CN201563262U

CN201563262U - LED driver

Info

Publication number: CN201563262U
Application number: CN2009202053309U
Authority: CN
Inventors: 赵一飞; 黄湘平
Original assignee: BYD Co Ltd
Current assignee: BYD Co Ltd
Priority date: 2009-09-25
Filing date: 2009-09-25
Publication date: 2010-08-25
Anticipated expiration: 2019-09-25

Abstract

The utility model provides an LED driver, which comprises a first output end used for providing an LED current to an LED path, a first circuit used for obtaining first signal respectively relevant to the LED peak current or valley current, and a second circuit used for generating a first control signal and a second control signal according to the first signal. Power stage of the LED current is adjusted according to the first control signal or the second control signal. The LED driver concerns the LED peak current or valley current when adjusting the current of an LED, and more precisely obtains required average current compared with the prior art.

Description

A kind of led driver

Technical field

The utility model relates to a kind of led driver.

Background technology

Compare with traditional light source, light-emitting diode (LED) possesses numerous advantages, and is low as operating voltage, efficiency height, very small and exquisite and generation directional light.They can provide extremely broad color and white light, do not produce infrared (IR) or ultraviolet (UV) radiation, and because they are solid state device, mechanically very strong, and it is not mercurous, when appropriate design and use, can have and surpass 50,000 hours working life, be longer than 1,000 hour life-span of standard incandescent lamp.These advantages make LED application more and more widely, nowadays had numerous application markets,, automobile backlight and solar energy etc. as construction landscape illumination, traffic lights, display screen, retail, small-medium size LCDs (LCD), and have increasing development space aspect backlight at street lighting, residential lighting and even middle large-scale LCD.As mentioned above, LED is voltage devices in essence; Different according to color and electric current, the forward voltage of LED is between not enough 2V to 4.5V.In addition, the LED stabilized illumination needs constant current drives, and since the illumination application extensively, the diversity ratio of its application conditions is bigger, especially original power supply, all kinds of powered battery, civil power Alternating Current Power Supply etc., this just needs corresponding power source conversion can adapt to different power supplys with the control solution, the LED constant-current driving structure that exists in the prior art as shown in Figure 1, comprise that electric energy transforms chip and peripheral circuit thereof, the detection leakage resistance that adopts this structure can only detect the LED electric current of ascent stage and can't detect the LED electric current of the decline stage of electric current, cause and can't accomplish accurate control to the mean value of electric current, thereby influence is to the control of LED.

The utility model content

Technology to be solved in the utility model is for to be entitled as: can only be according to the control through the average current of LED of the LED current convection of ascent stage in the prior art.

For solving the problems of the technologies described above, the utility model proposes following technical scheme: a kind of led driver comprises:

In order to first output of a LED electric current to a LED path to be provided; In order to obtain first circuit of first relevant with this LED peak current or the valley point current respectively signal; In order to produce the second circuit of first control signal or second control signal according to first signal; The power stage of regulating described LED electric current according to first control signal or second control signal.

Further, described power stage comprises: first switch, first inductance, first diode; First switch comprises: control end, first input end, second output; First inductance comprises: second input, the 3rd output; Control end is connected and disconnection according to first control signal or second control signal control first input end and second output; Described first input end links to each other with power supply, and described second output links to each other with the negative level of second input and first diode respectively; Described the 3rd output links to each other with LED is anodal; The positive pole of first diode links to each other with ground with the negative pole of LED respectively.

Further, described first circuit is one first resistance; Described first resistance string is connected between described second output and described second input; First resistance end closely links to each other with second circuit.

Further, described power stage comprises: first switch, first inductance, first diode; First switch comprises: control end, first input end, second output; First inductance comprises: second input, the 3rd output; Control end is connected and disconnection according to first control signal or second control signal control first input end and second output; Described first input end links to each other with power supply, and described second output links to each other with the positive pole of LED and the negative level of first diode respectively; The negative pole of LED links to each other with second input; The positive pole of described first diode links to each other with ground with the 3rd output respectively.

Further, described first circuit is one first resistance; Described first resistance string is connected between the positive pole of described second output and described LED; First resistance end closely links to each other with second circuit.

Further, above-mentioned first switching tube is N type metal-oxide-semiconductor or P type metal-oxide-semiconductor.

Further, described second circuit comprises: signal processing module, pulse modulation module; Described first signal is first voltage signal relevant with LED peak current or valley point current, and described signal processing module compares first voltage signal respectively with the first threshold signal or second threshold signal, corresponding first comparison signal or second comparison signal of producing; Pulse modulation module produces first control signal or produces second control signal according to second comparison signal according to first comparison signal.

Further, described signal processing module comprises first comparator, second comparator; Described first threshold signal is first upper voltage limit, and described second threshold signal is first lower voltage limit; Described first comparator comprises: four-input terminal, the 5th input, the 6th go out output; Described second comparator comprises: the 7th input, the 8th input, the 9th output; Described first voltage signal is connected with the 7th input with four-input terminal respectively; Described first upper voltage limit is connected with the 5th input; Described first lower voltage limit is connected with the 8th input; Described the 6th output is connected with pulse modulation module respectively with the 9th output.

A kind of led driver provided by the utility model, comprise: in order to first output of a LED electric current to a LED path to be provided, in order to obtain first circuit of first relevant with this LED peak current or the valley point current respectively signal, in order to producing the second circuit of first control signal or second control signal according to first signal, the power stage of regulating described LED electric current according to first control signal or second control signal; A kind of led driver provided by the utility model has been considered LED peak current or valley point current when the electric current to LED falls joint, compared with prior art can more accurately obtain needed average current.

Description of drawings

Fig. 1 is existing LED constant-current drive circuit figure;

Fig. 2 is the circuit diagram of the utility model embodiment one;

Fig. 3 is the circuit diagram of the utility model embodiment two;

Embodiment

In order to make purpose of the present invention, technical scheme and advantage clearer,, the present invention is further elaborated below in conjunction with drawings and Examples.Should be appreciated that specific embodiment described herein only in order to explanation the present invention, and be not used in qualification the present invention.

A kind of led driver provided by the utility model comprises in order to first output of a LED electric current to a LED path to be provided; In order to obtain first circuit of first relevant with this LED peak current or the valley point current respectively signal; In order to produce the second circuit of first control signal or second control signal according to first signal; The power stage of regulating described LED electric current according to first control signal or second control signal.

Fig. 2 is the circuit diagram of the utility model embodiment one; As shown in Figure 2: above-mentioned power stage comprises: the first switch Q, first inductance L, the first diode D; First switch comprises: control end, first input end, second output; First inductance comprises: second input, the 3rd output; Control end is connected and disconnection according to first control signal or second control signal control first input end and second output; Described first input end links to each other with power supply, and described second output links to each other with the negative level of second input and first diode respectively; Described the 3rd output links to each other with LED is anodal; The positive pole of first diode links to each other with ground GND with the negative pole of LED respectively; The first switch Q is a N type metal-oxide-semiconductor in the present embodiment, and the first switch Q also can be P type metal-oxide-semiconductor in certain embodiments, and its circuit structure also needs to do corresponding variation certainly, says easy realization for those skilled in the art, does not repeat them here.In certain embodiments, the position of inductance L and LED can exchange, and does not repeat them here.

Above-mentioned first circuit is one first resistance R, and the value of resistance R is generally 2-4 ohm; Described first resistance string is connected between described second output and described second input; First resistance end closely links to each other with second circuit.

Above-mentioned second circuit comprises: reference voltage module 10, signal processing module 20, pulse modulation module 30; Described reference voltage module provides the first threshold signal and second threshold signal; Described first signal is the first voltage signal VR relevant with LED peak current or valley point current, described signal processing module compares first voltage signal respectively with the first threshold signal or second threshold signal, corresponding first comparison signal or second comparison signal of producing; Pulse modulation module produces first control signal or produces second control signal according to second comparison signal according to first comparison signal.

Fig. 3 is the circuit diagram of the utility model embodiment two; The difference of embodiment two and embodiment has been to propose the physical circuit of signal processing module; As shown in Figure 3:

Described signal processing module comprises first comparator, second comparator; Described first threshold signal is the first upper voltage limit V1, and described second threshold signal is the first lower voltage limit V2; Described first comparator comprises: four-input terminal, the 5th input, the 6th go out output; Described second comparator comprises: the 7th input, the 8th input, the 9th output; The described first voltage signal VR is connected with the 7th input with four-input terminal respectively; Described first upper voltage limit is connected with the 5th input; Described first lower voltage limit is connected with the 8th input; Described the 6th output is connected with pulse modulation module respectively with the 9th output.

Below with reference to Fig. 3 the course of work of the present utility model is described further, when circuit is started working, pulse module is at first controlled the first switch Q conducting, this moment, inductance L had the voltage drop of second input to the, three outputs, rise since the electric current of second input to the, three outputs, electric current by inductance L and first resistance R, LED rises gradually, and the first ohmically pressure drop VR also increases thereupon and feeds back to the four-input terminal of first comparator and the 7th input of second comparator respectively; First comparator compares the voltage VR and the first upper voltage limit V1 that receives, when VR equals V1, the 6th output of first comparator is exported first comparison signal, and pulse modulation module is exported first control signal according to first comparison signal, controls the first switching tube Q and turn-offs;

The first switching tube Q closes and has no progeny, because the characteristic of inductance holding current, electric current on the inductance L passes through R, inductance itself, the load LED and the first diode path flow, at this moment just have the voltage from the 3rd output to second input that equals to drop on pressure drop sum on load LED, first diode, three devices on the inductance, at this moment the electric current that flows to the 3rd output from second input will descend gradually; Decline along with electric current on this moment inductance L, the electric current that flows through on the resistance R also descends, voltage VR also descends thereupon, this moment, second comparator compared the VR and the first lower voltage limit V2, when V2 equals the VR time, the 9th output of second comparator is exported second comparison signal, and pulse modulation module is exported second control signal according to second comparison signal, the conducting of control switch pipe.

The above only is preferred embodiment of the present utility model; not in order to restriction the utility model; all any modifications of within spirit of the present utility model and principle, being done, be equal to and replace and improvement etc., all should be included within the protection range of the present utility model.

Claims

1. a led driver is characterized in that, comprising: in order to first output of a LED electric current to a LED path to be provided; In order to obtain first circuit of first relevant with this LED peak current or the valley point current respectively signal; In order to produce the second circuit of first control signal or second control signal according to first signal; The power stage of regulating described LED electric current according to first control signal or second control signal.

2. led driver according to claim 1 is characterized in that, described power stage comprises: first switch, first inductance, first diode; First switch comprises: control end, first input end, second output; First inductance comprises: second input, the 3rd output; Control end is connected and disconnection according to first control signal or second control signal control first input end and second output; Described first input end links to each other with power supply, and described second output links to each other with the negative level of second input and first diode respectively; Described the 3rd output links to each other with LED is anodal; The positive pole of first diode links to each other with ground with the negative pole of LED respectively.

3. led driver according to claim 2 is characterized in that, described first circuit is one first resistance; Described first resistance string is connected between described second output and described second input; First resistance end closely links to each other with second circuit.

4. led driver according to claim 1 is characterized in that, described power stage comprises: first switch, first inductance, first diode; First switch comprises: control end, first input end, second output; First inductance comprises: second input, the 3rd output; Control end is connected and disconnection according to first control signal or second control signal control first input end and second output; Described first input end links to each other with power supply, and described second output links to each other with the positive pole of LED and the negative level of first diode respectively; The negative pole of LED links to each other with second input; The positive pole of described first diode links to each other with ground with the 3rd output respectively.

5. led driver according to claim 4 is characterized in that, described first circuit is one first resistance; Described first resistance string is connected between the positive pole of described second output and described LED; First resistance end closely links to each other with second circuit.

6. according to each described led driver of claim 2 to 5, it is characterized in that described first switching tube is N type metal-oxide-semiconductor or P type metal-oxide-semiconductor.

7. led driver according to claim 1 is characterized in that, described second circuit comprises: reference voltage module, signal processing module, pulse modulation module; Described reference voltage module provides the first threshold signal and second threshold signal; Described first signal is first voltage signal relevant with LED peak current or valley point current, and described signal processing module compares first voltage signal respectively with the first threshold signal or second threshold signal, corresponding first comparison signal or second comparison signal of producing; Pulse modulation module produces first control signal or produces second control signal according to second comparison signal according to first comparison signal.

8. led driver according to claim 7 is characterized in that, described signal processing module comprises first comparator, second comparator; Described first threshold signal is first upper voltage limit, and described second threshold signal is first lower voltage limit; Described first comparator comprises: four-input terminal, the 5th input, the 6th go out output; Described second comparator comprises: the 7th input, the 8th input, the 9th output; Described first voltage signal is connected with the 7th input with four-input terminal respectively; Described first upper voltage limit is connected with the 5th input; Described first lower voltage limit is connected with the 8th input; Described the 6th output is connected with pulse modulation module respectively with the 9th output.