CN104124860A - Switching-power-supply protective circuit and LED light fixture - Google Patents
Switching-power-supply protective circuit and LED light fixture Download PDFInfo
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- CN104124860A CN104124860A CN201310142691.4A CN201310142691A CN104124860A CN 104124860 A CN104124860 A CN 104124860A CN 201310142691 A CN201310142691 A CN 201310142691A CN 104124860 A CN104124860 A CN 104124860A
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Abstract
The invention belongs to the field of protective circuits and particularly relates to a switching-power-supply protective circuit and an LED light fixture. The switching-power-supply protective circuit is connected between a switching-power-supply output end and a load. The switching-power-supply protective circuit includes a voltage conversion unit, an open-circuit protective unit and a current sampling unit. In an open circuit of the load, the open-circuit protective unit is capable of controlling the intensity of voltage output by the voltage conversion unit through regulation and control of a feedback input end of the voltage conversion unit so as to protective the whole circuit. The switching-power-supply protective circuit is simple and reliable in design, low in cost, small in volume structure, easy to realize and suitable for being used as an open-circuit protective circuit of different types of switching power supplies.
Description
Technical field
The invention belongs to protective circuit field, relate in particular to a kind of protective circuit of switch power source and LED light fixture.
Background technology
Along with scientific and technical development, New Products & New Technology is constantly reformed, and LED is as new type light source, and it has energy-saving and environmental protection, feature efficiently, and LED technology is ripe and be applied to every field, has also occurred various switching power circuits thereupon.LED is a kind of current mode luminescent device, very responsive to flowing through self electric current, requires relatively also very harsh.
After processing through boosting taking Switching Power Supply, meet LED as example, in the time that load LED open a way, (have an open circuit such as in LED string), can cause output voltage phase step type sudden change rising, cause circuit because overtension and damage; Therefore, be badly in need of a kind of switching power circuit that can realize open-circuit-protection and solve above-mentioned technical problem.In fact,, with the switching circuit of the similar all kinds of home electronic appliances of LED, need to possess equally the function of open-circuit-protection.
Summary of the invention
In view of this, first object of the present invention is to provide a kind of protective circuit of switch power source, easily causes the impaired technical problem of whole circuit to solve existing switching power circuit because do not possess open circuit protecting function.
The technical solution used in the present invention is:
A kind of protective circuit of switch power source, comprising:
Voltage conversion unit, is connected between the output of described Switching Power Supply and the input of load, for input voltage is boosted or decompression transformation;
Open-circuit-protection unit, is attempted by between the input and output of load, for the size of the feedback input end control output voltage by described voltage conversion unit when the described load open circuit, protect whole circuit;
Current sampling unit, is connected between the output and ground of load, for the electric current of the described load of flowing through is sampled.
Further, described circuit also comprises: be connected between the output and ground of described voltage conversion unit, for the voltage that inputs to described load being carried out to the rectification filtering unit of rectifying and wave-filtering processing.
Particularly, described open-circuit-protection unit comprises voltage stabilizing didoe ZD1 and resistance R 2; The negative electrode of described voltage stabilizing didoe ZD1 connects the input of described load, and the anode of described voltage stabilizing didoe ZD1 connects the first end of described resistance R 2 and the feedback input end of described voltage conversion unit simultaneously; The output of load described in the second termination of described resistance R 2.Or described open-circuit-protection unit comprises voltage stabilizing didoe ZD2; The negative electrode of described voltage stabilizing didoe ZD2 connects the input of described load, and the anode of described voltage stabilizing didoe ZD2 connects the output of described load and the feedback input end of described voltage conversion unit simultaneously.
Particularly, described voltage conversion unit comprises boost converter U1, diode D1, resistance R 1, capacitor C 3 and inductance L 1, the voltage input pin of described boost converter U1 connects the output of described Switching Power Supply, the common pin of described boost converter U1 is successively by described resistance R 1, capacitor C 3 ground connection, the switch control pin of described boost converter U1 connects the first end of described inductance L 1 and the anode of described diode D1 simultaneously, the voltage input pin of boost converter U1 described in the second termination of described inductance L 1, the negative electrode of described diode D1 connects the input of described open-circuit-protection unit and the input of described load simultaneously, the feed back input pin of described boost converter U1 connects described open-circuit-protection unit.
Particularly, described current sampling unit comprises resistance R 3; Described resistance R 3 is connected between the output and ground of described load.
Rectification filtering unit comprises capacitor C 2 and capacitor C 4; Described capacitor C 2 and capacitor C 4 are attempted by respectively between the output and ground of described voltage conversion unit.
Further, the voltage input pin of described boost converter U1 is also by capacitor C 1 ground connection.
Another object of the present invention is to provide a kind of LED light fixture, this light fixture comprises one or more LED strings that are connected to Switching Power Supply output, and as improvement, described LED light fixture comprises a protective circuit of switch power source as above.
Protective circuit of switch power source provided by the invention and LED light fixture; in the time of load (such as LED string) open circuit; open-circuit-protection unit can pass through the regulation and control to voltage conversion unit feedback input end, controls from the voltage swing of voltage conversion unit output, and then protects whole circuit.The simplicity of design of this protective circuit of switch power source is reliable, with low cost and volume structure is little, is easy to realize, and is applicable to doing the open loop protection circuit of all kinds of Switching Power Supplies.
Brief description of the drawings
Fig. 1 is the structured flowchart of the protective circuit of switch power source that provides of first embodiment of the invention;
Fig. 2 is the structured flowchart of the protective circuit of switch power source that provides of second embodiment of the invention;
Fig. 3 is the electronic devices and components exemplary plot of the protective circuit of switch power source that provides of third embodiment of the invention.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearer, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein, only in order to explain the present invention, is not intended to limit the present invention.
Fig. 1 is the structured flowchart of the protective circuit of switch power source that provides of first embodiment of the invention; For convenience of explanation, only show the part relevant to the present embodiment, as shown in the figure:
A kind of protective circuit of switch power source, is connected between Switching Power Supply output and load 500, comprising: voltage conversion unit 100, open-circuit-protection unit 200 and current sampling unit 300;
Wherein, voltage conversion unit 100 is connected between the output Vin of Switching Power Supply and the input of load 500, for input voltage is boosted or decompression transformation; Open-circuit-protection unit 200, is attempted by between the input and output of load 500, for the size of the feedback input end control output voltage by voltage conversion unit 100 in the time that load 500 is opened a way, protect whole circuit; Current sampling unit 300, is connected between the output and ground of load 500, for the electric current of the load 500 of flowing through is sampled.
In general, at the output of Switching Power Supply, no matter be the voltage after a boost conversion unit or step-down converting unit are changed, in the time of load open circuit, capital causes jump stepwise sudden change of output voltage to rise, and so just may cause damage to whole circuit.And the protective circuit of switch power source providing according to this first embodiment; after voltage conversion unit, the two ends of load connect an open-circuit-protection unit; just can realize in the time of load open circuit the size of the feedback input end control output voltage by voltage conversion unit and then protect whole circuit.That is to say, as long as voltage conversion unit comprises a feedback input end, in the time of load open circuit, just can be by open-circuit-protection unit by the regulation and control to voltage conversion unit feedback input end, the size of regulation output voltage, protects whole circuit.
Further, as preferred embodiment, protective circuit of switch power source provided by the invention can also comprise a rectification filtering unit 400.As shown in Figure 2, Fig. 2 is the structured flowchart of the protective circuit of switch power source that provides of second embodiment of the invention.In this second embodiment; protective circuit of switch power source is except the modules structure that comprises the first embodiment and provide; also comprised a rectification filtering unit 400, this rectification filtering unit 400 is connected between the output and ground of voltage conversion unit 100, for the voltage that inputs to load 500 is carried out to rectifying and wave-filtering processing.
Fig. 3 is the electronic devices and components exemplary plot of the protective circuit of switch power source that provides of third embodiment of the invention.The electronic devices and components exemplary plot that this 3rd embodiment provides is the structured flowchart that provides taking the second embodiment as basis; that is to say; the protective circuit of switch power source that this 3rd embodiment provides comprises voltage conversion unit 100, open-circuit-protection unit 200, current sampling unit 300 and rectification filtering unit 400; and; for convenience of explanation; taking load 500 as LED strings as example, corresponding thereto, voltage conversion unit 100 is also a functional module that realizes boost conversion.
Specifically referring to Fig. 3.
It is LED string that open-circuit-protection unit 200 is attempted by load 500() two ends, comprise voltage stabilizing didoe ZD1 and resistance R 2; The negative electrode of voltage stabilizing didoe ZD1 connects the input of LED string 500, the first end of the anode while connecting resistance R2 of voltage stabilizing didoe ZD1 and the feedback input end of voltage conversion unit 200; The output of the second termination LED string 500 of resistance R 2.
Voltage conversion unit 100 comprises boost converter U1, diode D1, resistance R 1, capacitor C 3 and inductance L 1; The voltage input pin Vin of boost converter U1 connects the output of Switching Power Supply, and meanwhile, the voltage input pin of boost converter U1 is also by capacitor C 1 ground connection.The common pin COMP of boost converter U1 is successively by resistance R 1, capacitor C 3 ground connection; the switch control pin SW of boost converter U1 connects the first end of inductance L 1 and the anode of diode D1 simultaneously; the voltage input pin Vin of the second termination boost converter U1 of inductance L 1; the negative electrode of diode D1 connects rectification filtering unit 400, open-circuit-protection unit 200 and LED string 500 simultaneously, and the feed back input pin FB of boost converter U1 is connected on the voltage stabilizing didoe ZD1 of open-circuit-protection unit 200 and the public connecting end of resistance R 2.
In addition, rectification filtering unit 400 comprises capacitor C 2 and capacitor C 4, is attempted by respectively between the negative electrode and ground of diode D1.300 of current sampling unit comprise resistance R 3; This resistance R 3 is connected between the output and ground of LED string 500.
Suppose not comprise the circuit of open-circuit-protection unit 200; in the time that LED string is opened a way or is removed; current sampling resistor R3 is pulled down to ground connection; the voltage of the feed back input pin FB end of boost converter U1 is had by drop-down trend; as response; boost converter U1 can increase as much as possible its work duty ratio until maximum, and object is to make to maintain correct voltage on the feed back input pin FB of boost converter U1, is its internal reference voltage Vref.In the time that boost converter U1 approaches its maximum duty cycle, can produce very high output voltage, from formula Vout=1/ (1-D) * Vin, such as in the time that duty ratio arrives 0.9, the output voltage V out=1/ of circuit (1-0.9) * Vin=10Vin, and when ordinary circumstance D=0.5, Vout=1/ (1-0.5) * Vin=2Vin, that is to say, in the time of LED string open circuit, the output voltage of circuit can sharply rise and may damage circuit.
Taking the circuit structure shown in Fig. 3 as example, when circuit is normally worked, the voltage stabilizing didoe ZD1 in open-circuit-protection unit 200, because voltage is not high enough and not breakdown, does not have electric current process.Equally, at LED string open circuit or while being removed, voltage sharply rises, and causes voltage stabilizing didoe ZD1 breakdown, and meanwhile, flow through resistance R 2 and resistance R 3 ground connection of electric current form loops.In fact, when Vout rises to voltage stabilizing didoe ZD1 when breakdown, voltage on the feed back input pin FB of boost converter U1 exceedes its inner reference voltage Vref, as response, boost converter U1 can reduce dutyfactor value, output voltage V out is reduced, and object is to make to maintain correct voltage on the feed back input pin FB of boost converter U1, is its internal reference voltage Vref.The whole output current of realizing after open-circuit-protection is determined by the tandem compound of resistance R 2 and resistance R 3; because the voltage on the feed back input pin FB of boost converter U1 equals its internal reference voltage Vref; therefore; the protective current of output is defaulted as: Ipro=Vref/(R2+R3); and maximum output voltage Vout=VZD1+Vref; therefore realize the level that output voltage is limited in to a safety, realize simultaneously and in the time that open fault appears in LED string, reduce output current.
In the time of specific implementation, in order to ensure voltage stabilizing didoe, ZD1 closes completely during normal operation circuit, the voltage stabilizing didoe ZD1 selecting, its puncture voltage should be at least higher than maximum load voltage and be less than the regulation maximum output voltage of boost converter U1.In addition,, as preferred embodiment, in the time of specific implementation, the resistance of resistance R 2 should be large as much as possible, to minimize the power consumption of voltage stabilizing didoe ZD1.
In fact,, in the time of specific implementation open-circuit-protection, open-circuit-protection unit also can only include voltage stabilizing didoe ZD2; The negative electrode of voltage stabilizing didoe ZD2 connects the input of load 500, and anode connects the output of load 500 and the feedback input end of voltage conversion unit 100 simultaneously.That is to say, omit resistance R 2 and also can substantially realize open circuit protecting function.When open circuit, the size of output current is just only controlled by the resistance size of current sampling resistor R3.
The embodiment of the present invention also provides a kind of LED light fixture, and described light fixture comprises one or more LED strings that are connected to Switching Power Supply output, and as improvement, described LED light fixture comprises a protective circuit of switch power source as above.
Protective circuit of switch power source provided by the invention and LED light fixture; in the time of load (such as LED string) open circuit; open-circuit-protection unit can pass through the regulation and control to voltage conversion unit feedback input end, controls from the voltage swing of voltage conversion unit output, and then protects whole circuit.The simplicity of design of this protective circuit of switch power source is reliable, with low cost and volume structure is little, is easy to realize, and is applicable to doing the open loop protection circuit of all kinds of Switching Power Supplies.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, although the present invention has been carried out to more detailed explanation with reference to previous embodiment, for a person skilled in the art, its technical scheme that still can record aforementioned each embodiment is modified or part technical characterictic is wherein equal to replacement.All any amendments of doing within the spirit and principles in the present invention, be equal to and replace and improvement etc., within all should being included in protection scope of the present invention.
Claims (10)
1. a protective circuit of switch power source, is characterized in that, described circuit comprises:
Voltage conversion unit, is connected between the output of described Switching Power Supply and the input of load, for input voltage is boosted or decompression transformation;
Open-circuit-protection unit, is attempted by between the input and output of load, for the size of the feedback input end control output voltage by described voltage conversion unit when the described load open circuit, protect whole circuit;
Current sampling unit, is connected between the output and ground of load, for the electric current of the described load of flowing through is sampled.
2. protective circuit of switch power source as claimed in claim 1, is characterized in that, described circuit also comprises:
Be connected between the output and ground of described voltage conversion unit, for the voltage that inputs to described load being carried out to the rectification filtering unit of rectifying and wave-filtering processing.
3. protective circuit of switch power source as claimed in claim 2, is characterized in that, described open-circuit-protection unit comprises voltage stabilizing didoe ZD1 and resistance R 2;
The negative electrode of described voltage stabilizing didoe ZD1 connects the input of described load, and the anode of described voltage stabilizing didoe ZD1 connects the first end of described resistance R 2 and the feedback input end of described voltage conversion unit simultaneously; The output of load described in the second termination of described resistance R 2.
4. protective circuit of switch power source as claimed in claim 2, is characterized in that, described open-circuit-protection unit comprises voltage stabilizing didoe ZD2;
The negative electrode of described voltage stabilizing didoe ZD2 connects the input of described load, and the anode of described voltage stabilizing didoe ZD2 connects the output of described load and the feedback input end of described voltage conversion unit simultaneously.
5. the protective circuit of switch power source as described in claim 3 or 4, is characterized in that, described voltage conversion unit comprises boost converter U1, diode D1, resistance R 1, capacitor C 3 and inductance L 1;
The voltage input pin of described boost converter U1 connects the output of described Switching Power Supply, the common pin of described boost converter U1 is successively by described resistance R 1, capacitor C 3 ground connection, the switch control pin of described boost converter U1 connects the first end of described inductance L 1 and the anode of described diode D1 simultaneously, the voltage input pin of boost converter U1 described in the second termination of described inductance L 1, the negative electrode of described diode D1 connects the input of described open-circuit-protection unit and the input of described load simultaneously, the feed back input pin of described boost converter U1 connects described open-circuit-protection unit.
6. protective circuit of switch power source as claimed in claim 5, is characterized in that, described current sampling unit comprises resistance R 3; Described resistance R 3 is connected between the output and ground of described load.
7. protective circuit of switch power source as claimed in claim 5, is characterized in that, described rectification filtering unit comprises capacitor C 2 and capacitor C 4;
Described capacitor C 2 and capacitor C 4 are attempted by respectively between the output and ground of described voltage conversion unit.
8. protective circuit of switch power source as claimed in claim 5, is characterized in that, the voltage input pin of described boost converter U1 is also by capacitor C 1 ground connection.
9. a LED light fixture, comprises one or more LED strings that are connected to Switching Power Supply output, it is characterized in that, described LED light fixture comprises a protective circuit of switch power source, and described protective circuit of switch power source comprises:
Voltage conversion unit, is connected between the output of described Switching Power Supply and the input of described LED string, for input voltage is boosted or decompression transformation;
Open-circuit-protection unit, is attempted by between the input and output of described LED string, for controlling the size of output voltage when the described LED string open circuit, to protect whole circuit;
Current sampling unit, is connected between the output and ground of described LED string, for the electric current of the described LED string of flowing through is sampled.
10. LED light fixture as claimed in claim 9, is characterized in that, described protective circuit of switch power source is the circuit as described in claim 2-8 any one.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310142691.4A CN104124860A (en) | 2013-04-23 | 2013-04-23 | Switching-power-supply protective circuit and LED light fixture |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201310142691.4A CN104124860A (en) | 2013-04-23 | 2013-04-23 | Switching-power-supply protective circuit and LED light fixture |
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| CN104124860A true CN104124860A (en) | 2014-10-29 |
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| CN201310142691.4A Pending CN104124860A (en) | 2013-04-23 | 2013-04-23 | Switching-power-supply protective circuit and LED light fixture |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN201210761Y (en) * | 2008-05-29 | 2009-03-18 | 上海恒烁光电科技有限公司 | Road lamp controller |
| US20090195163A1 (en) * | 2008-02-06 | 2009-08-06 | Microsemi Corporation | Single LED String Lighting |
| CN201425279Y (en) * | 2009-06-11 | 2010-03-17 | 杭州海康蓝博电器有限公司 | LED surface light source lamp suitable for low-voltage power supply |
| CN201557283U (en) * | 2009-12-14 | 2010-08-18 | 高忠康 | LED energy-saving lamp with open-circuit protection |
| US20130002158A1 (en) * | 2010-04-15 | 2013-01-03 | Yung-Hsin Chiang | Two-terminal current controller and related led lighting device |
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2013
- 2013-04-23 CN CN201310142691.4A patent/CN104124860A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20090195163A1 (en) * | 2008-02-06 | 2009-08-06 | Microsemi Corporation | Single LED String Lighting |
| CN201210761Y (en) * | 2008-05-29 | 2009-03-18 | 上海恒烁光电科技有限公司 | Road lamp controller |
| CN201425279Y (en) * | 2009-06-11 | 2010-03-17 | 杭州海康蓝博电器有限公司 | LED surface light source lamp suitable for low-voltage power supply |
| CN201557283U (en) * | 2009-12-14 | 2010-08-18 | 高忠康 | LED energy-saving lamp with open-circuit protection |
| US20130002158A1 (en) * | 2010-04-15 | 2013-01-03 | Yung-Hsin Chiang | Two-terminal current controller and related led lighting device |
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Application publication date: 20141029 |