CN202713686U - LED open circuit protection circuit - Google Patents
LED open circuit protection circuit Download PDFInfo
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- CN202713686U CN202713686U CN 201220416173 CN201220416173U CN202713686U CN 202713686 U CN202713686 U CN 202713686U CN 201220416173 CN201220416173 CN 201220416173 CN 201220416173 U CN201220416173 U CN 201220416173U CN 202713686 U CN202713686 U CN 202713686U
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- 238000001514 detection method Methods 0.000 claims abstract description 30
- 238000005070 sampling Methods 0.000 claims abstract description 25
- 230000006698 induction Effects 0.000 claims description 3
- 230000003247 decreasing effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 4
- 230000003321 amplification Effects 0.000 description 3
- 238000005286 illumination Methods 0.000 description 3
- 238000003199 nucleic acid amplification method Methods 0.000 description 3
- 230000002950 deficient Effects 0.000 description 2
- 238000005516 engineering process Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
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Abstract
The utility model discloses an LED open circuit protection circuit. The LED open circuit protection circuit comprises a switching power supply and multiple LED branches, wherein the multiple LED branches are connected in parallel between the anode of the switching power supply and a sampling resistor Rs. By connecting the Rs with the cathode of the switching power supply, sampling value of the Rs is sent to an inverting input terminal of a voltage comparator; and the output terminal of the voltage comparator outputs control signals to the switching power supply. The LED open circuit protection circuit is characterized in that a noninverting input terminal of the voltage comparator is connected with a variable voltage output circuit, multiple open circuit detection circuits are in parallel connection in the input terminal of the variable voltage output circuit, and each open circuit detection circuit is connected to a corresponding LED branch. The LED open circuit protection circuit has the advantage that when open circuit occurs in one LED branch, open circuit detection signals control the variable voltage output circuit to output corresponding feedback voltage, thereby decreasing the total output current, preventing currents in other LED branches from increasing, and ensuring normal work of other LED branches.
Description
Technical field
The utility model relates to a kind of circuit protection device, specifically, is a kind of LED open loop protection circuit.
Background technology
At present since some Bottleneck Restrictions of LED encapsulation technology so that there is defective in the stability of LED luminous element self, this defective is mainly reflected in that the inner lead fracture can produce fatal impact to whole LED illuminator when breaking down in the LED use procedure.
As shown in Figure 1, the LED constant current-supplying mode of main flow is: LED adopts series-parallel system to form array, be voltage by sampling resistor Rs with the LED current conversion, compare by comparator U and feedback voltage V REF, control switch power supply duty ratio, because feedback voltage V REF is constant, make the output total current constant.This mode has a fatal shortcoming, if a LED series arm open circuit is wherein arranged, can cause other several branch currents to increase, thereby easier other LED series arm open circuit that causes forms vicious circle, causes large tracts of land to damage.
The utility model content
The purpose of this utility model provides a kind of LED open loop protection circuit, can protect other LED branch roads unaffected when a LED branch road open circuit.
For achieving the above object, the scheme that the utility model adopts is as follows:
A kind of LED open loop protection circuit; comprise Switching Power Supply and many LED branch roads; described many LED branch road parallel joins are between the end of Switching Power Supply positive pole and sampling resistor Rs; the other end of sampling resistor Rs is connected with the Switching Power Supply negative pole; the sampled value of sampling resistor Rs is sent to the inverting input of voltage comparator; the output of voltage comparator outputs a control signal to Switching Power Supply; its key is: the normal phase input end of described voltage comparator links to each other with the variable voltage output circuit; be provided with many open detection circuit in that the input of variable voltage output circuit is parallel, every open detection circuit is overlapped on the corresponding LED branch road.
To on each bar LED branch road, overlap respectively open detection circuit, during the normal operation of LED branch road, this open detection circuit output high level, when the LED branch road is opened a way, this open detection circuit output low level, the variable voltage output circuit changes output voltage values according to the result that many open circuits detect, and by the duty ratio of control switch power supply, guarantees every current constant on the LED branch road.
As further describing, described open detection circuit is provided with the resistance bridge that the first resistance R, the second resistance R a, the 3rd resistance R b and photo resistance form, wherein the first resistance R be connected the bridge contact of resistance R a and connect power Vcc, the bridge contact of the second resistance R a and the 3rd resistance R b connects the normal phase input end of comparator, the bridge contact ground connection of the 3rd resistance R b and photo resistance, the first resistance R is connected bridge contact and is connected the inverting input of comparator with photo resistance, the luminance of photo resistance induction LED branch road, the output output open circuit detection signal of comparator.
Dense degree according to the LED distribution, in larger LED illuminator, use photo resistance to realize Photoelectric Detection as sensor devices, when open circuit occurs in a certain LED branch road, because extinguishing so that intensity of illumination dies down of LED lamp, the resistance of photo resistance can change, and difference will appear in the voltage that this moment, got at the resistance bridge two ends, can judge the open circuit situation of LED branch road by the dividing potential drop result at comparator comparison resistance bridge two ends.
And in the illuminator of LED distribution comparatively dense, sensor devices is closed on to be affected greatlyr, is not suitable for using the Photoelectric Detection mode, needs to use the current detecting mode this moment.
Described open detection circuit is comprised of branch road sampling resistor, the first resistance R a, the second resistance R b and comparator, wherein, the branch road sampling resistor is serially connected on the LED branch road, the sampled value of this branch road sampling resistor is sent into the normal phase input end of comparator, the first resistance R a and the second resistance R b form bleeder circuit, the partial pressure value of this bleeder circuit is sent into the inverting input of comparator, the output output open circuit detection signal of comparator.
By the current situation of branch road sampling resistor collection branch road, if open a way, branch current is zero, and sampled value is different from default partial pressure value, and comparator is exportable corresponding detection signal, thereby determines whether the LED branch road opens a way.
Further describe, described variable voltage output circuit is the analog adder circuit again.
Remarkable result of the present utility model is: when open circuit occurs a LED branch road; open circuit detection signal control variable voltage output circuit is exported corresponding feedback voltage; total output current is reduced, and unlikely other LED branch current increases, thereby protects other LED branch road normal operation.
Description of drawings
Fig. 1 is existing LED power control circuit;
Fig. 2 is circuit theory diagrams of the present utility model;
Fig. 3 is the first circuit theory diagrams that open circuit detects among Fig. 2;
Fig. 4 is the second circuit schematic diagram that open circuit detects among Fig. 2;
Fig. 5 is the circuit theory diagrams of variable voltage output circuit among Fig. 2.
Embodiment
Below in conjunction with the drawings and specific embodiments the utility model is described in further detail.
As shown in Figure 2; a kind of LED open loop protection circuit; comprise Switching Power Supply and many LED branch roads; described many LED branch road parallel joins are between the end of Switching Power Supply positive pole and sampling resistor Rs; the other end of sampling resistor Rs is connected with the Switching Power Supply negative pole; the sampled value of sampling resistor Rs is sent to the inverting input of voltage comparator; the output of voltage comparator outputs a control signal to Switching Power Supply; the normal phase input end of described voltage comparator links to each other with the variable voltage output circuit; be provided with many open detection circuit in that the input of variable voltage output circuit is parallel, every open detection circuit is overlapped on the corresponding LED branch road.
Described open detection circuit can adopt Photoelectric Detection and current detecting dual mode according to LED distribution comparatively dense degree.
As shown in Figure 3: as a kind of execution mode, described open detection circuit is provided with the first resistance R, the second resistance R a, the resistance bridge that the 3rd resistance R b and photo resistance form, wherein the first resistance R be connected the bridge contact of resistance R a and connect power Vcc, the bridge contact of the second resistance R a and the 3rd resistance R b connects the normal phase input end of comparator, the bridge contact ground connection of the 3rd resistance R b and photo resistance, the first resistance R is connected bridge contact and is connected the inverting input of comparator with photo resistance, the luminance of photo resistance induction LED branch road, the output output open circuit detection signal of comparator.
Photo resistance is installed in the optional position of a LED branch road among the figure, but will prevent from being subjected to the illumination effect of other branch road, therefore than the LED lighting apparatus that is more suitable for relatively high power.Resistance R, Ra, Rb, photo resistance forms an electric bridge, and during the normal operation of LED branch road, photo resistance is subjected to illumination stronger, resistance is less, the b point voltage is lower than a point voltage, and comparator output high level is if there is open circuit to occur, the photo resistance resistance increases, the b point voltage is higher than a point voltage, and the comparator output low level can be judged the operating state of corresponding branch road according to the Output rusults of comparator.
As shown in Figure 4: as another execution mode, described open detection circuit is comprised of branch road sampling resistor, the first resistance R a, the second resistance R b and comparator, wherein, the branch road sampling resistor is serially connected on the LED branch road, the sampled value of this branch road sampling resistor is sent into the normal phase input end of comparator, the first resistance R a and the second resistance R b form bleeder circuit, and the partial pressure value of this bleeder circuit is sent into the inverting input of comparator, the output output open circuit detection signal of comparator.
At branch road sampling resistor that resistance is less of every branch road series connection, RS1 is the sampling resistor of a LED branch road wherein among the figure, Ra, a point voltage when Rb b point voltage is set to be lower than normal operation, make comparator output high level, if the corresponding LED branch road of RS1 is opened a way, a point voltage will be lower than the b point voltage this moment, the comparator output low level can be judged the operating state of corresponding branch road according to the Output rusults of comparator.
As shown in Figure 5: in implementation process; described variable voltage output circuit is the analog adder circuit; among the figure take three branch roads as example; by operational amplification circuit and resistance R 1; R2; R3; R4 forms the analog addition circuit; wherein resistance R 1; R2, the R3 resistance is identical, according to the analog addition circuit theory as can be known the operational amplification circuit output voltage be Vo=k (Vi1+Vi2+Vi3); k is the adder gain constant; if 3 inputs of add circuit all represent the branch road normal operation with the voltage of a certain about definite value, and 0V represents open circuit, is 0V if an input terminal voltage is arranged; the operational amplification circuit output voltage can drop to 2/3 of normal condition; the variable voltage output circuit can be exported corresponding feedback voltage according to the working condition of LED branch road like this, by comparing the sampled value of sampling resistor RS, the duty ratio of by-pass cock power supply; so that remaining LED branch current is constant, thereby protect other LED branch road normal operation.
Claims (4)
1. LED open loop protection circuit; comprise Switching Power Supply and many LED branch roads; described many LED branch road parallel joins are between the end of Switching Power Supply positive pole and sampling resistor Rs; the other end of sampling resistor Rs is connected with the Switching Power Supply negative pole; the sampled value of sampling resistor Rs is sent to the inverting input of voltage comparator; the output of voltage comparator outputs a control signal to Switching Power Supply; it is characterized in that: the normal phase input end of described voltage comparator links to each other with the variable voltage output circuit; be provided with many open detection circuit in that the input of variable voltage output circuit is parallel, every open detection circuit is overlapped on the corresponding LED branch road.
2. a kind of LED open loop protection circuit according to claim 1; it is characterized in that: described open detection circuit is provided with the first resistance R; the second resistance R a; the resistance bridge that the 3rd resistance R b and photo resistance form; wherein the first resistance R be connected the bridge contact of resistance R a and connect power Vcc; the bridge contact of the second resistance R a and the 3rd resistance R b connects the normal phase input end of comparator; the bridge contact ground connection of the 3rd resistance R b and photo resistance; the first resistance R is connected bridge contact and is connected the inverting input of comparator with photo resistance; the luminance of photo resistance induction LED branch road, the output output open circuit detection signal of comparator.
3. a kind of LED open loop protection circuit according to claim 1; it is characterized in that: described open detection circuit is comprised of branch road sampling resistor, the first resistance R a, the second resistance R b and comparator; wherein; the branch road sampling resistor is serially connected on the LED branch road; the sampled value of this branch road sampling resistor is sent into the normal phase input end of comparator; the first resistance R a and the second resistance R b form bleeder circuit; the partial pressure value of this bleeder circuit is sent into the inverting input of comparator, the output output open circuit detection signal of comparator.
4. a kind of LED open loop protection circuit according to claim 1, it is characterized in that: described variable voltage output circuit is the analog adder circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220416173 CN202713686U (en) | 2012-08-21 | 2012-08-21 | LED open circuit protection circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN 201220416173 CN202713686U (en) | 2012-08-21 | 2012-08-21 | LED open circuit protection circuit |
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|---|---|
| CN202713686U true CN202713686U (en) | 2013-01-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN 201220416173 Expired - Fee Related CN202713686U (en) | 2012-08-21 | 2012-08-21 | LED open circuit protection circuit |
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| CN (1) | CN202713686U (en) |
Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104167181A (en) * | 2014-05-23 | 2014-11-26 | 友达光电股份有限公司 | Display and sub-pixel driving method thereof |
| CN104955230A (en) * | 2015-06-12 | 2015-09-30 | 来安县新元机电设备设计有限公司 | Backlight source control circuit and display terminal |
| CN108541101A (en) * | 2018-04-10 | 2018-09-14 | 厦门元顺微电子技术有限公司 | The circuit structure of chip |
| CN108983453A (en) * | 2018-07-26 | 2018-12-11 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
| CN110870944A (en) * | 2018-08-29 | 2020-03-10 | 苏州景昱医疗器械有限公司 | Nerve stimulator and its overvoltage protection method |
| CN112202444A (en) * | 2020-10-30 | 2021-01-08 | 天津雅迪实业有限公司 | Waterproof circuit system of switch |
-
2012
- 2012-08-21 CN CN 201220416173 patent/CN202713686U/en not_active Expired - Fee Related
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104167181A (en) * | 2014-05-23 | 2014-11-26 | 友达光电股份有限公司 | Display and sub-pixel driving method thereof |
| CN104955230A (en) * | 2015-06-12 | 2015-09-30 | 来安县新元机电设备设计有限公司 | Backlight source control circuit and display terminal |
| CN108541101A (en) * | 2018-04-10 | 2018-09-14 | 厦门元顺微电子技术有限公司 | The circuit structure of chip |
| CN108541101B (en) * | 2018-04-10 | 2024-06-04 | 厦门元顺微电子技术有限公司 | Circuit structure of chip |
| CN108983453A (en) * | 2018-07-26 | 2018-12-11 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
| CN108983453B (en) * | 2018-07-26 | 2021-11-05 | 武汉天马微电子有限公司 | Backlight module detection device, detection jig and display module |
| CN110870944A (en) * | 2018-08-29 | 2020-03-10 | 苏州景昱医疗器械有限公司 | Nerve stimulator and its overvoltage protection method |
| CN112202444A (en) * | 2020-10-30 | 2021-01-08 | 天津雅迪实业有限公司 | Waterproof circuit system of switch |
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| C14 | Grant of patent or utility model | ||
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| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20130130 Termination date: 20150821 |
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| EXPY | Termination of patent right or utility model |