CN204259250U - Led drive circuit - Google Patents
Led drive circuit Download PDFInfo
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- CN204259250U CN204259250U CN201420806342.8U CN201420806342U CN204259250U CN 204259250 U CN204259250 U CN 204259250U CN 201420806342 U CN201420806342 U CN 201420806342U CN 204259250 U CN204259250 U CN 204259250U
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- drive circuit
- led drive
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Abstract
The utility model discloses a kind of LED drive circuit, comprise voltage sampling unit, rectification circuit, LED string and control unit, at least two capacitive circuits be connected in series, at least one switch element, each switch element is connected in parallel a capacitive circuit, external communication input power is connected to the ac input end of rectification circuit through the capacitive circuit that at least two are connected in series, the DC output end of rectification circuit connects LED string, control unit is connected with voltage sampling unit and each switch element respectively, external communication input supply voltage signal for collecting according to voltage sampling unit exports at least one control signal and comes each switching means conductive of corresponding control or disconnection.Enforcement the beneficial effects of the utility model are, control by adopting the capacitive circuit of control unit to serial or parallel connection, output end voltage fluctuation voltage fluctuation by input caused is limited within the scope of safety limit, improves stability and the life-span of LED drive circuit.
Description
Technical field
The utility model relates to LED application circuit field, more particularly, relates to a kind of LED drive circuit.
Background technology
The scheme can taked in low-power LED drive circuit at present has three kinds: a kind of is the Switching Power Supply the most often adopted, to ensure to cause LED reduced lifetime or damage because of curent change, but Switching Power Supply is applied in the restriction due to volume in low-power LED drive circuit, efficiency comparison is low, and there is the problem of EMI, cost is higher; The second adopts linear power supply, but the coupling of linear power supply to load and input voltage has strict demand, and input voltage is higher, and power consumption is larger; The third adopts capacitance-resistance voltage reduction circuit, and adopt capacitance-resistance voltage reduction circuit cost low, efficiency is high, but less stable, changes greatly, easily damage LED constantly when input voltage changes greatly to output current LED load with input voltage.
Utility model content
The technical problems to be solved in the utility model is, the above-mentioned existing drive circuit output current for prior art changes greatly with input voltage, less stable, easily damages the defect of LED, provides a kind of LED drive circuit.
The utility model solves the technical scheme that its technical problem adopts: construct a kind of LED drive circuit, comprise voltage sampling unit, rectification circuit and LED string, also comprise control unit, at least two capacitive circuits be connected in series, at least one switch element, switch element described in each is connected in parallel capacitive circuit described in respectively, external communication input power is connected to the ac input end of described rectification circuit through the capacitive circuit that at least two are connected in series, and the DC output end of described rectification circuit connects described LED string;
Wherein: described control unit respectively with described voltage sampling unit and each described in switch element is connected, and the external communication input supply voltage signal for collecting according to described voltage sampling unit export at least one control signal distinguish correspondence control each described in switching means conductive or disconnection.
In above-mentioned LED drive circuit, described LED drive circuit also comprises the power supply unit of powering to described control unit for external communication input power being converted to DC power supply.
In above-mentioned LED drive circuit, described LED drive circuit also comprises the filter unit between the DC output end being connected to described rectification circuit.
In above-mentioned LED drive circuit, described filter unit comprises a filter capacitor.
In above-mentioned LED drive circuit, capacitive circuit described in each comprises an electric capacity.
In above-mentioned LED drive circuit, the electric capacity that capacitive circuit described in each comprises a resistance and is connected with described resistor coupled in parallel.
In above-mentioned LED drive circuit, described rectification circuit is rectifier bridge.
Another embodiment of the utility model also provides a kind of LED drive circuit, comprise voltage sampling unit, rectification circuit and LED string, also comprise control unit, at least two capacitive circuits be connected in parallel, at least one switch element, switch element described in each is connected in series capacitive circuit described in respectively, external communication input power is connected to the ac input end of described rectification circuit through the capacitive circuit that at least two are connected in parallel, and the DC output end of described rectification circuit connects described LED string;
Wherein: described control unit respectively with described voltage sampling unit and each described in switch element is connected, and the external communication input supply voltage signal for collecting according to described voltage sampling unit export at least one control signal distinguish correspondence control each described in switching means conductive or disconnection.
In above-mentioned LED drive circuit, described LED drive circuit also comprises the power supply unit of powering to described control unit for external communication input power being converted to DC power supply.
In above-mentioned LED drive circuit, described LED drive circuit also comprises the filter unit between the DC output end being connected to described rectification circuit.
Implement LED drive circuit of the present utility model, there is following beneficial effect: control by adopting the capacitive circuit of control unit to serial or parallel connection, output end voltage fluctuation voltage fluctuation by input caused is limited within the scope of safety limit, improves stability and the life-span of LED drive circuit.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is described in further detail, in accompanying drawing:
Fig. 1 is the structural representation of a kind of LED drive circuit first of the utility model preferred embodiment;
Fig. 2 is a kind of circuit diagram of the utility model a kind of LED drive circuit first preferred embodiment;
Fig. 3 is the another kind of circuit diagram of the utility model a kind of LED drive circuit first preferred embodiment;
Fig. 4 is the structural representation of a kind of LED drive circuit second of the utility model preferred embodiment;
Fig. 5 is a kind of circuit diagram of the utility model a kind of LED drive circuit second preferred embodiment;
Fig. 6 is the another kind of circuit diagram of the utility model a kind of LED drive circuit second preferred embodiment.
Embodiment
In order to there be understanding clearly to technical characteristic of the present utility model, object and effect, now contrast accompanying drawing and describe embodiment of the present utility model in detail.
As shown in Figure 1, for the structural representation of a kind of LED drive circuit first of the utility model preferred embodiment, this LED drive circuit comprises voltage sampling unit 10, control unit 20, at least two capacitive circuits be sequentially connected in series 30, at least one switch element 40, rectification circuit 50 and LED string 60.Wherein: each switch element 40 is a capacitive circuit 30 in parallel respectively, voltage sampling unit 10 is connected with external communication input power, for sampling to outside alternating current input power supplying voltage, and export voltage sampling signal to control unit 20, external communication input power is connected to two ac input ends of rectification circuit 50 through these at least two capacitive circuits be connected in series 30, and two DC output ends of rectification circuit 50 are connected to LED string 60.
Especially, control unit 20 is connected with voltage sampling unit 10 and each switch element 40 respectively, this control unit 20 exports at least one control signal for the external communication input supply voltage signal obtained of sampling according to voltage sampling unit 10, this at least one control signal is respectively used to the corresponding conducting or the shutoff that control each switch element 40, when switch element 40 conducting, the capacitive circuit that this switch element of short circuit is in parallel, when switch element disconnects, this switch element capacitive circuit in parallel turns in this LED drive circuit, external communication input power flows through to rectification circuit through this capacitive circuit and carries out rectification.
In the present embodiment, LED drive circuit also comprises a power supply unit 70 and filter unit 80, this power supply unit 70 is connected between external communication input power and control unit 20, for external communication input power being converted to a suitable DC power supply to be supplied to the operating voltage needed for control unit 20.Filter unit 80 is connected between two DC output ends of rectification circuit 50, for supplying LED string 60 by after the direct current filtering after rectification circuit 50 rectification.
Particularly, as shown in Figure 2, for a kind of circuit diagram of the utility model LED drive circuit first preferred embodiment, each switch element 40 includes a switch, this switch is any device with switch conduction function, as the triode in switching tube, metal-oxide-semiconductor etc., when switch specifically refers to switching tube, control unit 20 is connected with the control end of each switching tube respectively.Each capacitive circuit refers to the circuit formed primarily of electric capacity, an electric capacity is exemplarily shown in the present embodiment, the electric capacity that can certainly comprise a resistance and be connected with this resistor coupled in parallel.When switch conduction, the capacitive circuit be connected with this switch in parallel is by short circuit, when switch disconnects, the capacitive circuit be connected with this switch in parallel turns in this LED drive circuit, after realizing carrying out step-down to alternating current input power supplying voltage, export to rectification circuit 50.Rectification circuit 50 adopts rectifier bridge in the present embodiment, filter unit 80 is a filter capacitor C, ac voltage signal step-down is become low-voltage AC by the capacitive circuit turned in this LED drive circuit, the direct voltage of output ripple after rectification circuit 50, by filter capacitor C, the Rectified alternating current that rectification circuit 50 exports is become smoother direct current supply LED string 60 again, as shown in Figure 2, LED string 60 comprises multiple LED be sequentially connected in series between two DC output ends of rectification circuit 50.
Especially, in the circuit, to comprise two capacitive circuits be connected in series 30 and a switch element 40, and two capacitive circuits are respectively electric capacity C1 and C2, and switch element 40 is K switch 1.When external communication input supply voltage acutely raises, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 exports a control signal control switch K1 according to the voltage sampling signal received and is in off-state, the now voltage fluctuation of external communication input " is released " by the electric capacity of two series connection, reduce the voltage exporting to LED string, reach output of releiving and be applied to voltage fluctuation on LED string, realize output voltage relatively stable.
Correspondingly, when external communication input supply voltage acutely reduces, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 exports a control signal control switch K1 according to the voltage sampling signal received and is in conducting state, the electric capacity C1 that short circuit is connected with this switch in parallel, capacitive reactance in this LED drive circuit can reduce to some extent, step-down value also just reduces, thus increase the voltage exporting to LED string, therefore the relatively stable of output voltage is also realized, namely the utility model LED drive circuit can realize the change reduction of the output end voltage (exporting to the voltage of LED string) when input terminal voltage (external communication input supply voltage) changes, thus reduce the impact of input voltage change on LED, by by the current limit of LED in certain scope, improve stability and the life-span of whole LED drive circuit.
Be understandable that, in the present embodiment, LED drive circuit comprises at least two capacitive circuits and at least one switch element, the number of switch element is not more than the number of capacitive circuit, such as, also can comprise the switch element be connected in parallel with electric capacity C2 in fig. 2, its operation principle is same as described above, does not repeat them here.As shown in Figure 3, be three for capacitive circuit 30 and switch element 40, and capacitive circuit 30 comprises an electric capacity respectively, namely three capacitive circuits are respectively electric capacity C1, C2 and C3, and three switch elements 40 are respectively K switch 1, K2, K3.When external communication input supply voltage acutely raises, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 is according to the voltage sampling signal received, in three outputs corresponding output three control signals respectively, these three control signals are corresponding respectively controls three K switch 1, one or more in K2 and K3 are in off-state, the now voltage fluctuation of external communication input " is released " by the electric capacity of all series connection, reduce the voltage exporting to LED string, reach output of releiving and be applied to voltage fluctuation on LED string, realize output voltage relatively stable.
Correspondingly, when external communication input supply voltage acutely reduces, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 is according to the voltage sampling signal received, in three outputs corresponding output three control signals respectively, these three control signals are corresponding respectively controls three K switch 1, one or more in K2 and K3 are in conducting state, the capacitive reactance turning on the capacitive circuit of all series connection in this LED drive circuit can reduce to some extent, step-down value also just reduces, thus increase the voltage exporting to LED string, therefore the relatively stable of output voltage is also realized, namely the utility model LED drive circuit can realize the change reduction of the output end voltage (exporting to the voltage of LED string) when input terminal voltage (external communication input supply voltage) changes, thus reduce the impact of input voltage change on LED, by by the current limit of LED in certain scope, improve stability and the life-span of whole LED drive circuit.
As shown in Figure 4, for the structural representation of the utility model LED drive circuit second preferred embodiment, not only comprise the voltage sampling unit 10 shown in Fig. 1, power supply unit 70, control unit 20, at least two capacitive circuits 30, at least one switch element 40, rectification circuit 50 and LED string 60, but with Fig. 1 unlike, in the present embodiment, all capacitive circuits 30 are connected in parallel, and each switch element 40 is connected in series a capacitive circuit 30 respectively.
Especially, control unit 20 is connected with voltage sampling unit 10 and each switch element 40 respectively, this control unit 20 is also export at least one control signal for the external communication input supply voltage signal obtained of sampling according to voltage sampling unit 10, and this at least one control signal is respectively used to being turned on or off of corresponding each switch element 40 of control.In Fig. 4, when switch element 40 conducting, the capacitive circuit be connected in series with this switch element turns in this LED drive circuit; When switch element 40 disconnects, the capacitive circuit be connected in series with this switch element does not also work.Afterwards, external communication input power through turn on all parallel connections in this LED drive circuit capacitive circuit flow through to rectification circuit and carry out rectification.
Particularly, as shown in Figure 5, be a kind of circuit diagram of the utility model LED drive circuit second preferred embodiment, still to comprise two capacitive circuits 30 and a switch element 40, and two capacitive circuits are respectively electric capacity C1 and C2, switch element 40 is K switch 1.But with Fig. 2 unlike, electric capacity C1 and C2 is connected in parallel, and K switch 1 and electric capacity C1 are connected in series, and as shown in the figure, when K switch 1 conducting, the electric capacity C1 be connected in series with this switch turns in this LED drive circuit; When switch disconnects, electric capacity C1 does not work.
When external communication input supply voltage acutely raises, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 exports control signal control switch K1 one by one according to the voltage sampling signal received and is in conducting state, realize electric capacity C1 and C2 parallel connection to connect, thus realize capacitive step-down, share the output end voltage fluctuation that input terminal voltage big ups and downs cause, thus realize output end voltage and stablize controlled, improve the useful life of LED.
Correspondingly, when external communication input supply voltage acutely reduces, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 exports a control signal control switch K1 according to the voltage sampling signal received and is in off-state, electric capacity C1 does not work, capacitive reactance in whole LED drive circuit can reduce to some extent, step-down value is just corresponding reduction also, thus increase the voltage exporting to LED string, therefore the relatively stable of output voltage is also achieved, no matter namely the utility model LED drive circuit can realize input terminal voltage (external communication input supply voltage) how big ups and downs, output end voltage (exporting to the voltage of LED string) is still stablized, can not big ups and downs or control fluctuation limit amplitude range in.
Be understandable that, in the present embodiment, LED drive circuit still comprises at least two capacitive circuits and at least one switch element, the number of switch element is not more than the number of capacitive circuit, such as, also can comprise the switch element be connected in series with electric capacity C2 in Figure 5, its operation principle is same as described above, does not repeat them here.
As shown in Figure 6, be still three for capacitive circuit 30 and switch element 40, and capacitive circuit 30 comprises an electric capacity respectively, namely three capacitive circuits are respectively electric capacity C1, C2 and C3, and three switch elements 40 are respectively K switch 1, K2, K3.When external communication input supply voltage acutely raises, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 is according to the voltage sampling signal received, in three outputs corresponding output three control signals respectively, these three control signals are corresponding respectively controls three K switch 1, one or more in K2 and K3 are in conducting state, realize Capacitance parallel connection to connect, thus realize capacitive step-down, share the output end voltage fluctuation that input terminal voltage big ups and downs cause, thus realize output end voltage and stablize controlled, improve the useful life of LED.
Correspondingly, when external communication input supply voltage acutely reduces, now the voltage signal of sampling is flowed to control unit 20 by voltage sampling unit 10, control unit 20 is according to the voltage sampling signal received, in three outputs corresponding output three control signals respectively, these three control signals are corresponding respectively controls three K switch 1, one or more in K2 and K3 are in off-state, capacitive reactance in whole LED drive circuit reduces to some extent, step-down value is just corresponding reduction also, thus increase the voltage exporting to LED string, therefore the relatively stable of output voltage is also achieved, no matter namely the utility model LED drive circuit can realize input terminal voltage (external communication input supply voltage) how big ups and downs, output end voltage (exporting to the voltage of LED string) is still stablized, can not big ups and downs or control fluctuation limit amplitude range in.
Certainly, capacitive circuit shown by above-described embodiment and the number of switch element just exemplarily carry out the operation principle introducing the utility model LED drive circuit in detail, be not restricted at this, such as, also can only include a switch element or two switch elements in Fig. 3 and Fig. 6, not repeat them here.
In addition, above-mentioned control unit 20 both can be a concrete circuit, also can be a control IC or control module, this control unit can be analyzed input voltage signal, control the break-make of capacitive circuit by being turned on or off of control switch unit, and voltage sampling unit 10 and power supply unit 70 all accessible site in this control unit.
In sum, implement the utility model LED drive circuit, the capacitive reactance of capacitances in series or parallel network in whole LED drive circuit is controlled thus the voltage changed on this network according to external communication input supply voltage, the change in voltage exporting to LED string when outside alternating current input power supplying change in voltage is reduced, thus reduce the impact of input voltage change on LED string, by the current limit by LED string in certain scope, namely by adopting the capacitive circuit of control unit to serial or parallel connection to control, output end voltage fluctuation voltage fluctuation by input caused is limited within the scope of safety limit, improve stability and the life-span of LED drive circuit.
By reference to the accompanying drawings embodiment of the present utility model is described above; but the utility model is not limited to above-mentioned embodiment; above-mentioned embodiment is only schematic; instead of it is restrictive; those of ordinary skill in the art is under enlightenment of the present utility model; do not departing under the ambit that the utility model aim and claim protect, also can make a lot of form, these all belong within protection of the present utility model.
Claims (10)
1. a LED drive circuit, comprise voltage sampling unit (10), rectification circuit (50) and LED string (60), it is characterized in that, also comprise control unit (20), at least two capacitive circuits be connected in series (30), at least one switch element (40), switch element described in each (40) is connected in parallel capacitive circuit described in (30) respectively, external communication input power is connected to the ac input end of described rectification circuit (50) through at least two capacitive circuits be connected in series (30), the DC output end of described rectification circuit (50) connects described LED string (60),
Wherein: described control unit (20) is connected with described voltage sampling unit (10) and switch element (40) described in each respectively, and the external communication input supply voltage signal for collecting according to described voltage sampling unit (10) exports at least one control signal distinguishes and corresponding control switch element (40) described in each and be turned on or off.
2. LED drive circuit according to claim 1, is characterized in that, described LED drive circuit also comprises the power supply unit (70) of powering to described control unit (20) for external communication input power being converted to DC power supply.
3. LED drive circuit according to claim 1, is characterized in that, described LED drive circuit also comprises the filter unit (80) between the DC output end being connected to described rectification circuit (50).
4. LED drive circuit according to claim 3, is characterized in that, described filter unit (80) comprises a filter capacitor.
5. LED drive circuit according to claim 1, is characterized in that, capacitive circuit described in each (30) comprises an electric capacity.
6. LED drive circuit according to claim 1, is characterized in that, the electric capacity that capacitive circuit described in each (30) comprises a resistance and is connected with described resistor coupled in parallel.
7. LED drive circuit according to claim 1, is characterized in that, described rectification circuit (50) is rectifier bridge.
8. a LED drive circuit, comprise voltage sampling unit (10), rectification circuit (50) and LED string (60), it is characterized in that, also comprise control unit (20), at least two capacitive circuits be connected in parallel (30), at least one switch element (40), switch element described in each (40) is connected in series capacitive circuit described in (30) respectively, external communication input power is connected to the ac input end of described rectification circuit (50) through at least two capacitive circuits be connected in parallel (30), the DC output end of described rectification circuit (50) connects described LED string (60),
Wherein: described control unit (20) is connected with described voltage sampling unit (10) and switch element (40) described in each respectively, and the external communication input supply voltage signal for collecting according to described voltage sampling unit (10) exports at least one control signal distinguishes and corresponding control switch element (40) described in each and be turned on or off.
9. LED drive circuit according to claim 8, is characterized in that, described LED drive circuit also comprises the power supply unit (70) of powering to described control unit (20) for external communication input power being converted to DC power supply.
10. LED drive circuit according to claim 8, is characterized in that, described LED drive circuit also comprises the filter unit (80) between the DC output end being connected to described rectification circuit (50).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420806342.8U CN204259250U (en) | 2014-12-17 | 2014-12-17 | Led drive circuit |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420806342.8U CN204259250U (en) | 2014-12-17 | 2014-12-17 | Led drive circuit |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN204259250U true CN204259250U (en) | 2015-04-08 |
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201420806342.8U Expired - Fee Related CN204259250U (en) | 2014-12-17 | 2014-12-17 | Led drive circuit |
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| Country | Link |
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| CN (1) | CN204259250U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104582146A (en) * | 2014-12-17 | 2015-04-29 | 深圳市众明半导体照明有限公司 | Led drive circuit |
-
2014
- 2014-12-17 CN CN201420806342.8U patent/CN204259250U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104582146A (en) * | 2014-12-17 | 2015-04-29 | 深圳市众明半导体照明有限公司 | Led drive circuit |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150408 Termination date: 20151217 |