CN107635324A - A kind of LED drive circuit with controllable silicon dimmer - Google Patents
A kind of LED drive circuit with controllable silicon dimmer Download PDFInfo
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Abstract
The invention discloses a kind of LED drive circuit with controllable silicon dimmer, including：Current drain module, LED current drive module, the present invention is before controlled silicon conducting, open leadage circuit, leakage current before avoiding the occurrence of due to controlled silicon conducting causes to open the problem of angle is inconsistent, after controlled silicon conducting, leadage circuit is closed, loss caused by reducing leakage current in the case of gauze voltage is less than LED load, waits gauze voltage to reopen leadage circuit again when being reduced to certain value；Meanwhile when gauze voltage is less than a default value, control the electric current of LED load constant, when gauze voltage is more than a default value, the conversion trend of electric current of LED load is controlled with the variation tendency of gauze voltage on the contrary, so as to further lift the efficiency of whole system.
Description
Technical field
The present invention relates to field of LED drive technology, more particularly to a kind of LED drive circuit with controllable silicon dimmer.
Background technology
Thyristor regulating just one of currently used light-dimming method, by the chopped phase for adjusting light modulator, thus it is possible to vary
Controlled silicon conducting phase angle size, so as to realize light modulation.Controllable silicon dimmer is generally used in combination with linear constant current control method, with
Realize LED dimmer application.Common linear controllable silicon light modulation constant current scheme at present, as shown in figure 1, including rectification module, can
Control silicon is released module, LED current control module and LED load.This application scheme is relative to Switching Power Supply scheme advantage
System architecture is simple, few using component, and shortcoming is system effectiveness than relatively low, and after controlled silicon conducting, gauze voltage is less than
When LED is pressed, leadage circuit is opened, and leakage current causes extra loss；Meanwhile during LED conducting, its electric current is：Iled
=Vref2/Rext2, with the rise of gauze voltage, metal-oxide-semiconductor Q2 loss increase.
To sum up, existing linear constant current drive mode is less efficient.
The content of the invention
The technical problem to be solved in the present invention is, for prior art it is above-mentioned less efficient the defects of, there is provided it is a kind of
LED drive circuit with controllable silicon dimmer.
The technical solution adopted for the present invention to solve the technical problems is：Construct a kind of LED with controllable silicon dimmer
Drive circuit, including：
Current drain module, for opening drainage function before controlled silicon conducting to export leakage current, in controllable silicon
Drainage function is closed after conducting to cut off leakage current, and opens when gauze voltage is decreased to certain value after controlled silicon conducting and lets out
Playing function；
LED current drive module, for controlling the electric current for flowing through LED load constant when gauze voltage is less than default value,
When gauze voltage is higher than the default value, the variation tendency of the electric current of LED load and the variation tendency of gauze voltage are flowed through in control
Conversely.
Of the present invention with the LED drive circuit of controllable silicon dimmer, the current drain module includes：
Release control unit, for obtaining the detection voltage VT1 related to gauze voltage, voltage VT1 is detected according to described
Climbing speed judge whether controllable silicon turns on, and in controlled silicon conducting previous existence into open signal of releasing, after controlled silicon conducting
Shutdown signal of releasing is exported, and detects output when voltage VT1 is decreased within predeterminated voltage VR1 after controlled silicon conducting and releases out
Open signal；
Vent unit, drainage function is closed for shutdown signal of being released according to, and according to the unlatching letter of releasing
Number open drainage function；
Of the present invention with the LED drive circuit of controllable silicon dimmer, the LED current drive module bag
Include：
Voltage detection unit, for obtaining and gauze voltage coherent detection voltage VT2；
LED current switch element, for being driven to the LED load；
LED current control unit, for when detection voltage VT2 is less than predeterminated voltage VR5, LED load to be flowed through in control
Electric current is constant, and when detection voltage VT2 is higher than predeterminated voltage VR5, variation tendency and the detection of the electric current of LED load are flowed through in control
Voltage VT2 variation tendency is opposite.
Of the present invention with the LED drive circuit of controllable silicon dimmer, the control unit of releasing is described
When detection voltage VT1 is equal to predeterminated voltage VR2, judge whether the detection voltage VT1 rises to default electricity in preset time
VR3 is pressed, if so, then judging controlled silicon conducting.
It is the input of vent unit, controlled of the present invention with the LED drive circuit of controllable silicon dimmer
End, output end connect the positive output end of rectification module, the output end for control unit of releasing, LED electricity in LED drive circuit respectively
Flow the connection end of releasing of switch element；
The first switch for being used to open and close drainage function in the input connection vent unit for control unit of releasing
The input of pipe；Or the LED drive circuit also includes voltage detection module, the input of the control unit of releasing connects
Connect the test side of the voltage detection module, the positive output end of the input connection rectification module of the voltage detection module or
The input of the first switch pipe, the negative output terminal of the output end connection rectification module of the voltage detection module；
The input of the LED current switch element, controlled end, output end connect the output end of LED load, LED respectively
The output end of current control unit, the negative output terminal of rectification module, the input of the LED load connect the just defeated of rectification module
Go out end, the input of LED current control unit connects the test side of the voltage detection unit；
In the positive output end or LED current switch element of the input connection rectification module of the voltage detection unit
For the input of the second switch pipe of control electric current circulation, the output end connection rectification module of the voltage detection unit is born
Output end.
Of the present invention with the LED drive circuit of controllable silicon dimmer, the voltage detection module includes the
One resistance, second resistance, the first end of the first resistor are the input of the voltage detection module, the second of first resistor
End and the first end of second resistance connect the test side to form the voltage detection module altogether, and the second end of second resistance is as voltage
The output end of detection module.
Of the present invention with the LED drive circuit of controllable silicon dimmer, the control unit of releasing includes the
One comparator, the second comparator, the 3rd comparator, logic unit, rest-set flip-flop, switching device；
Wherein, first comparator, the second comparator, the negative input end of the 3rd comparator connect to form the control list of releasing altogether
The input of member, the input of the switching device are the output end of the control unit of releasing；First comparator, second are compared
Device, the positive input terminal of the 3rd comparator receive the predeterminated voltage VR1, predeterminated voltage VR2, predeterminated voltage VR3 of setting respectively, and second
Comparator, the output end of the 3rd comparator connect the input of logic unit, the output end connection rest-set flip-flop of logic unit
Input S, the input R of the output end connection rest-set flip-flop of first comparator, the output end Q connecting valve devices of rest-set flip-flop
Controlled end, the switching device output termination low level；
Preset when the logic unit judges that the detection voltage VT1 is equal to according to the output signal of second comparator
During voltage VR2, if in preset time, if the logic unit judges the inspection according to the output signal of the 3rd comparator
Survey voltage VT1 and be equal to predeterminated voltage VR3, then the logic unit judges controlled silicon conducting and export trigger signal to touch to the RS
Hair device shutdown signal so that rest-set flip-flop output is released, so that vent unit closes drainage function.
Of the present invention with the LED drive circuit of controllable silicon dimmer, the vent unit includes the 3rd electricity
Resistance, the 4th resistance, first switch pipe, the 4th comparator；
Wherein, the first end of 3rd resistor is the input of the vent unit, and the first end of the 4th resistance is let out to be described
The output end of unit is put, the controlled end of first switch pipe is the controlled end of the vent unit；The second end connection of 3rd resistor
The input of first switch pipe, the output end of first switch pipe connect the second end of the 4th resistance, the positive input of the 4th comparator
End receives the predeterminated voltage VR4 of setting, the output end of the negative input end connection first switch pipe of the 4th comparator, the 4th comparator
Output end connection first switch pipe controlled end.
Of the present invention with the LED drive circuit of controllable silicon dimmer, LED current switch element includes second
Switching tube, the 7th resistance, the 5th comparator；
Wherein, the input of second switch pipe is the input of LED current switch element, and the first end of the 7th resistance is
The connection end of releasing of LED current switch element, the second end of the 7th resistance are the output end of LED current switch element, and the 5th compares
Positive input terminal compared with device is the controlled end of LED current switch element, and the output end of second switch pipe connects the first of the 7th resistance
End and the negative input end of the 5th comparator, the controlled end of second switch pipe connect the output end of the 5th comparator.
Of the present invention with the LED drive circuit of controllable silicon dimmer, voltage detection unit includes the 8th electricity
Resistance, the 9th resistance, the first end of the 8th resistance are the input of voltage detection unit, the second end of the 8th resistance and the 9th resistance
First end connect the test side to form voltage detection unit altogether, the second end of the 9th resistance is the output end of voltage detection unit.
Implement the LED drive circuit with controllable silicon dimmer of the present invention, have the advantages that：The present invention is can
Before controlling silicon conducting, leadage circuit is opened, the leakage current before avoiding the occurrence of due to controlled silicon conducting causes to open angle inconsistent
The problem of, after controlled silicon conducting, leadage circuit is closed, reduces vent discharge in the case of gauze voltage is less than LED load
Loss, waits gauze voltage to reopen leadage circuit again when being reduced to certain value caused by stream；Meanwhile it is less than one in gauze voltage
During default value, control the electric current of LED load constant, when gauze voltage is more than a default value, control the change of the electric current of LED load
Trend is changed with the variation tendency of gauze voltage on the contrary, so as to further lift the efficiency of whole system.
Brief description of the drawings
In order to illustrate more clearly about the embodiment of the present invention or technical scheme of the prior art, below will be to embodiment or existing
There is the required accompanying drawing used in technology description to be briefly described, it should be apparent that, drawings in the following description are only this
The embodiment of invention, for those of ordinary skill in the art, on the premise of not paying creative work, can also basis
The accompanying drawing of offer obtains other accompanying drawings：
Fig. 1 is the structural representation of LED drive circuit in the prior art；
Fig. 2 is the structured flowchart for the LED drive circuit that the embodiment of the present invention one provides；
Fig. 3 is the circuit diagram for the LED drive circuit that the embodiment of the present invention one provides；
Fig. 4 is the structured flowchart for the LED drive circuit that the embodiment of the present invention two provides；
Fig. 5 is the circuit diagram for the LED drive circuit that the embodiment of the present invention two provides；
Fig. 6 is the structured flowchart for the LED drive circuit that the embodiment of the present invention three provides；
Fig. 7 is the circuit diagram for the LED drive circuit that the embodiment of the present invention three provides；
Fig. 8 is the output voltage of the rectification module in LED drive circuit provided by the invention and the oscillogram of leakage current；
Fig. 9 is the oscillogram of the output voltage of the rectification module of LED drive circuit and leakage current in the prior art.
Embodiment
For the ease of understanding the present invention, the present invention is described more fully below with reference to relevant drawings.In accompanying drawing
Give the exemplary embodiments of the present invention.But the present invention can realize in many different forms, however it is not limited to this paper institutes
The embodiment of description.On the contrary, the purpose for providing these embodiments is made to the disclosure more thorough and comprehensive.
It should be noted that word " connected " or " connection ", not only include two entities being joined directly together, also include logical
Cross and be indirectly connected with other entities beneficial to improvement.Word " equal ", " identical " " simultaneously " or other similar use
Language, be not limited to it is absolute equal or identical in mathematical term, implement this patent described in right when, can be on engineering significance
It is close or in acceptable error range.
Unless otherwise defined, all of technologies and scientific terms used here by the article is with belonging to technical field of the invention
The implication that technical staff is generally understood that is identical.Term used in the description of the invention herein is intended merely to description tool
The purpose of the embodiment of body, it is not intended that in the limitation present invention.
The term comprising ordinal number such as " first " that is used in this specification, " second " can be used for illustrating various inscapes,
But these inscapes are not limited by these terms.It is only that using the purpose of these terms and distinguishes an inscape
In other inscapes.For example, on the premise of the interest field of the present invention is not departed from, the first inscape can be named as the
Two inscapes, similarly, the second inscape can also be named as the first inscape.
The total thinking of the present invention is：A kind of LED drive circuit with controllable silicon dimmer is constructed, including：Current drain
Module, LED current drive module.The present invention is same to current drain module, LED current drive module in order to improve system effectiveness
When be improved, in terms of two realize improve system effectiveness.
On the one hand, current drain module opens drainage function to export leakage current before controlled silicon conducting, can keep away
Exempt to occur because the leakage current before controlled silicon conducting causes to open the problem of angle is inconsistent, close and release after controlled silicon conducting
Function is to cut off leakage current, it is possible to reduce loss caused by leakage current in the case of gauze voltage is less than LED load,
And gauze voltage is decreased to open drainage function during certain value after controlled silicon conducting；
On the other hand, LED current drive module controls the electric current for flowing through LED load permanent when gauze voltage is less than default value
It is fixed, the variation tendency for the electric current for flowing through LED load is controlled when gauze voltage is higher than the default value with the change of gauze voltage
Trend is opposite, so as to further lift the efficiency of whole system.
In order to be better understood from above-mentioned technical proposal, below in conjunction with Figure of description and specific embodiment to upper
State technical scheme to be described in detail, it should be understood that the specific features in the embodiment of the present invention and embodiment are to the application
The detailed description of technical scheme, rather than the restriction to technical scheme, in the case where not conflicting, the present invention is implemented
Technical characteristic in example and embodiment can be mutually combined.
Embodiment one
With reference to figure 2, LED1-LEDn represents LED load in figure, and electric capacity C0 is in parallel with LED load.LED in embodiment one
Drive circuit includes：Rectification module 100, current drain module 200, LED current drive module 300, rectification module 100, are used for
Rectification is carried out to the AC power of access, this is prior art, and here is omitted.The following detailed description of current drain module
200th, LED current drive module 300.
The current drain module 200 includes release control unit 210 and vent unit 220, and the LED current drives mould
Block 300 includes voltage detection unit 310, LED current control unit 320, LED current switch element 330, wherein：
Control unit of releasing 210, for obtaining the detection voltage VT1 related to gauze voltage, according to the detection voltage
VT1 climbing speed judges whether controllable silicon turns on, and in controlled silicon conducting previous existence into open signal of releasing, in controlled silicon conducting
Shutdown signal of releasing is exported afterwards, and is detected output when voltage VT1 is decreased within predeterminated voltage VR1 after controlled silicon conducting and released
Open signal.Wherein, it is described to judge whether controllable silicon turns on specially：It is equal to predeterminated voltage VR2 in the detection voltage VT1
When, judge whether the detection voltage VT1 rises to predeterminated voltage VR3 in preset time, if so, then judging that controllable silicon is led
It is logical.Preferably, it can also be when the detection voltage VT1 is equal to predeterminated voltage VR2, and be delayed after certain time, judge institute
State whether detection voltage VT1 rises to predeterminated voltage VR3 in preset time, if so, then judging controlled silicon conducting.
Vent unit 220, drainage function is closed for shutdown signal of being released according to, and according to the unlatching of releasing
Signal opens drainage function；
Voltage detection unit 310, for obtaining and gauze voltage coherent detection voltage VT2；
LED current switch element 330, for being driven to the LED load；
LED current control unit 320, for when detection voltage VT2 is less than predeterminated voltage VR5, LED load to be flowed through in control
Electric current it is constant, detect voltage VT2 be higher than predeterminated voltage VR5 when, control flow through LED load electric current variation tendency and inspection
The variation tendency for surveying voltage VT2 is opposite.
In annexation, two inputs of the rectification module 100 are connected with AC power Vac, vent unit 220 it is defeated
Enter end, controlled end, output end and connect the positive output end of rectification module 100, the output end of control unit of releasing 210, LED electricity respectively
The connection end of releasing of switch element 330 is flowed, the input of control unit of releasing 210 connects to be used to open in vent unit 220
With the first switch pipe Q1 (with reference to figure 3) of closing drainage function input；The input of the LED current switch element 330,
Controlled end, output end connect the output end of LED load, the output end of LED current control unit 320, rectification module 100 respectively
Negative output terminal, the LED load input connection rectification module 100 positive output end, LED current control unit 320 it is defeated
Enter the test side that end connects the voltage detection unit 310, the input connection rectification module of the voltage detection unit 310
100 positive output end, the negative output terminal of the output end connection rectification module 100 of the voltage detection unit 310.
With reference to figure 3, specifically, the control unit 210 of releasing includes first comparator Comp1, the second comparator
Comp2, the 3rd comparator Comp3, logic unit 211, rest-set flip-flop, switching device.Wherein, first comparator Comp1, second
Comparator Comp2, the 3rd comparator Comp3 negative input end connect the input to form the control unit 210 of releasing altogether, described
The input of switching device is the output end of the control unit 210 of releasing；First comparator Comp1, the second comparator
Comp2, the 3rd comparator Comp3 positive input terminal receive the predeterminated voltage VR1, predeterminated voltage VR2, predeterminated voltage of setting respectively
VR3, wherein, predeterminated voltage VR1, predeterminated voltage VR2, predeterminated voltage VR3 magnitude of voltage raise successively, the second comparator Comp2,
The input of 3rd comparator Comp3 output end connection logic unit 211, the output end connection RS triggerings of logic unit 211
The input R of the input S of device, first comparator Comp1 output end connection rest-set flip-flop, the output end Q of rest-set flip-flop connect
Connect the controlled end of switching device, the output termination low level of the switching device；
When the logic unit 211 judges the detection voltage VT1 according to the output signal of the second comparator Comp2
During equal to predeterminated voltage VR2, if in preset time, if the logic unit 211 is according to the defeated of the 3rd comparator Comp3
Go out signal and judge that the detection voltage VT1 is equal to predeterminated voltage VR3, then the logic unit 211 judges controlled silicon conducting and defeated
Go out trigger signal to the rest-set flip-flop so that rest-set flip-flop exports shutdown signal of releasing, so that vent unit 220 is closed
Drainage function.
With continued reference to Fig. 3, specifically, the vent unit 220 includes 3rd resistor R3, the 4th resistance R4, first switch
Pipe Q1, the 4th comparator Comp4；
Wherein, 3rd resistor R3 first end is the input of the vent unit 220, and the 4th resistance R4 first end is
The output end of the vent unit 220, first switch pipe Q1 controlled end are the controlled end of the vent unit 220；3rd electricity
R3 the second end connection first switch pipe Q1 input is hindered, first switch pipe Q1 output end connects the second of the 4th resistance R4
End, the 4th comparator Comp4 positive input terminal receive the predeterminated voltage VR4 of setting, and the 4th comparator Comp4 negative input end connects
Connect first switch pipe Q1 output end, the 4th comparator Comp4 output end connection first switch pipe Q1 controlled end.
With continued reference to Fig. 3, specifically, voltage detection unit 310 includes the 8th resistance R8, the 9th resistance R9, the 8th resistance
R8 first end is the input of voltage detection unit 310, and the 8th resistance R8 the second end and the 9th resistance R9 first end are total to
The test side to form voltage detection unit 310 is connect, the 9th resistance R9 the second end is the output end of voltage detection unit 310.
With continued reference to Fig. 3, specifically, LED current switch element 330 includes second switch pipe Q2, the 7th resistance R7, the 5th
Comparator Comp5；Wherein, second switch pipe Q2 input be LED current switch element 330 input, the 7th resistance R7
First end be LED current switch element 330 connection end of releasing, the 7th resistance R7 the second end is LED current switch element
330 output end, the 5th comparator Comp5 positive input terminal are the controlled end of LED current switch element 330, second switch pipe
Q2 output end connects the 7th resistance R7 first end and the 5th comparator Comp5 negative input end, second switch pipe Q2's
Controlled end connects the 5th comparator Comp5 output end.
Specifically, LED current control unit 320 exports predeterminated voltage when detecting voltage VT2 and being less than predeterminated voltage VR5
VR5, the output detection voltage VT2 and predeterminated voltage VR5 differential pressure when detecting voltage VT2 and being higher than predeterminated voltage VR5.
In the present embodiment, N-type metal-oxide-semiconductor that the switching tube in the present embodiment uses, it is to be understood that the class of switching tube
Type and model are not limited, and can also be triode etc., and these are all the simple deformations for belonging to the present embodiment.
On the one hand the present embodiment can determine whether controllable silicon turns on according to detection voltage VT1 climbing speed, controllable
Before silicon does not turn on, leadage circuit is normally opened, and maximum current of releasing is：IBLD=VR4/ (R4+R7)；After controlled silicon conducting,
Closing is released, after detection voltage VT1 is decreased to predeterminated voltage VR1, that is, gauze voltage VIN is reduced to certain value
Afterwards, release and reopen, so as to which after LED closings, leakage current is not opened, the damage that the leakage current of reduction is brought at once
Consumption, so as to the efficiency of lifting.On the other hand, the control on LED load electric current, the output electricity of resistance R3, R4 detection rectifier bridge
Press VIN to obtain detecting voltage VT2, voltage VT2 will be detected and after internal predeterminated voltage VR5 progress computings, control flows through LED and born
The electric current of load, when VT2 is less than VR5, when being less than a default value equivalent to gauze voltage VIN, the electric current for flowing through Q2 is permanent for one
Determine electric current, when VT2 is more than VR5, when being higher than a default value equivalent to gauze voltage VIN, flow through Q2 electric current with gauze electricity
The increase of pressure and reduce, namely when Q2 drain terminal voltages are high, output current is reduced, to reduce Q2 loss, so as to raising efficiency.
Embodiment two
With reference to figure 4, the difference of embodiment two and embodiment one is, embodiment two also includes voltage detection module
400, the input of control unit of releasing 210 is no longer directly to first switch pipe Q1 input, but described in connecting
The test side of voltage detection module 400, the positive output end of the input connection rectification module 100 of the voltage detection module 400,
The negative output terminal of the output end connection rectification module 100 of the voltage detection module 400.
With reference to figure 5, the voltage detection module 400 includes first resistor R1, second resistance R2, the first resistor R1's
First end is the input of the voltage detection module 400, and first resistor R1 the second end and second resistance R2 first end are total to
Connect the test side to form the voltage detection module 400, the output of second resistance R2 the second end as voltage detection module 400
End.The structural reference embodiment one of other modules or unit in embodiment two, here is omitted.
Embodiment three
With reference to figure 6-7, the difference of embodiment three and embodiment two is, the connection of the input of voltage detection module 400
Node is no longer the positive output end of rectification module 100, but is connected to first switch pipe Q1 input.Similarly, voltage detecting
The connecting node of the input of unit 310 is no longer the positive output end of rectification module 100, but is connected to second switch pipe Q2's
Input.
It should be noted that voltage detection module 400, the connected mode of voltage detection unit 310 be not limited to it is as above several
It is no longer exhaustive herein shown in individual embodiment, as long as voltage detection module 400, voltage detection unit 310 can detect and gauze electricity
Press related voltage.In addition, resistance R3 is inessential resistance, it can also remove, have no effect on what the present embodiment to be reached
Final purpose.
The detailed operation principle of the above example of the present invention is as follows：
In terms of releasing, judge whether controllable silicon turns on by detecting VT1 climbing speed, when controllable silicon does not turn on,
In the presence of certain leakage current, now, leakage current is set by R4 and R7, R1, R2 or R3, R4 set VT1 voltages, make VT1
Voltage is less than VR1, so, before controllable silicon does not turn on, switch S1 is off, and system normally exports leakage current, with
It is consistent to ensure that controllable silicon opens phase angle；After controlled silicon conducting, busbar voltage is raised rapidly, and comparator Comp2 outputs are become by height
Low, timing T1 (i.e. the preset time) for a period of time after Comp2 step-downs of logic unit 211, if within the T1 times, Comp3 is defeated
Go out step-down, then it is assumed that controlled silicon conducting by comparator Comp2,3 VR2, VR3 (if change to negative input end, controlled silicon conducting
Show as after Comp2 is uprised that Comp3 is uprised in preset time), output signal closes set-reset flip-floop controlling switch S1, so as to
Leadage circuit is closed, until VT1 voltages are less than VR3, set-reset flip-floop resets again, and switch S1 disconnects, and drainage function is normally-open.
The output voltage of leakage current and rectification module 100 is as shown in Figure 8.Contrasted from Fig. 8 and Fig. 9, the application is led in controllable silicon
Without leakage current when gauze voltage VIN is less than VLED after logical, so as to reduce the vent discharge after gauze voltage VIN is less than LED pressure
Loss caused by stream.
In terms of the current control of LED load, after controlled silicon conducting, closing of releasing, Q2 is in the conduction state to realize perseverance
Stream output.Circuit introduces gauze voltage compensating function so that Q2 output currents show as two head heights, middle low waveform (such as Fig. 8
It is shown) so that when gauze voltage is relatively low, high current is exported, when gauze voltage is high, low current is exported, so as to reduce metal-oxide-semiconductor Q2
Loss, improve efficiency.Specifically, LED current control unit 320 can be realized in many ways, for example subtracted with VR5
VT2 is used as error amplifier EA2 positive input terminal voltage, thus when gauze voltage is high, i.e., when VT2 is big, EA2 positive input terminals
Voltage is smaller, and so as to which output current is smaller, current waveform corresponding to Q2 drain terminals is as shown in Figure 8.
In summary, implement the LED drive circuit with controllable silicon dimmer of the present invention, have the advantages that：
The present invention opens leadage circuit, the leakage current before avoiding the occurrence of due to controlled silicon conducting causes open-minded before controlled silicon conducting
The problem of angle is inconsistent, after controlled silicon conducting, leadage circuit is closed, reduces the situation for being less than LED load in gauze voltage
Under leakage current caused by loss, wait gauze voltage to reopen leadage circuit again when being reduced to certain value；Meanwhile in gauze
When voltage is less than a default value, control the electric current of LED load constant, when gauze voltage is more than a default value, control LED load
The conversion trend of electric current and the variation tendency of gauze voltage on the contrary, so as to further lift the efficiency of whole system.
Embodiments of the invention are described above in conjunction with accompanying drawing, but the invention is not limited in above-mentioned specific
Embodiment, above-mentioned embodiment is only schematical, rather than restricted, one of ordinary skill in the art
Under the enlightenment of the present invention, in the case of present inventive concept and scope of the claimed protection is not departed from, it can also make a lot
Form, these are belonged within the protection of the present invention.
Claims (9)
1. a kind of LED drive circuit with controllable silicon dimmer, is connected with LED load, it is characterised in that including：
Current drain module (200), for opening drainage function before controlled silicon conducting to export leakage current, in controllable silicon
Drainage function is closed after conducting to cut off leakage current, and opens when gauze voltage is decreased to certain value after controlled silicon conducting and lets out
Playing function；
LED current drive module (300), for controlling the electric current for flowing through LED load constant when gauze voltage is less than default value,
When gauze voltage is higher than the default value, the variation tendency of the electric current of LED load and the variation tendency of gauze voltage are flowed through in control
Conversely.
2. the LED drive circuit according to claim 1 with controllable silicon dimmer, it is characterised in that
Wherein, the current drain module (200) includes：
Control unit of releasing (210), for obtaining the detection voltage VT1 related to gauze voltage, according to the detection voltage VT1
Climbing speed judge whether controllable silicon turns on, and in controlled silicon conducting previous existence into open signal of releasing, after controlled silicon conducting
Shutdown signal of releasing is exported, and detects output when voltage VT1 is decreased within predeterminated voltage VR1 after controlled silicon conducting and releases out
Open signal；
Vent unit (220), drainage function is closed for shutdown signal of being released according to, and according to the unlatching letter of releasing
Number open drainage function；
Wherein, the LED current drive module (300) includes：
Voltage detection unit (310), for obtaining and gauze voltage coherent detection voltage VT2；
LED current switch element (330), for being driven to the LED load；
LED current control unit (320), for when detection voltage VT2 is less than predeterminated voltage VR5, LED load to be flowed through in control
Electric current is constant, and when detection voltage VT2 is higher than predeterminated voltage VR5, variation tendency and the detection of the electric current of LED load are flowed through in control
Voltage VT2 variation tendency is opposite.
3. the LED drive circuit according to claim 2 with controllable silicon dimmer, it is characterised in that the control of releasing
Whether unit (210) processed judges the detection voltage VT1 when default when the detection voltage VT1 is equal to predeterminated voltage VR2
It is interior to rise to predeterminated voltage VR3, if so, then judging controlled silicon conducting.
4. the LED drive circuit according to claim 2 with controllable silicon dimmer, it is characterised in that vent unit
(220) input, controlled end, output end connect the positive output end of the rectification module (100) in LED drive circuit, let out respectively
Put output end, the connection end of releasing of LED current switch element (330) of control unit (210)；
Be used to open and close drainage function the in input connection vent unit (220) of control unit of releasing (210)
The input of one switching tube；Or the LED drive circuit also includes voltage detection module (400), the control unit of releasing
(210) input connects the test side of the voltage detection module (400), the input of the voltage detection module (400)
The positive output end of rectification module (100) or the input of the first switch pipe are connected, the voltage detection module (400)
The negative output terminal of output end connection rectification module (100)；
The input of the LED current switch element (330), controlled end, output end connect the output end of LED load, LED respectively
The output end of current control unit (320), the negative output terminal of rectification module (100), the input connection rectification of the LED load
The positive output end of module (100), the input of LED current control unit (320) connect the inspection of the voltage detection unit (310)
Survey end；
The positive output end or LED current switch of the input connection rectification module (100) of the voltage detection unit (310) are single
The input of the second switch pipe for being used for control electric current circulation in first (330), the output end of the voltage detection unit (310)
Connect the negative output terminal of rectification module (100).
5. the LED drive circuit according to claim 4 with controllable silicon dimmer, it is characterised in that the voltage inspection
Surveying module (400) includes first resistor, second resistance, and the first end of the first resistor is the voltage detection module (400)
Input, the second end of first resistor and the first end of second resistance connect the inspection to form the voltage detection module (400) altogether
Survey end, the output end of the second end of second resistance as voltage detection module (400).
6. the LED drive circuit according to claim 4 with controllable silicon dimmer, it is characterised in that the control of releasing
Unit (210) processed includes first comparator, the second comparator, the 3rd comparator, logic unit (211), rest-set flip-flop, derailing switch
Part；
Wherein, first comparator, the second comparator, the negative input end of the 3rd comparator connect to form the control unit of releasing altogether
(210) input, the input of the switching device are the output end of control unit (210) of releasing；First comparator,
Second comparator, the positive input terminal of the 3rd comparator receive the predeterminated voltage VR1, predeterminated voltage VR2, predeterminated voltage of setting respectively
VR3, the second comparator, the 3rd comparator output end connection logic unit (211) input, logic unit (211) it is defeated
Go out the input S of end connection rest-set flip-flop, the input R of the output end connection rest-set flip-flop of first comparator, rest-set flip-flop
The controlled end of output end Q connecting valve devices, the output termination low level of the switching device；
When the logic unit (211) judges that the detection voltage VT1 is equal in advance according to the output signal of second comparator
If during voltage VR2, if in preset time, if the logic unit (211) is sentenced according to the output signal of the 3rd comparator
The detection voltage VT1 that breaks is equal to predeterminated voltage VR3, then the logic unit (211) judges controlled silicon conducting and exports triggering
Signal shutdown signal to the rest-set flip-flop so that rest-set flip-flop output is released, releases so that vent unit (220) is closed
Function.
7. the LED drive circuit according to claim 4 with controllable silicon dimmer, it is characterised in that the list of releasing
First (220) include 3rd resistor, the 4th resistance, first switch pipe, the 4th comparator；
Wherein, the first end of 3rd resistor is the input of the vent unit (220), and the first end of the 4th resistance is let out to be described
The output end of unit (220) is put, the controlled end of first switch pipe is the controlled end of the vent unit (220)；3rd resistor
Second end connects the input of first switch pipe, and the output end of first switch pipe connects the second end of the 4th resistance, and the 4th compares
The positive input terminal of device receives the predeterminated voltage VR4 of setting, and the negative input end of the 4th comparator connects the output end of first switch pipe,
The controlled end of the output end connection first switch pipe of 4th comparator.
8. the LED drive circuit according to claim 4 with controllable silicon dimmer, it is characterised in that LED current switchs
Unit (330) includes second switch pipe, the 7th resistance, the 5th comparator；
Wherein, the input of second switch pipe is the input of LED current switch element (330), and the first end of the 7th resistance is
The connection end of releasing of LED current switch element (330), the second end of the 7th resistance are the output of LED current switch element (330)
End, the positive input terminal of the 5th comparator are the controlled end of LED current switch element (330), and the output end of second switch pipe connects
The first end of 7th resistance and the negative input end of the 5th comparator, the controlled end of second switch pipe connect the defeated of the 5th comparator
Go out end.
9. the LED drive circuit according to claim 4 with controllable silicon dimmer, it is characterised in that voltage detecting list
First (310) include the 8th resistance, the 9th resistance, and the first end of the 8th resistance is the input of voltage detection unit (310), and the 8th
Second end of resistance and the first end of the 9th resistance connect the test side to form voltage detection unit (310) altogether, and the of the 9th resistance
Two ends are the output end of voltage detection unit (310).
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| CN201711083787.2A CN107635324B (en) | 2017-11-07 | 2017-11-07 | LED drive circuit with silicon controlled rectifier dimmer |
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