CN104994666A - Fixed-frequency constant-current BUCK circuit - Google Patents
Fixed-frequency constant-current BUCK circuit Download PDFInfo
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- CN104994666A CN104994666A CN201510475107.6A CN201510475107A CN104994666A CN 104994666 A CN104994666 A CN 104994666A CN 201510475107 A CN201510475107 A CN 201510475107A CN 104994666 A CN104994666 A CN 104994666A
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Abstract
The invention relates to the technical field of constant-current driving power supplies, and particularly relates to a fixed-frequency constant-current BUCK circuit. The fixed-frequency constant-current BUCK circuit is characterized in that a sampling circuit is arranged at the output end of a power supply terminal, voltage at both ends of the sampling circuit is relatively stable, the sampling circuit is connected with an LED circuit in series at the same time, acquisition current of the sampling circuit is equal to driving current of the LED circuit, a control circuit judges the state of the driving current of the LED circuit according to the acquisition current, a control signal is outputted when the driving current of the LED circuit stays at an unstable state so as to control the duty ratio of the PWM waveform, the operating state of a switching circuit can be changed by changing the duty ratio of the PWM waveform, and thus the driving current of the LED circuit is adjusted. By adopting the technical scheme provided by the invention, the acquisition current is stable, thus the driving current of the LED circuit is enabled to be relatively stable, and the service life of the LED circuit is prolonged.
Description
Technical field
The present invention relates to constant-current driving power supply technical field, particularly relate to a kind of fixed BUCK of constant current frequently circuit.
Background technology
LED illumination light source has the advantages such as environmental protection, energy-conservation, the life-span is long, and be regarded as the lighting source of 21st century most prospect, in recent years, along with LED illumination technical development, LED illumination light source has started to replace conventional light source extensive use in various lighting.Due to the voltage-current characteristic of LED light source, present white LED light source generally uses continuous current to drive, stable circuit is obtained in order to make LED light source, usually a series connection resistance between ground is come from LED light, because resistance is connected with LED light source, then ohmically electric current is identical with the electric current on LED light source, by gathering ohmically collection electric current and feeding back to predetermined adjusting device, regulated by adjusting device, make the electric current on LED light source be in steady state.But because one end of sampling resistor connects ground, because of the spread of voltage of sampling resistor brightness, and then make the acquisition precision of sample rate current lower, and then cause the electric current of LED light source unstable.
Summary of the invention
For the deficiencies in the prior art, the invention provides the high and current stability of a kind of sample circuit precision good determine frequency constant current BUCK circuit.
A kind of fixed BUCK of constant current frequently circuit, is applied to constant-current dimming system, wherein, comprises:
Sample circuit, connects the power end of an output voltage signal, in order to gather described voltage signal, and forms a sample rate current matched with described input signal and exports;
Control circuit, in order to receive the described sample rate current that described sample circuit exports, and forms a control signal output according to described sample rate current;
PWM produces circuit, and the control end that described PWM produces circuit connects described control circuit, in order to receive the described control signal that described control circuit exports, and forms a PWM wave form output matched with described control signal according to described control signal,
Switching circuit, control end connects the output that described PWM produces circuit, produces the described PWM waveform of circuit output, and work in conducting state or off state in order to receive described PWM under the control of described PWM waveform;
LED circuit, is electrically serially connected with between described power end and described switching circuit, is used to, under described switching circuit works in conducting state, described voltage signal is converted into light signal and exports.
Above-mentioned determines frequency constant current BUCK circuit, and wherein, described sample circuit comprises the first resistance branch, the second resistance branch, the 3rd resistance branch, the 4th resistance branch, the 5th resistance branch, first node, Section Point and the 3rd node; Described Section Point, described 3rd node form the output of described sample circuit respectively;
Described first resistance branch is connected between described power end and described first node;
Described second resistance branch is connected between described power end and described Section Point;
Described 3rd resistance branch is connected between described first node and described 3rd node;
Described 4th resistance branch is connected between described Section Point and ground;
Described 5th resistance branch is connected between described 3rd node and described ground;
Wherein, the resistance of described second resistance branch, the 3rd resistance branch, the 4th resistance branch, the 5th resistance branch is equal.
Above-mentioned determines frequency constant current BUCK circuit, and wherein, described control circuit is formed primarily of amplifier; The normal phase input end of described amplifier, inverting input connect the output of described sample circuit respectively, and the output of described amplifier connects the described control end that described PWM produces circuit; In described amplifier inverting input be connected a negative feedback branch road between described output.
Above-mentioned determines frequency constant current BUCK circuit, and wherein, it is that UC3843 chip is formed that described PWM produces circuit primarily of model.
Above-mentioned determines frequency constant current BUCK circuit, and wherein, described switching circuit is formed primarily of N channel depletion type metal-oxide-semiconductor,
The grid of described N channel depletion type metal-oxide-semiconductor connects the output that described PWM produces circuit,
The drain electrode of described N channel depletion type metal-oxide-semiconductor connects described LED circuit,
The source electrode of described N channel depletion type metal-oxide-semiconductor connects describedly.
Above-mentioned determines frequency constant current BUCK circuit, wherein, also comprise an accumulator, be connected between described LED circuit and described power end, when described power end exports described voltage signal, described accumulator works in storage of electrical energy state, and when described power end does not export described voltage signal, described accumulator works in release energy state.
Above-mentioned determines frequency constant current BUCK circuit, wherein, also comprises a freewheeling circuit, is connected between described accumulator and described power end, under described accumulator works in release energy state, provides electric energy by described freewheeling circuit to described LED circuit.
Above-mentioned determines frequency constant current BUCK circuit, wherein, also comprises a filter circuit, is parallel to described LED circuit two ends, in order to the ripple of voltage signal described in filtering.
Above-mentioned determines frequency constant current BUCK circuit, and wherein, described negative feedback branch road is formed primarily of the 6th resistance and the first capacitances in series.
Above-mentioned determines frequency constant current BUCK circuit, wherein, also comprises a frequency-selective network, and described frequency-selective network is formed primarily of the 7th resistance and the second capacitances in series, and described 7th resistance is connected with the tie point of described second electric capacity the frequency-selecting end that described PWM produces circuit.
Compared with prior art, advantage of the present invention is:
In the application, sample circuit is arranged at the output of power end, the voltage at sample circuit two ends is comparatively stable, sample circuit is connected with LED circuit simultaneously, then the collection electric current of sample circuit equals the drive current of LED circuit, control circuit judges the drive current state of LED circuit according to gathering electric current, drive current in LED circuit is in an unsure state down, export the duty ratio of a control signal control PWM waveform, the duty ratio changing PWM waveform can change the operating state of switching circuit, and then regulates the drive current of LED circuit.Adopt the technical scheme that the application provides, gather current stabilization, and then make the drive current of LED circuit comparatively stable, extend the useful life of LED circuit.
Accompanying drawing explanation
Fig. 1 is the one of the present invention BUCK of constant current frequently electrical block diagram surely.
Embodiment
Below in conjunction with the drawings and specific embodiments, the invention will be further described, but not as limiting to the invention.
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, the every other embodiment that those of ordinary skill in the art obtain under the prerequisite of not making creative work, all belongs to the scope of protection of the invention.
It should be noted that, when not conflicting, the embodiment in the present invention and the feature in embodiment can combine mutually.
Below in conjunction with the drawings and specific embodiments, the invention will be further described, but not as limiting to the invention.
As shown in Figure 1, a kind of fixed BUCK of constant current frequently circuit, is applied to constant-current dimming system, wherein, comprises:
Sample circuit 1, connects the power end of an output voltage signal, in order to gather described voltage signal, and forms a sample rate current matched with described input signal and exports;
Control circuit 2, in order to receive the described sample rate current that described sample circuit 1 exports, and forms a control signal output according to described sample rate current;
PWM produces circuit 3, and the control end that described PWM produces circuit 3 connects described control circuit 2, in order to receive the described control signal that described control circuit 2 exports, and forms a PWM wave form output matched with described control signal according to described control signal,
Switching circuit 4, control end connects the output that described PWM produces circuit 3, produces the described PWM waveform of circuit 3 output, and work in conducting state or off state in order to receive described PWM under the control of described PWM waveform;
LED circuit 5, is electrically serially connected with between described power end and described switching circuit 4, is used to, under described switching circuit 4 works in conducting state, described voltage signal is converted into light signal and exports.
Operation principle of the present invention is:
Sample circuit 1 is arranged between power end and LED circuit 5, the voltage signal that sample circuit 1 accurate acquisition power end exports, and voltage signal is converted into sample rate current and exports control circuit 2 to, control circuit 2 forms a control signal according to described sample rate current and exports PWM generation circuit 3 to, the duty ratio of this control signal in order to regulate described PWM to produce the PWM waveform that circuit 3 exports, switching circuit 4 works under the control of described PWM waveform; Under switching circuit 4 is in conducting state, LED circuit accepts the voltage signal also luminescence that power end exports.Under switching circuit 4 is in off state, LED circuit accepts the electric energy also luminescence that accumulator exports.In the application, sample circuit 1 is arranged at the output of power end, the voltage at sample circuit 1 two ends is comparatively stable, sample circuit 1 is connected with LED circuit 5 simultaneously, then the collection electric current of sample circuit 1 equals the drive current of LED circuit 5, control circuit 2 judges the drive current state of LED circuit 5 according to sample rate current, drive current in LED circuit 5 is in an unsure state down, export the duty ratio of control signal control PWM waveform, the duty ratio changing PWM waveform can change the operating state of switching circuit 4, and then regulates the drive current of LED circuit 5.Adopt the technical scheme that the application provides, sample rate current is stablized, and then makes the drive current of LED circuit 5 comparatively stable, extends the useful life of LED circuit 5.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, wherein, described sample circuit 1 comprises the first resistance branch R1, the second resistance branch R2, the 3rd resistance branch R3, the 4th resistance branch R4, the 5th resistance branch R5, first node 11, Section Point 12 and the 3rd node 13; Described Section Point 12 and described 3rd node 13 form the output of described sample circuit 1 respectively;
Described first resistance branch R1 is connected between described power end and described first node 11;
Described second resistance branch R2 is connected between described power end and described Section Point 12;
Described 3rd resistance branch R3 is connected between described first node 11 and described 3rd node 13;
Described 4th resistance branch R4 is connected between described Section Point 12 and ground;
Described 5th resistance branch R5 is connected between described 3rd node 13 and described ground;
Wherein, the resistance of described second resistance branch R2, the 3rd resistance branch R3, the 4th resistance branch R4, the 5th resistance branch R5 is equal.
Second resistance branch R2 and the 4th resistance branch R4 is series between power end and ground, 4th resistance branch R4 carries out the normal phase input end signal of dividing potential drop formation control circuit 2 to voltage signal, 3rd resistance branch R3, 5th resistance branch R5 is to the voltage signal dividing potential drop again through the first resistance branch R1 voltage division processing, the anti-phase input end signal of the pressure drop formation control circuit 2 of the 5th resistance branch R5, because of described second resistance branch R2, 3rd resistance branch R3, 4th resistance branch R4, the resistance of the 5th resistance branch R5 is equal, make to be formed between the normal phase input end of control circuit 2 and inverting input to gather voltage, and form collection electric current by the first resistance branch R1.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, and wherein, described control circuit 2 is formed primarily of amplifier; The normal phase input end of described amplifier, inverting input connect the output of described sample circuit 1 respectively, and the output of described amplifier connects the described control end that described PWM produces circuit 3; In described amplifier inverting input be connected a negative feedback branch road between described output.Further, described negative feedback branch road is connected primarily of the 6th resistance R6 and the first electric capacity C1 and is formed.Amplifier is provided with negative feedback branch road, makes amplifier operation in the range of linearity, forms the duty ratio of a control signal control PWM waveform by gathering electric current, and then regulates the drive current of LED circuit 5, makes it be in constant current state.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, and wherein, it is that UC3843 chip is formed that described PWM produces circuit 3 primarily of model.Further, also comprise a frequency-selective network, described frequency-selective network is connected primarily of the 7th resistance R7 and the second electric capacity C2 and is formed, and described 7th resistance R7 is connected with the tie point of described second electric capacity C2 the frequency-selecting end that described PWM produces circuit 3.Because the value of the second electric capacity C2 and the 7th resistance R7 is fixed, and then the frequency of PWM waveform is made to be in steady state.Adopt UC3843 chip to form PWM waveform, power consumption is less simultaneously.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, and wherein, described switching circuit 4 is formed primarily of N channel depletion type metal-oxide-semiconductor,
The grid of described N channel depletion type metal-oxide-semiconductor connects the output that described PWM produces circuit 3,
The drain electrode of described N channel depletion type metal-oxide-semiconductor connects described LED circuit 5,
The source electrode of described N channel depletion type metal-oxide-semiconductor connects describedly.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, wherein, also comprise an accumulator 6, be connected between described LED circuit 5 and described power end, when described power end exports described voltage signal, described accumulator 6 works in storage of electrical energy state, when described power end does not export described voltage signal, described accumulator 6 works in release energy state.
As further preferred embodiment, above-mentioned determines frequency constant current BUCK circuit, wherein, also comprise a freewheeling circuit D1, be connected between described accumulator 6 and described power end, under described accumulator 6 works in release energy state, provide electric energy by described freewheeling circuit D1 to described LED circuit 5.
Above-mentioned determines frequency constant current BUCK circuit, wherein, also comprises a filter circuit C3, is parallel to described LED circuit 5 two ends, in order to the ripple of voltage signal described in filtering.
The foregoing is only preferred embodiment of the present invention; not thereby embodiments of the present invention and protection range is limited; to those skilled in the art; should recognize and all should be included in the scheme that equivalent replacement done by all utilizations specification of the present invention and diagramatic content and apparent change obtain in protection scope of the present invention.
Claims (10)
1. the fixed BUCK of a constant current frequently circuit, is applied to constant-current dimming system, it is characterized in that, comprising:
Sample circuit, connects the power end of an output voltage signal, in order to gather described voltage signal, and forms a sample rate current matched with described voltage signal and exports;
Control circuit, in order to receive the described sample rate current that described sample circuit exports, and forms a control signal output according to described sample rate current;
PWM produces circuit, and the control end that described PWM produces circuit connects described control circuit, in order to receive the described control signal that described control circuit exports, and forms a PWM wave form output matched with described control signal according to described control signal,
Switching circuit, control end connects the output that described PWM produces circuit, produces the described PWM waveform of circuit output, and work in conducting state or off state in order to receive described PWM under the control of described PWM waveform;
LED circuit, is electrically serially connected with between described power end and described switching circuit, is used to, under described switching circuit works in conducting state, described voltage signal is converted into light signal and exports.
2. the fixed BUCK of constant current frequently circuit according to claim 1, it is characterized in that, described sample circuit comprises the first resistance branch, the second resistance branch, the 3rd resistance branch, the 4th resistance branch, the 5th resistance branch, first node, Section Point and the 3rd node; Described Section Point, described 3rd node form the output of described sample circuit respectively;
Described first resistance branch is connected between described power end and described first node;
Described second resistance branch is connected between described power end and described Section Point;
Described 3rd resistance branch is connected between described first node and described 3rd node;
Described 4th resistance branch is connected between described Section Point and ground;
Described 5th resistance branch is connected between described 3rd node and described ground;
Wherein, the resistance of described second resistance branch, the 3rd resistance branch, the 4th resistance branch, the 5th resistance branch is equal.
3. the fixed BUCK of constant current frequently circuit according to claim 1, it is characterized in that, described control circuit is formed primarily of amplifier; The normal phase input end of described amplifier, inverting input connect the output of described sample circuit respectively, and the output of described amplifier connects the described control end that described PWM produces circuit; In described amplifier inverting input be connected a negative feedback branch road between described output.
4. the fixed BUCK of constant current frequently circuit according to claim 1, is characterized in that, it is that UC3843 chip is formed that described PWM produces circuit primarily of model.
5. the fixed BUCK of constant current frequently circuit according to claim 1, it is characterized in that, described switching circuit is formed primarily of N channel depletion type metal-oxide-semiconductor,
The grid of described N channel depletion type metal-oxide-semiconductor connects the output that described PWM produces circuit,
The drain electrode of described N channel depletion type metal-oxide-semiconductor connects described LED circuit,
The source electrode of described N channel depletion type metal-oxide-semiconductor connects describedly.
6. determine the BUCK of constant current frequently circuit according to claim 1, it is characterized in that, also comprise an accumulator, be connected between described LED circuit and described power end, when described power end exports described voltage signal, described accumulator works in storage of electrical energy state, and when described power end does not export described voltage signal, described accumulator works in release energy state.
7. determine the BUCK of constant current frequently circuit according to claim 6, it is characterized in that, also comprise a freewheeling circuit, be connected between described accumulator and described power end, under described accumulator works in release energy state, provide electric energy by described freewheeling circuit to described LED circuit.
8. determine the BUCK of constant current frequently circuit according to claim 1, it is characterized in that, also comprise a filter circuit, be parallel to described LED circuit two ends, in order to the ripple of voltage signal described in filtering.
9. determine the BUCK of constant current frequently circuit according to claim 3, it is characterized in that, described negative feedback branch road is formed primarily of the 6th resistance and the first capacitances in series.
10. determine the BUCK of constant current frequently circuit according to claim 1, it is characterized in that, also comprise a frequency-selective network, described frequency-selective network is formed primarily of the 7th resistance and the second capacitances in series, and described 7th resistance is connected with the tie point of described second electric capacity the frequency-selecting end that described PWM produces circuit.
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| CN201510475107.6A CN104994666B (en) | 2015-08-05 | 2015-08-05 | Determine frequency constant current BUCK circuits |
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| CN201510475107.6A CN104994666B (en) | 2015-08-05 | 2015-08-05 | Determine frequency constant current BUCK circuits |
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| CN104994666A true CN104994666A (en) | 2015-10-21 |
| CN104994666B CN104994666B (en) | 2018-06-22 |
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| US20060139267A1 (en) * | 2004-12-28 | 2006-06-29 | Sanyo Electric Co., Ltd. | Light-emitting element driving apparatus |
| EP2533606A1 (en) * | 2011-06-08 | 2012-12-12 | Macroblock, Inc. | AC-DC dual-use LED driving circuit |
| CN103188851A (en) * | 2011-12-31 | 2013-07-03 | 海洋王照明科技股份有限公司 | Light-emitting diode (LED) constant current drive circuit |
| CN203279256U (en) * | 2013-04-08 | 2013-11-06 | 安徽华东光电技术研究所 | Light-adjustable LED constant current source drive circuit |
| CN203289699U (en) * | 2013-05-08 | 2013-11-13 | 高怡达科技(深圳)有限公司 | LED (light-emitting diode) high-power drive circuit |
| CN204316775U (en) * | 2014-12-30 | 2015-05-06 | 德尔福中央电气（上海）有限公司 | A kind of USB charging indicator light |
-
2015
- 2015-08-05 CN CN201510475107.6A patent/CN104994666B/en active Active
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20060139267A1 (en) * | 2004-12-28 | 2006-06-29 | Sanyo Electric Co., Ltd. | Light-emitting element driving apparatus |
| EP2533606A1 (en) * | 2011-06-08 | 2012-12-12 | Macroblock, Inc. | AC-DC dual-use LED driving circuit |
| CN103188851A (en) * | 2011-12-31 | 2013-07-03 | 海洋王照明科技股份有限公司 | Light-emitting diode (LED) constant current drive circuit |
| CN203279256U (en) * | 2013-04-08 | 2013-11-06 | 安徽华东光电技术研究所 | Light-adjustable LED constant current source drive circuit |
| CN203289699U (en) * | 2013-05-08 | 2013-11-13 | 高怡达科技(深圳)有限公司 | LED (light-emitting diode) high-power drive circuit |
| CN204316775U (en) * | 2014-12-30 | 2015-05-06 | 德尔福中央电气（上海）有限公司 | A kind of USB charging indicator light |
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| CN104994666B (en) | 2018-06-22 |
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Address after: No. 122315000 Jianlan Road, Gaoxin District, Ningbo, Zhejiang Patentee after: Ningbo sainaibi Photoelectric Technology Co.,Ltd. Address before: 315040 No. 56 Keda Road, high tech Zone, Ningbo, Zhejiang Patentee before: NINGBO SNAPPY OPTOELECTRONICS Co.,Ltd. |
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