CN104470099A - Light emitting diode driving circuit - Google Patents
Light emitting diode driving circuit Download PDFInfo
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- CN104470099A CN104470099A CN201410686259.6A CN201410686259A CN104470099A CN 104470099 A CN104470099 A CN 104470099A CN 201410686259 A CN201410686259 A CN 201410686259A CN 104470099 A CN104470099 A CN 104470099A
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Abstract
A light emitting diode (LED) driving circuit comprises a feedback loop and a power tube and is characterized by further comprising a start detection resistor, a current comparator and a power-on detection circuit, wherein the start detection resistor is connected with a load LED in series, the current comparator is used for detecting a voltage drop on the start detection resistor, the power-on detection circuit is used for detecting the power-on situation of the LED driving circuit, and the output end of the current comparator and the output end of the power-on detection circuit are connected with the input end and the reset end of a trigger respectively; the output end of an either-or gating switch is connected with the input end of a PWM comparator, the power-on detection circuit is an undervoltage comparator, and power voltage and undervoltage reference voltage are input into the two input ends of the undervoltage comparator respectively. By the adoption of the LED driving circuit, the on-off state of the power tube is controlled by detecting output voltage, continuous running is conducted at a large duty ratio at the starting stage until turn-on conditions of the load LED are met, the rising speed of the output voltage is increased, and start time is shortened.
Description
Technical field
The invention belongs to integrated circuit (IC) design field, relate to Switching Power Supply, particularly a kind of LED driving circuit.
Background technology
The one of semiconductor diode, can become luminous energy electric energy conversion.Light-emitting diode is the same with general-purpose diode to be made up of a PN junction, also has unilateral conduction.After adding forward voltage to light-emitting diode, be injected into the hole in N district from P district and be injected into the electronics in P district by N district.
LED can only toward a direction conducting (energising), be called forward bias (forward bias), when the current flows, electronics and hole compound and send monochromatic light within it, this is electroluminescent effect, compare with neon lamp with incandescent lamp bulb, the feature of light-emitting diode is: operating voltage very low (more several volts had); Operating current very little (the only zero point several milliamperes had can be luminous); Shock resistance and anti-seismic performance good, reliability is high, and the life-span is long; Can the power of modulated luminescence easily by modulating that the electric current that passes through is strong and weak.Owing to there being these features, utilizing and emitting ledly carry out illumination and be applied in more and more widely among scope.
In existing single-stage high-power rate factor LED illumination drive scheme, bulky capacitor in parallel (usual hundreds of microfarad) is needed to reduce the ripple of LED at LED output.This electric capacity initial voltage is 0V, needs the operating voltage tens volts of stable states charging to LED.If the soft start not adding chip internal controls, then easily there is output voltage overshoot when startup and cause LED to have startup Transient Currents.And chip internal increases soft start control, then can increase start-up time entirely bright from switch opens to LED, be difficult to needs start-up time meeting <0.5S.
Summary of the invention
For improving the toggle speed of LED drive circuit, the invention discloses a kind of LED driving circuit.
LED driving circuit, comprise feedback control loop and power tube, described feedback control loop comprises error amplifier, PWM comparator, logic drive circuit, the output of described logic drive circuit is connected with the control end of power tube, and described error amplifier is for detecting the output voltage of LED drive circuit;
It is characterized in that, also comprise the start detection resistance joined with load LED strip, and to the current comparator that the ohmically pressure drop of start detection detects, and for the power on detection circuit that testing circuit powers on, the output of described current comparator and power on detection circuit is connected with the input of trigger and reset terminal respectively;
The output of described error amplifier connects the first input end connection of alternative gating switch, and the second input of described alternative gating switch is connected with high position reference voltage; The described control end of alternative gating switch is connected with the output of trigger, and the output of described alternative gating switch is connected with the input of PWM comparator;
The reference voltage value of described high position reference voltage is not less than the supply voltage of error amplifier, and described power on detection circuit is under-voltage comparator, and two inputs of described under-voltage comparator connect supply voltage and under-voltage reference voltage respectively.
Preferably, described high position reference voltage is the supply voltage of described LED driving circuit.
Preferably, also comprise sample circuit, described sample circuit is the current sampling resistor be connected in load, and described current sampling resistor two ends connect the different inputs of error amplifier respectively.
Preferably, also building-out capacitor is connected with between described error amplifier and ground.
Preferably, described trigger is rest-set flip-flop.
Adopt LED driving circuit of the present invention, by detecting the on off state of output voltage control power tube, startup stage with big space rate continuous service until meet the turn-on condition of load LED, improve the rate of climb of output voltage, shorten start-up time.
Accompanying drawing explanation
Fig. 1 illustrates a kind of embodiment structural representation of the present invention.
Embodiment
Below in conjunction with accompanying drawing, the specific embodiment of the present invention is described in further detail.
LED driving circuit of the present invention, comprise feedback control loop and power tube, described feedback control loop comprises error amplifier, PWM comparator, logic drive circuit, the output of described logic drive circuit is connected with the control end of power tube, and described error amplifier is for detecting the output current of LED drive circuit.
Also comprise the start detection resistance joined with load LED strip, and to the current comparator that the ohmically pressure drop of start detection detects, and for the power on detection circuit that testing circuit powers on, the output of described current comparator and power on detection circuit is connected with the input of trigger and reset terminal respectively;
The output of described error amplifier connects the first input end connection of alternative gating switch, and the second input of described alternative gating switch is connected with high position reference voltage; The described control end of alternative gating switch is connected with the output of trigger, and the output of described alternative gating switch is connected with the input of PWM comparator.
The reference voltage value of described high position reference voltage is not less than the supply voltage of error amplifier, and described power on detection circuit is under-voltage comparator, and two inputs of described under-voltage comparator connect supply voltage and under-voltage reference voltage respectively.
Embodiment as shown in Figure 1, power on detection circuit is under-voltage comparator, two inputs of described under-voltage comparator connect supply voltage and under-voltage reference voltage respectively, when powering on, input capacitance CIN is charged, voltage rises gradually, under-voltage reference voltage is default system brownout threshold voltage, usually about 1.5-2.2V is arranged on, when CIN be charged to be greater than this under-voltage reference voltage time, under-voltage comparator output voltage overturns, trigger is made to export high level signal, trigger can select the simplest rest-set flip-flop formed with door by two, flipflop output signal is to single-pole double-throw switch (SPDT), control single-pole double-throw switch (SPDT) to be connected between PWM input and high position reference voltage.
Startup stage, as shown in Figure 1, two inputs of PWM comparator are connected between high position reference voltage and triangular-wave generator, high position reference voltage is higher than the supply voltage of error amplifier, PWM is made to compare the output voltage maximum being necessarily greater than error amplifier by comparative voltage of input, PWM comparator runs with maximum duty cycle, and the maximum duty cycle exporting square wave is determined by triangular-wave generator.After logic drive circuit, the square wave driving power pipe MN1 of this maximum duty cycle runs with maximum duty cycle, and output voltage rises fast, and in FIG, high position reference voltage directly can select the supply voltage VIN inputted, and need not redesign internal module.
Startup stage, because output voltage is not enough, the load LED of cascade cannot conducting, start detection resistance RCS does not have electric current to flow through, two ends pressure reduction is zero, when output voltage VO UT rises to certain value, such as each load LED conducting needs 3V voltage, then 10 LED strip connection need 30V to get final product conducting, now load LED conducting, generation current on RCS, RCS two ends produce pressure drop, current comparator output level reverses, flipflop output signal is reset, control alternative gating switch error amplifier output is connected with PWM comparator input terminal, thus realize normal FEEDBACK CONTROL, startup stage big space rate promote output voltage VO UT process and terminate.
Also comprise current sampling circuit in embodiment shown in Fig. 1, also comprise sample circuit, described sample circuit is the current sampling resistor be connected in load, and described current sampling resistor two ends connect the different inputs of error amplifier respectively.Which can convert output current to voltage signal and process.
Preferably, between the output of described error amplifier and ground, be connected with building-out capacitor C2, a dominant pole can be provided for control loop, the stability that reinforcing feedback controls.Switching Power Supply topology in Fig. 1 is BOOST structure, comprises inductance and rectifier diode, jointly forms BOOST framework with power tube MN1.
Adopt LED driving circuit of the present invention, by detecting the on off state of output voltage control power tube, startup stage with big space rate continuous service until meet the turn-on condition of load LED, improve the rate of climb of output voltage, shorten start-up time.
Previously described is each preferred embodiment of the present invention, preferred implementation in each preferred embodiment is if not obviously contradictory or premised on a certain preferred implementation, each preferred implementation can stack combinations use arbitrarily, design parameter in described embodiment and embodiment is only the invention proof procedure in order to clear statement inventor, and be not used to limit scope of patent protection of the present invention, scope of patent protection of the present invention is still as the criterion with its claims, the equivalent structure change that every utilization specification of the present invention and accompanying drawing content are done, in like manner all should be included in protection scope of the present invention.
Claims (5)
1. LED driving circuit, comprise feedback control loop and power tube, described feedback control loop comprises error amplifier, PWM comparator, logic drive circuit, the output of described logic drive circuit is connected with the control end of power tube, and described error amplifier is for detecting the output voltage of LED drive circuit;
It is characterized in that, also comprise the start detection resistance joined with load LED strip, and to the current comparator that the ohmically pressure drop of start detection detects, and for the power on detection circuit that testing circuit powers on, the output of described current comparator and power on detection circuit is connected with the input of trigger and reset terminal respectively;
The output of described error amplifier connects the first input end connection of alternative gating switch, and the second input of described alternative gating switch is connected with high position reference voltage; The described control end of alternative gating switch is connected with the output of trigger, and the output of described alternative gating switch is connected with the input of PWM comparator;
The reference voltage value of described high position reference voltage is not less than the supply voltage of error amplifier, and described power on detection circuit is under-voltage comparator, and two inputs of described under-voltage comparator connect supply voltage and under-voltage reference voltage respectively.
2. LED driving circuit as claimed in claim 1, it is characterized in that, described high position reference voltage is the supply voltage of described LED driving circuit.
3. LED driving circuit as claimed in claim 1, it is characterized in that, also comprise sample circuit, described sample circuit is the current sampling resistor be connected in load, and described current sampling resistor two ends connect the different inputs of error amplifier respectively.
4. LED driving circuit as claimed in claim 1, is characterized in that, be also connected with building-out capacitor between described error amplifier and ground.
5. LED driving circuit as claimed in claim 1, it is characterized in that, described trigger is rest-set flip-flop.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410686259.6A CN104470099B (en) | 2014-11-26 | 2014-11-26 | Light emitting diode driving circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201410686259.6A CN104470099B (en) | 2014-11-26 | 2014-11-26 | Light emitting diode driving circuit |
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| CN104470099A true CN104470099A (en) | 2015-03-25 |
| CN104470099B CN104470099B (en) | 2017-01-11 |
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| CN201410686259.6A Active CN104470099B (en) | 2014-11-26 | 2014-11-26 | Light emitting diode driving circuit |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104768292A (en) * | 2015-03-27 | 2015-07-08 | 绵阳豪迈电子科技有限公司 | Drive circuit applied to intelligent cell system |
| CN104767362A (en) * | 2015-03-27 | 2015-07-08 | 绵阳豪迈电子科技有限公司 | Parking lot management system drive circuit |
| CN104780684A (en) * | 2015-04-20 | 2015-07-15 | 成都岷创科技有限公司 | DC conversion LED drive circuit |
| CN106160712A (en) * | 2016-07-08 | 2016-11-23 | 深圳市博巨兴实业发展有限公司 | A kind of por circuit of band LVR function |
| CN109302777A (en) * | 2018-12-06 | 2019-02-01 | 深圳市德信创微电子有限公司 | LED dimming device and light adjusting system |
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| CN102088808A (en) * | 2010-11-30 | 2011-06-08 | 南京微盟电子有限公司 | Contact current LED driving circuit of snap switch |
| CN102510619A (en) * | 2011-10-27 | 2012-06-20 | 上海晶丰明源半导体有限公司 | Quick start-up device of LED (light-emitting diode) driving power supply |
| CN102802318A (en) * | 2012-08-28 | 2012-11-28 | 绍兴光大芯业微电子有限公司 | Flyback-type quick-start LED (Light-Emitting Diode) drive circuit structure |
| US8629631B1 (en) * | 2011-07-21 | 2014-01-14 | Cooper Technologies Company | Method and system for improving start-up time of a light emitting diode (LED) driver at reduced input voltage |
| CN204259231U (en) * | 2014-11-26 | 2015-04-08 | 成都岷创科技有限公司 | Possesses the LED driving circuit of start detection function |
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2014
- 2014-11-26 CN CN201410686259.6A patent/CN104470099B/en active Active
Patent Citations (5)
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| CN102088808A (en) * | 2010-11-30 | 2011-06-08 | 南京微盟电子有限公司 | Contact current LED driving circuit of snap switch |
| US8629631B1 (en) * | 2011-07-21 | 2014-01-14 | Cooper Technologies Company | Method and system for improving start-up time of a light emitting diode (LED) driver at reduced input voltage |
| CN102510619A (en) * | 2011-10-27 | 2012-06-20 | 上海晶丰明源半导体有限公司 | Quick start-up device of LED (light-emitting diode) driving power supply |
| CN102802318A (en) * | 2012-08-28 | 2012-11-28 | 绍兴光大芯业微电子有限公司 | Flyback-type quick-start LED (Light-Emitting Diode) drive circuit structure |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104768292A (en) * | 2015-03-27 | 2015-07-08 | 绵阳豪迈电子科技有限公司 | Drive circuit applied to intelligent cell system |
| CN104767362A (en) * | 2015-03-27 | 2015-07-08 | 绵阳豪迈电子科技有限公司 | Parking lot management system drive circuit |
| CN104780684A (en) * | 2015-04-20 | 2015-07-15 | 成都岷创科技有限公司 | DC conversion LED drive circuit |
| CN106160712A (en) * | 2016-07-08 | 2016-11-23 | 深圳市博巨兴实业发展有限公司 | A kind of por circuit of band LVR function |
| CN106160712B (en) * | 2016-07-08 | 2019-04-12 | 深圳市博巨兴实业发展有限公司 | A kind of por circuit of band LVR function |
| CN109302777A (en) * | 2018-12-06 | 2019-02-01 | 深圳市德信创微电子有限公司 | LED dimming device and light adjusting system |
| CN109302777B (en) * | 2018-12-06 | 2024-03-15 | 深圳市德信创微电子有限公司 | LED dimming device and dimming system |
Also Published As
| Publication number | Publication date |
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| CN104470099B (en) | 2017-01-11 |
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Effective date of registration: 20160419 Address after: 201204 Zhang Heng road Shanghai, Pudong New Area Zhangjiang hi tech Park Lane 666 No. 2 floor 504-511 room 5 Applicant after: Shanghai Bright Power Semiconductor Co.,Ltd. Address before: West high tech Zone Fucheng Road in Chengdu city of Sichuan province 610000 399 No. 6 Building 1 unit 10 floor No. 2 Applicant before: Chengdu Minchuang Science & Technology Co., Ltd. |
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Address after: 5 room 504-511, room 2, Lane 666, Zhang Heng Road, Pudong New Area, China (Shanghai) free trade zone, Shanghai, China () Patentee after: Shanghai semiconducto Limited by Share Ltd Address before: 201204 Zhang Heng road Shanghai, Pudong New Area Zhangjiang hi tech Park Lane 666 No. 2 floor 504-511 room 5 Patentee before: Shanghai Bright Power Semiconductor Co.,Ltd. |