CN101916550B - Light emitting diode driving circuit - Google Patents
Light emitting diode driving circuit Download PDFInfo
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- CN101916550B CN101916550B CN2010102564142A CN201010256414A CN101916550B CN 101916550 B CN101916550 B CN 101916550B CN 2010102564142 A CN2010102564142 A CN 2010102564142A CN 201010256414 A CN201010256414 A CN 201010256414A CN 101916550 B CN101916550 B CN 101916550B
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Abstract
The invention relates to a light emitting diode driving circuit for driving a plurality of light emitting diode chains. The light emitting diode driving circuit comprises a plurality of constant current circuits and a plurality of short-circuit protection circuits; a transistor and a detection resistor in each constant current circuit are coupled in series between the output end and the ground end of a corresponding light emitting diode chain; and when the constant current circuits work normally, by comparing a reference voltage with a detection voltage generated by the detection resistor, a feedback circuit in each constant current circuit outputs a signal to control the size of current passing through the transistor to achieve constant current control; in addition, each short-circuit protection circuit is coupled with the output end of the corresponding light emitting diode chain and the corresponding constant current circuit and is used for outputting a short circuit signal to cut off the transistor of the corresponding constant current circuit to turn off the corresponding light emitting diode chain when the voltage of the output end of the corresponding light emitting diode chain reaches a preset voltage and the voltage of the input end of a short circuit signal generation circuit in the short-circuit protection circuit reaches a preset voltage.
Description
Technical field
The present invention refers to a kind of LED driving circuit with short-circuit protection function especially relevant for a kind of LED driving circuit.
Background technology
Liquid crystal display product now brings into use the light source of being made up of light emitting diode as back light gradually.See also Fig. 1, Fig. 1 is a kind of circuit diagram of existing LED driving circuit 10.LED driving circuit 10 is in order to driving a plurality of LED light strings 22, and wherein each LED light string 22 all comprises the light emitting diode 26 of a plurality of coupled in series.The light source that a plurality of LED light strings 22 are formed can be applicable to the back light as liquid crystal display product.Each LED light string 22 has an input end 221 and an output terminal 223 respectively, and the input end 221 of all LED light strings 22 all couples a direct current voltage that always flow to 24 outputs of direct current (DC/DC) converter.Whether LED driving circuit 10 can be detected a plurality of LED light strings 22 has short circuit; And when being short-circuited, arbitrary LED light string 22 closes all LED light strings 22 detecting; Do not continued to damage with protection LED driving circuit 10 and LED light string 22 internal electrical components that short circuit took place, to reduce the liquid crystal display product security hidden trouble.
Each constant-current circuit 14 comprises a transistor 141, and detects a resistance 143 and a feedback circuit 145.Transistor 141 is held between 16 in the output terminal 223 and the ground of corresponding LED light string 22 with detection resistance 143 coupled in series; Feedback circuit 145 is in order to export a signal and control electric current (the being drain electrode-source current in this example) size that flows through transistor 141 detecting the detection voltage Vdet that is produced on the resistance 143 according to the electric current that flows through corresponding LED light string 22 when constant-current circuit 14 operate as normal, to reach the Current Control of deciding of corresponding LED light string 22.Short-circuit protection circuit 15 comprises a plurality of diode 151, a voltage stabilizing diode 152 and a short-circuit signal and produces circuit 153, and wherein voltage stabilizing diode 152 is called Zener (Zener) diode again.Each diode 151 is respectively coupled to the output terminal 223 of a corresponding LED light string 22, and a plurality of diodes 151 are interfering with each other in order to the voltage of the output terminal 223 of avoiding a plurality of LED light strings 22.Voltage stabilizing diode 152 is coupled to each diode 151 and short-circuit signal produces between the circuit 153.
When a plurality of LED light strings 22 have at least one light emitting diode 26 short circuit; Output terminal 223 voltages of the corresponding LED light string 22 that is short-circuited will raise; When output terminal 223 voltages surpass a predetermined voltage; Voltage stabilizing diode 152 will collapse, and when short-circuit signal generation circuit 153 input terminal voltages reached a predeterminated voltage, short-circuit signal produced circuit 153 internal transistor conductings; Short-circuit signal produced circuit 153 output terminals and will export a low level signal (being equivalent to export a short-circuit signal) and will draw from the switch controlling signal On/Off that motherboard circuit 12 is exported and be low level this moment; The switch controlling signal On/Off of low level ends through ON-OFF control circuit 13 outputs one Signal-controlled switch 11, make DC voltage Vcc no longer supply power to all constant-current circuits 14, so all constant-current circuits 14 is not worked; And then close all LED light strings 22, this moment, liquid crystal display product can't display frame.
Such liquid crystal display product may produce following problem: first; When people when using lcd-tv to watch highlight or when using multimedia LCD meeting or study; Because of light-emitting diodes tube short circuit in liquid crystal panel LED light string cause short-circuit protection circuit action whole liquid crystal panel picture do not worked, may cause the user that such liquid crystal display product is produced bigger complaint suddenly.Second; Because liquid crystal panel breaks down and can't design producer at liquid crystal display product usually and do maintenance; Do maintenance and will deliver to the former factory of liquid crystal panel usually, and some liquid crystal panel place of production abroad, thereby will cause maintenance cycle very long; If surpass the guarantee period then the user need spend higher upkeep cost, user can't be accepted for these.
Summary of the invention
The objective of the invention is to propose a kind of LED driving circuit; Be used for detecting a plurality of LED light strings whether short circuit is arranged separately; And can only close the LED light string that is short-circuited, but so still display frame of liquid crystal display product (though its picture brightness possibly descend to some extent or be not very even) according to the detecting result.
The present invention proposes a kind of LED driving circuit that is used to drive a plurality of LED light strings, and it comprises a plurality of constant-current circuits and a plurality of short-circuit protection circuit.One transistor AND gate one of each constant-current circuit detects the resistance series connection and is coupled between the output terminal and a ground end of a corresponding LED light string; And one feedback circuit of each constant-current circuit flows through this transistorized size of current through comparing a detection voltage that produces on a reference voltage and this detection resistance to export a signal controlling when the constant-current circuit operate as normal, to reach the Current Control of deciding of corresponding LED light string.In addition; Each short-circuit protection circuit is coupled to the corresponding constant-current circuit with of an output terminal of a corresponding LED light string; Being used to this corresponding LED light string has at least one light emitting diode to be short-circuited to cause its output end voltage to reach a predetermined voltage and when the inner short-circuit signal of short-circuit protection circuit produces circuit input end voltage and reaches a predeterminated voltage; Exporting a short-circuit signal ends this transistor of this corresponding constant-current circuit; Closing this corresponding LED light string, and the LED light string operate as normal that can keep other not to be short-circuited simultaneously.In each constant-current circuit; This transistor has one first end, one second end and a control end, and this detection resistance has one first end and one second end, and this feedback circuit comprises a parallelly connected voltage stabilizer; This shunt regulator has an anode tap, a cathode terminal and a reference edge; This transistorized first end is coupled to the output terminal of this corresponding LED light string, and this transistorized second end is coupled to first end of this detection resistance and the reference edge of this shunt regulator, and second end of this detection resistance is coupled to this ground end; The cathode terminal of this shunt regulator is coupled to this transistorized control end, and the anode tap of this shunt regulator is coupled to this ground end; Wherein each short-circuit protection circuit all also includes a voltage stabilizing diode; Output terminal and this short-circuit signal that this voltage stabilizing diode is coupled to this corresponding LED light string produce circuit, and the output end voltage that is used to this corresponding LED light string produces this short-circuit signal of circuit output via this short-circuit signal when reaching this predetermined voltage ends this transistor of this corresponding constant-current circuit; Wherein in each short-circuit protection circuit; This short-circuit signal produces circuit and includes one first resistance, one second resistance, an electric capacity and a switch; This voltage stabilizing diode has an anode tap and a cathode terminal; This first resistance has one first end and one second end, and this second resistance has one first end and one second end, and this electric capacity has one first end and one second end; This switch has one first end, one second end and a control end; The cathode terminal of this voltage stabilizing diode is coupled to the output terminal of this corresponding LED light string, and the anode tap of this voltage stabilizing diode is coupled to first end of this first resistance, and second end of this first resistance is coupled to the control end of this switch, first end of this electric capacity and first end of this second resistance; Second end of this switch is coupled to second end of this electric capacity, second end and this ground end of this second resistance, and first end of this switch is coupled to this transistorized control end of this corresponding constant-current circuit.
For let above and other objects of the present invention, feature and advantage can be more obviously understandable, hereinafter is special lifts preferred embodiment, and cooperates appended graphicly, elaborates as follows.
Description of drawings
Fig. 1 is a kind of circuit diagram of existing LED driving circuit.
Fig. 2 is the circuit diagram of the preferred embodiment of LED driving circuit of the present invention.
Fig. 3 is the circuit diagram that further specifies constant-current circuit shown in Figure 2 and short-circuit protection circuit.
[primary clustering symbol description]
10: driving circuit 11: switch
12: motherboard circuit 13: ON-OFF control circuit
14: constant-current circuit 141: transistor
143: detect resistance 145: feedback circuit
15: short-circuit protection circuit 151: diode
152: voltage stabilizing diode 153: short-circuit signal produces circuit
16: ground end 20: LED driving circuit
22: LED light string 221: input end
223: output terminal 24:DC/DC converter
26: light emitting diode 28: constant-current circuit
30: transistor 301: first end of transistor 30
302: second end 303 of transistor 30: the control end of transistor 30
32: detect resistance 321: first end that detects resistance 32
322: second end 34 that detects resistance 32: feedback circuit
36: short-circuit protection circuit 38: voltage stabilizing diode
381: the anode tap 382 of voltage stabilizing diode 38: the cathode terminal of voltage stabilizing diode 38
40: short-circuit signal produces circuit 42: shunt regulator
421: the anode tap 422 of shunt regulator 42: the cathode terminal of shunt regulator 42
423: 44: the first resistance of the reference edge of shunt regulator 42
Second end of 442: the first resistance 44 of first end of 441: the first resistance 44
First end of 461: the second resistance 46 of 46: the second resistance
Second end 48 of 461: the second resistance 46: electric capacity
481: first end 482 of electric capacity 48: second end of electric capacity 48
50: switch 501: first end of switch 50
502: second end 503 of switch 50: the control end of switch 50
52: ON-OFF control circuit 54: motherboard circuit
56: switch 561: first end of switch 56
562: second end 563 of switch 56: the control end of switch 56
58: the internal error amplifier of shunt regulator 42
581: the positive input terminal of the internal error amplifier 58 of shunt regulator 42
582: the negative input end of the internal error amplifier 58 of shunt regulator 42
583: the output terminal of the internal error amplifier 58 of shunt regulator 42
60: the internal reference voltage source 62 of shunt regulator 42: the internal transistor of shunt regulator 42
621: first end of the internal transistor 62 of shunt regulator 42
622: second end of the internal transistor 62 of shunt regulator 42
623: the control end 64 of the internal transistor 62 of shunt regulator 42: resistance
Vcc: DC voltage Vdet: detect voltage
Vref: reference voltage Dim: dimming control signal
On/Off: switch controlling signal.
Embodiment
See also Fig. 2, Fig. 2 is the circuit diagram of the preferred embodiment of LED driving circuit 20 of the present invention.In general, LED driving circuit 20 can be applicable to use the light source be made up of the light emitting diode liquid crystal display product as back light.LED driving circuit 20 is in order to drive the light source of being made up of a plurality of LED light strings 22, and wherein each LED light string 22 all comprises the light emitting diode 26 of a plurality of coupled in series.Each LED light string 22 has an input end 221 and an output terminal 223 respectively, and the input end 221 of all LED light strings 22 all couples a direct current voltage that always flow to 24 outputs of direct current (DC/DC) converter.
See also Fig. 3, Fig. 3 is the circuit diagram that further specifies constant-current circuit 28 shown in Figure 2 and short-circuit protection circuit 36.At first, further specify to constant-current circuit 28, the transistor 30 of constant-current circuit 28 has one first end 301, one second end 302 and a control end 303.Detect resistance 32 and have one first end 321 and one second end 322.Feedback circuit 34 can comprise a parallelly connected voltage stabilizer 42, and it has an anode tap 421, a cathode terminal 422 and a reference edge 423.Shunt regulator 42 for example is the TL431 integrated circuit; Its internal circuit synoptic diagram is as shown in the figure to comprise an error amplifier 58, a reference voltage source 60 and a transistor 62; Wherein error amplifier 58 has a positive input terminal 581, a negative input end 582 and an output terminal 583, and transistor 62 has one first end 621, one second end 622 and a control end 623.Its relation of coupling as follows; First end 301 of transistor 30 is coupled to the output terminal 223 of corresponding LED light string 22; Second end 302 of transistor 30 is coupled to first end 321 of detection resistance 32 and the reference edge 423 of shunt regulator 42; Second end 322 that detects resistance 32 is coupled to this ground end, and the cathode terminal 422 of shunt regulator 42 is coupled to the control end 303 of transistor 30, and the anode tap 421 of shunt regulator 42 is coupled to this ground end.Wherein transistor 30 is to can be a N-channel MOS pipe.The positive input terminal 581 of error amplifier 58 is coupled to the reference edge 423 of shunt regulator 42; The negative input end 582 of error amplifier 58 is coupled to the reference voltage Vref of reference voltage source 60 outputs; The output terminal 583 of error amplifier 58 is coupled to the control end 623 of transistor 62; First end 621 of transistor 62 is coupled to the cathode terminal 422 of shunt regulator 42, and second end 622 of transistor 62 is coupled to the anode tap 421 of shunt regulator 42.When constant-current circuit 28 operate as normal; Error amplifier 58 receives the detection voltage Vdet that detects generation on the resistance 32 through the reference edge 423 of shunt regulator 42; The reference voltage Vref that provides by its inside relatively again and the detection voltage Vdet difference of reception are to export electric current (the being collector-emitter current in this example) size that signal controlling flows through transistor 62; And then control end 303 voltage swings that reach oxide-semiconductor control transistors 30 control the electric current that flows through transistor 30 (being drain electrode-source current in this example) size, to reach the Current Control of deciding of corresponding LED light string 22.
Moreover, further specifying to short-circuit protection circuit 36, the short-circuit signal of short-circuit protection circuit 36 produces circuit 40 and includes one first resistance 44, one second resistance 46, an electric capacity 48 and a switch 50.Voltage stabilizing diode 38 has an anode tap 381 and a cathode terminal 382.First resistance 44 has one first end 441 and one second end 442.Second resistance 46 has one first end 461 and one second end 462.Electric capacity 48 has one first end 481 and one second end 482.Switch 50 has one first end 501, one second end 502 and a control end 503.Wherein switch 50 is to can be the semiconductor switch, for example a NPN transistor.Its relation of coupling as follows; The cathode terminal 382 of voltage stabilizing diode 38 is coupled to the output terminal 223 of corresponding LED light string 22; The anode tap 381 of voltage stabilizing diode 38 is coupled to first end 441 of first resistance 44, and second end 442 of first resistance 44 is coupled to the control end 503 of switch 50, first end 481 of electric capacity 48 and first end 461 of second resistance 46.In addition; Second end 502 of switch 50 is coupled to second end 482 of electric capacity 48, second end 462 and this ground end of second resistance 46, and first end 501 of switch 50 is coupled to control end 303 and the cathode terminal 422 of shunt regulator 42 of the transistor 30 of corresponding constant-current circuit 28.
In addition, LED driving circuit 20 can comprise an ON-OFF control circuit 52 in addition.ON-OFF control circuit 52 is coupled to the control end 563 of a switch 56; First end 561 of switch 56 is coupled to a direct current voltage vcc; Second end 562 of switch 56 is coupled to 422 ends and 303 ends of a plurality of constant-current circuits 28 through a resistance 64; And ON-OFF control circuit 52 also is coupled to a motherboard circuit 54, and wherein switch 56 is to can be a PNP transistor.When 56 conductings of ON-OFF control circuit 52 CSs, DC voltage Vcc through a resistance 64 provide bias voltage pass through 422 ends to shunt regulator 42 and through 303 ends to transistor 30, make constant-current circuit 28 be able to operate as normal.Motherboard circuit 54 outputs one switch controlling signal On/Off give ON-OFF control circuit 52 with a dimming control signal Dim who is used for burst mode (burst mode) light modulation; Wherein relation and the effect of switch controlling signal On/Off and dimming control signal Dim are: first; When the switch controlling signal On/Off from motherboard circuit 54 outputs is input to ON-OFF control circuit 52 for the high levle signal and when the dimming control signal Dim from motherboard circuit 54 outputs is input to ON-OFF control circuit 52; ON-OFF control circuit 52 comes the ON time of CS 56 and the ratio of turn-off time according to the responsibility cycle (duty cycle) of dimming control signal Dim; Controlling the ratio of corresponding 22 normal working hourss of LED light string and shut-in time, and then control the mean flow rate that corresponding LED light string 22 provides the liquid crystal panel picture.The second, when the switch controlling signal On/Off from motherboard circuit 54 outputs is input to ON-OFF control circuit 52 for the low level signal, no matter whether have or not dimming control signal Dim to be input to ON-OFF control circuit 52, switch 56 all will turn-off.
Need to prove; Suppose that each lamp string 22 is composed in series (n is the integer greater than 1) in order by n light emitting diode 26; Each light emitting diode 26 forward conduction voltage is Vf, so the input end 221 voltage V221 of each lamp string 22 and output terminal 223 voltage V223 relation is: V223=V221-n * Vf.In addition; When transistor 30 conducting operate as normal; Each light emitting diode 26 forward voltage in the corresponding lamp string 22 for example are about Vf=3.0V ~ 3.2V; And when transistor 30 ended, there was the critical collapse forward voltage that for example is about Vf=2.0V ~ 2.4V in each light emitting diode 26 in the corresponding lamp string 22.When i lamp string in the middle of these lamp strings 22 has m light emitting diode short circuit to occur (m is the integer more than or equal to 1); I lamp string output end voltage is V223=V221-(n-m) * Vf; I.e. i lamp string output end voltage rising and the voltage that rises are m * Vf; What short-circuit protection circuit 36 was detected is lamp string output terminal 223 maximum value voltages; And since transistor 30 by the time its corresponding light emitting diode forward voltage Vf (its corresponding light emitting diode forward voltage Vf during=2.0V ~ 2.4V) than transistor 30 conductings (and=3.0V ~ 3.2V) little, make transistor 30 by the time lamp string output terminal 223 voltage much bigger during than transistor turns, so 36 detectings of common holding circuit is transistor 30 voltage when ending; When the voltage that rises reaches a certain value; Voltage stabilizing diode 38 conductings, have a current flowing resistance 44 and 46 this moment, and produce a dividing potential drop at resistance 46 first ends; When this voltage during greater than the forward voltage of transistor 50; Transistor 50 conductings because of first end 501 of transistor 50 is connected with the control end 303 of shunt regulator 42 cathode terminals 422 and transistor 30, are stopped work so the control end 303 of shunt regulator 42 cathode terminals 422 and transistor 30 connects to low level causes constant-current circuit 28; And then control corresponding lamp string 22 and do not worked by protection, but and other lamp string 22 does not receive still operate as normal of its corresponding short-circuit protection circuit 36 protections.Therefore, when short-circuit protection circuit 36 can be set to corresponding lamp string 22 m light-emitting diodes tube short circuit arranged, corresponding short-circuit protection circuit 36 began to do the protection action, and this lamp string 22 is when having only m-1 light-emitting diodes tube short circuit, but this lamp string 22 operate as normal still.
In sum, LED driving circuit 20 of the present invention is whether to reach a predetermined voltage in order to output terminal 223 voltages of detecting each LED light string 22, and carries out corresponding short-circuit protection function according to the detecting result.When wherein output terminal 223 voltages of a LED light string 22 did not surpass this predetermined voltage, LED driving circuit 20 drove aforementioned LED light string 22 operate as normal; Otherwise when wherein output terminal 223 voltages of a LED light string 22 surpass this predetermined voltage; It can cause the voltage stabilizing diode 38 of corresponding short-circuit protection circuit 36 to collapse; And the transistor 30 of corresponding constant-current circuit 28 is ended when short-circuit protection circuit 36 inner short-circuit signals produce the short-circuit signal generation circuit 40 output short-circuit signals that cause aforementioned short-circuit protection circuit 36 when circuit 40 input terminal voltages reach a predeterminated voltage; Use and close aforementioned LED light string 22 carrying out short-circuit protection function, this moment, other LED light string 22 was still unaffected and can continue operate as normal.
Compared to prior art; LED driving circuit of the present invention is whether the output end voltage of detecting a plurality of LED light strings respectively reaches this predetermined voltage, and this LED light string with short circuit light emitting diode is closed in the work that whether will stop corresponding constant-current circuit with decision.Therefore LED driving circuit of the present invention only can stop the work of its corresponding constant-current circuit when one of them LED light string short circuit, uses and closes this LED light string to reach protective effect.Though this moment, liquid crystal display product can make its picture brightness descend to some extent because of the quantity minimizing of the LED light string that is used as back light or picture brightness is not very even; But the user still can continue to use this liquid crystal display product; Such liquid crystal display product more meets the interests of terminal client and can reduce client's complaint, does not cause all LED light strings to be compelled to the shortcoming of closing all simultaneously and do not have in the prior art because of a LED light string short circuit wherein.
Though embodiments of the invention disclose as stated; So be not in order to limit the present invention; Any common knowledge the knowledgeable with the affiliated technical field of the present invention all can do a little change to shape of the present invention, structure or characteristic according to the content that embodiments of the invention disclosed.Therefore, the protection domain that the present invention advocated must be looked the appended claim person of defining of this instructions and be as the criterion.
Claims (4)
1. LED driving circuit; Be used to drive a plurality of LED light strings; Each LED light string all comprises the light emitting diode of a plurality of coupled in series, and each LED light string all has an input end and an output terminal, and the input end of these a plurality of LED light strings all couples a direct current voltage; It is characterized in that this LED driving circuit includes:
A plurality of constant-current circuits; Wherein each constant-current circuit all comprises a transistor, a detection resistance and a feedback circuit; The series connection of this detection resistance of this transistor AND gate is coupled between the output terminal and a ground end of a corresponding LED light string, and this feedback circuit flows through this transistorized size of current to reach the Current Control of deciding of this corresponding LED light string through a detection voltage that produces on a reference voltage relatively and this detection resistance to export a signal controlling; And
A plurality of short-circuit protection circuits; Wherein each short-circuit protection circuit is coupled to the corresponding constant-current circuit with of output terminal of a corresponding LED light string; Export a short-circuit signal when input terminal voltage that produces circuit when the output end voltage that is used to this corresponding LED light string reaches a predetermined voltage and when the inner short-circuit signal of this short-circuit protection circuit reaches a predeterminated voltage this transistor of this corresponding constant-current circuit is ended, to close this corresponding LED light string;
In each constant-current circuit; This transistor has one first end, one second end and a control end, and this detection resistance has one first end and one second end, and this feedback circuit comprises a parallelly connected voltage stabilizer; This shunt regulator has an anode tap, a cathode terminal and a reference edge; This transistorized first end is coupled to the output terminal of this corresponding LED light string, and this transistorized second end is coupled to first end of this detection resistance and the reference edge of this shunt regulator, and second end of this detection resistance is coupled to this ground end; The cathode terminal of this shunt regulator is coupled to this transistorized control end, and the anode tap of this shunt regulator is coupled to this ground end;
Wherein each short-circuit protection circuit all also includes a voltage stabilizing diode; Output terminal and this short-circuit signal that this voltage stabilizing diode is coupled to this corresponding LED light string produce circuit, and the output end voltage that is used to this corresponding LED light string produces this short-circuit signal of circuit output via this short-circuit signal when reaching this predetermined voltage ends this transistor of this corresponding constant-current circuit;
Wherein in each short-circuit protection circuit; This short-circuit signal produces circuit and includes one first resistance, one second resistance, an electric capacity and a switch; This voltage stabilizing diode has an anode tap and a cathode terminal; This first resistance has one first end and one second end, and this second resistance has one first end and one second end, and this electric capacity has one first end and one second end; This switch has one first end, one second end and a control end; The cathode terminal of this voltage stabilizing diode is coupled to the output terminal of this corresponding LED light string, and the anode tap of this voltage stabilizing diode is coupled to first end of this first resistance, and second end of this first resistance is coupled to the control end of this switch, first end of this electric capacity and first end of this second resistance; Second end of this switch is coupled to second end of this electric capacity, second end and this ground end of this second resistance, and first end of this switch is coupled to this transistorized control end of this corresponding constant-current circuit.
2. LED driving circuit according to claim 1 is characterized in that: wherein this transistor is the N-channel MOS pipe.
3. LED driving circuit according to claim 1 is characterized in that: wherein this switch is a NPN transistor.
4. LED driving circuit according to claim 1; It is characterized in that; Also comprise: an ON-OFF control circuit; Be coupled to motherboard circuit; In order to opening or to close the LED light string of not closed as yet through these a plurality of constant-current circuits by short-circuit protection circuit according to a switch controlling signal from motherboard circuit output, and according to the mean flow rate of adjusting as yet not the LED light string of being closed by short-circuit protection circuit from a dimming control signal of this motherboard circuit output through these a plurality of constant-current circuits.
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| Application Number | Priority Date | Filing Date | Title |
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| CN2010102564142A CN101916550B (en) | 2010-08-18 | 2010-08-18 | Light emitting diode driving circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2010102564142A CN101916550B (en) | 2010-08-18 | 2010-08-18 | Light emitting diode driving circuit |
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| CN101916550A CN101916550A (en) | 2010-12-15 |
| CN101916550B true CN101916550B (en) | 2012-06-27 |
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| US20080100561A1 (en) * | 2006-10-31 | 2008-05-01 | Price Erin L | System and Method for Managing LED Backlight Performance in a Display |
| US20080143266A1 (en) * | 2006-12-18 | 2008-06-19 | Microsemi Corp. - Analog Mixed Signal Group Ltd. | Voltage Range Extender Mechanism |
| CN101776222A (en) * | 2009-05-14 | 2010-07-14 | 浙江西子光电科技有限公司 | Light emitting diode (LED) lighting device having open/short circuit protection function and lighting circuit |
| CN201689649U (en) * | 2010-08-18 | 2010-12-29 | 福建捷联电子有限公司 | Light-emitting diode driving circuit |
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2010
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20080100561A1 (en) * | 2006-10-31 | 2008-05-01 | Price Erin L | System and Method for Managing LED Backlight Performance in a Display |
| US20080143266A1 (en) * | 2006-12-18 | 2008-06-19 | Microsemi Corp. - Analog Mixed Signal Group Ltd. | Voltage Range Extender Mechanism |
| CN101776222A (en) * | 2009-05-14 | 2010-07-14 | 浙江西子光电科技有限公司 | Light emitting diode (LED) lighting device having open/short circuit protection function and lighting circuit |
| CN201689649U (en) * | 2010-08-18 | 2010-12-29 | 福建捷联电子有限公司 | Light-emitting diode driving circuit |
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