CN103889088A - Light emitting diode driving circuit and operation method thereof - Google Patents
Light emitting diode driving circuit and operation method thereof Download PDFInfo
- Publication number
- CN103889088A CN103889088A CN201310237655.6A CN201310237655A CN103889088A CN 103889088 A CN103889088 A CN 103889088A CN 201310237655 A CN201310237655 A CN 201310237655A CN 103889088 A CN103889088 A CN 103889088A
- Authority
- CN
- China
- Prior art keywords
- mentioned
- voltage
- transistor
- resistance
- led
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- 238000000034 method Methods 0.000 title claims description 14
- 230000003321 amplification Effects 0.000 claims description 7
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 7
- 230000008859 change Effects 0.000 claims description 6
- 238000010586 diagram Methods 0.000 description 11
- 230000000694 effects Effects 0.000 description 6
- 239000008186 active pharmaceutical agent Substances 0.000 description 2
- 230000015572 biosynthetic process Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000003467 diminishing effect Effects 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000001105 regulatory effect Effects 0.000 description 1
Images
Landscapes
- Led Devices (AREA)
- Circuit Arrangement For Electric Light Sources In General (AREA)
Abstract
A light emitting diode driving circuit is coupled with a light emitting diode string and an adjusting resistor. The light emitting diode driving circuit comprises a reference current generating unit, a first resistor, a first transistor, a second resistor, a parameter adjusting unit and an operational amplifier. The reference current generating unit provides a reference current according to the adjusting resistor. The first transistor is coupled with the light emitting diode string and the first resistor. The parameter adjusting unit is coupled to the reference current generating unit. A reference voltage node between the reference current generating unit and the parameter adjusting unit provides a reference voltage. The operational amplifier is coupled to the parameter adjustment unit, the first resistor, the second resistor and the first transistor. When the LED current exists among the LED string, the first transistor and the first resistor, the reference voltage is changed along with the LED current.
Description
Technical field
The present invention is relevant with drive circuit, particularly about a kind of LED driving circuit and How It Works thereof.
Background technology
As shown in Figure 1, the LED driving circuit 1 that is applied at present backlight module is according to different setting resistance R
sETadjust LED current I
lEDsize.First, in LED driving circuit 1, can be by by transistor N0 and N1, setting resistance R
sETthe characteristic of first group of voltage follower (Voltage follower) circuit forming with amplifier OP1 obtains setting voltage V
sETequal reference settings voltage V
sETREF, and utilize the current mirror (Current mirror) that transistor N1 and N2 form to obtain reference current I
rEF.
Then, can be with reference to electric current I
rEFbe multiplied by resistance R
tcan obtain reference voltage V
rEF, then pass through by amplifier OP2, resistance R
s, second group of voltage follower circuit forming of transistor MS and light-emitting diodes pipe string LED obtain voltage V
sequal reference voltage V
rEF.Due to LED current I
lEDequal voltage V
sdivided by resistance R
s, therefore, by setting the setting resistance R of different sizes
sETmode can obtain corresponding LED current I
lED.
But, the channel voltage V of each passage (Channel)
cHbe multiplied by LED current I
lEDequal the consumed power size of each passage, that is the consumed power of each passage equals channel voltage V
cHbe multiplied by LED current I
lED.Therefore, at identical LED current I
lEDunder, channel voltage V
cHsize can directly reflect the size of the consumed power of passage.Because power loss can discharge by heat energy conventionally, thereby directly cause the surface temperature of integrated circuit to rise.Especially in the application of the light-emitting diode (LED) backlight module of multichannel (Multi-channel), the surface temperature rise phenomenon of extra integrated circuit that power loss causes is more notable.
Due to channel voltage V
cHequal voltage V
sadd that transistor MS's draws source voltage V
dS, in order effectively to reduce the consumed power size of passage, conventionally can set resistance R by increasing
sETreduce LED current I
lEDsize, and then reduce voltage V
s(reference voltage V
rEF) value, make channel voltage V
cHdiminish.If but do not want to sacrifice LED current I
lEDsize reduces power consumption, certainly will will increase the area of transistor MS, draws source voltage V effectively to reduce it
dSsize, and then make channel voltage V
cHdiminish, but the area of increase transistor MS will cause the raising of production cost.
As shown in Figure 2, suppose that light-emitting diode (LED) backlight module has n the passages such as CH1～CHn, its channel voltage V
cHbe respectively V
cH1～V
cHn.The practice of the power loss that is used for traditionally reducing each passage roughly has following two kinds:
(1) suppose the reference voltage level V of the positive input terminal of error amplifier Gm+receive
fIXfor fixed value, at different LED current I
lEDunder setting, it is upper that all the other voltages all drop on transistor MS, therefore at LED current I
lEDin less situation, fall within power consumption on transistor MS by even more serious.
(2) suppose the reference voltage level V of the positive input terminal of error amplifier Gm+receive
fIXalong with voltage V
sproduce slight variations, due to reference voltage level V
fIXequal smallest passage voltage V
cH,
minalso equal voltage V
sadd that transistor MS's draws source voltage V
dSand draw source voltage V
dSfor fixed value, if LED current I
lEDless, voltage V
sless, make reference voltage level V
fIXalso can produce slight variations, but in fact for overall power consumption and heat energy to improve effect not remarkable.
Therefore, the present invention proposes a kind of LED driving circuit and How It Works thereof, the above-mentioned variety of problems being suffered to solve prior art.
Summary of the invention
A category of the present invention is to propose a kind of LED driving circuit.In a preferred embodiment, LED driving circuit couples light-emitting diodes pipe string and adjusting resistance.LED driving circuit comprises reference current generation unit, the first resistance, the first transistor, the second resistance, parameter adjustment unit and operational amplifier.Reference current generation unit couples adjusting resistance, and provides reference current according to adjusting resistance.The first transistor couples respectively light-emitting diodes pipe string and the first resistance.Parameter adjustment unit couples reference current generation unit, and has reference voltage node between reference current generation unit and parameter adjustment unit, so that reference voltage to be provided.Operational amplifier couples respectively parameter adjustment unit, the first resistance, the second resistance and the first transistor.In the time there is LED current between light-emitting diodes pipe string, the first transistor and the first resistance, reference voltage changes with LED current.
In an embodiment, parameter adjustment unit is transistor seconds.
In an embodiment, parameter adjustment unit is the 3rd resistance.
In an embodiment, LED driving circuit also comprises error amplifier, in order to receive respectively the channel voltage between reference voltage and light-emitting diodes pipe string and the first transistor, and produces error amplification signal according to reference voltage and channel voltage.
In an embodiment, between the first transistor and the first resistance, there is first node, so that the first voltage to be provided, between parameter adjustment unit and the second resistance, there is Section Point, so that second voltage to be provided, second voltage equals reference voltage and deducts the parameter adjustment voltage of parameter adjustment unit, and operational amplifier receives respectively the first voltage and second voltage, and output transistor controls signal to the first transistor.
In an embodiment, the parameter adjustment voltage of parameter adjustment unit draws source voltage with first of the first transistor and equates.
In an embodiment, between the first resistance and the second resistance, there is proportionate relationship.
In an embodiment, between the second size of the first size of the first transistor and transistor seconds, there is proportionate relationship.
In an embodiment, the product of channel voltage and LED current is passage consumed power, and in the time that reference voltage changes with LED current, channel voltage changes thereupon, causes passage consumed power also to change thereupon.
Another category of the present invention is to propose a kind of LED driving circuit How It Works.In a preferred embodiment, LED driving circuit couples light-emitting diodes pipe string and adjusting resistance, and LED driving circuit comprises reference current generation unit, the first resistance, the first transistor, parameter adjustment unit, the second resistance and operational amplifier.Above-mentioned LED driving circuit How It Works comprises the following steps: that (a) reference current generation unit provides reference current according to adjusting resistance; (b) reference voltage node between reference current generation unit and parameter adjustment unit provides reference voltage; (c) operational amplifier respectively the Section Point between the first node between the first transistor and the first resistance and parameter adjustment unit and the second resistance receive the first voltage and second voltage, and output transistor controls signal to the first transistor; (d) in the time there is LED current between light-emitting diodes pipe string, the first transistor and the first resistance, reference voltage changes with LED current.
Compared to prior art, can there is following advantages according to LED driving circuit of the present invention and How It Works thereof: (1) does not need the area that additionally increases integrated circuit can reach the effect that reduces power loss and reduce integrated circuit temperature, to promote service efficiency and the life-span of integrated circuit; (2) in the time increasing setting resistance with minimizing LED current, the reference voltage of error amplifier also declines thereupon, therefore can reduce power loss and reduce integrated circuit temperature; (3) be applied to while having multichannel light-emitting diode (LED) backlight module, the effect that reduces power loss and reduction integrated circuit temperature will be more remarkable; (4), applicable to various LED driving circuit frameworks, for example alternating current AC/ direct current DC adds that the framework of current balance type (Current balance), framework that Boost adds current balance type or Buck/Boost add the framework of current balance type.
Can be further understood by the following detailed description and accompanying drawings about the advantages and spirit of the present invention.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of LED driving circuit of the prior art.
Fig. 2 is the schematic diagram of error amplifier of the prior art.
Fig. 3 A is according to the schematic diagram of the LED driving circuit of a specific embodiment of the present invention.
Fig. 3 B is according to the schematic diagram of the LED driving circuit of another specific embodiment of the present invention.
Fig. 4 is according to the schematic diagram of the error amplifier of a specific embodiment of the present invention.
Fig. 5 is according to the schematic diagram of the LED driving circuit of another specific embodiment of the present invention.
Fig. 6 is the schematic diagram that couples the LED driving circuit of a plurality of light-emitting diodes pipe strings.
Fig. 7 and Fig. 8 are respectively current regulator in Fig. 6 and the detailed circuit diagram of current setting unit setting.
Fig. 9 is according to the flow chart of the LED driving circuit How It Works of another specific embodiment of the present invention.
Main element symbol description:
S10～S22: process step
1,3A, 3B, 5,6: LED driving circuit
I
lED, I
lED1～I
lEDn: LED current
LED, LED1～LEDn: light-emitting diodes pipe string
V
dS, V
dS2: draw source voltage
R
sET: adjusting resistance I
rEF: reference current
N0, N1, N2, MS, MT: transistor
10,30,60: smallest passage voltage selector
Embodiment
A preferred embodiment according to the present invention is a kind of LED driving circuit.In fact, the LED driving circuit in this embodiment is applied to be had in multichannel light-emitting diode (LED) backlight module or other light-emitting diode assemblies, in order to drive and to control the running of light-emitting diode.The mode that LED driving circuit in this embodiment is set resistance by change is adjusted the size of LED current and is downgraded according to this reference voltage of error amplifier, therefore can reduce power loss and reduce integrated circuit temperature, to promote service efficiency and the life-span of integrated circuit.
Please refer to Fig. 3 A, Fig. 3 A is according to the schematic diagram of the LED driving circuit of this embodiment.As shown in Figure 3A, LED driving circuit 3A couples light-emitting diodes pipe string LED and adjusting resistance R
sET.LED driving circuit 3A comprises reference current generation unit RCG, the first resistance R
s, the first transistor MS, the second resistance R
t, parameter adjustment unit R AU, operational amplifier OP and error amplifier GM.
Reference current generation unit RCG couples adjusting resistance R
sET.Parameter adjustment unit R AU is coupled to reference current generation unit RCG and the second resistance R
tbetween.The second resistance R
tbe coupled to earth terminal.Between reference current generation unit RCG and parameter adjustment unit R AU, there is reference voltage node 33, so that reference voltage V to be provided
rEF.The first transistor MS is coupled to light-emitting diodes pipe string LED and the first resistance R
sbetween.The first resistance R
sbe coupled to earth terminal.Light-emitting diodes pipe string LED couples output voltage V
oUT.
The positive input terminal of operational amplifier OP+be coupled to parameter adjustment unit R AU and the second resistance R
tbetween Section Point 32, to receive second voltage V2.The negative input end of operational amplifier OP-be coupled to the first transistor MS and the first resistance R
sbetween first node 31, to receive the first voltage V1.The output K of operational amplifier OP couples the gate of the first transistor MS.The positive input terminal of error amplifier GM+couple reference voltage V
rEF.The negative input end of error amplifier GM-be coupled to the channel voltage node 34 between light-emitting diodes pipe string LED and the first transistor MS, with receive path voltage V
cH.
Reference current generation unit RCG couples operating voltage V
dDand according to adjusting resistance R
sETreference current I is provided
rEFto parameter adjustment unit R AU.In practical application, parameter adjustment unit R AU can be transistor or resistance.Parameter adjustment unit R AU has parameter adjustment voltage V
rA, and parameter adjustment voltage V
rAdraw source voltage V with first of the first transistor MS
dSequate, therefore the second voltage V2 of Section Point 32 equals reference voltage V
rEFdeduct parameter adjustment voltage V
rA.
The first voltage V1 as for first node 31 equals channel voltage V
cHdeduct first of the first transistor MS and draw source voltage V
dS.The negative input end of operational amplifier OP-and positive input terminal+receive respectively the first voltage V1 and second voltage V2, and output transistor control signal CTR is to the first transistor MS.
The positive input terminal of error amplifier GM+and negative input end-receive respectively reference voltage V
rEFand the channel voltage V of channel voltage node 34
cH, and according to reference voltage V
rEFwith channel voltage V
cHproduce error amplification signal Comp.
When light-emitting diodes pipe string LED, the first transistor MS and the first resistance R
sbetween there is LED current I
lEDtime, reference voltage V
rEFwill be with LED current I
lEDchange.In more detail, user can set resistance R by increase
sETmode reduce LED current I
lED, the reference voltage V that error amplifier GM adopts
rEFalso decline thereupon, make channel voltage V
cHalso diminish.Because passage consumed power equals channel voltage V
cHwith LED current I
lEDproduct, when set resistance R
sETwhen increase, LED current I
lEDand channel voltage V
cHall reduce, therefore, passage consumed power also can reduce, and does not need the area that additionally increases integrated circuit can reach the effect that reduces power loss and reduce integrated circuit temperature, to promote service efficiency and the life-span of integrated circuit.
Please refer to Fig. 3 B, the parameter adjustment unit R AU that Fig. 3 B illustrates in Fig. 3 A is an embodiment of transistor seconds MT.As shown in Figure 3 B, transistor seconds MT is in order to the parameter adjustment unit R AU as in Fig. 3 A.The source electrode of transistor seconds MT and drain couple respectively reference current generation unit RCG and the second resistance R
t.The gate of transistor seconds MT couples operating voltage V
dD.
Reference current generation unit RCG comprises transistor N0～N2 and operational amplifier OP1.Wherein, the relative formation current mirror that couples of gate of the gate of transistor N1 and transistor N2.The positive input terminal of operational amplifier OP1+couple reference settings voltage V
sETREF, its negative input end-be coupled to transistor N0 and adjusting resistance R
sETbetween node 36, to receive setting voltage V
sET, its output K1 couples the gate of transistor N0.Adjusting resistance R
sETbe coupled between transistor N0 and earth terminal.Transistor N0 couples respectively transistor N1, adjusting resistance R
sETand operational amplifier OP1.Transistor N1 is coupled to operating voltage V
dDand between transistor N0.Transistor N2 is coupled to operating voltage V
dDand between transistor seconds MT.The gate of transistor N1 is coupled to the node 35 between transistor N1 and N0 with the relative node coupling 37 of gate of transistor N2.
Set electric current I
sETtransistor N1, N0 and adjusting resistance R flow through
sET.Reference current I
rEFflow through transistor N2, transistor seconds MT and the second resistance R
t.Suppose the to flow through setting electric current I of transistor N1
sETvia becoming N reference current I doubly after the gate of the transistor N1 current mirror that couples formation relative to the gate of transistor N2
rEF, that is to say the reference current I of the transistor N2 that flows through
rEFfor the setting electric current I of the transistor N1 that flows through
sETn doubly, N is greater than zero.
Suppose the first resistance R
swith the second resistance R
tbetween proportionate relationship be the second resistance R
tit is the first resistance R
sm doubly, and the proportionate relationship between the first size of the first transistor MS and the second size of transistor seconds MT be the first size of the first transistor MS be transistor seconds MT the second size m doubly, m is greater than zero, in order to make second of transistor seconds MT draw source voltage V
dS2draw source voltage V with first of the first transistor MS
dSequate the second drain of transistor seconds MT-source resistance R
dS2be required to be the first drain-source resistance R of the first transistor MS
dS1m doubly, therefore, the LED current I of the light-emitting diodes pipe string LED that flows through
lEDfor the reference current I of the transistor seconds MT that flows through
rEFm doubly.Can obtain LED current I by following formula 1
lEDbe by variable adjusting resistance R
sETdecide:
I
lED=m*I
rEF=m* (N*I
sET)=m*N* (V
sETREF/ R
sET) (formula 1)
By following the second drain that the can be calculated transistor seconds MT-source resistance R that derives formula 2
dS2for the first drain-source resistance R of the first transistor MS
dS1m doubly:
V
DS=I
LED*R
DS1
V
DS2=I
REF*R
DS2
Due to V
dS=V
dS2and I
lED=m*I
rEF
Therefore (m*I
rEF) * R
dS1=I
rEF* R
dS2
Therefore can obtain R
dS2=m*R
dS1(formula 2)
It should be noted that the reference voltage V of the reference voltage node 33 between transistor N2 and transistor seconds MT
rEFbe to offer error amplifier GM, clearly, reference voltage V
rEFequal second of transistor seconds MT and draw source voltage V
dS2with second voltage V2 sum.By following derive formula 3 can be calculated reference voltage V
rEFalso along with adjusting resistance R
sETand become:
Due to V
dS2=I
rEF* R
dS2
V2=I
REF*R
T
I
REF=N*I
SET=N*(V
SET/R
SET)
Therefore V
rEF=V
dS2+ V2=(I
rEF* R
dS2)+(I
rEF* R
t)
=N*(V
SET/R
SET)(R
DS2+R
T)
And V
sET=V
sETREF
Therefore V
rEF=N* (V
sETREF/ R
sET) (R
dS2+ R
t)
=(1/R
sET) * N*V
sETREF* (R
dS2+ R
t) (formula 3)
From the above: by changing adjusting resistance R
sETthe flow through LED current I of light-emitting diodes pipe string LED of resistance value capable of regulating
lEDsize, meanwhile, also can change the reference voltage V between transistor N2 and transistor seconds MT
rEFsize.For example, if increase adjusting resistance R
sETresistance value, not only can downgrade the LED current I of the light-emitting diodes pipe string LED that flows through
lEDsize, also can downgrade reference voltage V
rEFsize.
Due to channel voltage V
cHequal the first voltage V1 and add that first of the first transistor MS draws source voltage V
dS, and the first transistor MS first draw source voltage V
dSequal second of transistor seconds MT and draw source voltage V
dS2if, ignoring in the situation of offset voltage (Offset Voltage) of operational amplifier OP, the first voltage V1 equals second voltage V2, therefore under the operation of stable state (Steady State), channel voltage V
cHequal reference voltage V
rEF:
V
CH=V1+V
DS
V
REF=V2+V
DS2
Suppose not consider the offset voltage of operational amplifier OP1
V1=V2 and V
dS=V
dS2
Therefore V
cH=V
rEF(formula 4)
Because the passage consumed power of each passage equals channel voltage V
cHbe multiplied by LED current I
lED.Therefore, at identical LED current I
lEDunder, each channel voltage V
cHsize can directly reflect the size of the passage consumed power of above-mentioned passage.From the above: as adjusting resistance R
sETresistance value while increasing, not only can downgrade the LED current I of the light-emitting diodes pipe string LED that flows through
lEDsize, also can downgrade reference voltage V
rEFsize, therefore in LED current I
lEDelectric current when diminishing, channel voltage V
cHalso diminish thereupon, thus can more effective minimizing passage consumed power.
As shown in Figure 4, suppose that light-emitting diode (LED) backlight module comprises n light-emitting diodes pipe string altogether, that is have n passage, its channel voltage is respectively V
cH1～V
cHn.N the channel voltage V by smallest passage voltage selector 30 from n passage
cH1～V
cHnin select smallest passage voltage V
cH,
minand exported to the negative input end of error amplifier Gm-.The negative input end of error amplifier Gm-with positive input terminal+receive respectively smallest passage voltage V
cH, minwith reference voltage V
rEF, and produce according to this error amplification signal Comp.
Fig. 5 illustrates another embodiment of LED driving circuit of the present invention.LED driving circuit 5 in Fig. 5 is with the LED driving circuit 3B difference in Fig. 3 B: be coupled to transistor N2 and the second resistance R
tbetween parameter adjustment unit be not transistor, but resistance R
m.Across resistance R
mthe parameter adjustment voltage V at two ends
rMequal reference voltage V
rEFdeduct second voltage V2, also equal first of the first transistor MS and draw source voltage V
dS.Because the LED driving circuit 3B in operation situation and Fig. 3 B of the LED driving circuit 5 in Fig. 5 is roughly the same, therefore do not repeat separately in this.
Next, comparison prior art and institute of the present invention consumed power will be come with the LED driving circuit with single channel.Suppose resistance R
sbe 4 ohm, in the time that the first voltage V1 is respectively 0.4 volt, 0.2 volt and 0.1 volt, can obtain LED current I
lEDbe respectively 100 milliamperes, 50 milliamperes and 25 milliamperes.
In the case of the size constancy of the first transistor MS, if prior art adopts stationary conduit voltage V
cHbe the mode of 1 volt, as LED current I
lEDbe respectively 100 milliamperes, 50 milliamperes and 25 MAHs, passage consumed power is respectively 100 milliwatts, 50 milliwatts and 25 milliwatts.If prior art adopts first of fixing the first transistor MS to draw source voltage V
dSbe the mode of 0.6 volt, as LED current I
lEDbe respectively 100 milliamperes, 50 milliamperes and 25 MAHs, channel voltage V
cHequal the first voltage V1 and first and draw source voltage V
dSsum, is respectively 1 volt, 0.8 volt and 0.7 volt, therefore passage consumed power is respectively 100 milliwatts, 40 milliwatts and 17.5 milliwatts.From the above: the method that prior art adopts all only can slightly reduce passage consumed power.
But, if the LED driving circuit framework that adopts the present invention to carry, when user increases variable adjusting resistance R
sETresistance value time, LED current I
lEDwill diminish, first of the first transistor MS draws source voltage V
dSalso can diminish, and the first voltage V1 also diminishes, due to channel voltage V
cHequal the first voltage V1 and first and draw source voltage V
dSsum, therefore channel voltage V
cHwill diminish, and passage consumed power equals LED current I thereupon
lEDwith channel voltage V
cHproduct, therefore passage consumed power also can diminish thereupon.Therefore, as LED current I
lEDbe respectively 100 milliamperes, 50 milliamperes and 25 MAHs, first draws source voltage V
dSbe respectively 0.6 volt, 0.3 volt and 0.15 volt, channel voltage V
cHbe respectively 1 volt, 0.5 volt and 0.25 volt, passage consumed power is respectively 100 milliwatts, 25 milliwatts and 6.25 milliwatts, therefore LED driving circuit of the present invention really can significantly reduce passage consumed power.
Please refer to Fig. 6, Fig. 6 is the schematic diagram with the LED driving circuit of plurality of channels.As shown in Figure 6, LED driving circuit 6 couples n light-emitting diodes pipe string LED1～LEDn and adjusting resistance R
sET.LED driving circuit 6 comprises n current regulator CR1～CRn, smallest passage voltage selector 60, current setting unit setting 62 and error amplifier Gm.One end of light-emitting diodes pipe string LED1～LEDn is all coupled to output voltage V
oUT, the other end is coupled to respectively current regulator CR1～CRn.Current regulator CR1～CRn is all coupled to current setting unit setting 62.Error amplifier Gm couples smallest passage voltage selector 60 and current setting unit setting 62.
Between light-emitting diodes pipe string LED1～LEDn and current regulator CR1～CRn, there is respectively n channel voltage V of a corresponding n passage
cH1～V
cHn.Smallest passage voltage selector 60 will receive this n channel voltage V
cH1～V
cHn, and from wherein selecting smallest passage voltage V
cH, min.Between current regulator CR1～CRn and current setting unit setting 62, all there is identical second voltage V2.Error amplifier Gm receives smallest passage voltage V from smallest passage voltage selector 60 and current setting unit setting 62 respectively
cH, minand reference voltage V
rEF, and according to smallest passage voltage V
cH, minwith reference voltage V
rEFoutput error amplifying signal Comp.
Be respectively current regulator CR1 in Fig. 6 and the detailed circuit diagram of current setting unit setting 62 as for Fig. 7 and Fig. 8.Because its circuit framework all can be with reference to Fig. 3 B, therefore do not repeat separately in this.
In sum, LED driving circuit disclosed in this invention is applicable to various LED driving circuit frameworks, and for example alternating current AC/ direct current DC adds that the framework of current balance type (Current balance), framework that Boost adds current balance type or Buck/Boost add the framework of current balance type.
Another specific embodiment of the present invention is a kind of LED driving circuit method of operation.In this embodiment, LED driving circuit method of operation is in order to operating light-emitting diodes (leds) drive circuit.LED driving circuit couples light-emitting diodes pipe string and adjusting resistance, and LED driving circuit comprises reference current generation unit, the first resistance, the first transistor, parameter adjustment unit, the second resistance and operational amplifier.
Please refer to Fig. 9, Fig. 9 is according to the flow chart of the LED driving circuit How It Works of this embodiment.As shown in Figure 9, in step S10, reference current generation unit provides reference current according to adjusting resistance.In step S12, the reference voltage node between reference current generation unit and parameter adjustment unit provides reference voltage.In step S14, the operational amplifier respectively Section Point between the first node between the first transistor and the first resistance and parameter adjustment unit and the second resistance receives the first voltage and second voltage.In step S16, operational amplifier produces transistor controls signal to the first transistor according to the first voltage and second voltage.
Wherein, first of the first transistor draws source voltage and equates with the parameter adjustment voltage of parameter adjustment unit, and has proportionate relationship between the first size of the first transistor and the second size of parameter adjustment unit.In fact, parameter adjustment unit can be transistor or resistance, and the parameter adjustment voltage of parameter adjustment unit can be transistorized source voltage or the magnitude of voltage across resistance two ends of drawing.
In step S18, said method receives respectively the channel voltage between reference voltage and light-emitting diodes pipe string and the first transistor, and produces error amplification signal according to reference voltage and channel voltage.In step S20, in the time there is LED current between light-emitting diodes pipe string, the first transistor and the first resistance, reference voltage changes with LED current.In step S22, in the time that reference voltage changes with LED current, channel voltage changes thereupon, causes passage consumed power also to change thereupon.
Suppose that LED driving circuit couples a plurality of light-emitting diodes pipe strings, that is there is plurality of channels, in step S18, said method can first be selected minimum channel voltage from the plurality of channels voltage corresponding to plurality of channels, and amplifies reference voltage generation error amplification signal according to minimum channel voltage and error.
For example, suppose the second resistance be the first resistance m doubly, and the first size of the first transistor also for the m of the second size of parameter adjustment unit doubly, m is greater than zero.The the second drain-source resistance of parameter adjustment unit be the first transistor the first drain-source resistance m doubly, and the LED current of the light-emitting diodes pipe string of flowing through be flow through parameter adjustment unit reference current m doubly.
Compared to prior art, can there is following advantages according to LED driving circuit of the present invention and How It Works thereof: (1) does not need the area that additionally increases integrated circuit can reach the effect that reduces power loss and reduce integrated circuit temperature, to promote service efficiency and the life-span of integrated circuit; (2) in the time increasing setting resistance with minimizing LED current, the error of error amplifier is amplified reference voltage and is also declined thereupon, therefore can reduce power loss and reduce integrated circuit temperature; (3) be applied to while having multichannel light-emitting diode (LED) backlight module, the effect that reduces power loss and reduction integrated circuit temperature will be more remarkable; (4), applicable to various LED driving circuit frameworks, for example alternating current AC/ direct current DC adds that the framework of current balance type, framework that Boost adds current balance type or Buck/Boost add the framework of current balance type.
By the above detailed description of preferred embodiments, hope can be known description feature of the present invention and spirit more, and not with above-mentioned disclosed preferred embodiment, category of the present invention is limited.On the contrary, its objective is that hope can contain in the category of the scope of the claims of being arranged in of various changes and tool equality institute of the present invention wish application.
Claims (14)
1. a LED driving circuit, is characterized in that, couples a light-emitting diodes pipe string and an adjusting resistance, and above-mentioned LED driving circuit comprises:
One reference current generation unit, couples above-mentioned adjusting resistance, and provides a reference current according to above-mentioned adjusting resistance;
One first resistance;
One the first transistor, couples respectively above-mentioned light-emitting diodes pipe string and above-mentioned the first resistance;
One parameter adjustment unit, couples above-mentioned reference current generation unit, and has a reference voltage node between above-mentioned reference current generation unit and above-mentioned parameter adjustment unit, so that a reference voltage to be provided;
One second resistance; And
One operational amplifier, couples respectively above-mentioned parameter adjustment unit, above-mentioned the first resistance, above-mentioned the second resistance and above-mentioned the first transistor,
Wherein, in the time there is a LED current between above-mentioned light-emitting diodes pipe string, above-mentioned the first transistor and above-mentioned the first resistance, above-mentioned reference voltage changes with above-mentioned LED current.
2. LED driving circuit as claimed in claim 1, is characterized in that, above-mentioned parameter adjustment unit is a transistor seconds.
3. LED driving circuit as claimed in claim 1, is characterized in that, above-mentioned parameter adjustment unit is one the 3rd resistance.
4. LED driving circuit as claimed in claim 1, is characterized in that, above-mentioned LED driving circuit also comprises:
One error amplifier, in order to receive respectively the channel voltage between above-mentioned reference voltage and above-mentioned light-emitting diodes pipe string and above-mentioned the first transistor, and produces an error amplification signal according to above-mentioned reference voltage and above-mentioned channel voltage.
5. LED driving circuit as claimed in claim 1, it is characterized in that, between above-mentioned the first transistor and above-mentioned the first resistance, there is a first node, so that one first voltage to be provided, between above-mentioned parameter adjustment unit and above-mentioned the second resistance, there is a Section Point, so that a second voltage to be provided, above-mentioned second voltage equals above-mentioned reference voltage and deducts a parameter adjustment voltage of above-mentioned parameter adjustment unit, above-mentioned operational amplifier receives respectively above-mentioned the first voltage and above-mentioned second voltage, and exports a transistor controls signal to above-mentioned the first transistor.
6. LED driving circuit as claimed in claim 5, is characterized in that, the above-mentioned parameter adjustment voltage of above-mentioned parameter adjustment unit draws source voltage with one first of above-mentioned the first transistor and equates.
7. LED driving circuit as claimed in claim 1, is characterized in that, between above-mentioned the first resistance and above-mentioned the second resistance, has a proportionate relationship.
8. LED driving circuit as claimed in claim 2, is characterized in that, between one second size of a first size of above-mentioned the first transistor and above-mentioned transistor seconds, has a proportionate relationship.
9. LED driving circuit as claimed in claim 4, it is characterized in that, the product of above-mentioned channel voltage and above-mentioned LED current is a passage consumed power, in the time that above-mentioned reference voltage changes with above-mentioned LED current, above-mentioned channel voltage changes thereupon, causes above-mentioned passage consumed power also to change thereupon.
10. the method for running one LED driving circuit, it is characterized in that, above-mentioned LED driving circuit couples a light-emitting diodes pipe string and an adjusting resistance, above-mentioned LED driving circuit comprises a reference current generation unit, one first resistance, a first transistor, a parameter adjustment unit, one second resistance and an operational amplifier, and said method comprises the following steps:
(a) above-mentioned reference current generation unit provides a reference current according to above-mentioned adjusting resistance;
(b) reference voltage node between above-mentioned reference current generation unit and above-mentioned parameter adjustment unit provides a reference voltage;
(c) above-mentioned operational amplifier Section Point reception one first voltage and the second voltage between the first node between above-mentioned the first transistor and above-mentioned the first resistance and above-mentioned parameter adjustment unit and above-mentioned the second resistance respectively, and export a transistor controls signal to above-mentioned the first transistor; And
(d) in the time there is a LED current between above-mentioned light-emitting diodes pipe string, above-mentioned the first transistor and above-mentioned the first resistance, above-mentioned reference voltage changes with above-mentioned LED current.
11. methods as claimed in claim 10, is characterized in that, above-mentioned parameter adjustment unit is a transistor seconds.
12. methods as claimed in claim 10, is characterized in that, above-mentioned parameter adjustment unit is one the 3rd resistance.
13. methods as claimed in claim 10, is characterized in that, said method also comprises the following steps:
Receive respectively the channel voltage between above-mentioned reference voltage and above-mentioned light-emitting diodes pipe string and above-mentioned the first transistor, and produce an error amplification signal according to above-mentioned reference voltage and above-mentioned channel voltage.
14. methods as claimed in claim 10, it is characterized in that, the product of above-mentioned channel voltage and above-mentioned LED current is a passage consumed power, in the time that above-mentioned reference voltage changes with above-mentioned LED current, above-mentioned channel voltage changes thereupon, causes above-mentioned passage consumed power also to change thereupon.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| TW101149053 | 2012-12-21 | ||
| TW101149053A TWI466587B (en) | 2012-12-21 | 2012-12-21 | Light-emitting diode driving circuit and operating method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN103889088A true CN103889088A (en) | 2014-06-25 |
| CN103889088B CN103889088B (en) | 2015-10-14 |
Family
ID=50957754
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201310237655.6A Active CN103889088B (en) | 2012-12-21 | 2013-06-17 | Light emitting diode driving circuit and operation method thereof |
Country Status (2)
| Country | Link |
|---|---|
| CN (1) | CN103889088B (en) |
| TW (1) | TWI466587B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104602396A (en) * | 2014-11-21 | 2015-05-06 | 深圳市海思半导体有限公司 | WLED (White Light Emitting Diode) driver and driving control method thereof |
| CN111083831A (en) * | 2019-07-01 | 2020-04-28 | 友达光电股份有限公司 | Light emitting diode driving circuit |
| CN115079765A (en) * | 2022-08-23 | 2022-09-20 | 上海韬润半导体有限公司 | Linear voltage regulator and integrated circuit device including the same |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080068298A1 (en) * | 2006-09-18 | 2008-03-20 | Vastview Technology Inc. | System and method for constant power LED driving and a redundancy dircuit thereof |
| CN101330787A (en) * | 2007-06-21 | 2008-12-24 | 东部高科股份有限公司 | LED drive circuit |
| CN101707822A (en) * | 2009-09-25 | 2010-05-12 | 苏州工业园区古电科技有限公司 | LED drive circuit |
| CN102067405A (en) * | 2008-06-17 | 2011-05-18 | 皇家飞利浦电子股份有限公司 | Harmonic compensation circuit and method for an LED light unit |
| CN102223741A (en) * | 2010-04-14 | 2011-10-19 | 日隆电子股份有限公司 | Control circuit and control method applied in light-emitting diode (LED) driver |
| CN102413608A (en) * | 2011-10-31 | 2012-04-11 | 杭州矽力杰半导体技术有限公司 | Reference voltage regulation method and circuit as well as constant-current source driving circuit utilizing same |
| CN102497701A (en) * | 2011-12-05 | 2012-06-13 | 北方工业大学 | Power factor correction circuit for reducing harmonic distortion of LED (light-emitting diode) drive circuit |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN201207738Y (en) * | 2008-01-11 | 2009-03-11 | 白浩秦 | Electronic type LED power supply device |
| KR20120124840A (en) * | 2011-05-04 | 2012-11-14 | 삼성전자주식회사 | Light emitting diode driving apparatus and method for driving the same |
| CN102395230B (en) * | 2011-05-04 | 2013-06-12 | 凹凸电子（武汉）有限公司 | Controller and method for controlling dimming of light sources, and light source driving circuit |
| TWM435128U (en) * | 2012-04-11 | 2012-08-01 | Tpv Electronics Fujian Co Ltd | Light-emitting diode driving circuit |
-
2012
- 2012-12-21 TW TW101149053A patent/TWI466587B/en active
-
2013
- 2013-06-17 CN CN201310237655.6A patent/CN103889088B/en active Active
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080068298A1 (en) * | 2006-09-18 | 2008-03-20 | Vastview Technology Inc. | System and method for constant power LED driving and a redundancy dircuit thereof |
| CN101330787A (en) * | 2007-06-21 | 2008-12-24 | 东部高科股份有限公司 | LED drive circuit |
| CN102067405A (en) * | 2008-06-17 | 2011-05-18 | 皇家飞利浦电子股份有限公司 | Harmonic compensation circuit and method for an LED light unit |
| CN101707822A (en) * | 2009-09-25 | 2010-05-12 | 苏州工业园区古电科技有限公司 | LED drive circuit |
| CN102223741A (en) * | 2010-04-14 | 2011-10-19 | 日隆电子股份有限公司 | Control circuit and control method applied in light-emitting diode (LED) driver |
| CN102413608A (en) * | 2011-10-31 | 2012-04-11 | 杭州矽力杰半导体技术有限公司 | Reference voltage regulation method and circuit as well as constant-current source driving circuit utilizing same |
| CN102497701A (en) * | 2011-12-05 | 2012-06-13 | 北方工业大学 | Power factor correction circuit for reducing harmonic distortion of LED (light-emitting diode) drive circuit |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104602396A (en) * | 2014-11-21 | 2015-05-06 | 深圳市海思半导体有限公司 | WLED (White Light Emitting Diode) driver and driving control method thereof |
| US9622305B2 (en) | 2014-11-21 | 2017-04-11 | Huawei Technologies Co., Ltd. | WLED driver and drive control method |
| CN111083831A (en) * | 2019-07-01 | 2020-04-28 | 友达光电股份有限公司 | Light emitting diode driving circuit |
| CN115079765A (en) * | 2022-08-23 | 2022-09-20 | 上海韬润半导体有限公司 | Linear voltage regulator and integrated circuit device including the same |
Also Published As
| Publication number | Publication date |
|---|---|
| TWI466587B (en) | 2014-12-21 |
| TW201427476A (en) | 2014-07-01 |
| CN103889088B (en) | 2015-10-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Li et al. | Novel self-configurable current-mirror techniques for reducing current imbalance in parallel light-emitting diode (LED) strings | |
| TW201230859A (en) | LED driver with adaptive dynamic headroom voltage control | |
| KR101121956B1 (en) | Driver IC for electrical road and driving method thereof | |
| US8742689B2 (en) | Light emitting diode driving apparatus | |
| US20080272651A1 (en) | LED current control circuits and methods | |
| CN105657899B (en) | Multipath LED constant current drive circuit and its control method | |
| US9429965B2 (en) | Multiple chip voltage feedback technique for driving LED's | |
| US10178716B2 (en) | LED driver circuit and method | |
| CN105934029B (en) | A kind of multipath LED constant current drive circuit | |
| CN103037597A (en) | Multi-channel LED (Light Emitting Diode) constant current control circuit and LED light source control system | |
| CN102033561A (en) | Power supply circuit | |
| CN101909387A (en) | Light emitting element driving circuit, light emitting device array controller and control method thereof | |
| KR101778898B1 (en) | Led backlight driving circuit and liquid crystal display | |
| CN103889088B (en) | Light emitting diode driving circuit and operation method thereof | |
| EP3314985B1 (en) | Commutation circuit for sequential linear led drivers | |
| KR101154837B1 (en) | Driver IC for electrical road and driving method thereof | |
| KR101247506B1 (en) | Driving apparatus for led string | |
| KR101427251B1 (en) | Current distributor | |
| JP2012253006A (en) | Led driving circuit | |
| CN104168688B (en) | Possesses the light emitting diode illuminating apparatus in multiple drive power stage | |
| CN103796398B (en) | A kind of drive circuit of multi-path parallel LEDs lamp string and driving method | |
| JP5788762B2 (en) | LIGHT EMITTING ELEMENT DRIVE CIRCUIT, LIGHT EMITTING DEVICE USING SAME, AND DISPLAY DEVICE | |
| CN201489798U (en) | Display device capable of improving optical uniformity and current sharing circuit | |
| US12113428B2 (en) | Regulator circuit | |
| KR100996460B1 (en) | Apparatus for optimizing supply voltage |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant |