CN103813596A - LED (Light-Emitting Diode) driving circuit and method for reducing LED current ripple - Google Patents
LED (Light-Emitting Diode) driving circuit and method for reducing LED current ripple Download PDFInfo
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- CN103813596A CN103813596A CN201410085182.7A CN201410085182A CN103813596A CN 103813596 A CN103813596 A CN 103813596A CN 201410085182 A CN201410085182 A CN 201410085182A CN 103813596 A CN103813596 A CN 103813596A
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Abstract
The invention provides an LED (Light-Emitting Diode) driving circuit and method for reducing LED current ripple. The LED driving circuit comprises a constant-current driver for generating input current with a constant average value, a first capacitor of which the first end is connected with the first output end of the constant-current driver and the second end is connected with the second output end of the constant-current driver and grounded, and a linear constant-current control circuit which is connected in series between an LED load and the ground. The LED load and the linear constant-current control circuit are connected in parallel with the first capacitor after being connected in series. Current controlled by external reference voltage is provided by the linear constant-current control circuit, and the average voltage of a serial connection point between the linear constant-current control circuit and the LED load is controlled to be equal to the external reference voltage. By adopting the method, the current ripple on the LED load can be reduced and even eliminated.
Description
Technical field
The present invention relates to LED Driving technique, relate in particular to a kind of method of LED drive circuit and reduction LED current ripples.
Background technology
With reference to figure 1, traditional LED drive circuit by Alternating Current Power Supply comprises constant-flow driver 101, output filter capacitor C1 and LED load.In the constant current output signal Iin of constant-flow driver 101, generally contain low-frequency ac composition, output filter capacitor C1 can filtering radio-frequency component and a part of industrial frequency AC composition.But for the occasion that has power factor to require, the industrial frequency AC composition that outputs to the electric current of LED load will be larger.For example, for the mains frequency of conventional 50Hz, the electric current that outputs to LED load contains 100Hz power frequency composition, will produce like this stroboscopic of 100Hz, this stroboscopic can affect the life-span of LED load, and can cause user's visual fatigue, easily causes myopia.
Therefore the working frequency ripple wave, how reducing in LED load is urgent problem.
Summary of the invention
The technical problem to be solved in the present invention is to provide a kind of method of LED drive circuit and reduction LED current ripples, can reduce the current ripples of even eliminating in LED load.
For solving the problems of the technologies described above, the invention provides a kind of LED drive circuit, comprising:
Constant-flow driver, produces the input current that mean value remains unchanged;
The first electric capacity, its first end connects the first output of this constant-flow driver, and its second end connects the second output the ground connection of this constant-flow driver;
Linearity constant current control circuit, be connected between LED load and ground, this LED load after series connection and linearity constant current control circuit and described the first Capacitance parallel connection, this linearity constant current control circuit provides by the voltage-controlled electric current of the outside reference of presetting, and this electric current is the change in voltage a little that is connected in series with LED load with this linearity constant current control circuit not.
According to one embodiment of present invention, this linearity constant current control circuit comprises error amplifier, compensating network and constant-current source circuit, wherein,
The first input end of described error amplifier receives described outside reference voltage, and its second input connects being connected in series a little of described linearity constant current control circuit and LED load, calculates this outside reference voltage and this is connected in series the error voltage between voltage a little;
Described compensating network, its input connects the output of described error amplifier, and the error voltage integration that described error amplifier is exported is with controlled voltage;
Described constant-current source circuit, is connected between described serial connection point and ground and receives described control voltage, to the current value on ground, this current value is not changed according to serial connection point described in described control voltage control with the change in voltage of described serial connection point.
According to one embodiment of present invention, described constant-current source circuit is Voltage-controlled Current Source structure.
According to one embodiment of present invention, described constant-current source circuit comprises: the first nmos pass transistor, and its drain electrode connects described serial connection point, its source ground, its grid receives described control voltage.
According to one embodiment of present invention, described constant-current source circuit comprises:
Amplifier, its first input end receives described control voltage;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
According to one embodiment of present invention, described constant-current source circuit comprises:
Voltage overlaying circuit, its first input end receives described control voltage, and its second input receives default reference voltage, and described control voltage and described reference voltage are superposeed to obtain superimposed voltage;
Amplifier, its first input end receives described superimposed voltage;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
According to one embodiment of present invention, described constant-current source circuit comprises:
Amplifying circuit, its input receives described control voltage, and described control voltage is zoomed in or out;
Amplifier, its first input end connects the output of described amplifying circuit;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
According to one embodiment of present invention, described constant-current source circuit comprises:
See-saw circuit, its input receives described control voltage, carries out anti-phase to described control voltage;
Amplifier, its first input end connects the output of described see-saw circuit;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
According to one embodiment of present invention, the second input of described error amplifier is connected with described serial connection point via the first grounding through resistance and via the second resistance.
According to one embodiment of present invention, described error amplifier is transconductance type error amplifier.
According to one embodiment of present invention, described compensating network is made up of electric capacity, or is made up of electric capacity and resistance.
According to one embodiment of present invention, described compensating network comprises:
The second electric capacity, its first end connects the output of described error amplifier, its second end ground connection;
The 3rd resistance, its first end connects the first end of described the second electric capacity;
The 3rd electric capacity, its first end connects the second end of described the 3rd resistance, its second end ground connection.
According to one embodiment of present invention, the mean value that the magnitude of voltage of described outside reference voltage equals the ripple voltage that described input current produces on described the first electric capacity adds default voltage deviation.
The present invention also provides a kind of method of the LED of reduction current ripples, comprising:
Constant-current source circuit is connected between described LED load and ground to this constant-current source circuit after series connection and LED load and the first Capacitance parallel connection;
The sample voltage a little that is connected in series of this constant-current source circuit and LED load, carries out error by this voltage and default outside reference voltage and amplifies and obtain error voltage, to the controlled voltage of this error voltage integration;
Adopt the current value of constant-current source circuit described in this control voltage control, the magnitude of voltage of this current value and described control voltage is corresponding and do not change with the change in voltage of described serial connection point one by one.
According to one embodiment of present invention, determine in the following way described outside reference voltage:
Determine the mean value of the ripple voltage producing on described the first electric capacity;
The mean value of described ripple voltage adds that default voltage deviation obtains described outside reference voltage.
Compared with prior art, the present invention has the following advantages:
The LED drive circuit of the embodiment of the present invention adopts linearity constant current control circuit to connect with LED load, the electric current that this linearity constant current control circuit provides is the average voltage control a little that is connected in series with LED load by this linearity constant current control circuit, and the average voltage of this serial connection point is set by outside reference voltage, do not change with power frequency through loop compensation make the to flow through electric current of LED load, and the AC portion of the input current changing with power frequency all flows into filter capacitor substantially, thereby can effectively reduce the current ripples of even eliminating in LED load.
Accompanying drawing explanation
Fig. 1 is the structural representation of a kind of LED drive circuit in prior art;
Fig. 2 is the electrical block diagram of the LED drive circuit of first embodiment of the invention;
Fig. 3 is the electrical block diagram of the LED drive circuit of second embodiment of the invention;
Fig. 4 is the electrical block diagram of a kind of constant-current source circuit in the embodiment of the present invention;
Fig. 5 is the electrical block diagram of another kind of constant-current source circuit in the embodiment of the present invention;
Fig. 6 is the electrical block diagram of the LED drive circuit of third embodiment of the invention;
Fig. 7 is the electrical block diagram of the LED drive circuit of fourth embodiment of the invention.
Embodiment
Below in conjunction with specific embodiments and the drawings, the invention will be further described, but should not limit the scope of the invention with this.
The first embodiment
Comprise constant-flow driver 101, the first capacitor C 1 and existing constant-current control circuit 200 with reference to the LED drive circuit in figure 2, the first embodiment, wherein the first capacitor C 1 is called again filter capacitor in this article.
Furthermore, the input current Iin that constant-flow driver 101 remains unchanged for generation of mean value, this input current Iin can contain the alternating component of power frequency.Constant-flow driver 101 can adopt any suitable constant-current drive circuit structure, example constant-flow driver 101 as shown in Figure 1.
The first end of the first capacitor C 1 connects the first output of this constant-flow driver 101, and the second end connects the second output the ground connection GND of this constant-flow driver 101, and in other words, this first capacitor C 1 is connected in parallel on the output port of constant-flow driver 101.The first capacitor C 1 is for filtering, and the voltage at its two ends is denoted as Vin.
Linearity constant current control circuit 200 is connected between LED load and ground GND, and the linearity constant current control circuit 200 after series connection and LED load are in parallel with the first capacitor C 1 again, and linearity constant current control circuit 200 is designated as D point with the point that is connected in series of LED load.Linearity constant current control circuit 200 provides electric current to LED load, and the current value of this electric current is controlled by the outside reference voltage VREF1 presetting, and the current value of this electric current does not change with the variation of the voltage that is connected in series some D.
Further, this linearity constant current control circuit 200 can comprise error amplifier 201, compensating network 202 and constant-current source circuit 203.
Wherein, the first input end of error amplifier 201 receives outside reference voltage VREF1, the second input connects serial connection point D, this error amplifier 201 calculates outside reference voltage VREF1 and the error voltage being connected in series between the voltage of some D, and this error voltage is exported by the output COMP of error amplifier 201.This error amplifier can be for example the error amplifier of transconductance type error amplifier or other appropriate configuration.
Wherein, outside reference voltage VREF1 is preferably in the following way and sets: the ripple size of the input current producing according to constant-flow driver 101 obtains the magnitude of voltage of the upper ripple voltage V1 producing of filter capacitor C1, and the size of this ripple voltage V1 has determined that LED drive circuit reduces the efficiency of ripple; On the basis of the mean value of ripple voltage V1, add default voltage deviation V2 afterwards, thereby obtain the magnitude of voltage of outside reference voltage VREF1.V2 is larger for this voltage deviation, and the effect of eliminating ripple current is better, but efficiency is also just lower.
The input of compensating network 202 connects the output COMP of error amplifier 201, and the error voltage integration that error amplifier 201 is exported is with controlled voltage Vcomp.Compensating network 202 can be made up of electric capacity, or also can be made up of electric capacity and resistance.As a nonrestrictive example, this compensating network 202 can comprise the second capacitor C 2, and its first end connects the output COMP of error amplifier 201, its second end ground connection; The 3rd resistance R 3, its first end connects the first end of the second capacitor C 2; The 3rd capacitor C 3, its first end connects the second end of the 3rd resistance R 3, its second end ground connection.
Constant-current source circuit 203 is connected between serial connection point D and ground GND and receives controls voltage Vcomp, controls the current value of serial connection point D to ground GND according to controlling voltage Vcomp, and this current value is not changed with the change in voltage of serial connection point D.More specifically, in the situation that control voltage Vcomp is fixing, contact D does not change with the change in voltage of serial connection point D to the current value of ground GND, thereby can realize the object that reduces LED load output current ripple.
This constant-current source circuit 203 can be Voltage-controlled Current Source structure, particularly, can under the control of controlling voltage Vcomp, provide corresponding electric current to LED load.
These linearity constant current control circuit 200 entirety are a loop structure, constantly feed back in the course of the work, error amplifier 201 carries out error amplification by outside reference voltage VREF1 with the voltage that is connected in series some D, again via the controlled voltage Vcomp of compensating network 202 integration, the size of the electric current that this control voltage Vcomp control constant-current source circuit 203 provides, can provide fixing current value for given control voltage Vcomp.After loop stability, the mean value of the voltage of serial connection point D equates with the magnitude of voltage of outside reference voltage VREF1, therefore, the mean value of the voltage of serial connection point D can be set by the magnitude of voltage of outside reference voltage VREF1 is set.
In addition, after loop stability, the electric current that flows through LED load equals the mean value of the input AC electric current that inputs to constant-flow driver 101, and ripple current flow into filter capacitor C1 substantially completely, thereby has realized the object that reduces current ripples.
The second embodiment
With reference to figure 3, the circuit structure shown in structure and the Fig. 2 of the LED drive circuit of the second embodiment shown in Fig. 3 is substantially similar, also comprises constant-flow driver 101, the first capacitor C 1 and linearity constant current control circuit 300.This linearity constant current control circuit 300 comprises error amplifier 301, compensating network 302 and constant-current source circuit 303.
Wherein place's difference is, in the second embodiment, the second input of error amplifier 301 is via the first resistance R 1 ground connection, and in addition, the second input of error amplifier 301 is also connected with serial connection point D through the second resistance R 2.
The voltage that the voltage of serial connection point D transfers to the second input of error amplifier 301 via the second resistance R 2 is designated as sampled voltage V
sAMPLE.Sampled voltage V
sAMPLEcan adopt following formula to calculate: V
sAMPLE=V
d* R1/(R1+R2), wherein, V
dfor the magnitude of voltage of serial connection point D, R1 and R2 are respectively the resistance values of the first resistance R 1 and the second resistance R 2.
The structure of compensating network 302 is identical with the first embodiment, also comprises the second capacitor C 2, the 3rd capacitor C 3 and the 3rd resistance R 3.Compensating network 302 can filtering power frequency component, and controlled voltage Vcomp controls voltage Vcomp and is direct current signal or is similar to direct current signal.
Other place's difference is, has provided the concrete structure of constant-current source circuit 303 in the second embodiment, and this constant-current source circuit 303 comprises: the first nmos pass transistor N1, and its drain electrode connects serial connection point D, its source ground GND, its grid receives controls voltage Vcomp.In the situation that control voltage Vcomp is constant, the source-drain current of the first nmos pass transistor N1 is relevant to the source-drain voltage of the first nmos pass transistor N1, and therefore, the characteristic of the constant-current source circuit 303 shown in Fig. 3 is not ideal.For this problem, can improve the structure of constant-current source circuit 303.
With reference to figure 4, Fig. 4 shows a kind of preferred constant-current source circuit, and this constant-current source circuit comprises: amplifier AMP1, the second nmos pass transistor N2 and sampling resistor Rcs.Wherein, the first input end of amplifier AMP1 receives and controls voltage Vcomp; The drain electrode of the second nmos pass transistor N2 connects serial connection point D, and its source electrode connects the second input of amplifier AMP1, and its grid connects the output of amplifier AMP1; The first end of sampling resistor Rcs connects the source electrode of the second nmos pass transistor N2, its second end ground connection.The electric current that the constant-current source circuit of this structure provides can adopt following formula to calculate: Vcomp/Rcs, and wherein Vcomp is the magnitude of voltage of controlling voltage Vcomp, Rcs is the resistance value of sampling resistor Rcs.Compare the constant-current source circuit 303 in Fig. 3, the constant-current source circuit in Fig. 4 has better characteristic.
With reference to figure 5, Fig. 5 shows another kind of preferred constant-current source circuit, and this constant-current source circuit comprises: voltage overlaying circuit 51, amplifier AMP1, the second nmos pass transistor N2 and sampling resistor Rcs.Wherein, the first input end of voltage overlaying circuit 51 receives controls voltage Vcomp, and its second input receives default reference voltage VREF3, and control voltage Vcomp and this reference voltage VREF3 are superposeed to obtain superimposed voltage Vcomp1; The first input end of amplifier AMP1 receives superimposed voltage Vcomp1; The drain electrode of the second nmos pass transistor N2 connects serial connection point D, and its source electrode connects the second input of amplifier AMP1, and its grid connects the output of amplifier AMP1; The first end of sampling resistor Rcs connects the source electrode of the second nmos pass transistor N2, its second end ground connection GND.
In the structure shown in Fig. 5, constant current value is controlled by superimposed voltage Vcomp1, can calculate by following formula: Vcomp1/Rcs.This superimposed voltage Vcomp1 can use adder to obtain, and also can adopt subtracter to obtain.Because reference voltage VREF3 is default fixed value, therefore for fixing control voltage Vcomp, there is a unique constant current value Vcomp1/Rcs corresponding with it.
The 3rd embodiment
With reference to figure 6, the circuit structure shown in structure and the Fig. 3 of the LED drive circuit of the 3rd embodiment shown in Fig. 6 is substantially similar, also comprises constant-flow driver 101, the first capacitor C 1 and linearity constant current control circuit 400.This linearity constant current control circuit 400 comprises error amplifier 401, compensating network 402 and constant-current source circuit 403.
Mainly difference is, in the 3rd embodiment, constant-current source circuit 403 has adopted another kind of preferred circuit structure.This constant-current source circuit 403 comprises amplifying circuit 4031, amplifier 4032, the second nmos pass transistor N2 and sampling resistor Rcs.
Wherein, the input of amplifying circuit 4031 receives controls voltage Vcomp, zooms in or out controlling voltage Vcomp; The first input end of amplifier 4032 connects the output of amplifying circuit 4031; The drain electrode of the second nmos pass transistor N2 connects serial connection point D, and its source electrode connects the second input of amplifier 4032, and its grid connects the output of amplifier 4032; The first end of sampling resistor Rcs connects the source electrode of the second nmos pass transistor N2, its second end ground connection GND.Control the size of removing again to control constant current value after voltage Vcomp zooms in or out via amplifying circuit 4031, the constant current value that constant-current source circuit 403 is provided remains that voltage Vcomp controls by controlling.
The 4th embodiment
With reference to figure 7, the circuit structure shown in structure and the Fig. 6 of the LED drive circuit of the 4th embodiment shown in Fig. 7 is substantially similar, also comprises constant-flow driver 101, the first capacitor C 1 and linearity constant current control circuit 500.This linearity constant current control circuit 500 comprises error amplifier 501, compensating network 502 and constant-current source circuit 503.
Main difference is, in the 4th embodiment, the first input end of error amplifier 501 is positive input terminal, the second input is negative input end, namely the positive input terminal of this error amplifier 501 receives outside reference voltage VREF2, and its negative input end connects serial connection point D via the first resistance R 1 ground connection and via the second resistance R 2.Correspondingly, constant-current source circuit 503 has adopted see-saw circuit 5031, and this constant-current source circuit 503 comprises see-saw circuit 5031, amplifier 5032, the second nmos pass transistor N2 and sampling resistor Rcs.
Wherein, the input of see-saw circuit 5031 receives controls voltage Vcomp, carries out anti-phase to controlling voltage Vcomp; The first input end of amplifier 5032 connects the output of see-saw circuit 5031; The drain electrode of the second nmos pass transistor N2 connects serial connection point D, and its source electrode connects the second input of amplifier 5032, and its grid connects the output of amplifier 5032; The first end of sampling resistor Rcs connects the source electrode of the second nmos pass transistor N2, its second end ground connection GND.Control voltage Vcomp anti-phase via see-saw circuit 4031 after, control constant current value with anti-phase control voltage Vcomp, can realize the effect of the elimination LED ripple voltage identical with Fig. 6.
No matter it should be noted that, be above-mentioned which embodiment, and the magnitude of voltage of the outside reference voltage that error amplifier receives can be determined according to the mean value of the ripple voltage producing on the first electric capacity.Particularly, first determine the magnitude of voltage of the ripple voltage V1 on the first electric capacity, on the basis of the mean value of this ripple voltage V1, add predeterminated voltage deviation V2 afterwards, thereby obtain the magnitude of voltage of outside reference voltage.V2 is larger for this voltage deviation, and the effect of eliminating ripple current is better, but efficiency is also just lower.
In addition, the present invention also provides a kind of method of the LED of reduction current ripples, and the method comprises the steps:
Constant-current source circuit is connected between LED load and ground, this constant-current source circuit after series connection and LED load again with the first Capacitance parallel connection, the constant current value of the electric current that this constant-current source circuit provides is subject to loop control;
According to the size of electric current AC ripple, obtain the mean value of the ripple voltage V1 producing on the first electric capacity, the mean value of this ripple voltage V1 has determined to reduce the efficiency of ripple voltage;
On the mean value basis of ripple voltage V1, add that default voltage deviation V2 is to obtain outside reference voltage VREF1, V2 is larger for this voltage deviation, and the effect of eliminating ripple current is better, but efficiency is lower;
Sampling obtain constant-current source circuit and LED load be connected in series a little on voltage, namely obtain dropping to the voltage on constant-current source circuit, this voltage and outside reference voltage VREF1 are carried out to error amplification, the controlled voltage Vcomp of integration;
Adopt this control voltage Vcomp to control the constant current value of constant-current source circuit, obtain a fixing constant current value for given error voltage Vcomp, namely this constant current value is corresponding one by one with the magnitude of voltage of controlling voltage Vcomp, do not change with the change in voltage being connected in series a little of LED load with constant-current source circuit, thereby the electric current that flows through LED load is remained unchanged.
After loop stability, the electric current that flows through LED load equals the mean value of the input AC electric current of inputting constant-flow driver, and ripple current flow on the first electric capacity substantially completely, has realized the object that reduces current ripples.
The above, be only preferred embodiment of the present invention, not the present invention done to any pro forma restriction.Therefore, every content that does not depart from technical solution of the present invention, just according to technical spirit of the present invention to any simple modification made for any of the above embodiments, the conversion that is equal to, all still belong in the protection range of technical solution of the present invention.
Claims (15)
1. a LED drive circuit, is characterized in that, comprising:
Constant-flow driver, produces the input current that mean value remains unchanged;
The first electric capacity, its first end connects the first output of this constant-flow driver, and its second end connects the second output the ground connection of this constant-flow driver;
Linearity constant current control circuit, be connected between LED load and ground, this LED load after series connection and linearity constant current control circuit and described the first Capacitance parallel connection, this linearity constant current control circuit provides by the voltage-controlled electric current of the outside reference of presetting, and this electric current is the change in voltage a little that is connected in series with LED load with this linearity constant current control circuit not.
2. LED drive circuit according to claim 1, is characterized in that, this linearity constant current control circuit comprises error amplifier, compensating network and constant-current source circuit, wherein,
The first input end of described error amplifier receives described outside reference voltage, and its second input connects being connected in series a little of described linearity constant current control circuit and LED load, calculates this outside reference voltage and this is connected in series the error voltage between voltage a little;
Described compensating network, its input connects the output of described error amplifier, and the error voltage integration that described error amplifier is exported is with controlled voltage;
Described constant-current source circuit, is connected between described serial connection point and ground and receives described control voltage, to the current value on ground, this current value is not changed according to serial connection point described in described control voltage control with the change in voltage of described serial connection point.
3. LED drive circuit according to claim 2, is characterized in that, described constant-current source circuit is Voltage-controlled Current Source structure.
4. LED drive circuit according to claim 3, is characterized in that, described constant-current source circuit comprises: the first nmos pass transistor, and its drain electrode connects described serial connection point, its source ground, its grid receives described control voltage.
5. LED drive circuit according to claim 3, is characterized in that, described constant-current source circuit comprises:
Amplifier, its first input end receives described control voltage;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
6. LED drive circuit according to claim 3, is characterized in that, described constant-current source circuit comprises:
Voltage overlaying circuit, its first input end receives described control voltage, and its second input receives default reference voltage, and described control voltage and described reference voltage are superposeed to obtain superimposed voltage;
Amplifier, its first input end receives described superimposed voltage;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
7. LED drive circuit according to claim 3, is characterized in that, described constant-current source circuit comprises:
Amplifying circuit, its input receives described control voltage, and described control voltage is zoomed in or out;
Amplifier, its first input end connects the output of described amplifying circuit;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
8. LED drive circuit according to claim 3, is characterized in that, described constant-current source circuit comprises:
See-saw circuit, its input receives described control voltage, carries out anti-phase to described control voltage;
Amplifier, its first input end connects the output of described see-saw circuit;
The second nmos pass transistor, its drain electrode connects described serial connection point, and its source electrode connects the second input of described amplifier, and its grid connects the output of described amplifier;
Sampling resistor, its first end connects the source electrode of described the second nmos pass transistor, its second end ground connection.
9. according to the LED drive circuit described in any one in claim 4 to 8, it is characterized in that, the second input of described error amplifier is connected with described serial connection point via the first grounding through resistance and via the second resistance.
10. LED drive circuit according to claim 2, is characterized in that, described error amplifier is transconductance type error amplifier.
11. LED drive circuits according to claim 2, is characterized in that, described compensating network is made up of electric capacity, or are made up of electric capacity and resistance.
12. LED drive circuits according to claim 2, is characterized in that, described compensating network comprises:
The second electric capacity, its first end connects the output of described error amplifier, its second end ground connection;
The 3rd resistance, its first end connects the first end of described the second electric capacity;
The 3rd electric capacity, its first end connects the second end of described the 3rd resistance, its second end ground connection.
13. LED drive circuits according to claim 1, is characterized in that, the mean value that the magnitude of voltage of described outside reference voltage equals the ripple voltage that described input current produces on described the first electric capacity adds default voltage deviation.
14. 1 kinds are reduced the method for LED current ripples, it is characterized in that, comprising:
Constant-current source circuit is connected between described LED load and ground to this constant-current source circuit after series connection and LED load and the first Capacitance parallel connection;
The sample voltage a little that is connected in series of this constant-current source circuit and LED load, carries out error by this voltage and default outside reference voltage and amplifies and obtain error voltage, to the controlled voltage of this error voltage integration;
Adopt the current value of constant-current source circuit described in this control voltage control, the magnitude of voltage of this current value and described control voltage is corresponding and do not change with the change in voltage of described serial connection point one by one.
15. methods according to claim 14, is characterized in that, determine in the following way described outside reference voltage:
Determine the mean value of the ripple voltage producing on described the first electric capacity;
The mean value of described ripple voltage adds that default voltage deviation obtains described outside reference voltage.
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| CN104883793A (en) * | 2015-06-09 | 2015-09-02 | 南京矽力杰半导体技术有限公司 | Multi-path LED current-constant drive circuit and drive method |
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| US10390393B2 (en) | 2015-12-22 | 2019-08-20 | Silergy Semiconductor Technology (Hangzhou) Ltd | Ripple suppression circuit, suppression method and LED lighting apparatus |
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| CN106132031B (en) * | 2016-08-20 | 2018-07-17 | 杰华特微电子（杭州）有限公司 | A kind of ripple eliminates circuit, ripple removing method and applies its LED circuit |
| CN106132031A (en) * | 2016-08-20 | 2016-11-16 | 杰华特微电子（杭州）有限公司 | A kind of ripple eliminates circuit, ripple removing method and applies its LED circuit |
| CN106658862A (en) * | 2017-01-17 | 2017-05-10 | 厦门奇力微电子有限公司 | Current ripple removal circuit and method |
| CN106879109A (en) * | 2017-02-09 | 2017-06-20 | 上海晶丰明源半导体股份有限公司 | Controller, chip and method for eliminating LED drive system current ripples |
| CN106658866A (en) * | 2017-02-09 | 2017-05-10 | 上海晶丰明源半导体股份有限公司 | Controller, chip and method for eliminating current ripple of LED driving system |
| CN106879127A (en) * | 2017-04-19 | 2017-06-20 | 上海晶丰明源半导体股份有限公司 | A kind of pair of controller of LED drive system, chip and method |
| CN107979899A (en) * | 2017-12-27 | 2018-05-01 | 苏州菲达旭微电子有限公司 | A kind of linear general pump feeds constant-current circuit and has its LED light |
| CN109167506A (en) * | 2018-10-26 | 2019-01-08 | 苏州菲达旭微电子有限公司 | A kind of current filtering circuit |
| CN109743811A (en) * | 2018-12-24 | 2019-05-10 | 欧普照明股份有限公司 | A kind of current control circuit |
| CN109890101A (en) * | 2019-01-29 | 2019-06-14 | 威创集团股份有限公司 | A kind of linear constant current circuit |
| CN109890101B (en) * | 2019-01-29 | 2021-06-08 | 威创集团股份有限公司 | Linear constant current circuit |
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