CN104640268A - High-power-factor constant-current control circuit and LED (light emitting diode) illuminating equipment - Google Patents
High-power-factor constant-current control circuit and LED (light emitting diode) illuminating equipment Download PDFInfo
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- CN104640268A CN104640268A CN201310552793.3A CN201310552793A CN104640268A CN 104640268 A CN104640268 A CN 104640268A CN 201310552793 A CN201310552793 A CN 201310552793A CN 104640268 A CN104640268 A CN 104640268A
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Abstract
The invention belongs to the technical field of LED (light emitting diode) illumination driving, and provides a high-power-factor constant-current control circuit and LED illuminating equipment. The high-power-factor constant-current control circuit is characterized in that a constant-current source circuit is arranged in a constant-current driving chip on the basis of the existing high-power-factor constant-current control circuit, an error amplifying circuit in the constant-current driving chip is used for sampling a voltage of a first end of the constant-current source circuit, the sampled voltage is compared to a reference voltage, the sampled voltage and the reference voltage are subjected to error amplification and then are outputted to a conduction time control circuit, the inputting voltage of the constant-current source circuit is adjusted by controlling make and break of a switch circuit, the constant-current source circuit can work in a normal constant-current state, constant current flows through an LED load, influences of ripple waves on the LED load are eliminated, strobing is eliminated, eyes of people can be protected, and user experiences are improved.
Description
Technical field
The invention belongs to LED illumination Driving technique field, particularly relate to a kind of High-power-factor constant current control circuit and LED illumination device.
Background technology
Obtaining alternating current from electrical network and power for load equipment after rectification is a kind of conventional drive scheme.If but the power factor of the load equipment of incoming transport electrical network is on the low side, then can cause harmonic pollution to a certain degree to utility network.
In LED illumination Driving technique field, in order to while meeting constant current driving, meet High Power Factor requirement, prior art proposes a kind of by being integrated with active power factor correction and constant current output function in the constant-current driven chip inside of constant-current control circuit, to realize the implementation that high power factor constant current drives, as Fig. 1 shows the structure that existing employing this kind of mode realizes the constant-current control circuit that high power factor constant current drives.
Wherein, switching circuit be used for by off operating mode control output from rectifier circuit to LED load whether, pulse signal generative circuit is for generating the modulation signal of control switch connecting and disconnecting of the circuit state, after error amplifying circuit is used for that the voltage of the voltage of switching circuitry output and reference voltage source is carried out error amplification, export to ON time control circuit, ON time control circuit is used for when the ON time of switching circuit reaches very first time preset value, export to pulse signal generative circuit and turn off control signal, turn-off time control circuit is used for exporting to pulse signal generative circuit when the turn-off time of switching circuit reaches preset value opening control signal.In this circuit, because the mean value the flowing through switching circuit instantaneous value that is the voltage that one exports with rectifier circuit differs the same frequency in-phase signal of a fixed amount, thus achieve High Power Factor.
But in the circuit shown in Fig. 1, in side circuit, the output of rectifier circuit has the half-sinusoid signal with two frequency multiplication same frequencys of civil power, directly LED load is outputted to after switching circuit, therefore can there is the stroboscopic with two frequency multiplication same frequencys of civil power in LED load, the health of infringement human eye, user experience is poor.
Summary of the invention
The object of the embodiment of the present invention is to provide a kind of High-power-factor constant current control circuit, is intended to solve the existing High-power-factor constant current control circuit for driving LED load and makes LED load produce stroboscopic, the health of infringement human eye, the problem of user experience difference.
The embodiment of the present invention is achieved in that a kind of High-power-factor constant current control circuit, comprises rectifier circuit and constant-current driven chip, and described constant-current driven chip comprises:
Switching circuit, for controlled by off operating mode output from described rectifier circuit to LED load whether;
Pulse signal generative circuit, for generating the modulation signal of the on off operating mode controlling described switching circuit;
ON time control circuit, for when the ON time of described switching circuit reaches very first time preset value, exports to described pulse signal generative circuit and turns off control signal, turns off to control described switching circuit;
Turn-off time control circuit, opens control signal, to control described switching circuit conducting for exporting to described pulse signal generative circuit;
Constant-current source circuit, during change in voltage for the first end at constant-current source circuit, produces constant output current, passes through constant current to make described LED load;
Error amplifying circuit, the voltage for the first end to constant-current source circuit samples, and exports to described ON time control circuit after the voltage of sampling voltage and the 3rd reference voltage source is carried out error amplification.
Another object of the embodiment of the present invention is to provide a kind of LED illumination device, comprise LED load and the High-power-factor constant current control circuit being connected described LED load, described High-power-factor constant current control circuit is High-power-factor constant current control circuit as above.
The High-power-factor constant current control circuit that the embodiment of the present invention proposes is on existing High-power-factor constant current control circuit basis, in constant-current driven chip, increase by a constant-current source circuit, error amplifying circuit in constant-current driven chip is by sampling the first end voltage of this constant-current source circuit, sampling voltage and a reference voltage are compared, both amplify through error, output to ON time control circuit, then by the break-make of control switch circuit, the input voltage of adjustment constant-current source circuit, constant-current source circuit is made to be operated in normal constant current state, constant current is passed through to make LED load, thus eliminate the impact of ripple on LED load, and then eliminate stroboscopic phenomenon, human eye health can be protected, promote user experience.
Accompanying drawing explanation
Fig. 1 is the structure chart of the High-power-factor constant current control circuit that prior art provides;
Fig. 2 is the structure chart of the High-power-factor constant current control circuit that first embodiment of the invention provides;
Fig. 3 is the circuit diagram of Fig. 2;
Fig. 4 is the structure chart of the High-power-factor constant current control circuit that second embodiment of the invention provides;
Fig. 5 is the circuit diagram of Fig. 4;
Fig. 6 is the structure chart of the High-power-factor constant current control circuit that third embodiment of the invention provides;
Fig. 7 is the structure chart of the High-power-factor constant current control circuit that fourth embodiment of the invention provides.
Embodiment
In order to make object of the present invention, technical scheme and advantage clearly understand, below in conjunction with drawings and Examples, the present invention is further elaborated.Should be appreciated that specific embodiment described herein only in order to explain the present invention, be not intended to limit the present invention.
For prior art Problems existing, the present invention proposes a kind of High-power-factor constant current control circuit, this circuit is on existing High-power-factor constant current control circuit basis, in constant-current driven chip, increase by a constant-current source circuit, error amplifying circuit in constant-current driven chip is sampled by first end (or claiming input) voltage to this constant-current source circuit, sampling voltage and a reference voltage are compared, both amplify through error, output to ON time control circuit, then by the break-make of control switch circuit, the first end voltage of adjustment constant-current source circuit, constant-current source circuit is made to be operated in normal constant current state, constant current is passed through to make LED load.
Fig. 2 shows the structure of the High-power-factor constant current control circuit that first embodiment of the invention provides, and for convenience of explanation, illustrate only the part relevant to first embodiment of the invention.
Specifically, this High-power-factor constant current control circuit comprise to electric main Vac carry out rectification and export rectifier circuit 2, constant-current driven chip 1, first electric capacity C1, the second electric capacity C2, the first diode D1, inductance L 1.
Wherein, constant-current driven chip 1 comprises: switching circuit 11, the input of switching circuit 11 connects the output of rectifier circuit 2, and the output of switching circuit 11 connects the first end of the first electric capacity C1 and the negative electrode of the first diode D1, the plus earth of the first diode D1; The pulse signal generative circuit 12 of connecting valve circuit 11; The error amplifying circuit 13 of the output of connecting valve circuit 11; Connect the ON time control circuit 14 of pulse signal generative circuit 12 and error amplifying circuit 13, and the output of the first end of the second electric capacity C2 and the input of ON time control circuit 14 and error amplifying circuit 13 connects altogether, second end of the second electric capacity C2 connects equipotential signal ground SGND; Connect the turn-off time control circuit 15 of pulse signal generative circuit 12.
In order to solve prior art Problems existing, different from shown in Fig. 1, in first embodiment of the invention, constant-current driven chip 1 also comprises: constant-current source circuit 16.Now, the output of the first end connecting valve circuit 11 of constant-current source circuit 16, the second end of constant-current source circuit 16 connects the first end of LED load, and the second end of LED load connects second end of the first electric capacity C1, and the second end of LED load is also by inductance L 1 ground connection.Meanwhile, the first end of pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15, constant-current source circuit 16, LED load connects equipotential signal ground SGND; The power end of pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15, constant-current source circuit 16 connects direct current VCC jointly.
In first embodiment of the invention, switching circuit 11 for controlled by off operating mode output from rectifier circuit 2 to load whether, when switching circuit 11 is in conducting state, rectifier circuit 2 exports electric energy to load, inductance L 1 stored energy simultaneously, when switching circuit 11 is in off state, rectifier circuit 2 does not export electric energy to LED load, and inductance L 1 pair of LED load releases energy; Pulse signal generative circuit 12 is for generating the modulation signal of control switch circuit 11 on off operating mode; Error amplifying circuit 13 samples for the voltage of the first end (also claiming input) to constant-current source circuit 16, and after the voltage of sampling voltage and the 3rd reference voltage source is carried out error amplification, exports to ON time control circuit 14; ON time control circuit 14 is for producing relatively-stationary ON time and very first time preset value according to the output of error amplifying circuit 13, and when the ON time of switching circuit 11 reaches very first time preset value, export to pulse signal generative circuit 12 and turn off control signal, turn off with control switch circuit 11; Turn-off time control circuit 15, for when the turn-off time of switching circuit 11 reaches the second time preset value, exports to pulse signal generative circuit 12 and opens control signal, with control switch circuit 11 conducting; Constant-current source circuit 16, for when the change in voltage of its first end, produces constant output current, passes through constant current to make LED load.
The above-mentioned High-power-factor constant current control circuit that below explanation first embodiment of the invention provides realizes the principle that constant current drives: as seen from Figure 2, the size of current flowing through LED load is equal with the size of current flowing through constant-current source circuit 16, direction is identical, therefore only need ensure constant-current source circuit 16 output constant current.According to the operation principle of constant-current source, as long as constant-current source works normally, get final product constant current output.。
The above-mentioned High-power-factor constant current control circuit that below explanation first embodiment of the invention provides realizes the principle of High Power Factor: as shown in Figure 2, error amplifying circuit 13 and the second electric capacity C2 form an average current ring, because average current ring has switch periods average value filtering effect, therefore, the negative terminal input signal of error amplifying circuit 13, also the first end voltage of constant-current source circuit 16 is, the input voltage of constant-current source circuit 16 and the voltage of the 3rd reference voltage source compare, therebetween error is after average current ring amplifies, it is one superposed the low-frequency ripple of twice AC network frequency and the DC level of high frequency switching ripple that average current ring exports (being also the output of error amplifying circuit 13).ON time control circuit 14 modulates a corresponding ON time Ton as very first time preset value according to the DC level that average current ring exports, when the conducting duration of switching circuit 11 reaches Ton, ON time control circuit 14 produces a shutoff control signal and carrys out shutdown switch circuit 11, the the second time preset value set according to turn-off time control circuit 15 afterwards produces a unlatching control signal and carrys out opening switch circuit 11, so repeatedly, the break-make that a switch modulation signal carrys out control switch circuit 11 is formed.Be fixed value by setting the second time preset value Toff, select suitable inductance L 1, make system works under discontinuous operating mode, suppose that the instantaneous value of the voltage that rectifier circuit 2 exports is Uin (t), it is half-sinusoid signal, output voltage is Vout, and the peak current that each switch periods flows through inductance L 1 is Ip (t), and the volt-second characteristic according to discontinuous operating mode has:
（Uin(t)-Vout）×Ton=L1×Ip(t)（3）
Hypothesis flows through the mean value of electric current in each switch periods of switching circuit 11 is again Im (t), and duty ratio is D, and switch periods is T, then, under discontinuous mode, the size of input average current is:
Im(t)=1/2×Ip(t)×D=1/2×Ip(t)×Ton/T（4）
Convolution (3) and formula (4) known:
Im(t)=1/2×Ip(t)×D=1/2×（Ton×Ton/L1/T）×（Uin(t)-Vout）（5）
From formula (5), because Ton, T and L1 are fixed amounts, the mean value therefore flowing through switching circuit 11 is a same frequency in-phase signal differing a fixed amount with Uin (t), thus achieves High Power Factor.
Fig. 3 shows the circuit of Fig. 2.
Particularly, switching circuit 11 can comprise: the first metal-oxide-semiconductor Q1 of N-type, the drain electrode of the first metal-oxide-semiconductor Q1 is as the input of switching circuit 11, and the source electrode of the first metal-oxide-semiconductor Q1 is as the output of switching circuit 11, and the grid of the first metal-oxide-semiconductor Q1 connects pulse signal generative circuit 12.
Particularly, pulse signal generative circuit 12 can comprise: the 5th metal-oxide-semiconductor Q5 of N-type, the 6th metal-oxide-semiconductor Q6 of N-type, the first inverter U7, rest-set flip-flop U6.Wherein, the drain electrode of the 5th metal-oxide-semiconductor Q5 connects direct current VCC, and the source electrode of the 5th metal-oxide-semiconductor Q5 connects the drain electrode of the 6th metal-oxide-semiconductor Q6 and the source electrode of connecting valve circuit the 11, six metal-oxide-semiconductor Q6 meets equipotential signal ground SGND; The grid of the 6th metal-oxide-semiconductor Q6 connects the output of the first inverter U7, and the input of the first inverter U7 connects the grid of the 5th metal-oxide-semiconductor Q5, and connects the same-phase output pin Q of rest-set flip-flop U6; The same-phase output pin Q of rest-set flip-flop U6 connects turn-off time control circuit 15 and ON time control circuit 14 simultaneously; The S pin of rest-set flip-flop U6 connects turn-off time control circuit 15; The R pin of rest-set flip-flop U6 connects ON time control circuit 14.
Particularly, error amplifying circuit 13 can comprise: the first error amplifier U3 and the 3rd reference voltage source 131.Wherein, 3rd reference voltage source 131 connects the positive input terminal of the first error amplifier U3, the negative input end of the first error amplifier U3 connects the first end of the first electric capacity C1, and the output of the first error amplifier U3 connects the first end of ON time control circuit and the second electric capacity C2.
Particularly, ON time control circuit 14 can comprise: the 3rd metal-oxide-semiconductor Q3, the 3rd electric capacity C3 of the 4th metal-oxide-semiconductor Q4, P type of the first comparator U5, the first current source A1, the second inverter U4, N-type.Wherein, the input of the second inverter U4 connects pulse signal generative circuit 12, specifically connects the same-phase output pin Q of rest-set flip-flop U6 in pulse signal generative circuit 12, and the output of the second inverter U4 connects the grid of the 4th metal-oxide-semiconductor Q4; The source electrode of the 4th metal-oxide-semiconductor Q4 is connected equipotential signal ground jointly with the first end of the 3rd electric capacity C3, the drain electrode of the 4th metal-oxide-semiconductor Q4 connects the drain electrode of second end of the 3rd electric capacity C3, the negative input end of the first comparator U5 and the 3rd metal-oxide-semiconductor Q3, and the source electrode of the 3rd metal-oxide-semiconductor Q3 connects the output of the first current source A1; The positive input terminal of the first comparator U5 connects the output connection pulse signal generative circuit 12 of error amplifying circuit 13, first comparator U5, connects the R pin of rest-set flip-flop U6 specifically.
Particularly, turn-off time control circuit 15 can comprise: the 7th metal-oxide-semiconductor Q7, the 4th electric capacity C4 of the 8th metal-oxide-semiconductor Q8, P type of the second comparator U2, the second reference voltage source 151, second current source A2, N-type.Wherein, the grid of the 8th metal-oxide-semiconductor Q8 connects pulse signal generative circuit 12, specifically connect the same-phase output pin Q of rest-set flip-flop U6 in pulse signal generative circuit 12, the source electrode of the 8th metal-oxide-semiconductor Q8 is connected equipotential signal ground SGND jointly with the first end of the 4th electric capacity C4, and the drain electrode of the 8th metal-oxide-semiconductor Q8 connects the drain electrode of second end of the 4th electric capacity C4, the negative input end of the second comparator U2 and the 7th metal-oxide-semiconductor Q7; The source electrode of the 7th metal-oxide-semiconductor Q7 connects the output of the second current source A2, and the grid of the 7th metal-oxide-semiconductor Q7 connects the grid of the 8th metal-oxide-semiconductor Q8; The positive input terminal of the second comparator U2 connects the output connection pulse signal generative circuit 12 of the second reference voltage source 151, second comparator U2, specifically connects the S pin of rest-set flip-flop U6.
Particularly, constant-current source circuit 16 can comprise: the first reference voltage source 161, second error amplifier U1, the second metal-oxide-semiconductor Q2 of N-type, the first resistance R1.Wherein, the positive input terminal of the second error amplifier U1 connects the first reference voltage source 161, the negative input end of the second error amplifier U1 connects the source electrode of the second metal-oxide-semiconductor Q2, the source electrode of the second metal-oxide-semiconductor Q2 connects the first end of the first resistance R1, second end of the first resistance R1 is as the second end of constant-current source circuit 16, the drain electrode of the second metal-oxide-semiconductor Q2 is as the first end of constant-current source circuit 16, and the grid of the second metal-oxide-semiconductor Q2 connects the output of the second error amplifier U1.
Below describe the operation principle of circuit shown in Fig. 3 in detail:
First, when the same-phase output pin Q of rest-set flip-flop U6 exports as high level, first metal-oxide-semiconductor Q1 conducting, the high level that the same-phase output pin Q of rest-set flip-flop U6 exports feeds back to the second inverter U4, second inverter U4 exports as low level, make the 3rd metal-oxide-semiconductor Q3 conducting and the 4th metal-oxide-semiconductor Q4 ends, first current source A1 charges to the 3rd electric capacity C3, and when the voltage of second end of the 3rd electric capacity C3 is less than the DC level Vcomp of error amplifying circuit 13 output, first comparator U5 exports high level, and namely the R pin of rest-set flip-flop U6 is high level; Simultaneously, the high level of the same-phase output pin Q output of rest-set flip-flop U6 feeds back to the grid of the 8th metal-oxide-semiconductor Q8, make the 8th metal-oxide-semiconductor Q8 conducting and the 7th metal-oxide-semiconductor Q7 ends, the negative input end of the second comparator U2 is low level, the output of the second comparator U2 is high level, namely the S pin of rest-set flip-flop U6 is high level, because the R pin of now rest-set flip-flop U6 is also high level, therefore the same-phase output pin Q of rest-set flip-flop U6 keeps current high level output, to maintain the conducting of the first metal-oxide-semiconductor Q1.
Afterwards, along with the charging voltage of second end of the 3rd electric capacity C3 constantly increases, when it is greater than the DC level Vcomp of error amplifying circuit 13 output, first comparator U5 output low level, the R pin saltus step making rest-set flip-flop U6 is low level, and because the S pin of now rest-set flip-flop U6 is high level, therefore the same-phase output pin Q saltus step of rest-set flip-flop U6 is low level, make the 6th metal-oxide-semiconductor Q6 conducting and the 5th metal-oxide-semiconductor Q5 ends, and then turn off the first metal-oxide-semiconductor Q1.
Afterwards, at the first metal-oxide-semiconductor Q1 blocking interval, the low level of the same-phase output pin Q output of rest-set flip-flop U6 feeds back to the input of the second inverter U4, the output of the second inverter U4 is made to be high level, 4th metal-oxide-semiconductor Q4 conducting and the 3rd metal-oxide-semiconductor Q3 ends, and then make the output of the first comparator U5 be high level, namely the R pin of rest-set flip-flop U6 is high level, because the S pin of now rest-set flip-flop U6 is high level, therefore the same-phase output pin Q of rest-set flip-flop U6 keeps current low level output, to maintain the shutoff of the first metal-oxide-semiconductor Q1, simultaneously, the low level of the same-phase output pin Q output of rest-set flip-flop U6 feeds back to the grid of the 8th metal-oxide-semiconductor Q8, 8th metal-oxide-semiconductor Q8 is ended and the 7th metal-oxide-semiconductor Q7 conducting, 4th electric capacity C4 starts charging, when the voltage of second end of the 4th electric capacity C4 is greater than the second reference voltage source 151, second comparator U2 output low level, namely the S pin of rest-set flip-flop U6 is low level, and now the R pin of rest-set flip-flop U6 is high level, therefore the same-phase output pin Q of rest-set flip-flop U6 exports high level, the first metal-oxide-semiconductor Q1 is made to recover conducting, so repeatedly, the break-make realizing switching circuit controls, turn-off time control circuit 15 sets the fixing turn-off time, by selecting suitable inductance L 1, make system works under discontinuous mode.
Error amplifying circuit 13 is by sampling the first end voltage (that is to say the source voltage of the second metal-oxide-semiconductor Q2) of constant-current source circuit, the voltage of sampling voltage and the 3rd reference voltage source is compared, and after error amplification is carried out to both, output to ON time control circuit 14, then by the break-make of control switch circuit 11, the first end voltage of adjustment constant-current source circuit 16, voltage between the source drain that is to say adjustment second metal-oxide-semiconductor Q2, constant-current source circuit 16 is made to be operated in normal constant current state, and then make the constant current hold inputting LED load.
Fig. 4 shows the structure of the High-power-factor constant current control circuit that second embodiment of the invention provides, and for convenience of explanation, illustrate only the part relevant to second embodiment of the invention.
Different from the first embodiment, this High-power-factor constant current control circuit also comprises the second resistance R2 and the 3rd resistance R3, between the earth terminal that second resistance R2 and the 3rd resistance R3 is connected in parallel on inductance L 1 after connecting and the first end of LED load, and one end that the second resistance R2 is connected with resistance R3 connects turn-off time control circuit 15 simultaneously.
Now, different from the first embodiment, turn-off time control circuit 15 is for according to the voltage division signal of the second resistance R2 and the 3rd resistance R3 (in real work, the voltage division signal of the second resistance R2 and the 3rd resistance R3 sets up the detection signal of the zero crossing counting inductive current), export to pulse signal generative circuit 12 and open control signal, with control switch circuit 11 conducting, but not when the turn-off time of switching circuit 11 reaches the second time preset value, export to pulse pulse signal generating circuit 12 and open control signal.That is to say, under this kind of structure, the opening of switching circuit 11 controls by the working condition of LED load, but not the set time control arranged by constant-current driven chip 1 internal circuit, user is by adjusting the opening time of switching circuit 11 to the resistance setting of the second resistance R2 and the 3rd resistance R3, flexibility is higher.
Fig. 5 shows the circuit of Fig. 4.
Different from shown in Fig. 3, now, in pulse signal generative circuit 12, the same-phase output pin Q of rest-set flip-flop U6 is not connected with turn-off time control circuit 15; Turn-off time control circuit 15 can comprise: the second comparator U2, the second reference voltage source 151.Wherein, one end that the negative input end of the second comparator U2 connects the second resistance R2, that be connected with the 3rd resistance R3, the positive input terminal of the second comparator U2 connects the second reference voltage source 151, the output of the second comparator U2 connects pulse signal generative circuit 12, specifically connects the S pin of rest-set flip-flop U6.Structure and the annexation of all the other each several parts are same as shown in Figure 3, are not repeated herein.
Fig. 6 shows the structure of the High-power-factor constant current control circuit that third embodiment of the invention provides, and for convenience of explanation, illustrate only the part relevant to third embodiment of the invention.
Different with the second embodiment from the first embodiment, this High-power-factor constant current control circuit adopts reverse exciting topological structure, comprise rectification is carried out to electric main Vac and the rectifier circuit 2 exported, constant-current driven chip 1, first transformer T1, the 4th resistance R4, the 5th resistance R5, the 5th electric capacity C5, the second diode D2, the second electric capacity C2.
Wherein, the first end of the former limit winding B1 of the first transformer T1 connects the output of rectifier circuit 2, second end of former limit winding B1 connects constant-current driven chip 1, the first end of the vice-side winding B2 of the first transformer T1 connects the anode of the second diode D2, and the negative electrode of the second diode D2 connects the first end of LED load and connects equipotential signal ground SGND by the 5th electric capacity C5; The first end of the auxiliary winding B3 of the first transformer T1 connects second end of vice-side winding B2 and connects equipotential signal ground SGND, after the 4th resistance R4 and the 5th resistance R5 connects, between the first end being connected in parallel on auxiliary winding B3 and the second end; Second end of LED load connects constant-current driven chip 1.
Now, constant-current driven chip 1 comprises: switching circuit 11, and the input of switching circuit 11 connects second end of former limit winding B1; Pulse signal generative circuit 12, pulse signal generative circuit 12 connecting valve circuit 11; Error amplifying circuit 13, error amplifying circuit 13 connects the first end of constant-current source circuit 16 and the second end of LED load; ON time control circuit 14, ON time control circuit 14 connects pulse signal generative circuit 12 and error amplifying circuit 13, and the output of the first end of the second electric capacity C2 and the input of ON time control circuit 14 and error amplifying circuit 13 connects altogether, second end of the second electric capacity C2 connects equipotential signal ground SGND; Turn-off time control circuit 15, turn-off time control circuit 15 connects pulse signal generative circuit 12, and turn-off time control circuit 15 connects one end that the 4th resistance R4 is connected with the 5th resistance R5 simultaneously; Constant-current source circuit 16, the first end of constant-current source circuit 16 connects the second end of LED load, and the second end of constant-current source circuit 16 connects equipotential signal ground SGND.Meanwhile, pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15 connect equipotential signal ground SGND; The power end of pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15, constant-current source circuit 16 connects direct current VCC jointly.In constant-current driven chip 1, the concrete structure of each circuit is as described in embodiment two, is not repeated herein.
Different with the second embodiment from the first embodiment, the first end of constant-current source circuit 16 connects second end (i.e. the output of LED load) of LED load, error amplifying circuit 13 is by sampling the first end voltage (i.e. LED load output end voltage) of this constant-current source circuit 16, sampling voltage and a reference voltage are compared, both amplify through error, output to ON time control circuit, then by the break-make of control switch circuit, the input voltage of adjustment constant-current source circuit, constant-current source circuit is made to be operated in normal constant current state, constant current is passed through to make LED load.In addition, turn-off time control circuit 15 is for the voltage division signal according to the 4th resistance R4 and the 5th resistance R5, export to pulse signal generative circuit 12 and open control signal, open with control switch circuit 11, that is to say, under this kind of structure, the opening of switching circuit 11 is control by the working condition of LED load equally, but not the set time control arranged by constant-current driven chip 1 internal circuit, user is by adjusting the opening time of switching circuit 11 to the resistance setting of the 4th resistance R4 and the 5th resistance R5, flexibility is higher.
Fig. 7 shows the structure of the High-power-factor constant current control circuit that fourth embodiment of the invention provides, and for convenience of explanation, illustrate only the part relevant to fourth embodiment of the invention.
Different from previous embodiment, this High-power-factor constant current control circuit adopt boost topology, comprise to electric main Vac carry out rectification and export rectifier circuit 2, constant-current driven chip 1, second transformer T2, the 6th resistance R6, the 7th resistance R7, the 6th electric capacity C6, the 3rd diode D3, the second electric capacity C2.
Wherein, the first end of the former limit winding B4 of the second transformer T2 connects the output of rectifier circuit 2, second end of former limit winding B4 connects constant-current driven chip 1, and connecting the anode of the 3rd diode D3, the negative electrode of the 3rd diode D3 connects the first end of LED load and connects equipotential signal ground SGND by the 6th electric capacity C6; The first end of the vice-side winding B5 of the second transformer T2 is connected equipotential signal ground SGND by the 6th resistance R6 of series connection mutually with the 7th resistance R7, and second end of vice-side winding B5 connects equipotential signal ground SGND; Second end of LED load connects constant-current driven chip 1.
Now, constant-current driven chip 1 comprises: switching circuit 11, and the input of switching circuit 11 connects second end of former limit winding B4; Pulse signal generative circuit 12, pulse signal generative circuit 12 connecting valve circuit 11; Error amplifying circuit 13, error amplifying circuit 13 connects the first end of constant-current source circuit 16 and the second end of LED load; ON time control circuit 14, ON time control circuit 14 connects pulse signal generative circuit 12 and error amplifying circuit 13, and the output of the first end of the second electric capacity C2 and the input of ON time control circuit 14 and error amplifying circuit 13 connects altogether, second end of the second electric capacity C2 connects equipotential signal ground SGND; Turn-off time control circuit 15, turn-off time control circuit 15 connects pulse signal generative circuit 12, and turn-off time control circuit 15 connects one end that the 6th resistance R6 is connected with the 7th resistance R7 simultaneously; Constant-current source circuit 16, the first end of constant-current source circuit 16 connects the second end of LED load, and the second end of constant-current source circuit 16 connects equipotential signal ground SGND.Meanwhile, pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15 connect equipotential signal ground SGND; The power end of pulse signal generative circuit 12, error amplifying circuit 13, ON time control circuit 14, turn-off time control circuit 15, constant-current source circuit 16 connects direct current VCC jointly.In constant-current driven chip 1, the concrete structure of each circuit is as described in embodiment two, is not repeated herein.
Identical with embodiment three, the first end of constant-current source circuit 16 connects LED load output, error amplifying circuit 13 is by sampling the first end voltage (i.e. LED load output end voltage) of this constant-current source circuit 16, sampling voltage and a reference voltage are compared, both amplify through error, output to ON time control circuit 14, then by the break-make of control switch circuit, the input voltage of adjustment constant-current source circuit, make constant-current source circuit be operated in normal constant current state, pass through constant current to make LED load.In addition, turn-off time control circuit 15 is for the voltage division signal according to the 6th resistance R6 and the 7th resistance R7, export to pulse signal generative circuit 12 and open control signal, open with control switch circuit 11, that is to say, under this kind of structure, the opening of switching circuit 11 is control by the working condition of LED load equally, but not the set time control arranged by constant-current driven chip 1 internal circuit, user is by setting to the resistance of the 6th resistance R6 and the 7th resistance R7 the opening time adjusting switching circuit 11, and flexibility is higher.
Fifth embodiment of the invention provides a kind of LED illumination device, comprise LED load and the High-power-factor constant current control circuit being connected LED load, this High-power-factor constant current control circuit is the High-power-factor constant current control circuit as above in first embodiment of the invention to the 4th embodiment described in any embodiment, is not repeated herein.
The High-power-factor constant current control circuit that the present invention proposes is on existing High-power-factor constant current control circuit basis, in constant-current driven chip, increase by a constant-current source circuit, error amplifying circuit in constant-current driven chip is by sampling the first end voltage of this constant-current source circuit, sampling voltage and a reference voltage are compared, both amplify through error, output to ON time control circuit, then by the break-make of control switch circuit, the first end voltage of adjustment constant-current source circuit, constant-current source circuit is made to be operated in normal constant current state, constant current is passed through to make LED load, thus eliminate the impact of ripple on LED load, and then eliminate stroboscopic phenomenon, human eye health can be protected, promote user experience.
The foregoing is only preferred embodiment of the present invention, not in order to limit the present invention, all any amendments done within the spirit and principles in the present invention, equivalent replacement and improvement etc., all should be included within protection scope of the present invention.
Claims (11)
1. a High-power-factor constant current control circuit, comprises rectifier circuit and constant-current driven chip, it is characterized in that, described constant-current driven chip comprises:
Switching circuit, for controlled by off operating mode output from described rectifier circuit to LED load whether;
Pulse signal generative circuit, for generating the modulation signal of the on off operating mode controlling described switching circuit;
ON time control circuit, for when the ON time of described switching circuit reaches very first time preset value, exports to described pulse signal generative circuit and turns off control signal, turns off to control described switching circuit;
Turn-off time control circuit, opens control signal, to control described switching circuit conducting for exporting to described pulse signal generative circuit;
Constant-current source circuit, during change in voltage for the first end at described constant-current source circuit, produces constant output current, passes through constant current to make described LED load;
Error amplifying circuit, the voltage for the first end to described constant-current source circuit samples, and exports to described ON time control circuit after the voltage of sampling voltage and the 3rd reference voltage source is carried out error amplification.
2. High-power-factor constant current control circuit as claimed in claim 1, it is characterized in that, described High-power-factor constant current control circuit also comprises the first electric capacity, the second electric capacity, the first diode, inductance;
The output of described switching circuit connects the first end of described first electric capacity and the negative electrode of described first diode, the plus earth of described first diode;
The first end of described constant-current source circuit connects the output of described switching circuit, described constant-current source circuit the second end connect the first end of described LED load, second end of described LED load connects the second end of described first electric capacity, and the second end of described LED load is also by described inductance ground connection;
The input of the first end of described second electric capacity and the output of described error amplifying circuit and described ON time control circuit connects altogether, and the second end of described second electric capacity connects equipotential signal ground.
3. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described pulse signal generative circuit comprises: the 5th metal-oxide-semiconductor of N-type, the 6th metal-oxide-semiconductor of N-type, the first inverter, rest-set flip-flop;
The drain electrode of described 5th metal-oxide-semiconductor connects direct current, the source electrode of described 5th metal-oxide-semiconductor connects the drain electrode of described 6th metal-oxide-semiconductor and connects described switching circuit, the source electrode of described 6th metal-oxide-semiconductor connects equipotential signal ground, the grid of described 6th metal-oxide-semiconductor connects the output of described first inverter, the input of described first inverter connects the grid of described 5th metal-oxide-semiconductor, and connect the same-phase output pin of described rest-set flip-flop, the same-phase output pin of described rest-set flip-flop connects described ON time control circuit simultaneously, the S pin of described rest-set flip-flop connects described turn-off time control circuit, the R pin of described rest-set flip-flop connects described ON time control circuit.
4. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described ON time control circuit comprises: the 4th metal-oxide-semiconductor of the first comparator, the first current source, the second inverter, N-type, the 3rd metal-oxide-semiconductor of P type, the 3rd electric capacity;
The input of described second inverter connects described pulse signal generative circuit, the output of described second inverter connects the grid of described 4th metal-oxide-semiconductor, the source electrode of described 4th metal-oxide-semiconductor is connected equipotential signal ground jointly with the first end of described 3rd electric capacity, the drain electrode of described 4th metal-oxide-semiconductor connects the second end of described 3rd electric capacity, the negative input end of described first comparator, and the drain electrode of described 3rd metal-oxide-semiconductor, the source electrode of described 3rd metal-oxide-semiconductor connects the output of described first current source, the positive input terminal of described first comparator connects described error amplifying circuit, the output of described first comparator connects described pulse signal generative circuit.
5. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described error amplifying circuit comprises: the first error amplifier and the 3rd reference voltage source;
Described 3rd reference voltage source connects the positive input terminal of described first error amplifier, the negative input end of described first error amplifier connects the first end of described constant-current source circuit, and the output of described first error amplifier connects the first end of described ON time control circuit and described second electric capacity.
6. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described constant-current source circuit comprises: the second metal-oxide-semiconductor of the first reference voltage source, the second error amplifier, N-type;
The positive input terminal of described second error amplifier connects described first reference voltage source, the negative input end of described second error amplifier connects the source electrode of described second metal-oxide-semiconductor, the source electrode of described second metal-oxide-semiconductor is as the second end of described constant-current source circuit, the drain electrode of described second metal-oxide-semiconductor is as the first end of described constant-current source circuit, and the grid of described second metal-oxide-semiconductor connects the output of described second error amplifier.
7. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described turn-off time control circuit comprises: the 8th metal-oxide-semiconductor of the second comparator, the second reference voltage source, the second current source, N-type, the 7th metal-oxide-semiconductor of P type, the 4th electric capacity;
The grid of described 8th metal-oxide-semiconductor connects described pulse signal generative circuit, the source electrode of described 8th metal-oxide-semiconductor is connected equipotential signal ground jointly with the first end of the 4th electric capacity, the drain electrode of described 8th metal-oxide-semiconductor connects the second end of described 4th electric capacity, the negative input end of described second comparator, and the drain electrode of described 7th metal-oxide-semiconductor, the source electrode of described 7th metal-oxide-semiconductor connects the output of described second current source, the grid of described 7th metal-oxide-semiconductor connects the grid of described 8th metal-oxide-semiconductor, the positive input terminal of described second comparator connects described second reference voltage source, the output of described second comparator connects described pulse signal generative circuit.
8. High-power-factor constant current control circuit as claimed in claim 2, it is characterized in that, described High-power-factor constant current control circuit also comprises the second resistance and the 3rd resistance, is connected in parallel between the earth terminal of described inductance and the first end of described LED load after described second resistance and described 3rd resistant series; Described turn-off time control circuit comprises: the second comparator, the second reference voltage source;
One end that the negative input end of described second comparator connects described second resistance, that be connected with described 3rd resistance, the positive input terminal of described second comparator connects described second reference voltage source, is that the output of the second comparator connects described pulse signal generative circuit.
9. High-power-factor constant current control circuit as claimed in claim 1, it is characterized in that, described High-power-factor constant current control circuit also comprises the first transformer, the 4th resistance, the 5th resistance, the 5th electric capacity, the second diode, the second electric capacity;
The first end of the former limit winding of described first transformer connects the output of described rectifier circuit, second end of described former limit winding connects described constant-current driven chip, the first end of the vice-side winding of described first transformer connects the anode of described second diode, the negative electrode of described second diode connects the first end of described LED load and connects equipotential signal ground by described 5th electric capacity, the first end of the auxiliary winding of described first transformer connects the second end of described vice-side winding and connects described equipotential signal ground, after described 4th resistance and described 5th resistant series, between the first end being connected in parallel on described auxiliary winding and the second end, second end of described LED load connects described constant-current driven chip,
The input of described switching circuit connects the second end of described former limit winding, described error amplifying circuit connects the first end of described constant-current source circuit and the second end of described LED load, described turn-off time control circuit connects one end that described 4th resistance is connected with described 5th resistance, the first end of described constant-current source circuit connects the second end of described LED load, second end of described constant-current source circuit connects described equipotential signal ground, the first end of described second electric capacity and the input of described ON time control circuit and the output of described error amplifying circuit connect altogether, and the second end of described second electric capacity connects described equipotential signal ground.
10. High-power-factor constant current control circuit as claimed in claim 1, it is characterized in that, described High-power-factor constant current control circuit also comprises the second transformer, the 6th resistance, the 7th resistance, the 6th electric capacity, the 3rd diode, the second electric capacity;
The first end of the former limit winding of described second transformer connects the output of described rectifier circuit, second end of described former limit winding connects described constant-current driven chip, and connect the anode of described 3rd diode, the negative electrode of described 3rd diode connects the first end of described LED load and connects equipotential signal ground by described 6th electric capacity, the first end of the vice-side winding of described second transformer is connected described equipotential signal ground by described 6th resistance of series connection mutually with described 7th resistance, second end of described vice-side winding connects described equipotential signal ground, second end of described LED load connects described constant-current driven chip,
The input of described switching circuit connects the second end of described former limit winding, described error amplifying circuit connects the first end of described constant-current source circuit and the second end of described LED load, described turn-off time control circuit connects one end that described 6th resistance is connected with described 7th resistance, the first end of described constant-current source circuit connects the second end of described LED load, second end of described constant-current source circuit connects described equipotential signal ground, the first end of described second electric capacity and the input of described ON time control circuit and the output of described error amplifying circuit connect altogether, and the second end of described second electric capacity connects described equipotential signal ground.
11. 1 kinds of LED illumination device, comprise LED load and the High-power-factor constant current control circuit being connected described LED load, it is characterized in that, described High-power-factor constant current control circuit is the High-power-factor constant current control circuit as described in any one of claim 1 to 10.
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