CN104010404A - Light-emitting-diode drive unit - Google Patents
Light-emitting-diode drive unit Download PDFInfo
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- CN104010404A CN104010404A CN201310056534.1A CN201310056534A CN104010404A CN 104010404 A CN104010404 A CN 104010404A CN 201310056534 A CN201310056534 A CN 201310056534A CN 104010404 A CN104010404 A CN 104010404A
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Abstract
Disclosed is a light-emitting-diode drive unit which includes a first constant-current source circuit and a voltage control circuit. The first constant-current source circuit outputs a first constant current to a first node so that the first constant current passes a first LED module arranged between a drive node and the first node, wherein the first constant-current source circuit is provided with a first detection node and generates a first detection signal corresponding to a voltage level at the first node. The voltage control circuit is coupled to the first detection node and generates a control signal coupled to a voltage stabilizing circuit in response to the first detection signal so as to control and adjust the voltage stabilizing circuit to output a drive voltage to the drive node. The light-emitting-diode drive unit can be integrated to an integrated circuit and can automatically adjust the voltage stabilizing circuit to output and maintain a low work voltage without affecting the normal work of a light emitting diode.
Description
Technical field
The present invention has about drive unit, relevant especially light emitting diode drive device.
Background technology
Light-emitting diode (LED) drive unit is widely used in LED drive system, it can be used for detecting the operating state of light-emitting diode and regulate the pressurizer in LED drive system, drives light-emitting diode to export suitable driving voltage.
In traditional light emitting diode drive device, optical assembly is commonly used to detect the cross-pressure of light-emitting diode, but optical assembly difficulty is integrated into integrated circuit (integratedcircuit; IC) in.In view of this, need to there is a kind of brand-new light emitting diode drive device, can be integrated in integrated circuit, also can be used for regulating the driving voltage of pressurizer output to be maintained at low-work voltage and can not affect normal function, to avoid surplus power consumption to produce, reach effect of power saving.
Summary of the invention
The invention provides a kind of light-emitting diode (LED) drive unit, comprise one first constant current source circuit and a voltage control circuit.Electric current to one first node is determined in this first constant current source circuit output one first, makes to be arranged at one first LED module between a driving node and this first node and circulates that this first determines electric current; Wherein, this first constant current source circuit has one first detecting node, and produces one first detection signal corresponding to the voltage level at this first node place.This voltage control circuit couples this first detecting node, and responds this first detection signal and produce a control signal that is coupled to a voltage stabilizing circuit, to control and to regulate this voltage stabilizing circuit to export a driving voltage to this driving node.
Light emitting diode drive device of the present invention can be integrated in integrated circuit, and can automatically adjust voltage stabilizing circuit output and maintain a low-work voltage, normally works and do not affect light-emitting diode.
Brief description of the drawings
Fig. 1 shows the schematic diagram that is coupled to voltage stabilizing circuit and LED module according to the light emitting diode drive device described in one embodiment of the invention.
Fig. 2 shows according to the light emitting diode drive device collocation voltage stabilizing circuit described in another embodiment of the present invention to drive the schematic diagram of many group LED modules.
Fig. 3 shows according to the light emitting diode drive device collocation voltage stabilizing circuit described in one embodiment of the invention to drive the schematic diagram of many group LED modules.
Fig. 4 is the enforcement example that shows the voltage control circuit in light emitting diode drive device shown in Fig. 3.
Fig. 5 A is an enforcement example that shows the voltage stabilizing circuit described in aforementioned each light emitting diode drive device embodiment according to the present invention.
Fig. 5 B is another enforcement example showing according to the voltage stabilizing circuit described in another embodiment of the present invention.
Fig. 6 shows the light emitting diode drive device of implementing according to earlier figures 3 embodiment frameworks, and collocation voltage stabilizing circuit is to drive the schematic diagram of two groups of LED modules.
Fig. 7 A shows that the embodiment of Fig. 6 according to the present invention is in the voltage oscillogram in when operation.
Fig. 7 B shows that the embodiment of Fig. 6 according to the present invention is in the voltage oscillogram in when action.
Fig. 8 shows the schematic diagram that couples two groups of LED modules and voltage stabilizing circuit according to the light emitting diode drive device described in one embodiment of the invention.
Fig. 9 A is the enforcement example that shows this detecting comparison circuit of Fig. 8.
Fig. 9 B shows according to the detecting comparison circuit described in another embodiment of the present invention.
Figure 10 A shows that an embodiment of Fig. 8 according to the present invention is in the voltage oscillogram in when operation.
Figure 10 B shows that another embodiment of Fig. 8 according to the present invention is in the voltage oscillogram in when operation.
Figure 11 shows according to the constant current source circuit described in one embodiment of the invention.
Being simply described as follows of symbol in accompanying drawing:
105,205,305,605,805: light-emitting diode (LED) drive unit
110: the first LED modules
115: the second LED modules
120: the first constant current source circuits
125: the second constant current source circuits
1100: constant current source circuit
130,430,830: voltage control circuit
140,540,545: voltage stabilizing circuit
N
lED: drive node
N1: first node
N2: Section Point
Nd1: the first detecting node
Nd2: the second detecting node
Vin: power supply
150: the first comparators
155: the second comparators
Vref: set voltage
431: or door
432: counter
433: analog converter
CLK: clock signal
560: pressurizer
R1-R5: first-five resistors
Vc[1]: the first comparison signal
Vc[2]: the second comparison signal
Vc, Vc ': control signal
V
lED: driving voltage
831,931,932: detecting comparison circuit
AMP1: operational amplifier
D1-D2: the first-the second diode
M1-M2: first-transistor seconds
V1-V2: first-second voltage
Sd1: the first detection signal
Sd2: the second detection signal
V
nd1A, V
nd1B: the voltage level of the first detection signal
V
nd2A, V
nd2B: the voltage level of the second detection signal
Sc: control signal
Path A: path A
Path B: path B
Tf: feedback end
Tc: control input end
C1: voltage regulation capacitor
V
work: operating voltage
Vr: reference voltage
561: error amplifier
562: voltage regulator circuit
Vt1, Vt2: the current potential of target drives voltage
V
fB: the current potential of feedback end Tf.
Embodiment
Manufacture and the using method of various embodiments of the invention will be discussed in detail below.But it should be noted that many feasible inventive concepts provided by the present invention may be implemented in various particular ranges.These specific embodiments are only for illustrating manufacture of the present invention and using method, but non-for limiting scope of the present invention.
Fig. 1 shows the schematic diagram that is coupled to voltage stabilizing circuit and LED module according to the light emitting diode drive device described in one embodiment of the invention.As shown in Figure 1, light-emitting diode (LED) drive unit 105 comprises: one first constant current source circuit 120 and a voltage control circuit 130.In addition, there is a power supply Vin to be coupled to a voltage stabilizing circuit 140 so that electric power to be provided; This voltage stabilizing circuit 140 and this light emitting diode drive device 105 are coupled to reference to ground connection.This first constant current source circuit 120 provides one first to determine electric current, makes to be arranged at a driving node N
lEDand one one first LED module 110 between first node N1 circulate and one first determine electric current.In addition, this first constant current source circuit 120 has one first detecting node Nd1.This first detecting node Nd1 can produce the one first detection signal Sd1 corresponding to this first node N1 voltage level.This voltage control circuit 130 couples this first detecting node Nd1, responds this first detection signal Sd1 and produces a control signal Sc and export this voltage stabilizing circuit 140 to, to control and to regulate this voltage stabilizing circuit 140 to export a driving voltage V
lEDexport this driving node N to
lED.
Fig. 2 shows according to the light emitting diode drive device collocation voltage stabilizing circuit described in another embodiment of the present invention to drive the schematic diagrames of many group LED modules, at this to drive two groups of LED modules 110 and 115 as example.Compared to Fig. 1, Fig. 2 also comprises one second constant current source circuit 125, in order to provide one second to determine electric current, makes to be arranged at this driving node N
lEDand one this second LED module 115 between Section Point N2 circulate and one second determine electric current.In addition, this second constant current source circuit 125 has one second detecting node Nd2, produces the one second detection signal Sd2 corresponding to this Section Point N2 voltage level.This voltage control circuit 130 of Fig. 2 be coupled to this first and second detecting node (Nd1, Nd2) with receive simultaneously this first and this second detection signal Sd1 and Sd2.Again, this voltage control circuit 130 according to this first and this second detection signal Sd1 and Sd2 and produce this control signal Sc and regulate this driving voltage V to control this voltage stabilizing circuit 140
lED.Fig. 1 and Fig. 2 show that respectively light emitting diode drive device couples one group of LED module and two groups of LED modules.But the present invention is not limited to this, light emitting diode drive device of the present invention can drive multiple LED modules.
Fig. 3 shows according to the light emitting diode drive device collocation voltage stabilizing circuit described in one embodiment of the invention to drive the schematic diagrames of many group LED modules, at this to drive two groups of LED modules 110 and 115 as example.Light emitting diode drive device 305 is to control voltage stabilizing circuit 140 in the mode of digital voltage control (Digtial Voltage Control) to regulate this driving voltage V
lED.Compared to Fig. 2, this light emitting diode drive device 305 also comprises one first comparator 150 and one second comparator 155.This first comparator 150 is located between this first detecting node Nd1 and this voltage control circuit 130, in order to this first detection signal Sd1 and a set voltage Vref are compared; One second comparator 155 is located between this second detecting node Nd2 and this voltage control circuit 130, in order to this second detection signal Sd2 and this set voltage Vref are compared.This voltage control circuit 130 is exported this control signal Sc according to the comparative result of this first comparator 150 and this second comparator 155 and is regulated this driving voltage V to control this voltage stabilizing circuit 140
lED.
Fig. 4 is the enforcement example that shows the voltage control circuit in light emitting diode drive device shown in Fig. 3.The voltage control circuit 430 of Fig. 4 comprises: one or door 431, a counter 432 and a digital analog converter 433.This counter 432 couples output and the digital analog converter 433 of a clock signal CLK or door 431.
Fig. 5 A is an enforcement example that shows the voltage stabilizing circuit described in aforementioned each light emitting diode drive device embodiment according to the present invention.In Fig. 5 A, this voltage stabilizing circuit 540 comprises: pressurizer 560, one first to 1 a 3rd resistor R1～R3.In the time that this voltage stabilizing circuit 140 of Fig. 3 is implemented with the framework of this voltage stabilizing circuit 540 of Fig. 5 A, one end of the 3rd resistor R3 couples this control signal Sc that this voltage control circuit 130 is exported, the other end is couple to this first resistor R1 and the tandem node of this second resistor R2 and a feedback end Tf of this pressurizer 560, and wherein this feedback end Tf has a current potential V
fB.Again, this first resistor R1 of series winding and this second resistor R2 are coupled in this driving node N
lEDand this is with reference between ground connection.One voltage regulation capacitor C1 couples this driving node N
lEDand this is with reference between ground connection.This pressurizer 560, for example, also comprise an error amplifier (error amplifier) 561 and a voltage regulator circuit 562, wherein a first end in1 of this comparator 561 is coupled to this feedback end Tf, and one second end in2 is coupled to a reference voltage Vr and an output ou1 couples this voltage regulator circuit 562.This voltage regulator circuit 562, according to the output of this error amplifier 561, adjusts the output to this driving node N constantly
lEDthis driving voltage V
lED, until the current potential V of this feedback end Tf
fBlevel off to (equaling in fact) this reference voltage Vr.
Fig. 5 B is another enforcement example showing according to the voltage stabilizing circuit described in another embodiment of the present invention.In Fig. 5 B, this voltage stabilizing circuit 545 comprises: a pressurizer 560, the 4th resistor R4 and one the 5th resistor R5.In the time that the voltage stabilizing circuit 140 of Fig. 3 is implemented with the framework of this voltage stabilizing circuit 545 of Fig. 5 B, one control input end Tc of this pressurizer 560, this feedback end Tf that couples this control signal Sc that this voltage control circuit 130 exports and this pressurizer 560 is coupled to the tandem node of the 4th resistor R4 and the 5th resistor R5, and wherein the 4th resistor R4 and the 5th resistor R5 of series winding are coupled to this driving node N
lEDand this is with reference between ground connection.One voltage regulation capacitor C1 couples this driving node N
lEDand this is with reference between ground connection.This voltage stabilizing circuit 545 receives this control signal Sc by this control input end Tc, and adjusts the output to according to this this driving node N
lEDthis driving voltage V
lED; This control signal Sc for example receiving as this control input end Tc is during in first level, and this voltage stabilizing circuit 545 continues to regulate this driving voltage V
lEDuntil this control signal Sc just stops while being changed to a second electrical level regulating.This pressurizer 560 of it should be noted that Fig. 5 A, Fig. 5 B can be switching type voltage stabilizer or linear formula pressurizer, but is not limited to this.
Fig. 6 shows the light emitting diode drive device 605 of implementing according to earlier figures 3 embodiment frameworks, and collocation voltage stabilizing circuit 540 is to drive the schematic diagram of two groups of LED modules.Identical with shown in Fig. 3 of the circuit framework of Fig. 6, difference is only that Fig. 6 further discloses more detailed circuit implementation detail.As shown in Figure 6, this voltage control circuit 130 of Fig. 3 can replace with this voltage control circuit 430 of Fig. 4; Again as shown in Figure 6, this voltage stabilizing circuit 140 of Fig. 3 can replace with this voltage stabilizing circuit 540 of Fig. 5 A.Should or door 431 input be couple to the output of this first comparator 150 and the output of this second comparator 155 to receive one first comparison signal Vc[1] and one second comparison signal Vc[2].This digital analog converter 433 this control signal of output Sc, to this voltage stabilizing circuit 540, regulate this driving voltage V to control this voltage stabilizing circuit 540
lED.In addition, above-mentioned execution mode is only the use of demonstration, but not is used for limiting circuit structure of the present invention.
Fig. 7 A shows that the embodiment of Fig. 6 according to the present invention is in the voltage oscillogram in when operation.With reference to Fig. 6, Fig. 7 A is depicted as the voltage level V of this first detection signal Sd1
nd1Aforward is corresponding to this first node N1 voltage level, the voltage level V of this second detection signal Sd2
nd2Aforward is corresponding to this Section Point N2 voltage level; That is this first and the voltage level V of this second detection signal Sd1 and Sd2
nd1Aand V
nd2A, all forward variations along with the variation of the voltage level of this first node N1 and this Section Point N2.One first comparator 150 and one second comparator 155 are respectively by the voltage level V of this first detecting node Nd1 and this second detecting node Nd2
nd1Aand V
nd2Acompare with a set voltage Vref.
As this voltage stabilizing circuit 540 (power supply Vin provides electrical power to this voltage stabilizing circuit 540 second in t1) in the time that the time, t1 powered on, the voltage level V of this first detection signal Sd1
nd1Aand the voltage level V of this second detection signal Sd2
nd2Aall be less than this set voltage Vref, the one first comparison signal Vc[1 that therefore this first comparator 150 and this second comparator 155 are exported] and one second comparison signal Vc[2] be the logical one of high potential.
During time t1～t2, due to the voltage level V of this first detection signal Sd1
nd1Aand the voltage level V of this second detection signal Sd2
nd2Astill be less than this set voltage Vref, therefore this first comparison signal Vc[1] and this second comparison signal Vc[2] be the logical one of high potential, this or this counter 432 of door 431 activations are counted according to clock signal CLK (being not illustrated in Fig. 7 A), and this digital analog converter 433 changes the current potential Vc of this control signal Sc according to the count value of this counter 432.This voltage control circuit 430 is according to this first comparison signal Vc[1] and this second comparison signal Vc[2] export this control signal Sc current potential Vc can with the every counting of this counter 432 be once stepped down do change.This voltage stabilizing circuit 540 is exported this driving voltage V according to the current potential Vc of this control signal Sc
lED, wherein this driving voltage V
lEDcurrent potential, along with the decline of the current potential Vc of this control signal Sc, and do stepped increase.
In the time of time t2, the voltage level V of this second detection signal Sd2
nd2Abe greater than this set voltage Vref, this second comparison signal Vc[2 that therefore this second comparator 155 is exported] be the logical zero of electronegative potential.But, due to the voltage level V of this first detection signal Sd1
nd1Astill be less than this set voltage Vref, this first comparison signal Vc[1] be still logical one, this or door 431 still this counter 432 of activation are counted.Therefore the current potential of the current potential Vc of this control signal Sc continues to change from stepped down work of high potential; And this driving voltage V
lEDcurrent potential continue to do stepped increase.
After time t3, due to the voltage level V of this first detection signal Sd1
nd1Aand the voltage level V of this second detection signal Sd2
nd2Aall be greater than this set voltage Vref, therefore this first comparison signal Vc[1] and this second comparison signal Vc[2] logic be all " 0 ", should or door 431 make this counter 432 anergies.In this voltage control circuit 430, the current potential Vc current potential of this control signal Sc that this digital analog converter 433 is exported stops declining, therefore this driving voltage V
lEDjust no longer increase.Now, this driving voltage V
lEDbe in suitable low-work voltage and can not affect normal function.
In Fig. 6, this voltage stabilizing circuit 540 can also adopt the voltage stabilizing circuit 545 shown in Fig. 5 B; And this voltage control circuit 430 also can form with simple logical circuit, for example, use separately this or door 431 to supply with this control input end Tc of this voltage stabilizing circuit 545 to produce the current potential Vc ' of this control signal Sc.Please refer to again Fig. 7 A, during time t1 ~ t3, this first comparison signal Vc[1] and this second comparison signal Vc[2] logical value be not " 0 " simultaneously, therefore should or the current potential Vc ' of this control signal Sc of door 431 outputs be still the state that maintains logical one, so this driving voltage V that this voltage stabilizing circuit 545 is exported
lEDcurrent potential present stepped increase.After the t3 time, this first comparison signal Vc[1] and this second comparison signal Vc[2] logic be " 0 " simultaneously, the current potential Vc ' of this control signal Sc that this or door 431 are exported is the state at logical zero, so this voltage stabilizing circuit 545 can not adjusted this driving voltage V again
lEDcurrent potential.
Fig. 7 B shows that the embodiment of Fig. 6 according to the present invention is in the voltage oscillogram in when action.With reference to Fig. 6, Fig. 7 B is depicted as the voltage level V of this first detection signal Sd1
nd1Bthe reverse voltage level corresponding to this first node N1, the voltage level V of this second detection signal Sd2
nd2Bthe reverse voltage level corresponding to this Section Point N2; That is this first and the voltage level V of this second detection signal Sd1 and Sd2
nd1Band V
nd2B, all oppositely variations along with the variation of the voltage level of this first node N1 and this Section Point N2.This first comparator 150 and this second comparator 155 are respectively by the voltage level V of this first detecting node Nd1 and this first detecting node Nd2
nd1Band V
nd2Bcompare with this set voltage Vref.In this example, as voltage level V
nd1B(V
nd2B) Vref while being less than this set voltage, this first comparison signal Vc[1] logical value of (this second comparison signal Vc[2]) is " 0 ".
During time t1 ~ t3, this first comparison signal Vc[1] and this second comparison signal Vc[2] logical value be not " 0 " simultaneously, this or this counter 432 of 431 activations are counted according to clock signal CLK (being not illustrated in Fig. 7 B).As previously mentioned, the current potential Vc of this control signal Sc can steppedly down do to change, and this voltage stabilizing circuit 540 makes this driving voltage V
lEDcurrent potential continue to do stepped increase.
After time t3, this first comparison signal Vc[1] and this second comparison signal Vc[2] logical value be " 0 " simultaneously, therefore this voltage stabilizing circuit 540 this driving voltage V that no longer raises
lED.Now, this driving voltage V
lEDbe in suitable operating voltage and can not affect normal function.
Fig. 8 shows the schematic diagram that couples two groups of LED modules and voltage stabilizing circuit according to the light emitting diode drive device described in one embodiment of the invention.In Fig. 8, this light emitting diode drive device 805 is to control this voltage stabilizing circuit 140 in the mode of analog voltage control (Analog Voltage Control) to regulate this driving voltage V
lED.Wherein, identical with shown in Fig. 2 of the circuit framework of Fig. 8, difference is only that Fig. 8 further discloses more detailed circuit implementation detail.In Fig. 8, a voltage control circuit 830 also comprises a detecting comparison circuit 831.This detecting comparison circuit 831 receives and relatively this first detection signal Sd1 and this second detection signal Sd2, controls and regulate this voltage stabilizing circuit 140 this driving voltage of output V to export this control signal Sc
lEDto this driving node N
lED.
Fig. 9 A is the enforcement example that shows this detecting comparison circuit 831 of Fig. 8.In Fig. 9 A, one detecting comparison circuit 931 comprises: an operational amplifier AMP1, one first diode D1 and one second diode D2, the anode of this first diode D1 and this second diode D2 all couples the positive input terminal (+) of this operational amplifier AMP1, an operating voltage V
workcouple the negative input end (-) of this operational amplifier AMP1.When the voltage level forward of this first detection signal Sd1 is corresponding to the voltage level of this first node N1 and the voltage level forward of this second detection signal Sd2 during corresponding to the voltage level of this Section Point N2, this detecting comparison circuit 831 in Fig. 8 can adopt this detecting comparison circuit 931 shown in Fig. 9 A.In this detecting comparison circuit 931, the negative electrode of this first diode D1 and this second diode D2 is coupled to respectively this first detecting node Nd1 and this second detecting node Nd2, to receive this first detection signal Sd1 and this second detection signal Sd2; This operational amplifier AMP1 exports this control signal Sc.Based on the circuit structure of this detecting comparison circuit 931, in this first detection signal Sd1 and this second detection signal Sd2, there is lower voltage level person, will appear at the positive input terminal (+) of this operational amplifier AMP1 and determine the voltage level Vc of this control signal Sc.
Fig. 9 B is the enforcement example that shows this detecting comparison circuit 831 of Fig. 8.In Fig. 9 B, a detecting comparison circuit 932 comprises: an operational amplifier AMP1, one first diode D1 and one second diode D2.The negative electrode of this first diode D1 and this second diode D2 all couples the negative input end (-) of this operational amplifier AMP1, this operating voltage V
workcouple the positive input terminal (+) of this operational amplifier AMP1.When the voltage level of this first detection signal Sd1 is oppositely corresponding to the voltage level of this first node N1 and the voltage level of this second detection signal Sd2 during oppositely corresponding to the voltage level of this Section Point N2, this detecting comparison circuit 831 in Fig. 8 can adopt this detecting comparison circuit 932 shown in Fig. 9 B.In this detecting comparison circuit 932, the anode of the anode of this first diode D1 and this second diode D2 is coupled to respectively this first detecting node Nd1 and this second detecting node Nd2, to receive this first detection signal Sd1 and this second detection signal Sd2; This operational amplifier AMP1 exports this control signal Sc.Based on the circuit structure of this detecting comparison circuit 932, in this first detection signal Sd1 and this second detection signal Sd2, there is higher voltage level person, will appear at the negative input end (-) of this operational amplifier AMP1 and determine the voltage level Vc of this control signal Sc.
Figure 10 A shows that an embodiment of Fig. 8 according to the present invention is in the voltage oscillogram in when operation.In Figure 10 A, this is first and the voltage level V of this second detection signal Sd1 and Sd2 years old
nd1Aand V
nd2Aforward is corresponding to the voltage level of this first node N1 and this Section Point N2, therefore the detecting comparison circuit 831 of Fig. 8 is implemented with this detecting comparison circuit 931 of Fig. 9 A respectively.In the present embodiment, the voltage stabilizing circuit 140 of Fig. 8 can adopt the voltage stabilizing circuit 540 of Fig. 5 A to implement.
When this voltage stabilizing circuit 540 (being that power supply Vin provides electrical power to this voltage stabilizing circuit 540 in time t1) after the time, t1 powered on, the voltage level of this first node N1 and this Section Point N2 starts to be propradation, and the voltage level V of this first detection signal Sd1 and this second detection signal Sd2
nd1A, V
nd2Aalso be to be propradation.In Figure 10 A, during time t1～t2, due to the voltage level V of this first detection signal Sd1
nd1Abe less than the voltage level V of this second detection signal Sd2
nd2Atherefore the voltage of this operational amplifier AMP1 positive input terminal (+) depends on this first detection signal Sd1.This operational amplifier AMP1 amplifies this first detection signal Sd1 and this operating voltage V
workdifference and export the voltage level Vc of this control signal Sc.
Known as described in Fig. 5 A, this voltage stabilizing circuit 540 changes outputting drive voltage V according to the variation of the voltage level Vc of this control signal Sc
lED, the wherein voltage level Vc of this control signal Sc, this driving voltage V
lEDvoltage V with this feedback end Tf
fBrelationship as shown below:
During time t1～tc, this voltage stabilizing circuit 540 is to this voltage regulation capacitor C1 charging, therefore this driving voltage V
lEDrise gradually, and the voltage level V of this first, second detection signal
nd1Awith V
nd2Aalso forward is corresponding rises.The current potential of the positive input terminal (+) of this detecting comparison circuit 931 is the voltage level V of this first detection signal
nd1Aand be less than this operating voltage V
work, this operational amplifier AMP1 amplifies the difference of positive and negative input (+) and (-); Wherein the voltage level Vc of this control signal Sc of this operational amplifier AMP1 output has exceeded the output area (Vin ~ 0V) of this operational amplifier AMP1, and therefore the voltage level Vc of this control signal Sc is zero potential (the output saturation current potential of this operational amplifier AMP1).T1～tc during this period, due to the voltage V of this feedback end Tf
fBbe less than this reference voltage Vr, this voltage stabilizing circuit 540 continues to promote this driving voltage V
lEDtoward potential vt 1 convergence of target drives voltage.
During time tc～t2, the voltage level V of this first detection signal
nd1Anear this operating voltage V
workthe voltage level Vc of this control signal Sc of this operational amplifier AMP1 output does not exceed the output area (i.e. the voltage level Vc of this control signal Sc of this operational amplifier AMP1 output departs from saturation region) of this operational amplifier AMP1, so the voltage level Vc of this control signal Sc starts to increase, and then make the voltage V of this feedback end Tf
fBalong with the change of the voltage level Vc of this control signal Sc and change (with reference to the signal V of formula (1) and Figure 10 A
fB).The voltage V of this feedback end Tf
fBin the time of time t2, equate with this reference voltage Vr ahead of time, therefore this voltage stabilizing circuit 540 no longer promotes this driving voltage V
lED.The current potential of this target drives voltage is also because the variation of the voltage level Vc of this control signal Sc changes over Vt2 by Vt1.Now this driving voltage V
lEDcurrent potential equate with the potential vt 2 of this target drives voltage, therefore this driving voltage V
lEDreach stable state.Due to this driving voltage V
lEDreach stable state, therefore the voltage level V of this first, second detection signal
nd1A, V
nd2Aalso no longer increase, and then the voltage level Vc of this control signal Sc is no longer increased.
Figure 10 B shows that another embodiment of Fig. 8 according to the present invention is in the voltage oscillogram in when operation.In Figure 10 B, this is first and the voltage level V of this second detection signal Sd1 and Sd2 years old
nd1Aand V
nd2Bthe reverse voltage level corresponding to this first node N1 and this Section Point N2 respectively, therefore the detecting comparison circuit 831 of Fig. 8 is implemented with this detecting comparison circuit 932 of Fig. 9 B.In the present embodiment, the voltage stabilizing circuit 140 of Fig. 8 can adopt the voltage stabilizing circuit 540 of Fig. 5 A to implement.When this voltage stabilizing circuit 540 (being that power supply Vin provides electrical power to this voltage stabilizing circuit 540 in time t1) after the time, t1 powered on, the voltage level of this first node N1 and this Section Point N2 starts to be propradation, and the voltage level V of this first detection signal Sd1 and this second detection signal Sd2
nd1B, V
nd2Boppositely to be decline state.In Figure 10 B, during time t1～t2, the voltage level V of this first detection signal Sd1
nd1Bbe greater than the voltage level V of this second detection signal Sd2
nd2Btherefore the voltage of the negative input end (-) of this operational amplifier AMP1 depends on this first detection signal Sd1.This operational amplifier AMP1 amplifies this first detection signal Sd1 and this operating voltage V
workdifference and export the voltage level Vc of this control signal Sc.
In like manner, known as described in Fig. 5 A, this voltage stabilizing circuit 540 changes outputting drive voltage V according to the variation of the current potential Vc of this control signal Sc
lED.During time t1～tc, the voltage V of this feedback end Tf
fBbe less than this reference voltage Vr, this voltage stabilizing circuit 540 continues to promote this driving voltage V
lED.In time t2, the voltage V of this feedback end Tf
fBequal this reference voltage Vr, this pressurizer 560 no longer promotes this driving voltage V
lED.
Figure 11 shows according to the constant current source circuit described in one embodiment of the invention.Multiple constant current source circuits that this second constant current source circuit 125 shown in this first constant current source circuit 120 shown in Fig. 1～3,6,8, Fig. 2～3,6,8 or light emitting diode drive device use all can Figure 11 certain power circuit 1100 implement.
This constant current source circuit 1100 comprises: the first transistor M1, transistor seconds M2 and an operational amplifier OP.In the present embodiment, the first transistor M1, transistor seconds M2 are nmos pass transistor, but are not limited to this.The source electrode of this first transistor M1 and this transistor seconds M2 series winding and this transistor seconds M2 is coupled to this with reference to ground connection, and wherein the grid of this transistor seconds M2 couples one first voltage V1.The first input end (anode of OP) of this operational amplifier OP couples a second voltage V2, and the second input (negative terminal of OP) couples the tandem node of this first transistor M1 and this transistor seconds M2 and an output and couple the grid of this first transistor M1.In addition, this constant current source circuit 1100 comprises a detecting node.
The present embodiment is taking this first constant current source circuit 120 as example, and in the time that this first constant current source circuit 120 is implemented with this constant current source circuit 1100, the drain electrode of this first transistor M1 couples this first node N1, and this detecting node is as this first detecting node Nd1.If this first detecting node Nd1 is connected to this first node N1 by one first path Path A, this first detection signal Sd1 forward that this first detecting node Nd1 records is corresponding to the voltage level of this first node N1; If this first detecting node Nd1 is connected to the output of this operational amplifier OP by one second path P ath B, this first detection signal Sd1 that this first detecting node Nd1 records is oppositely corresponding to the voltage level of this first node N1.
In like manner, in the time that this second constant current source circuit 125 is implemented with this constant current source circuit 1100, the drain electrode of this first transistor M1 couples this Section Point N2, and this detecting node is as this second detecting node Nd2.This second detecting node Nd2 connects respectively the output of this Section Point or this operational amplifier OP by a Path A or this second path P ath B, can record the second detection signal Sd2 corresponding to this Section Point N2 voltage level forward or backwards.
In preferred embodiment of the present invention, light emitting diode drive device 105,205,305,605,805,1100 can be integrated in integrated circuit and can automatically adjust voltage stabilizing circuit output and maintain a low-work voltage, normally works and do not affect light-emitting diode.
The foregoing is only preferred embodiment of the present invention; so it is not in order to limit scope of the present invention; anyone familiar with this technology; without departing from the spirit and scope of the present invention; can do on this basis further improvement and variation, therefore protection scope of the present invention is when being as the criterion with the application's the scope that claims were defined.
Claims (10)
1. a light emitting diode drive device, is characterized in that, comprising:
One first constant current source circuit, output one first is determined electric current to first node, makes to be arranged at one first LED module between a driving node and this first node and circulates that this first determines electric current; Wherein, this first constant current source circuit has one first detecting node, and produces one first detection signal corresponding to the voltage level at this first node place; And
One voltage control circuit, couples this first detecting node, and responds this first detection signal and produce a control signal that is coupled to a voltage stabilizing circuit, to control and to regulate this voltage stabilizing circuit to export a driving voltage to this driving node.
2. light emitting diode drive device according to claim 1, it is characterized in that, also comprise: one second constant current source circuit, output one second is determined electric current to Section Point, makes to be arranged at one second LED module between this driving node and this Section Point and circulates that this second determines electric current; Wherein, this second constant current source circuit has one second detecting node, and produces one second detection signal corresponding to the voltage level at this Section Point place; Wherein, this voltage control circuit couples this second detecting node, and produces this control signal according to this first detection signal and this second detection signal, regulates this driving voltage to control this voltage stabilizing circuit.
3. light emitting diode drive device according to claim 2, is characterized in that, also comprises: one first comparator, be located between this first detecting node and this voltage control circuit, in order to this first detection signal and a set voltage are compared; And
One second comparator, is located between this second detecting node and this voltage control circuit, in order to this second detection signal and this set voltage are compared;
Wherein, this voltage control circuit is exported this control signal according to the comparative result of this first comparator and this second comparator, regulates this driving voltage to control this voltage stabilizing circuit.
4. light emitting diode drive device according to claim 3, it is characterized in that, in the time that this first detection signal forward is less than this set voltage corresponding to the voltage level at this first node place and this comparative result for this first detection signal or this second detection signal, this this voltage stabilizing circuit of voltage control circuit control this driving voltage that raises; In the time that this first detection signal is oppositely greater than this set voltage corresponding to the voltage level at this first node place and this comparative result for this first detection signal or this second detection signal, this this voltage stabilizing circuit of voltage control circuit control this driving voltage that raises.
5. light emitting diode drive device according to claim 2, is characterized in that, this voltage control circuit comprises a detecting comparison circuit, this detecting comparison circuit reception relatively this first detection signal and this second detection signal;
When this first detection signal forward is during corresponding to the voltage level at this first node place, the output of this detecting comparison circuit corresponding to the difference of have low voltage level in this first detection signal and this second detection signal person and an operating voltage as this control signal, to control this voltage stabilizing circuit this driving voltage that raises;
When this first detection signal is during oppositely corresponding to the voltage level at this first node place, the output of this detecting comparison circuit corresponding to the difference of have high-voltage level in this first detection signal and this second detection signal person and this operating voltage as this control signal, to control this voltage stabilizing circuit this driving voltage that raises.
6. light emitting diode drive device according to claim 1, is characterized in that, this first constant current source circuit comprises:
The first transistor and transistor seconds, be arranged at this first node and with reference between ground connection after serial connection mutually, and the grid of this transistor seconds couples one first voltage; And
One operational amplifier, its first input end couples a second voltage, and its second input couples the tandem node of this first transistor and this transistor seconds, and its output couples the grid of this first transistor.
7. light emitting diode drive device according to claim 6, is characterized in that, this first detecting node is the output of this first node or this operational amplifier.
8. light emitting diode drive device according to claim 7, wherein, this the first detecting node is this first node, in the time that this voltage control circuit judges that this first detection signal is less than a set voltage, this voltage control circuit is exported this control signal, to control this voltage stabilizing circuit this driving voltage that raises.
9. light emitting diode drive device according to claim 7, it is characterized in that, the output that this first detecting node is this operational amplifier, in the time that this voltage control circuit judges that this first detection signal is greater than a set voltage, this voltage control circuit is exported this control signal, to control this voltage stabilizing circuit this driving voltage that raises.
10. light emitting diode drive device according to claim 1, also comprises this voltage stabilizing circuit.
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| CN201310056534.1A CN104010404B (en) | 2013-02-22 | 2013-02-22 | Light emitting diode drive device |
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