CN203675371U - LED constant current drive circuit - Google Patents
LED constant current drive circuit Download PDFInfo
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- CN203675371U CN203675371U CN201320807054.XU CN201320807054U CN203675371U CN 203675371 U CN203675371 U CN 203675371U CN 201320807054 U CN201320807054 U CN 201320807054U CN 203675371 U CN203675371 U CN 203675371U
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Abstract
The utility model provides an LED constant current drive circuit. The circuit at least comprises: a voltage input module including a high-voltage AC power supply, an electronic transformer or an SCR TRIAC dimmer, and a rectification unit; an LED module connected to the voltage input module; a constant current control module connected to the LED module; a regulating resistor connected to the voltage input module; a power tube which is connected to the regulating resistor and is regulated to make a current flowing through the electronic transformer or the SCR TRIAC dimmer greater than a holding current thereof; a filter filtering a detection voltage; a comparator comparing a voltage output by the filter and a reference voltage; a control circuit determining if an output signal is a pulse signal or a low level according to comparison results; and a drive circuit for driving a gate voltage of the power tube. The provided circuit is compatible with the electronic transformer or the SCR TRIAC dimmer, and thus an LED light does not flash.
Description
Technical field
The utility model relates to LED Drive Control Technique field, particularly relates to a kind of LED constant-current drive circuit.
Background technology
LED is the semiconductor device of working under a kind of low-voltage direct condition.For illumination application, LED is because it is energy-conservation and life-span length is paid close attention to more and more widely, the high lumen degree of LED makes it be widely used in substituting dissimilar MR16 cup lamp, but ubiquity a problem in the high-frequency electronic transformer LED drive circuit of existing alternative MR16 cup lamp, that is exactly and electronic transformer cannot be compatible reliably.
Figure 1 shows that the existing Buck type LED drive circuit 1 of commonplace alternative MR16 cup lamp on the market, due to electronic transformer output is the high frequency ac signal of 12vrms, therefore need to convert alternating voltage to direct voltage to meet the condition of work of LED by rectifier bridge, simultaneously again because Buck circuit has requirement for minimum operating voltage, voltage after rectification must be greater than the threshold voltage Vf of LED lamp string, therefore after rectification unit, also must increase a larger electrochemical capacitor C of capacitance carrys out filtering and improves minimum voltage, just because of the existence of this electrochemical capacitor C, make just this electrochemical capacitor C to be full of in a bit of time of electronic transformer in power frequency period, other times do not have electric current and flow through from electronic transformer, and electronic transformer need to be after triggering can latching current, and the conduction period after triggering can maintain it and keep electric current.If can not meet this two conditions, electronic transformer there will be false triggering, and therefore the existence of larger electrochemical capacitor C will cause electronic transformer normally to work, and occurs intermittent output, practical manifestation out be exactly LED illumination flicker.Same problem also appears in the use of TRIAC dimmer.
LED drive circuit and high-frequency electronic transformer or TRIAC dimmer be incompatible, easily occur that the flicker of LED lamp is the significant problem that existing LED drive scheme faces, and is present LED Driving technique field problem demanding prompt solution.
Utility model content
The shortcoming of prior art in view of the above, the purpose of this utility model is to provide a kind of LED constant-current drive circuit, be used for solving prior art LED drive circuit and high-frequency electronic transformer or TRIAC dimmer is incompatible, easily occur the problem of LED lamp flicker.
For achieving the above object and other relevant objects, the utility model provides a kind of LED constant-current drive circuit, and described LED constant-current drive circuit at least comprises:
Voltage input module, described voltage input module comprises high-voltage ac power, is connected in electronic transformer or the TRIAC dimmer of described High Level AC Voltage source output terminal and is connected in described electronic transformer or the rectification unit of TRIAC dimmer output;
LED module, is connected in described voltage input module;
LED constant-current control module, is connected in described LED module, for realizing the constant current control of described LED module;
Regulating resistance, is connected in described voltage input module, regulates by conducting or the shutoff of described regulating resistance the electric current that flows through described electronic transformer or TRIAC dimmer, makes this electric current be not less than maintenance electric current;
Power tube, is connected in described regulating resistance, for controlling conducting or the shutoff of described regulating resistance;
Filter, for a detection voltage is carried out to filtering output voltage, wherein, the size of described detection voltage is determined by output voltage or the output current size of described voltage input module;
Comparator, is connected in the output of described filter, for the output voltage of described filter and reference voltage are compared, and exports a comparative result;
Control circuit, is connected in described comparator output terminal and is connected with a pulse signal, determines that according to the comparative result of described comparator the Output rusults of described control circuit follows described pulse signal or direct output low level;
Drive circuit, is connected between described control circuit and the control end of described power tube, for drive the gate voltage of described power tube according to the output signal of described control circuit.
Preferably, described rectification unit comprises two groups of diode groups in parallel, and each diode group comprises two diodes of series connection, and the two poles of the earth of described electronic transformer or TRIAC dimmer are connected between two diodes of each diode group.
Preferably, the voltage of described voltage input module output is for increasing continuously or reducing continuously.
Preferably, also comprise a filter capacitor, described filter capacitor one end is connected with the output of described voltage input module, other end ground connection.
Preferably, also comprise testing circuit, described testing circuit is connected in described voltage input module, and for detection of output voltage or output current size the output detections voltage of described voltage input module, described testing circuit comprises: detect resistance; The voltage that is connected in described detection resistance two ends turns current circuit, for the voltage drop at described detection resistance two ends is converted to current signal; Be connected in the electric current that described voltage turns current circuit and turn potential circuit, be converted to the detection voltage as reference level taking ground for described voltage being turned to the output current of current circuit.
Preferably, described reference voltage is default definite value or changing value.
Preferably, also comprise oscillator, described oscillator is connected in the input of described control circuit, for the pulse signal of controlling described power tube switch is provided.
Preferably, the comparative result that the output signal of described control circuit is exported by described comparator determines, in the time that comparative result is high level, the output signal of described control circuit is the pulse signal that described oscillator produces; In the time that comparative result is low level, the output signal of described control circuit is low level.
Preferably, also comprise a filter capacitor, described filter capacitor is parallel to described LED module.
Preferably, described control circuit is logical AND gate.
As mentioned above, LED constant-current drive circuit of the present utility model, there is following beneficial effect: LED constant-current drive circuit of the present utility model can with most electronic transformer or TRIAC dimmer compatibility, there will not be the phenomenon of LED lamp flicker, particularly, replacing in the application of existing MR16 cup lamp, can not need to reequip existing circuit, directly replace MR16 cup lamp, save and changed electronic transformer or TRIAC dimmer and reequip the trouble of other circuit, economical and effective.
Brief description of the drawings
Fig. 1 is shown as Buck type LED drive circuit schematic diagram of the prior art.
Fig. 2 is shown as LED constant-current drive circuit schematic diagram of the present utility model.
The LED constant-current control module that Fig. 3 is shown as LED constant-current drive circuit of the present utility model is the circuit diagram of the topological structure of switch and linear combination.
Fig. 4 is shown as the waveform schematic diagram of the input voltage vin after the rectification of LED constant-current drive circuit of the present utility model.
Fig. 5 is shown as detection voltage Vcs, the voltage Vfb of filter output and the waveform schematic diagram of reference voltage Vref 1 of LED constant-current drive circuit of the present utility model.
Fig. 6 is shown as the comparator output voltage V o of LED constant-current drive circuit of the present utility model.
Fig. 7 is shown as the waveform schematic diagram of the power tube M1 gate voltage Vg1 of LED constant-current drive circuit of the present utility model.
Fig. 8 is shown as the waveform schematic diagram of the power tube M2 gate voltage Vg2 of LED constant-current drive circuit of the present utility model.
Fig. 9 is shown as the circuit diagram that the detection voltage Vcs of LED constant-current drive circuit of the present utility model is produced by testing circuit.
Element numbers explanation
1 Buck type LED drive circuit
2 LED constant-current drive circuits
21 voltage input modules
211 high-voltage ac powers
212 electronic transformers
213 rectification units
22 LED modules
23 LED constant-current control modules
24 filters
25 comparators
26 control circuits
27 drive circuits
28 oscillators
29 testing circuits
291 voltages turn current circuit
292 electric currents turn potential circuit
M1 power tube
M2 power tube
Embodiment
By specific instantiation, execution mode of the present utility model is described below, those skilled in the art can understand other advantages of the present utility model and effect easily by the disclosed content of this specification.The utility model can also be implemented or be applied by other different embodiment, and the every details in this specification also can be based on different viewpoints and application, carries out various modifications or change not deviating under spirit of the present utility model.
Refer to Fig. 2 to Fig. 9.It should be noted that, the diagram providing in the present embodiment only illustrates basic conception of the present utility model in a schematic way, satisfy and only show with assembly relevant in the utility model in graphic but not component count, shape and size drafting while implementing according to reality, when its actual enforcement, kenel, quantity and the ratio of each assembly can be a kind of random change, and its assembly layout kenel also may be more complicated.
Embodiment mono-
As shown in Figure 2, the utility model provides a kind of LED constant-current drive circuit 2, and described LED constant-current drive circuit 2 at least comprises:
As shown in Figure 2, described voltage input module 21 comprises high-voltage ac power 211, is connected in the electronic transformer 212 of described High Level AC Voltage source output terminal, the present embodiment is for convenience of explanation only taking electronic transformer 212 as example, and TRIAC dimmer is also applicable to the utility model in actual applications.And be connected in the rectification unit 213 of described electronic transformer 212 outputs, described rectification unit 213 comprises two groups of diode groups in parallel, each diode group comprises two diodes of series connection, and the two poles of the earth of described electronic transformer 212 are connected between two diodes of each diode group.The voltage that described voltage input module 21 is exported is the commutating voltage after the continuous sinusoidal voltage rectification increasing or reduce continuously.
The output of described voltage input module 21 can connect filter capacitor also can not connect filter capacitor, as shown in Figure 2, in the present embodiment, the output of voltage input module 21 is connected with filter capacitor C2, described filter capacitor C2 one end is connected with the output of described voltage input module 21, other end ground connection.
Described LED module 22 is connected in described voltage input module, as lighting apparatus.
As shown in Figure 2, described LED module 22 is made up of the LED lamp of 3 series connection, and the two ends of described LED module 22 are parallel with filter capacitor C1, and described filter capacitor C1 is used for preventing surge phenomenon, and protection LED module is operated under stable state.
As shown in Figure 2, described LED constant-current control module 23 is connected in described LED module 22, and for realizing the constant current control of described LED module 22, described LED constant-current control module 23 can be randomly topologically structured LED constant-current control module.
As shown in Figure 2, described regulating resistance Rbleed is connected in described voltage input module 21, conducting or shutoff by described regulating resistance Rbleed regulate the electric current that flows through described electronic transformer 212, make this electric current be not less than maintenance electric current, described regulating resistance Rbleed can be that variable resistor can be also fixed value resistance, as shown in Figure 2, in the present embodiment, regulating resistance Rbleed is predefined fixed value resistance.
As shown in Figure 2, described power tube M1 is connected in described regulating resistance Rbleed, the voltage control that exported by described drive circuit 27, control conducting or the shutoff of described regulating resistance Rbleed by adjusting the gate voltage of described power tube M1, thereby ensure that the electric current that flows through described electronic transformer 212 is greater than its maintenance electric current, reaches the object that LED drive circuit and described electronic transformer 212 match.
As shown in Figure 2, described filter 24 is for carrying out filtering to detecting voltage Vcs, and described detection voltage Vcs detects and obtains from outer detecting circuit, can be also to detect and obtain from LED internal path.
As shown in Figure 2, described comparator 25 is connected in the output of described filter 24, for the output voltage V fb of described filter 24 and reference voltage Vref 1 are compared, and exports a comparative result Vo.Described reference voltage Vref 1 can be that default definite value can be also changing value.
As shown in Figure 2, described control circuit 26 is connected in the output of described comparator 25 and is connected with a pulse signal Vosc, determines that according to the comparative result of described comparator 25 Output rusults of described control circuit 26 follows described pulse signal or direct output low level.As shown in Figure 2, control circuit 26 described in the present embodiment is logical AND gate, and in the time that described comparator 25 Output rusults are high level, high level and described pulse signal do and computing, Output rusults afterpulsing signal; In the time that described comparator 25 Output rusults are low level, it is low level that low level and described pulse signal do with the result of computing, in the time flowing through the maintenance electric current that the electric current of described electronic transformer 212 is less than them, the electric current that makes described power tube M1 be subject to the control of described pulse signal Vosc to go to draw high to flow through described electronic transformer 212 is to meet its job requirement, in the time flowing through the maintenance electric current that the electric current of described electronic transformer 212 is greater than them, described power tube M1 is turn-offed.The duty ratio of described pulse signal Vosc can be changeless value, can be also the value constantly changing with a certain control signal.
As shown in Figure 2, shown in drive circuit 27 be connected between described control circuit 26 and the control end of described power tube M1, for drive the gate voltage of described power tube M1 according to the output signal of described control circuit 26.
The operation principle of above-mentioned LED constant-current drive circuit 2 is as follows:
As shown in Figure 2, after the normal work of internal power source voltage, input voltage vin constantly increases, detecting voltage Vcs can be to detect and obtain from outer detecting circuit, also can be to detect and obtain from LED internal path, this voltage Vcs be relevant with the output current Iin of voltage input module, and this detection voltage Vcs is carried out to filtering by filter 24, obtain the output voltage V fb of filter 24, the output voltage V fb of filter 24 compares by comparator and reference voltage Vref 1.When the electric current that flows through electronic transformer 212 hour, corresponding Vcs and Vfb are also less, be that Vfb is less than Vref1, comparative result Vo is output as high level so, the output signal of control circuit 26 is the pulse signal changing with Vosc, drive again the turn-on and turn-off of this pulse signal power ratio control pipe M1 via drive circuit 27, now, the less conducting LED module 22 that is also not enough to of input voltage vin, on LED module 22, do not have electric current to flow through, the electric current that flows through electronic transformer 212 equals to flow through the electric current of power tube M1; In the time that the electric current that flows through electronic transformer 212 is enough large, corresponding Vcs and Vfb are also enough large, be that Vfb is greater than reference voltage Vref 1, comparative result Vo is output as low level so, the output signal of control circuit 26 is low, by this low signal after drive circuit, power tube M1 is turn-offed, the branch circuit break of Rbleed and power tube M1, do not have electric current to flow through, the electric current that now flows through electronic transformer 212 equals to flow through the electric current of LED module 22, and the electric current that flows through LED module 22 is enough to make electronic transformer 212 normally to be worked.
Embodiment bis-
As shown in Figure 3, the present embodiment provides a kind of LED constant-current drive circuit, and its basic circuit structure, as embodiment mono-, wherein, is with the difference of embodiment mono-:
1, the output of the voltage input module 21 of the present embodiment does not connect filter capacitor, and as shown in Figure 4, input voltage vin is the output voltage with jumbo filter capacitor not after sinusoidal voltage rectification, and this voltage is taking front half period of sinusoidal signal as one-period.
2, the LED constant-current control module 23 of the present embodiment is the topological structure of switch and linear combination, described LED constant-current control module 23 comprises: be connected in the power tube M2 of LED module 22, by regulating the conducting resistance of described power tube M2 can realize the constant current of LED module 22; Sampling resistor Rcs1, judges by the size of the upper voltage Vcs of described sampling resistor Rcs1 the size of current that flows through described LED module 22; Constant-current control circuit 231, is connected in the output of described power tube M2, and the switching signal that produces different duty according to the value that detects voltage Vcs is to control conducting or the shutoff of described power tube M2.
3, the detection voltage Vcs in the present embodiment detects and obtains from LED internal path, and this detection voltage Vcs is consistent with the detection voltage of controlling constant current in described LED constant-current control module 23.
4, the pulse signal Vosc in the present embodiment is the signal that duty ratio constantly changes, and this pulse signal Vosc is consistent with the switching signal Vg2 of the M2 conducting of power ratio control pipe or shutoff in LED constant-current control module 23.
The operation principle of the LED constant-current drive circuit of the present embodiment is as follows:
As shown in Figure 3, detecting voltage Vcs is the voltage relevant with input voltage vin detecting from the path of LED constant-current control module 23, as shown in Figure 5, detect voltage Vcs and reflected the curent change that flows through LED module 22, present the voltage waveform of similar LED current waveform, because the signal of power ratio control pipe M2 gate voltage is the pulse signal with certain duty ratio, therefore, detecting voltage Vcs is that the pulsed with similar input voltage envelope detects voltage.In the time that input voltage vin does not reach the threshold voltage Vf of LED, power tube M2 is controlled by switching signal Vg2 and does switch motion, and as shown in Figure 8, Vg2 is the pulse signal with certain duty ratio.Now LED module 22 does not have conducting, does not therefore have electric current to flow through power tube M2 and sampling resistor Rcs1, and the value of Vcs is 0 so.Vcs after filtering device 24 obtains Vfb, and as shown in Figure 5, Vfb is for having certain ripple, the low frequency signal consistent with the frequency of input voltage.Now Vfb is still 0, then compares by comparator 25 and reference voltage Vref 1, and as shown in Figure 5, reference voltage Vref 1 is a predefined definite value.Because Vfb is less than reference voltage Vref 1, the comparative result Vo obtaining is high level, as shown in Figure 6.Because the gate voltage Vg2 of Vosc and power tube M2 is now consistent, therefore obtain the gate voltage Vg1 of power tube M1 and the gate voltage Vg2 of power tube M2 is consistent, as shown in Figure 7.Power tube M1 and power tube M2 carry out switch motion with identical frequency, extract electric current from electronic transformer 212, and can adjust this electric current by regulating resistance Rbleed, make its maintenance electric current that is greater than electronic transformer 212, thereby make electronic transformer 212 keep normal operating conditions.When input voltage vin is a little more than the threshold voltage Vf of LED, the current ratio that now flows through LED hour, the voltage Vfb that Vcs obtains by filter 24 is still less than reference voltage Vref 1, comparative result Vo now is also still high level, the same when therefore the switch motion of power tube M1 is still less than Vf with Vin.In the time that input voltage vin is greater than the threshold voltage Vf of LED, the current ratio that now flows through LED is larger, and the voltage Vfb that Vcs obtains by filter 24 is greater than reference voltage Vref 1, and comparative result Vo now becomes low level, as shown in Figure 6.After control circuit 26, directly output low level, therefore the gate voltage Vg1 of power tube M1 is also low level, irrelevant with pulse signal Vosc, as shown in Figure 7.Now, power tube M1 closes, and does not have electric current to flow through the branch road of power tube M1 and regulating resistance Rbleed, and the electric current that now flows through LED module 22 namely flows through the electric current of electronic transformer 212, the maintenance electric current that is far longer than electronic transformer 212, electronic transformer 212 keeps normal operating conditions.
More than that single cycle 10ms is with the interior course of work.Other time is the work in this cycle of repetition.The utility model is from Vcs, and the loop forming by constant-current control circuit 231 and power tube M1 ensures that the electric current that flows through LED within the cycle of 10ms is held constant at Vref2/Rcs1.
Embodiment tri-
As shown in Figure 9, the present embodiment provides a kind of LED constant-current drive circuit, and its basic circuit structure, as embodiment mono-, wherein, is with the difference of embodiment mono-:
1, the output of the voltage input module 21 of the present embodiment does not connect filter capacitor.
2, pulse signal Vosc produces by oscillator 28.
3, detect voltage Vcs and obtain by testing circuit 29, described testing circuit 29 comprises: detect resistance R cs2; The voltage that is connected in described detection resistance R cs2 two ends turns current circuit 291, and described voltage turns current circuit 291 voltage drop at Rcs2 two ends is converted to current signal; Be connected in the electric current that described voltage turns current circuit 291 and turn potential circuit 292, described electric current turns potential circuit 292 this current signal is converted to the detection voltage as reference level taking ground.
The operation principle of the LED constant-current drive circuit of the present embodiment is as follows:
The present embodiment carrys out by detecting resistance R cs2 one of the rear increase of voltage input module 21 size of current that Real-Time Monitoring extracts from electronic transformer 212, convert the pressure drop Δ V on Rcs2 to electric current again, then to turn by electric current that potential circuit 292 becomes this current conversion take ground as the detection voltage Vfb of reference level.Suitable Rcs2 resistance is set, make the electric current flowing out from electronic transformer 212 be slightly less than maintenance electric current, be that Vfb is while being slightly less than Vref1, Vo saltus step becomes high level, and the output signal of oscillator 28 is directly transferred to Vg1, power ratio control pipe M1, extract the electric current of electronic transformer 212, adjust this electric current by adjustment Rbleed resistance and be greater than maintenance electric current, thereby ensure that electronic transformer 212 remains on normal operating state, avoid occurring the phenomenon of LED flicker.When the electric current flowing out from electronic transformer 212 is greater than maintenance electric current, when Vfb is greater than Vref1, Vo saltus step becomes low level, and power tube M1 is turned off, and the electric current that flows through LED module 22 is enough to make electronic transformer 212 normally to be worked.
In sum, LED constant-current drive circuit of the present utility model, by detecting directly or indirectly the size of current extracting from electronic transformer, in the time that this electric current is less than the maintenance electric current of electronic transformer, unlatching is specifically designed to the power tube M1 of earial drainage, make the electric current extracting from electronic transformer be greater than maintenance electric current, thereby ensure the electronic transformer state in normal work always, avoid occurring LED flicker.Meanwhile, the utility model is equally applicable to solve the compatibility issue of TRIAC light modulation, because TRIAC dimmer needs a minimum maintenance electric current just can maintain normal operating conditions equally, otherwise there will be the phenomenon of LED lamp flicker.LED constant-current drive circuit of the present utility model can with all electronic transformer or TRIAC dimmer compatibilities, there will not be the phenomenon of LED lamp flicker, particularly in the application of the existing MR16 cup lamp of replacement, can not need to reequip existing circuit, directly replace MR16 cup lamp, save the trouble of changing electronic transformer or TRIAC dimmer and other circuit of repacking, economical and effective.So the utility model has effectively overcome various shortcoming of the prior art and tool high industrial utilization.
Above-described embodiment is illustrative principle of the present utility model and effect thereof only, but not for limiting the utility model.Any person skilled in the art scholar all can, under spirit of the present utility model and category, modify or change above-described embodiment.Therefore, have in technical field under such as and conventionally know that the knowledgeable modifies or changes not departing from all equivalences that complete under spirit that the utility model discloses and technological thought, must be contained by claim of the present utility model.
Claims (10)
1. a LED constant-current drive circuit, is characterized in that, described LED constant-current drive circuit at least comprises:
Voltage input module, described voltage input module comprises high-voltage ac power, is connected in electronic transformer or the TRIAC dimmer of described High Level AC Voltage source output terminal and is connected in described electronic transformer or the rectification unit of TRIAC dimmer output;
LED module, is connected in described voltage input module;
LED constant-current control module, is connected in described LED module, for realizing the constant current control of described LED module;
Regulating resistance, is connected in described voltage input module, regulates by conducting or the shutoff of described regulating resistance the electric current that flows through described electronic transformer or TRIAC dimmer, makes this electric current be not less than maintenance electric current;
Power tube, is connected in described regulating resistance, for controlling conducting or the shutoff of described regulating resistance;
Filter, for a detection voltage is carried out to filtering output voltage, wherein, the size of described detection voltage is determined by output voltage or the output current of described voltage input module;
Comparator, is connected in the output of described filter, for the output voltage of described filter and reference voltage are compared, and exports a comparative result;
Control circuit, is connected in the output of described comparator and is connected with a pulse signal, determines that according to the comparative result of described comparator the output signal of described control circuit follows described pulse signal or output low level;
Drive circuit, is connected between described control circuit and the control end of described power tube, for drive the gate voltage of described power tube according to the output signal of described control circuit.
2. LED constant-current drive circuit according to claim 1, it is characterized in that: described rectification unit comprises two groups of diode groups in parallel, each diode group comprises two diodes of series connection, and the two poles of the earth of described electronic transformer or TRIAC dimmer are connected between two diodes of each diode group.
3. LED constant-current drive circuit according to claim 1, is characterized in that: the voltage of described voltage input module output is for increasing continuously or reducing continuously.
4. LED constant-current drive circuit according to claim 1, is characterized in that: also comprise a filter capacitor, described filter capacitor one end is connected with the output of described voltage input module, other end ground connection.
5. LED constant-current drive circuit according to claim 1, it is characterized in that: also comprise testing circuit, described testing circuit is connected in described voltage input module, for detection of output voltage or output current size the output detections voltage of described voltage input module, described testing circuit comprises: detect resistance; The voltage that is connected in described detection resistance two ends turns current circuit, for the voltage drop at described detection resistance two ends is converted to current signal; Be connected in the electric current that described voltage turns current circuit and turn potential circuit, be converted to the detection voltage as reference level taking ground for described voltage being turned to the output current of current circuit.
6. LED constant-current drive circuit according to claim 1, is characterized in that: described reference voltage is default definite value or changing value.
7. LED constant-current drive circuit according to claim 1, is characterized in that: also comprise oscillator, described oscillator is connected in the input of described control circuit, for the pulse signal of controlling described power tube switch is provided.
8. LED constant-current drive circuit according to claim 1, it is characterized in that: the comparative result that the output signal of described control circuit is exported by described comparator determines, in the time that comparative result is high level, the output signal of described control circuit is the pulse signal that described oscillator produces; In the time that comparative result is low level, the output signal of described control circuit is low level.
9. LED constant-current drive circuit according to claim 1, is characterized in that: also comprise a filter capacitor, described filter capacitor is parallel to described LED module.
10. LED constant-current drive circuit according to claim 1, is characterized in that: described control circuit is logical AND gate.
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| CN201320807054.XU CN203675371U (en) | 2013-12-09 | 2013-12-09 | LED constant current drive circuit |
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| CN201320807054.XU CN203675371U (en) | 2013-12-09 | 2013-12-09 | LED constant current drive circuit |
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| CN104797062A (en) * | 2015-05-13 | 2015-07-22 | 魏其萃 | Non-strobe high-efficiency LED (light-emitting diode) driving manner compatible with phase-controlled light modulator |
| CN104797062B (en) * | 2015-05-13 | 2017-04-26 | 魏其萃 | Non-strobe high-efficiency LED (light-emitting diode) driving manner compatible with phase-controlled light modulator |
| WO2017063609A1 (en) * | 2015-10-16 | 2017-04-20 | 得能创科有限公司 | Drive power source return stability improvement circuit |
| US10292228B2 (en) | 2015-10-16 | 2019-05-14 | Delight Innovative Technologies Limited | Circuit for improving stability of backfeed of driving power supplies |
| CN108617061A (en) * | 2016-12-13 | 2018-10-02 | 无锡友达电子有限公司 | Drive current adjustment device |
| CN108617061B (en) * | 2016-12-13 | 2020-07-28 | 无锡友达电子有限公司 | Drive current adjusting device |
| CN107027224A (en) * | 2017-06-09 | 2017-08-08 | 厦门奇力微电子有限公司 | A kind of LED light adjusting circuits and LED drive circuit |
| CN112839406A (en) * | 2019-11-07 | 2021-05-25 | 华润微集成电路(无锡)有限公司 | Linear LED driving system and driving method |
| CN112839406B (en) * | 2019-11-07 | 2023-05-30 | 华润微集成电路(无锡)有限公司 | Linear LED driving system and driving method |
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