circuit of the utility model.

Embodiment

Fig. 1 shows first execution mode according to the LED control circuit of the utility model.After comprising in order, the LED control circuit is connected to the rectification unit 1 of dimmer (not shown), a unique two-stage step-down converting unit 2 and a plurality of load group LED string_1 that occur with the different LED lamp string form of color ... LED string_N.In this LED control circuit, comprise electromagnetic interface filter 11 and rectifier bridge 12 respectively as electric current supply rectification unit 1 partly and two-stage step-down converting unit 2 and be used for first step-down controller 21 of correcting power factors and the second stagnant ring step-down controller 22 that carries out the DC-to-dc conversion, wherein first step-down controller 21 and the second stagnant ring step-down controller 22 are connected with corresponding power factor correction controller 8 and stagnant ring buck controller 9 respectively.Because adopt the ring control mode that stagnates fast, the output current Io of led driver always keeps constant, even the voltage of LED lamp string is always in dynamically saltus step.

This LED control circuit also comprises ratio module 6, micro-control unit 3, signal converter 4 and the Temperature Detector 5 of common formation adjusting control circuit, and wherein micro-control unit 3 comprises signal processor 31, central processing unit 32 and analog to digital converter 33.Directly between rectification unit 1 and two-stage step-down converting unit 2, obtain the AC voltage signal that characterizes dimming state and ratio module 6, be converted into dim signal S1, so that input micro-control unit 3 through ratio.Correspondingly, the signal processor 31 in the micro-control unit 3 this be real-time waveform analyzer 31 '.The real-time waveform analyzer 31 ' dim signal S1 that receives is sent to central processing unit 32 through after the analyzing and processing.Also import central processing unit 32 after temperature signal S2 process analog to digital converter 33 conversions of while from the voltage form of Temperature Detector 5.At this; Temperature Detector 5 comprises first resistance R 1 and thermistor NTC, and wherein an end of first resistance R 1 connects DC power supply VDD, and the other end connects the end of thermistor NTC; The other end ground connection of thermistor NTC, analog to digital converter 33 are connected between first resistance R 1 and the thermistor NTC.

Central processing unit 32 can obtain respectively the signal from light modulation and temperature two aspects thus; The dimming effect that reaches is as required being kept under the constant situation of whole LED colour temperature (CCT); Respectively to each load group LED string_1; ... LED string_N output relevant pulse width modulation signals PWM_1 ... PWM_N.These pulse-width signals PWM_1 ... PWM_N converts to after through signal converter 4 and can control each load group LED string_1 ... the respective switch Q of LED string_N ₁... Q _NControl signal S3 ₁... S3 _NThe switch Q that exists with the MOSFET form ₁... Q _NGrid be connected to signal converter 4 to obtain control signal corresponding S3 ₁... S3 _N, each load group LED string_1 ... LED string_N is connected to corresponding MOSFET Q ₁... Q _NDrain electrode and source electrode between, in addition, also at each MOSFET Q ₁... Q _NDrain electrode and source electrode between connected and corresponding load group LED string_1 ... the filter capacitor C of LED string_N parallel connection ₁... C _N

Fig. 2 shows second execution mode according to the LED control circuit of the utility model.Be that with the difference part of first execution mode of Fig. 1 adjusting control circuit does not directly partly receive the dim signal S1 that characterizes dimming state from the electric current supply of LED control circuit, but utilizes port 7 directly to receive corresponding dim signal S1 from dimmer.Particularly, cancelled the ratio module 6 that is connected between rectification unit 1 and the microprocessor 3 in this embodiment, be used to receive the dim signal S1 of port 7 input of external signal from dimmer through microprocessor 3.Signal processor 31 is specifically designed to decoding signals 31 for this reason ", it can be decoded to dim signal S1.Because other functional modules in second execution mode and device are identical with first execution mode among Fig. 1, at this no longer to this repeat specification.

Fig. 3 shows the 3rd execution mode according to the LED control circuit of the utility model.Be with the difference part of first execution mode of Fig. 1; The power factor correction controller 8 that is used for controlling first step-down controller 21 be used to control second stagnate ring step-down controller 22 stagnant ring buck controller 9 be not arranged on the LED control circuit individually, but be integrated on the same chip with micro-control unit 3 and signal converter 4.The structure space of whole LED control circuit be can reduce thus, the compactedness and the integration that realize thus advantageously embodied.

List of reference characters:

1 rectification unit

11 electromagnetic interface filters

12 rectifier bridges

2 two-stage step-down converting units

21 first step-down controllers

22 second stagnate encircles step-down controller

3 micro-control units

31 signal processors

31 ' real-time waveform analyzer

31 " decoding signals

32 central processing units

33 analog to digital converters

4 signal converters

5 Temperature Detectors

6 ratio modules

7 ports

8 power factor correction controllers

9 stagnate encircles buck controller

C ₁... C _NFilter capacitor

I _OOutput current

LED string_1 ... LED string_N load group

The NTC thermistor

PWM_1 ... the PWM_N pulse-width signal

Q ₁... Q _NSwitch/MOSEFT

The VDD DC power supply

R1 first resistance

The S1 dim signal

The S2 temperature signal

S3 ₁... S3 _NControl signal

Claims

1. LED control circuit; Comprise rectification unit (1) and have a plurality of load group (the LED string_1 that is cascaded; ... LED string_N) load group branch road and a plurality of and load group separately (LED string_1 ... LED string_N) switch (Q of parallel connection ₁... Q _N), it is characterized in that said LED control circuit also comprises adjusting control circuit, said adjusting control circuit receives the dim signal (S1) that characterizes dimming state and characterizes the temperature signal (S2) of said load group branch road temperature and to each switch (Q ₁... Q _N) output control signal (S3 ₁... S3 _N).

2. LED control circuit according to claim 1; It is characterized in that; Said adjusting control circuit comprises micro-control unit (3), signal converter (4) and Temperature Detector (5), and said micro-control unit (3) receives said dim signal (S1) and by the detected said temperature signal of said Temperature Detector (5) (S2), and sends corresponding to each load group (LED string_1 to said signal converter (4); ... LED string_N) pulse-width signal (PWM 1; ... PWM N), said signal converter (4) according to said pulse-width signal (PWM_1 ... PWM N) respectively to each switch (Q ₁... Q _N) send control signal corresponding (S3 ₁... S3 _N).

3. LED control circuit according to claim 2 is characterized in that, said micro-control unit (3) receives the signal of the said dimmer output after rectification unit (1) rectification as dim signal (S1).

4. LED control circuit according to claim 2 is characterized in that, said micro-control unit (3) receives the direct signal of being exported by said dimmer as dim signal (S1).

5. according to claim 3 or 4 described LED control circuits; It is characterized in that; Said micro-control unit (3) comprises signal processor (31), central processing unit (32) and analog to digital converter (33); Wherein said dim signal (S1) is input to said central processing unit (32) through said signal processor (31), and said temperature signal (S2) is input to said central processing unit (32) through said analog to digital converter (33).

6. LED control circuit according to claim 5; It is characterized in that; Also comprise ratio module (6); Be connected to said rectification unit (1) behind one end of said ratio module (6), and the other end connects said signal processor (31), said dim signal (S1) is input to said central processing unit (32) through said ratio module (6), said signal processor (31).

7. LED control circuit according to claim 6 is characterized in that, said signal processor (31) is real-time waveform analyzer (31 ').

8. LED control circuit according to claim 5 is characterized in that, said signal processor (31) is to be connected directly to decoding signals (31 ") of dimmer to obtain said dim signal (S1).

9. according to each described LED control circuit among the claim 2-4, it is characterized in that, between said rectification unit (1) and said load group branch road, be connected with a unique two-stage step-down converting unit (2).

10. LED control circuit according to claim 9 is characterized in that, said two-stage step-down converting unit (2) comprises first step-down controller (21) of correcting power factors and carries out the second stagnant ring step-down controller (22) of DC-to-dc conversion.

11. LED control circuit according to claim 10; It is characterized in that said LED control circuit also comprises power factor correction controller (8) that is connected with said first step-down controller (21) and the stagnant ring buck controller (9) that is connected with the said second stagnant ring step-down controller (22).

12. LED control circuit according to claim 11 is characterized in that, the said power factor correction controller (8) and the ring buck controller (9) that stagnates are integrated on the same chip with said micro-control unit (3) and signal converter (4).

13. according to each described LED control circuit among the claim 2-4; It is characterized in that; Said Temperature Detector (5) comprises first resistance (R1) and thermistor (NTC), and an end of wherein said first resistance (R1) connects DC power supply (VDD), and the other end connects an end of said thermistor (NTC); The other end ground connection of said thermistor (NTC), said micro-control unit (3) are connected between said first resistance (R1) and the said thermistor (NTC).

14., it is characterized in that said switch (Q according to each described LED control circuit among the claim 2-4 ₁... Q _N) be MOSFET (Q ₁... Q _N), wherein said MOSFET (Q ₁... Q _N) grid connect said signal converter (4) obtain control signal corresponding (S31 ... S3N), each load group (LED string_1 ... LED string_N) be connected to corresponding MOSFET (Q ₁... Q _N) drain electrode and source electrode between, said LED control circuit also comprise with said each load group (LED string_1 ... LED string_N) parallel connection be connected said MOSFET (Q ₁... Q _N) drain electrode and the filter capacitor (C between the source electrode ₁... C _N).

15. according to each described LED control circuit among the claim 2-4; It is characterized in that; Said rectification unit (1) comprises electromagnetic interface filter (11) and rectifier bridge (12); Be connected to behind the wherein said electromagnetic interface filter (11) said dimmer and before be connected to said rectifier bridge (12), the preceding said step-down converting unit (2) that is connected to of said rectifier bridge (12).