CN102573189B - Step-down light-emitting diode (LED) driving circuit - Google Patents
Step-down light-emitting diode (LED) driving circuit Download PDFInfo
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- CN102573189B CN102573189B CN201010606752.4A CN201010606752A CN102573189B CN 102573189 B CN102573189 B CN 102573189B CN 201010606752 A CN201010606752 A CN 201010606752A CN 102573189 B CN102573189 B CN 102573189B
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Abstract
The invention belongs to the field of light-emitting diode (LED) driving circuits, and discloses a step-down LED driving circuit which comprises a power supply, a filter unit, a constant current unit and an LED, wherein the filter unit is electrically connected between the power supply and the constant current unit, and the constant current unit supplies constant current to the LED. According to the circuit, the design is simple and reliable, the current of an LED lamp group can be designed only by changing the value of voltage sampling resistance R2, and the circuit is simple, convenient, stable and reliable.
Description
Technical field
The invention belongs to LED drive circuit, particularly relate to the voltage-dropping type LED drive circuit of the input of a kind of direct current Width funtion, constant current output.
Background technology
LED is as new type light source, and it has energy-saving and environmental protection, efficiently feature, and technology is ripe and be applied to every field, and LED is widely used as lighting source, has also occurred various LED drive circuit thereupon.LED is as constant current operation load, and because LED self is harsher to operating voltage requirement, overtension is too low all can cause LED work abnormal, so the power supply quality of supply voltage directly affects the reliability of LED.Current people's custom constant current chip technology carrys out driving LED, it has the advantages such as power consumption is little, efficiency is high, unit power volume is little, lightweight, but its output current is fixed, output current is not set by external devices, the control of PWM stepless dimming can not be carried out, bring serious inconvenience to user.
Summary of the invention
Based on the problems referred to above, the object of the present invention is to provide a kind of voltage-dropping type LED drive circuit.
Technical scheme of the present invention is as follows:
A kind of voltage-dropping type LED drive circuit, comprises power supply, filter unit, constant current unit, and LED; Wherein, described filter unit is connected electrically between power supply and constant current unit, and constant current unit provides constant electric current for LED;
Wherein, described constant current unit comprises constant current chip U1, energy storage inductor L1, sustained diode 1, and voltage sample resistance R2; Energy storage inductor L1 one end is connected with the voltage output pin SW of constant current chip U1, and the other end is connected with the positive pole of LED; The negative pole of sustained diode 1 is connected with the voltage output pin SW of constant current chip U1, the plus earth of sustained diode 1; Voltage sample resistance R2 one end is connected with the feedback pin FB of constant current chip U1, other end ground connection, and the tie point between voltage sample resistance R2 and the feedback pin FB of constant current chip U1 is connected with LED negative pole.
Described voltage-dropping type LED drive circuit, wherein, the resistance of described voltage sample resistance R2 is 2.7 ohm, and precision is 1%.
Described voltage-dropping type LED drive circuit, wherein, described constant current unit also comprises a pull-up resistor R1, is connected in series in control pin EN and the voltage input pin Vin of described constant current chip U1.
Described voltage-dropping type LED drive circuit, wherein, described constant current unit also comprises a stabilization resistance R3, this stabilization resistance R3 is connected in series between the feedback pin FB of constant current chip U1 and voltage sample resistance R2, and this stabilization resistance R3 is connected with the negative electricity of LED with the tie point between voltage sample resistance R2.
Described voltage-dropping type LED drive circuit, wherein, the tie point between stabilization resistance R3 and voltage sample resistance R2 is by one the 3rd filter capacitor C6 ground connection.
Described voltage-dropping type LED drive circuit, wherein, described constant current unit also comprises the second storage capacitor C4 and the second filter capacitor C5, between the tie point that described second storage capacitor C4 and the second filter capacitor C5 is connected in described energy storage inductor L1 and LED positive pole respectively in parallel and ground.
Described voltage-dropping type LED drive circuit, wherein, described constant current unit also comprises shunt capacitance C3, between the voltage output pin SW that these shunt capacitance C3 two ends are connected to described constant current chip U1 and auxiliary foot BST.
Described voltage-dropping type LED drive circuit, wherein, described filter unit comprises the first storage capacitor C1 and the first filter capacitor C2, between the tie point that described first storage capacitor C1 and the first filter capacitor C2 is connected in the positive pole of power supply and the voltage input pin Vin of constant current chip U1 respectively in parallel and ground.
Described voltage-dropping type LED drive circuit also comprises PWM generator, and this PWM generator is connected with the control pin EN of described constant current chip U1.
Described voltage-dropping type LED drive circuit, wherein, the model of described constant current chip U1 is MP2359.
The voltage-dropping type LED drive circuit of circuit of the present invention, adopts the design of voltage-dropping type constant current chip, DC input voitage wide ranges, can allow LED pressure limiting constant current operation, ensures that LED operates at full capacity, overcomes the shortcoming of output current instability, greatly meet the demand of people; Meanwhile, this circuit design is simple and reliable, and only need change the resistance of voltage sample resistance R2, just can design LED group electric current, circuit is simple and convenient, reliable and stable.
Accompanying drawing explanation
Fig. 1 is the block diagram of voltage-dropping type LED drive circuit of the present invention;
Fig. 2 is the circuit theory diagrams of an embodiment of voltage-dropping type LED drive circuit of the present invention.
Embodiment
Below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in further detail.
The invention provides the voltage-dropping type LED drive circuit of the input of a kind of direct current Width funtion, constant current output, shown in Fig. 1 and 2, this voltage-dropping type LED drive circuit comprises power supply 100(the present invention and adopts DC power supply), filter unit 200, constant current unit 300, and LED400; Filter unit 200 is connected electrically between power supply 100 and constant current unit 300 control end, and constant current unit 300 provides constant electric current for LED400; Wherein, constant current unit 300 comprises constant current chip U1, energy storage inductor L1, sustained diode 1, and voltage sample resistance R2; Energy storage inductor L1 one end is connected with the voltage output pin SW of constant current chip U1, and the other end is connected with the positive pole of LED; The negative pole of sustained diode 1 is connected with the voltage output pin SW of constant current chip U1, the plus earth of sustained diode 1; Voltage sample resistance R2 one end is connected with the feedback pin FB of constant current chip U1, other end ground connection, and the tie point between voltage sample resistance R2 and the feedback pin FB of constant current chip U1 is connected with LED negative pole.
Constant current chip U1 by the constant current voltage of power supply 100 step-down needed for LED400, and according to the quantity of LED400, can provide the constant operation electric current of different pressure drop, and this constant current chip U1 adopts MP2359 type; The resistance of voltage sample resistance R2 can be 2.7 ohm, and its precision is 1%.
In practical application, above-mentioned constant current unit 300 also comprises pull-up resistor R1, stabilization resistance R3, the second storage capacitor C4 and the second filter capacitor C5 and shunt capacitance C3.
Pull-up resistor R1 is connected in series between the control pin EN of constant current chip U1 and voltage input pin Vin, plays metering function, for the protection of constant current chip U1, avoids burning out constant current chip U1 because mains input current is excessive.
Stabilization resistance R3 is connected in series between the feedback pin FB of constant current chip U1 and voltage sample resistance R2, and this stabilization resistance R3 is connected with the negative electricity of LED with the tie point between voltage sample resistance R2; Tie point between stabilization resistance R3 and voltage sample resistance R2 is by one the 3rd filter capacitor C6 ground connection.Like this, logical when circuit has interference signal, by the time-lag action of stabilization resistance R3, make interference signal decay and be absorbed, thus 3 pin of constant current chip U1 can not be arrived, namely filter action.
Between the tie point that second storage capacitor C4 and the second filter capacitor C5 is connected in described energy storage inductor L1 and LED positive pole in parallel and ground, in order to ensure that output supply voltage steadily fluctuates and the high frequency spurs in power supply signal is coupled in filtering.
Between the voltage output pin SW that shunt capacitance C3 is connected to described constant current chip U1 and auxiliary foot BST, for 1 pin of constant current chip U1 provides driving voltage.
Above-mentioned filter unit 200 comprises the first storage capacitor C1 and the first filter capacitor C2.Between the tie point that first storage capacitor C1 and the first filter capacitor C2 is connected in the positive pole of DC power supply and the voltage input pin Vin of constant current chip U1 respectively in parallel and ground.This filter unit 200, in order to ensure input supply voltage and steadily fluctuate and high frequency spurs in power supply signal is coupled in filtering, ensures that supply voltage is powered stable.
Further improvement, this voltage-dropping type LED drive circuit also comprises PWM generator, and this PWM generator is connected with the control pin EN of described constant current chip U1.Controlling by PWM generator, by regulating the duty ratio of PWM to realize LED400 stepless dimming, meeting the demand of people to light modulation.Wherein, PWM generator can select the single-chip microcomputer or trigger that can go out PWM waveform.
This voltage-dropping type LED drive circuit specific implementation principle is as follows:
After circuit turn-on, power supply 100 outputs current to 5 pin of constant current chip U1, and namely voltage input pin Vin obtains electric, 4 pin (the i.e. control pin EN of constant current chip U1, also be the enable pin of work), be pulled to high level after being connected with positive source by pull-up resistor R1, now constant current chip U1 works.The control pin EN of constant current chip U1 also can directly be connected with PWM generator, as PWM brightness adjustment control, realizes LED group stepless dimming by the duty ratio of control PWM; 6 pin of constant current chip U1, be voltage output pin SW output voltage, now, current circuit is: power supply 100 by constant current chip U1, energy storage inductor L1, LED400, voltage sample resistance R2, and constant current chip U1, form current work loop, and constant current is exported under constant current chip U1 controls, for LED provides constant operation electric current, realize the reliable and stable work of LED.
Back-end circuit cut-off refers to that the metal-oxide-semiconductor between 5 pin of constant current chip U1 and 6 pin closes (instead of saying do not have input power), power supply 100 has electric current to export 5 pin of constant current chip U1 to, i.e. voltage input pin Vin, now, 4 pin (the i.e. control pin EN of constant current chip U1, also be the enable pin of work) be connected with positive source by pull-up resistor R1, therefore 4 pin of constant current chip U1 are high level, now constant current chip U1 works.Now current circuit is: energy storage inductor L1, LED400, voltage sample resistance R2, sustained diode 1, form current work loop, and constant current is exported under constant current chip U1 controls, for LED provides constant operation electric current, realize the reliable and stable work of LED.
This circuit design is simple and reliable, and only need change the resistance of voltage sample resistance R2, just can design LED group electric current, circuit is simple and convenient, reliable and stable.
Should be understood that, the above-mentioned statement for present pre-ferred embodiments is comparatively detailed, and therefore can not think the restriction to scope of patent protection of the present invention, scope of patent protection of the present invention should be as the criterion with claims.
Claims (5)
1. a voltage-dropping type LED drive circuit, comprises power supply, filter unit, constant current unit, and LED; Wherein, described filter unit is connected electrically between power supply and constant current unit, and constant current unit provides constant electric current for LED;
It is characterized in that, described constant current unit comprises constant current chip U1, energy storage inductor L1, sustained diode 1, and voltage sample resistance R2; Energy storage inductor L1 one end is connected with the voltage output pin SW of constant current chip U1, and the other end is connected with the positive pole of LED; The negative pole of sustained diode 1 is connected with the voltage output pin SW of constant current chip U1, the plus earth of sustained diode 1; Voltage sample resistance R2 one end is connected with the feedback pin FB of constant current chip U1, other end ground connection, and the tie point between voltage sample resistance R2 and the feedback pin FB of constant current chip U1 is connected with LED negative pole; Described constant current unit also comprises the second storage capacitor C4 and the second filter capacitor C5, between the tie point that described second storage capacitor C4 and the second filter capacitor C5 is connected in described energy storage inductor L1 and LED positive pole respectively in parallel and ground, constant current chip U1 can by the constant current voltage of power voltage step down needed for described LED, and according to the quantity of described LED, the constant operation electric current of different pressure drop can be provided;
Described voltage-dropping type LED drive circuit also comprises PWM generator, and this PWM generator is connected with the control pin EN of described constant current chip U1, realizes described LED stepless dimming by regulating the duty ratio of PWM;
Described constant current unit also comprises a pull-up resistor R1, is connected in series in control pin EN and the voltage input pin Vin of described constant current chip U1;
Described constant current unit also comprises a stabilization resistance R3, and this stabilization resistance R3 is connected in series between the feedback pin FB of constant current chip U1 and voltage sample resistance R2, and this stabilization resistance R3 is connected with the negative electricity of LED with the tie point between voltage sample resistance R2;
Tie point between stabilization resistance R3 and voltage sample resistance R2 is by one the 3rd filter capacitor C6 ground connection.
2. voltage-dropping type LED drive circuit according to claim 1, is characterized in that, the resistance of described voltage sample resistance R2 is 2.7 ohm, and precision is 1%.
3. voltage-dropping type LED drive circuit according to claim 1, is characterized in that, described constant current unit also comprises shunt capacitance C3, between the voltage output pin SW that these shunt capacitance C3 two ends are connected to described constant current chip U1 and auxiliary foot BST.
4. voltage-dropping type LED drive circuit according to claim 1, it is characterized in that, described filter unit comprises the first storage capacitor C1 and the first filter capacitor C2, between the tie point that described first storage capacitor C1 and the first filter capacitor C2 is connected in the positive pole of power supply and the voltage input pin Vin of constant current chip U1 respectively in parallel and ground.
5., according to the arbitrary described voltage-dropping type LED drive circuit of Claims 1-4, it is characterized in that, the model of described constant current chip U1 is MP2359.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201010606752.4A CN102573189B (en) | 2010-12-27 | 2010-12-27 | Step-down light-emitting diode (LED) driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201010606752.4A CN102573189B (en) | 2010-12-27 | 2010-12-27 | Step-down light-emitting diode (LED) driving circuit |
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| CN102573189A CN102573189A (en) | 2012-07-11 |
| CN102573189B true CN102573189B (en) | 2015-07-08 |
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| CN104467504A (en) * | 2014-11-29 | 2015-03-25 | 成都思茂科技有限公司 | Low-pass filtering inverter system based on linear driving |
| CN108882433B (en) * | 2017-11-09 | 2020-07-14 | 李淑媛 | Light-emitting diode lighting device capable of stably dimming and stable dimming method |
| CN108989910A (en) * | 2018-09-07 | 2018-12-11 | 瑞纳智能设备股份有限公司 | A kind of low-power consumption bus takes electric MBUS communication interface circuit |
| CN109947688A (en) * | 2019-04-03 | 2019-06-28 | 昆山通达测科电子科技有限公司 | UART/I2C bus programmable pulls up voltage control circuit |
| CN110768525A (en) * | 2019-11-29 | 2020-02-07 | 上海海洋大学 | Large-current DC-DC conversion device |
| CN111614248A (en) * | 2020-06-15 | 2020-09-01 | 大峡谷照明系统（苏州）股份有限公司 | Direct current voltage reduction circuit and method and step type direct current voltage reduction circuit |
| CN112333887B (en) * | 2020-10-14 | 2023-03-14 | 深圳篆意科技有限公司 | LED drive circuit |
| CN112271924A (en) * | 2020-11-11 | 2021-01-26 | 湖北华中光电科技有限公司 | Constant-current output circuit and method based on voltage feedback of buck converter |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| KR20100054053A (en) * | 2008-11-13 | 2010-05-24 | 주식회사 비엔씨넷 | Constant current type led driver circuit for led stoplight |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101827479A (en) * | 2010-05-10 | 2010-09-08 | 杭州奥能照明电器有限公司 | Wireless control system for dimming light-emitting diode |
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Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR20100054053A (en) * | 2008-11-13 | 2010-05-24 | 주식회사 비엔씨넷 | Constant current type led driver circuit for led stoplight |
Non-Patent Citations (1)
| Title |
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| MPS.MP2359 REV1.1-1.2A,24V,1.4MHZ-STEP-DOWN CONVERTER IN A TSOT23-6.《MP2359 REV1.1 1.2A,24V,1.4MHZ-STEP-DOWN CONVERTER IN A TSOT23-6》.HTTP://WENKU.BAIDU.COM/VIEW/5417C4D184254B35EEFD341C.HTML,2006, * |
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Granted publication date: 20150708 Termination date: 20181227 |