CN206948659U - A kind of LED drive circuit of fixed turn-off time - Google Patents
A kind of LED drive circuit of fixed turn-off time Download PDFInfo
- Publication number
- CN206948659U CN206948659U CN201720486544.2U CN201720486544U CN206948659U CN 206948659 U CN206948659 U CN 206948659U CN 201720486544 U CN201720486544 U CN 201720486544U CN 206948659 U CN206948659 U CN 206948659U
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- Prior art keywords
- comparator
- gate
- drive circuit
- led drive
- circuit
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
- Y02B20/30—Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]
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- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
The utility model discloses a kind of LED drive circuit of fixed turn-off time, including PWM circuit, the PWM circuit is provided with comparator, and the comparator exports upper limit trigger signal, the PWM circuit is additionally provided with monostable flipflop, and the monostable flipflop is provided with：Receive the input of the upper limit trigger signal, temporary stable period closes the power switch pipe and steady-state period opens the output end of power switch pipe.The LED drive circuit of the structure possesses stable state and temporary stable state this feature using monostable flipflop, eliminate the comparator of limitation lower limit, so that the circuit at least only needs a comparator just can complete the driving work of LED, the electric energy loss of drive circuit itself is reduced, improves the power-efficient of LED drive circuit.
Description
Technical field
Field of LED illumination is the utility model is related to, more particularly to a kind of LED drive circuit of fixed turn-off time.
Background technology
Existing decompression transducer is the converter commonly used in LED drive power, and its operation principle is：Utilize a work(
Rate switching tube under the control of pulse-width signal, is alternatively switched on input voltage, disconnects energy storage electricity as switching device
Sense, because energy storage inductor electric current can not be undergone mutation in moment, therefore energy storage inductor can produce inverse electromotive force to maintain to pass through
The electric current of energy storage inductor is constant.
The control of unlatching and the disconnection of switching device is completed by PWM circuit, the work side of existing PWM circuit
Formula is that, when electric current is more than the higher limit of setting, switching device disconnects, when electric current is less than the lower limit of setting, switching device
Open.The unlatching and disconnection of switching device are realized using the method for setting bound.The PWM circuit of this framework at least needs
Want two comparators：The trigger signal of one comparator output upper limit, the trigger signal of another comparator bottoming；And compare
It is bigger compared with the general power consumption of device, therefore the power-efficient for the LED drive circuit for carrying the PWM circuit of this framework and forming
It is not high.
Utility model content
The purpose of this utility model is to provide a kind of high LED drive circuit of power-efficient.
The solution that the utility model solves its technical problem is：A kind of LED drive circuit of fixed turn-off time, bag
PWM circuit is included, the PWM circuit is provided with comparator, and the comparator exports upper limit trigger signal, and the PWM is adjusted
Circuit processed is additionally provided with monostable flipflop, and the monostable flipflop is provided with：Receive the upper limit trigger signal input, temporarily
Close the power switch pipe stable period and steady-state period opens the output end of power switch pipe.
Further, the monostable flipflop includes：First nor gate, the second nor gate, the first electric capacity and first resistor,
The output end of first nor gate is connected by input of first electric capacity with the second nor gate, the input of the second nor gate
End pull-up first resistor, the output end of the second nor gate respectively with the second input of the first nor gate and the control of power switch pipe
End connection processed, the first input end of first nor gate are connected with the output end of the comparator.
Further, in addition to sampling voltage is fed back to the comparator by voltage feedback circuit, the voltage feedback circuit,
The comparator exports upper limit trigger signal according to the sampling voltage, and the voltage feedback circuit includes second resistance and second
Electric capacity, the second resistance and the second electric capacity it is parallel with one another after connected with the power switch pipe.
Further, in addition to Schottky diode, the Schottky diode are opened as fly-wheel diode and the power
Close pipe series connection.
The beneficial effects of the utility model are：The LED drive circuit of the structure using monostable flipflop possess stable state and
This feature of temporary stable state, eliminate the comparator of limitation lower limit so that the circuit at least only needs a comparator just can complete
The driving work of LED, reduces the electric energy loss of drive circuit itself, improves the power-efficient of LED drive circuit.
Brief description of the drawings
, below will be to needed for embodiment description in order to illustrate more clearly of the technical scheme in the embodiment of the utility model
The accompanying drawing to be used is briefly described.Obviously, described accompanying drawing is part of the embodiment of the present utility model, rather than entirely
Portion's embodiment, those skilled in the art on the premise of not paying creative work, can also obtain it according to these accompanying drawings
His design and accompanying drawing.
Fig. 1 is the connection diagram of the LED drive circuit of embodiment 1；
Fig. 2 is the connection diagram of the LED drive circuit after monostable flipflop optimization in embodiment 1.
Embodiment
Design, concrete structure and caused technique effect of the present utility model are carried out below with reference to embodiment and accompanying drawing
Clearly and completely describe, to be completely understood by the purpose of this utility model, feature and effect.Obviously, described embodiment
It is part of the embodiment of the present utility model, rather than whole embodiments, based on embodiment of the present utility model, the skill of this area
The other embodiment that art personnel are obtained on the premise of not paying creative work, belong to the model of the utility model protection
Enclose.In addition, all connection/annexations being previously mentioned in text, not singly refer to component and directly connect, and refer to can be according to specific reality
Situation is applied, by adding or reducing couple auxiliary, to form more excellent draw bail.Each technology in the invention is special
Sign, can be with combination of interactions on the premise of not conflicting conflict.
Embodiment 1, with reference to figure 1, a kind of LED drive circuit of fixed turn-off time, the circuit passes through direct current pressure side DC
Powered to LED, PWM adjustment circuits are by controlling power switch pipe so that input voltage is alternatively switched on, disconnects energy storage electricity
Sense.So as to realize the driving of LED, wherein PWM circuit a1 is provided with comparator and monostable flipflop a2, the comparator
Anti-phase termination reference voltage value 250mV, positive terminal connection voltage feedback circuit a3, voltage feedback circuit a3 is by the second electric capacity C2
Form, connected after the second electric capacity C2 and second resistance R2 parallel connections with power switch pipe, the comparator is just with second resistance R2
Phase end receives sampling voltage from i ends, because the second electric capacity C2 is in parallel with second resistance R2, so that the voltage from i ends will not
Undergo mutation, advantageously receive sampling voltage from i ends with comparator and protect comparator, lift the life-span of comparator.
When the sampling voltage at i ends is more than reference voltage, comparator is high level from low transition, produces a upper limit
Trigger signal, the power switch pipe that the upper limit trigger signal refers to need the cue closed or opened, are originally embodied as work(
Rate switching tube needs the cue closed, and signal type is rising edge, and monostable flipflop a2 receives this upper limit and touched
Temporary stable state is converted into from stable state after signalling, the monostable flipflop a2 of the present embodiment stable state is low level, and temporary stable state is height
Level, power switch pipe cut-off, the sampling voltage at i ends decline, and the present embodiment is using P channel MOS transistor as power switch
Pipe.After temporary stable state terminates, monostable flipflop a2 replys stable state, power switch pipe conducting, the sampling voltage at i ends rise until
Sampling voltage is more than reference voltage again.Circulate successively like this so as to drive LED.
The LED drive circuit of the fixation turn-off time at least only needs a comparator just can complete the driving work of LED
Make, reduce the electric energy loss of drive circuit itself, improve the power-efficient of LED drive circuit.
With reference to Fig. 2, as optimization, the monostable flipflop a2 includes：First nor gate D1, the second nor gate D2,
One electric capacity C1 and first resistor R1, the first nor gate D1 output end are by the first electric capacity C1 with the second nor gate D2's
Input connects, and the second nor gate D2 input pull-up first resistor R1, the second nor gate D2 output end is respectively with first
Nor gate D1 the second input connects with the control terminal of power switch pipe, the first input end of the first nor gate D1 and institute
State the output end connection of comparator.
Simply using nor gate composition monostable flipflop a2, and the first electric capacity C1 and first resistor R1 compositions are delayed
Resistor-Capacitor Unit, first resistor R1 pull-up VDD, monostable flipflop a2 temporary stable state can be adjusted by adjusting the first electric capacity C1
In the cycle, such monostable flipflop a2 is simple in construction, multiple functional.Be advantageous to large-scale integrated.
As optimization, in addition to Schottky diode, the Schottky diode is as fly-wheel diode and the power
Switching tube is connected.Schottky diode has the high advantage such as low with forward voltage drop of switching frequency, can in this, as fly-wheel diode
Preferably to discharge the induced current of energy storage inductor.
Better embodiment of the present utility model is illustrated above, but the invention be not limited to it is described
Embodiment, those skilled in the art can also make a variety of equivalent changes on the premise of without prejudice to the utility model spirit
Type or replacement, these equivalent modifications or replacement are all contained in the application claim limited range.
Claims (4)
1. a kind of LED drive circuit of fixed turn-off time, including PWM circuit, the PWM circuit, which is provided with, to be compared
Device, the comparator export upper limit trigger signal, it is characterised in that：The PWM circuit is additionally provided with monostable flipflop, institute
Monostable flipflop is stated to be provided with：Receive the input of the upper limit trigger signal, temporary steady-state period closes power switch pipe and steady
The state cycle opens the output end of the power switch pipe.
A kind of 2. LED drive circuit of fixed turn-off time according to claim 1, it is characterised in that the monostable
Trigger includes：First nor gate, the second nor gate, the first electric capacity and first resistor, the output end of first nor gate are led to
Cross input of first electric capacity with the second nor gate to be connected, the input pull-up first resistor of the second nor gate, second or non-
The output end of door is connected with the second input of the first nor gate and the control terminal of power switch pipe respectively, first nor gate
First input end be connected with the output end of the comparator.
A kind of 3. LED drive circuit of fixed turn-off time according to claim 1, it is characterised in that：Also include voltage
Sampling voltage is fed back to the comparator by feedback circuit, the voltage feedback circuit, and the comparator is according to the sampling electricity
Pressure output upper limit trigger signal, the voltage feedback circuit include second resistance and the second electric capacity, the second resistance and second
Connected after electric capacity is parallel with one another with the power switch pipe.
A kind of 4. LED drive circuit of fixed turn-off time according to claim 1, it is characterised in that：Also include Xiao Te
Based diode, the Schottky diode are connected as fly-wheel diode with the power switch pipe.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720486544.2U CN206948659U (en) | 2017-05-03 | 2017-05-03 | A kind of LED drive circuit of fixed turn-off time |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201720486544.2U CN206948659U (en) | 2017-05-03 | 2017-05-03 | A kind of LED drive circuit of fixed turn-off time |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN206948659U true CN206948659U (en) | 2018-01-30 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201720486544.2U Expired - Fee Related CN206948659U (en) | 2017-05-03 | 2017-05-03 | A kind of LED drive circuit of fixed turn-off time |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN206948659U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110729991A (en) * | 2019-11-13 | 2020-01-24 | 珠海格力电器股份有限公司 | Time delay circuit and servo driver |
-
2017
- 2017-05-03 CN CN201720486544.2U patent/CN206948659U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110729991A (en) * | 2019-11-13 | 2020-01-24 | 珠海格力电器股份有限公司 | Time delay circuit and servo driver |
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| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20180130 Termination date: 20210503 |
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| CF01 | Termination of patent right due to non-payment of annual fee |