CN103379697B - LED driving circuit - Google Patents
LED driving circuit Download PDFInfo
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- CN103379697B CN103379697B CN201210120292.3A CN201210120292A CN103379697B CN 103379697 B CN103379697 B CN 103379697B CN 201210120292 A CN201210120292 A CN 201210120292A CN 103379697 B CN103379697 B CN 103379697B
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Abstract
The invention provides a kind of LED driving circuit, comprise a change-over circuit, a current regulating circuit, a conversion control circuit and a low light modulation protection blocking circuit.Change-over circuit carries out an electric power conversion one input power to be converted to a driving voltage to drive a light-emitting diode (LED) module luminous.Current regulating circuit couples light-emitting diode (LED) module to regulate the LED current flowing through light-emitting diode (LED) module; wherein current regulating circuit stops or switched-on light emitting diodes electric current according to a dim signal, and carries out a defence program when light-emitting diode (LED) module occurs abnormal.Conversion control circuit is according to the electric power conversion of the Automatic level control change-over circuit of at least one tie point of light-emitting diode (LED) module and current regulating circuit.Low light modulation protection blocking circuit couples current regulating circuit and change-over circuit, and carries out defence program at driving voltage lower than stopping current regulating circuit during a scheduled voltage.
Description
Technical field
The invention relates to a kind of LED driving circuit, espespecially a kind of LED driving circuit with low light modulation protection blocking function.
Background technology
Refer to Fig. 1, Fig. 1 is the circuit diagram of traditional LED driving circuit.LED driving circuit comprises change-over circuit 130, current regulating circuit and a conversion control circuit 120.Change-over circuit couples an input power Vin, carries out an electric power conversion to export a driving voltage Vout to drive a light-emitting diode (LED) module LM luminous.Current regulating circuit comprises current regulation control device 100, transistor M and current sense resistor R.Transistor M mono-first end couples one end of light-emitting diode (LED) module LM, and one second end couples current sense resistor R.The electric current flowing through light-emitting diode (LED) module LM flows through current sense resistor R to produce a current detection signal Cs simultaneously.One tie point of conversion control circuit 120 coupling transistors M and light-emitting diode (LED) module LM, to control the electric power conversion of change-over circuit 130 according to a voltage feedback signal VFB of tie point.
Current regulation control device 100 comprises a control circuit 102, and to open a way comparator 104, timing circuit 115 and one or door 110.Control circuit 102 to produce a current controling signal Ga, to adjust the conduction impedance of transistor M, makes the current stabilization of light-emitting diode (LED) module LM in a predetermined current value according to a current detection signal Cs and reference voltage signal Vr.When open circuit occurs light-emitting diode (LED) module LM, change-over circuit 130 is caused no longer to provide electrical power to light-emitting diode (LED) module LM.Now, a level of current detection signal Cs can drop to and judge voltage Vop close to 0 volt lower than an open circuit.When comparator 104 of opening a way judges voltage Vop at the level of current detection signal Cs lower than open circuit, by generation one high level signal.Timing circuit 115 couples a timer capacitor Ct, carries out timing, to avoid the erroneous judgement because dim signal or other noises cause when receiving the high level signal that open circuit comparator 104 produces.When the time that comparator 104 of opening a way produces high level signal is longer than a predetermined period of time of timing circuit 115 setting, timing circuit 115 exports a stopping Continuity signal Fa.Or door 110 couples timing circuit 115 and receives a dim signal Dim, adjusts current controling signal Ga according to dim signal Dim, to stop or the electric current of switched-on light emitting diodes module LM.When timing circuit 115 exports stopping Continuity signal Fa, then control circuit 102 continues to turn off transistor M, makes light-emitting diode (LED) module LM no longer On current.
When dim signal Dim is a low-key light, change-over circuit 130 and conversion control circuit 120 operate normal, the level of the tie point of transistor M and light-emitting diode (LED) module LM can maintain higher level.Now, conversion control circuit 120 can judge that driving voltage Vout is too high and reduce driving voltage Vout.Even if now transistor M conducting according to dim signal Dim, the level of current detection signal Cs still can judge voltage Vop lower than open circuit.Now current regulation control device 100 can be judged light-emitting diode (LED) module LM generation open circuit by accident and carry out fastening lock protection.Therefore, when low light modulation or noise cause and judge into dim signal by accident, traditional LED driving circuit has the problem that cannot start, even and if dim signal transfer to one to a high-profile light time LED driving circuit also lock protection cannot recover because fastening.
Summary of the invention
In view of traditional LED driving circuit of the prior art is when carrying out low-key light, have the problem that cannot start.The present invention utilizes a low light modulation protection blocking circuit, forbids that current regulation control device is protected when low light modulation being detected or driving voltage is too low, LED driving circuit is unlikely enter to fasten lock protection and cannot ongoing operation.
For reaching above-mentioned purpose, the invention provides a kind of LED driving circuit, comprising a change-over circuit, a current regulating circuit, a conversion control circuit and a low light modulation protection blocking circuit.Change-over circuit carries out an electric power conversion one input power to be converted to a driving voltage to drive a light-emitting diode (LED) module luminous.Current regulating circuit couples light-emitting diode (LED) module to regulate the LED current flowing through light-emitting diode (LED) module; wherein current regulating circuit stops or switched-on light emitting diodes electric current according to a dim signal, and carries out a defence program when light-emitting diode (LED) module occurs abnormal.Conversion control circuit is according to the electric power conversion of the Automatic level control change-over circuit of at least one tie point of light-emitting diode (LED) module and current regulating circuit.Low light modulation protection blocking circuit couples current regulating circuit and change-over circuit, and low light modulation protection blocking circuit, when driving voltage is lower than a scheduled voltage, stops current regulating circuit carrying out defence program.
Present invention provides a kind of LED driving circuit, comprise a change-over circuit, a current regulating circuit, a conversion control circuit and a low light modulation protection blocking circuit.Change-over circuit carries out an electric power conversion one input power to be converted to a driving voltage to drive a light-emitting diode (LED) module luminous.Current regulating circuit couples light-emitting diode (LED) module to regulate the LED current flowing through light-emitting diode (LED) module; wherein current regulating circuit stops or switched-on light emitting diodes electric current according to a dim signal, and carries out a defence program when light-emitting diode (LED) module occurs abnormal.Conversion control circuit is according to the electric power conversion of the Automatic level control change-over circuit of at least one tie point of light-emitting diode (LED) module and current regulating circuit.Low light modulation protection blocking circuit, couples current regulating circuit, and low light modulation protection blocking circuit receives dim signal, and stops current regulating circuit carrying out defence program when a conducting pulsewidth of dim signal is less than a predetermined pulse width value.
Present invention also offers a kind of LED driving circuit, comprise a change-over circuit, a current regulating circuit, a conversion control circuit and a low light modulation protection blocking circuit.Change-over circuit carries out an electric power conversion one input power to be converted to a driving voltage to drive a light-emitting diode (LED) module luminous.Current regulating circuit couples light-emitting diode (LED) module to regulate the LED current flowing through light-emitting diode (LED) module.Wherein current regulating circuit has at least one current regulation unit, and each current regulation unit comprises a transistor, a control circuit and a protective circuit.A drive end corresponding in transistor couples light-emitting diode (LED) module, to regulate the electric current flowing through transistor according to a current controling signal.Control circuit detects the electric current flowing through transistor, generation current control signal accordingly, and stops or On current according to a dim signal.Protective circuit detects the state of transistor, to judge whether light-emitting diode (LED) module exception occurs, if then transistor is turned off.Conversion control circuit is according to the electric power conversion of the Automatic level control change-over circuit of at least one tie point of light-emitting diode (LED) module and current regulating circuit.Low light modulation protection blocking circuit couples current regulating circuit, and low light modulation protection blocking circuit receives at least one current controling signal, and when at least one current controling signal arbitrary is less than a predetermined pulse width value, stops the protective circuit of current regulating circuit.
Above general introduction and ensuing detailed description are all exemplary in nature, are to further illustrate claim of the present invention.And other objects and advantages for the present invention, set forth in follow-up explanation and accompanying drawing.
Accompanying drawing explanation
Fig. 1 is the circuit diagram of traditional LED driving circuit;
Fig. 2 is the circuit diagram of the LED driving circuit according to one first preferred embodiment of the present invention;
Fig. 3 is the circuit diagram of the LED driving circuit according to one second preferred embodiment of the present invention;
Fig. 4 is the circuit diagram of the low light modulation protection blocking circuit according to another preferred embodiment of the present invention;
Fig. 5 is the circuit diagram of the low light modulation protection blocking circuit according to still another preferred embodiment of the present invention.
Description of reference numerals:
Prior art:
100: current regulation control device;
102: control circuit;
104: open circuit comparator;
110: or door;
115: timing circuit 115;
120: conversion control circuit 120;
130: change-over circuit 130;
Vin: input power;
Vout: driving voltage;
LM: light-emitting diode (LED) module;
M: transistor;
R: current sense resistor;
Cs: current detection signal;
VFB: voltage feedback signal;
Vr: reference voltage signal;
Ga: current controling signal;
Vop: open circuit judges voltage;
Ct: timer capacitor;
Dim: dim signal;
Fa: stop Continuity signal.
The present invention:
120: conversion control circuit;
130: change-over circuit;
150: current regulation control device;
152: control circuit;
154: open circuit comparator;
156: short circuit comparator;
160,160 ': or door;
165: timing circuit;
200,300,400,500: low light modulation protection blocking circuit;
210,310,510: dimming detection circuit;
220,320,420: output voltage detecting circuit;
230,330: protection halt circuit;
Vin: input power;
Vout: driving voltage;
LM: light-emitting diode (LED) module;
I, I1, I2: LED current;
Dim: dim signal;
M: transistor;
R: current sense resistor;
Cs, Cs1, Cs2: current detection signal;
VFB: voltage feedback signal;
Vr: reference voltage signal;
G1, G2: current controling signal;
Vop: open circuit judges voltage;
VS: voltage detection signal;
Vsh: short circuit judges voltage;
Ct: timer capacitor;
F1, F2: stop Continuity signal;
Sps: protection stop signal;
SW1, SW2, SW3, SW4, SW5: switch;
Rd1, Rd2: resistance;
LM1, LM2: light-emitting diode string;
150 ': current regulating circuit;
150a, 150b: current regulation unit;
D1, D2: terminal voltage;
Fault: fault notification signal;
Dd, Dd1, Dd2, Dd3, Dd4; Diode;
Rov, Rd1, Rd2, Rd3, Rd4, Rd5, Rd6: resistance;
C1, C2, C3, C4: electric capacity;
Z1, Z2: Zener diode;
360: overvoltage crowbar;
ERR: overvoltage notification signal;
425: comparator;
Vps: judge voltage;
Vdd: positive supply;
105: light-emitting diode abnormal detection circuit;
145: minimum voltage testing circuit.
Embodiment
Refer to Fig. 2, Fig. 2 is the circuit diagram of the LED driving circuit according to one first preferred embodiment of the present invention.LED driving circuit comprises conversion control circuit 120, change-over circuit 130, current regulating circuit and a low light modulation protection blocking circuit 200.Change-over circuit 130 carries out an electric power conversion one input power Vin to be converted to a driving voltage Vout to drive a light-emitting diode (LED) module LM luminous.Current regulating circuit couples light-emitting diode (LED) module LM to regulate the LED current I flowing through light-emitting diode (LED) module LM.Current regulating circuit also stops or switched-on light emitting diodes electric current I according to a dim signal Dim, and carries out a defence program when light-emitting diode (LED) module LM occurs abnormal.
Current regulating circuit comprises current regulation control device 150, transistor M and current sense resistor R.Transistor M mono-first end couples one end of light-emitting diode (LED) module LM, and one second end couples current sense resistor R.LED current I flows through current sense resistor R to produce a current detection signal Cs.One tie point of conversion control circuit 120 coupling transistors M and light-emitting diode (LED) module LM, to control the electric power conversion of change-over circuit 130 according to a voltage feedback signal VFB of tie point.Current regulation control device 150 comprises a control circuit 152, protective circuit and one or door 160, and wherein protective circuit comprises open circuit comparator 154, short circuit comparator 156, timing circuit 165.Control circuit 152 to produce a current controling signal G1, to adjust the conduction impedance of transistor M, makes LED current I be stable at a predetermined current value according to a current detection signal Cs and reference voltage signal Vr.When open circuit occurs light-emitting diode (LED) module LM, change-over circuit 130 is caused no longer to provide electrical power to light-emitting diode (LED) module LM.Now, a level of current detection signal Cs can drop to and judge voltage Vop close to 0 volt lower than an open circuit.When comparator 154 of opening a way judges voltage Vop at the level of current detection signal Cs lower than open circuit, by generation one high level signal.The tie point of one light-emitting diode abnormal detection circuit 105 coupling transistors M and light-emitting diode (LED) module LM, has a resistance of series connection and an electric capacity to carry out filtering and to detect to produce a voltage detection signal VS.When light-emitting diode (LED) module LM is short-circuited, the tie point of transistor M and light-emitting diode (LED) module LM can rise to an abnormal high level and maintain, and now a level of voltage detection signal VS can judge voltage Vsh higher than a short circuit.When short circuit comparator 156 judges voltage Vsh at the level of voltage detection signal VS higher than short circuit, by generation one high level signal.
Timing circuit 165 couples a timer capacitor Ct, carries out timing when receiving open circuit comparator 154 and short circuit comparator 156 arbitrary sends high level signal, to avoid the open circuit that causes because of dim signal Dim or other noises can the erroneous judgement of short circuit.When the time that open circuit comparator 154 or short circuit comparator 156 produce high level signal is longer than a predetermined period of time of timing circuit 165 setting, timing circuit 165 exports a stopping Continuity signal F1.Or door 160 couples timing circuit 165 and receives dim signal Dim, adjust current controling signal G1, to stop or switched-on light emitting diodes electric current I according to dim signal Dim.When timing circuit 165 judges that light-emitting diode (LED) module LM generation open circuit or short circuit export stopping Continuity signal F1 extremely; then control circuit 152 will carry out a defence program, such as: temporarily turn off transistor M to Abnormality remove, shutoff transistor M until current regulating circuit is restarted.
Low light modulation protection blocking circuit 200 comprises dimming detection circuit 210, output voltage detecting circuit 220 and a protection halt circuit 230.Dimming detection circuit 210 has a diode Dd and a RC filter circuit, and wherein RC filter circuit comprises the anode of a resistance Rd1 in parallel and an electric capacity C1, diode Dd in order to receive dim signal Dim, and negative terminal couples RC filter circuit.When dim signal Dim inputs, no matter how little its pulse duration is, all can charge the electric capacity C1 in RC filter circuit to produce a protection stop signal Sps.Output voltage detecting circuit 220 comprises a bleeder circuit and an interrupteur SW 2, and bleeder circuit one end couples change-over circuit 130 to determine whether actuating switch SW2 according to driving voltage Vout.One end of interrupteur SW 2 couples dimming detection circuit 210, one level of drop-down protection stop signal Sps when conducting, to stop the generation protecting stop signal Sps.That is, when driving voltage Vout is lower than a scheduled voltage, interrupteur SW 2 is for turning off, and dimming detection circuit 210 normally can produce protection stop signal Sps.And when driving voltage Vout is greater than or equal to scheduled voltage, interrupteur SW 2 is conducting, stopping produces by protection stop signal Sps.Protection halt circuit 230 comprises a resistance Rd2 and an interrupteur SW 1, couples the protective circuit in dimming detection circuit 210 and current regulation control device 150, when receiving protection stop signal Sps, forbids that current regulating circuit carries out defence program.
Refer to Fig. 3, Fig. 3 is the circuit diagram of the LED driving circuit according to one second preferred embodiment of the present invention.Compared to the embodiment shown in Fig. 2, Main Differences point is that the light-emitting diode (LED) module in the present embodiment is many string light-emitting diode strings, and the current controling signal that low light modulation protection blocking circuit produces according to current regulating circuit judges.Be described in detail as follows.
Light-emitting diode (LED) module comprises at least two light-emitting diode string LM1, LM2, is coupled to current regulation unit 150a, 150b corresponding in a current regulating circuit 150 ' respectively.The circuit structure of current regulation unit 150a, 150b can with reference to the current regulation control device 150 shown in figure 2.LED current I1, the I2 of light-emitting diode string LM1, LM2 flow through a current sense resistor R with generation current detection signal Cs1, Cs2.Current regulation unit 150a, 150b be generation current control signal G1, G2 according to current detection signal Cs1, Cs2 respectively, makes LED current I1, I2 is stable at a predetermined current value.One minimum voltage testing circuit 145 couples the negative terminal of at least two light-emitting diode string LM1, LM2, to produce a voltage feedback signal VFB according to the lowest in terminal voltage D1, D2.One conversion control circuit 120 controls an electric power conversion of a change-over circuit 130, to regulate a driving voltage Vout according to voltage feedback signal VFB.
The state of current regulation unit 150a, 150b each Autonomous test light-emitting diode string LM1, LM2 of current regulating circuit 150 ', and detecting that abnormal also timing produces stopping Continuity signal F1, F2 more than a predetermined period of time, wherein the length of predetermined period of time sets according to a timer capacitor Ct.One or door 160 ' couple current regulation unit 150a, 150b, receive stop Continuity signal F1, F2 arbitrary time, produce a fault notification signal Fault to conversion control circuit 120, make conversion control circuit 120 stop the electric power of change-over circuit 130 to change.
One low light modulation protection blocking circuit 300 comprises dimming detection circuit 310, output voltage detecting circuit 320 and a protection halt circuit 330.Dimming detection circuit 310 has at least two diode Dd1, Dd2 and a RC filter circuit.The anode of diode Dd1, Dd2 is coupled to current regulation unit 150a, 150b corresponding in current regulating circuit 150 ', in order to received current control signal G1, G2, negative terminal couples RC filter circuit, and wherein RC filter circuit comprises an a resistance Rd2 in parallel and electric capacity C2.During one dim signal Dim input current regulating circuit 150 ', current regulating circuit 150 ' is by generation current control signal G1, G2.When dimming detection circuit 310 detects current controling signal G1, G2 arbitrary, no matter how little its pulse duration is, all can charge to produce a protection stop signal Sps to electric capacity C2.Output voltage detecting circuit 320 comprises Zener diode Z1, a bleeder circuit and an interrupteur SW 4.The negative terminal of Zener diode Z1 couples change-over circuit 130, and anode couples bleeder circuit, at driving voltage Vout greater than or equal to actuating switch SW4 during a scheduled voltage.The effect that this increases Zener diode Z1 be can control switch SW4 is switched on more accurately time corresponding driving voltage Vout.One end of interrupteur SW 4 couples dimming detection circuit 310, one level of drop-down protection stop signal Sps when conducting, to stop the generation protecting stop signal Sps.Protection halt circuit 330 comprises a diode Dd3, a resistance Rd3 and an interrupteur SW 3; couple the timer capacitor Ct in dimming detection circuit 310 and current regulating circuit; when receiving protection stop signal Sps; timer capacitor Ct is discharged, current regulation unit 150a, 150b cannot be reached according to timer capacitor Ct timing and forbid that current regulating circuit carries out the effect of defence program.
In addition, also additionally increase by an overvoltage crowbar 360 in the present embodiment.Overvoltage crowbar 360 comprises a resistance Rov and Zener diode Z2.The negative terminal of Zener diode Z2 couples a dividing point of bleeder circuit in output voltage detecting circuit 320, and one end of anode coupling resistance Rov is to produce an overvoltage notification signal ERR, the other end ground connection of resistance Rov.When driving voltage Vout normal (higher than scheduled voltage); because of the action of output voltage detecting circuit 320, low light modulation protection blocking circuit 300 can not discharge to timer capacitor Ct and current regulating circuit 150 ' can be protected for the exception of light-emitting diode (LED) module.So when the breakdown voltage of the level that driving voltage Vout continues the dividing point rising to bleeder circuit in output voltage detecting circuit 320 abnormally also higher than Zener diode Z2; overvoltage crowbar 360 can produce overvoltage notification signal ERR to conversion control circuit 120, makes conversion control circuit 120 carry out one and crosses high voltage protective.
If whether the low light modulation protection blocking main circuit in above-mentioned two embodiments carrys out lower than scheduled voltage the defence program whether stopping current regulating circuit with driving voltage Vout, and dim signal or current controling signal are auxiliary judgment, are to be omitted.Refer to Fig. 4, Fig. 4 is the circuit diagram of the low light modulation protection blocking circuit according to another preferred embodiment of the present invention.Compared to the low light modulation protection blocking circuit 200 shown in Fig. 2, a low light modulation protection blocking circuit 400 of the present embodiment replaces dimming detection circuit 210 and output voltage detecting circuit 220 with an output voltage detecting circuit 420.Output voltage detecting circuit 420 comprises a bleeder circuit and a comparator 425.Bleeder circuit couples change-over circuit to produce a dividing potential drop according to driving voltage Vout, and comparator 425 compares this dividing potential drop and and judges voltage Vps.When driving voltage Vout is lower than a scheduled voltage, dividing potential drop can make comparator 425 produce a protection stop signal Sps to protection halt circuit 230 lower than judging voltage Vps.The explanation of protection halt circuit 230 refers to corresponding explanation in Fig. 2.
Refer to Fig. 5, Fig. 5 is the circuit diagram of the low light modulation protection blocking circuit according to still another preferred embodiment of the present invention.From the difference of the low light modulation protection blocking circuit 300 shown in Fig. 3, the one low light modulation protection blocking circuit 500 of the present embodiment is that the circuit framework of dimming detection circuit is different, remaining circuit is all identical.One dimming detection circuit 510 comprises a diode Dd4, a RC filter circuit and a decision circuitry, and wherein RC filter circuit comprises an electric capacity C4 and resistance Rd5, Rd6, and decision circuitry comprises a resistance Rd4, interrupteur SW 5 and an electric capacity C3.The anode of diode Dd4 is in order to receive dim signal Dim, and negative terminal is coupled to the RC filter circuit be made up of resistance Rd6 and electric capacity C4 by resistance Rd5.The effect of resistance Rd5 is to adjust dim signal Dim also reaches protection simultaneously effect to the charging rate of electric capacity C4.RC filter circuit couples a controlled end of interrupteur SW 5.One end of resistance Rd4 couples a positive supply Vdd, and the other end couples interrupteur SW 5, and a tie point of electric capacity C3 coupling resistance Rd4 and interrupteur SW 5.Dim signal Dim is charged to electric capacity C4 by resistance Rd5, and resistance Rd6 discharges to electric capacity C4.Therefore, when the pulsewidth of conducting representated by dim signal Dim (ON) is less than a predetermined pulse width, the voltage of electric capacity C4 cannot rise to the level being enough to actuating switch SW5.Now interrupteur SW 5 is for turning off, and positive supply Vdd is charged to electric capacity C3 by resistance Rd4 and produces a protection stop signal Sps.When the conducting pulsewidth of dim signal Dim is equal to or greater than predetermined pulse width, the voltage of electric capacity C4 can arrive the level being enough to actuating switch SW5, and electric capacity C3 is discharged.Now the voltage waveform of electric capacity C3 is triangular wave and the level that peak value deficiency reaches conducting protection halt circuit 330 breaker in middle be equal to stop producing and protects stop signal Sps.Therefore, the low light modulation protection blocking circuit of the present embodiment also can judge that a conducting pulsewidth of dim signal Dim determines whether the advantage that protection halt circuit 330 is started further.Certainly, the present embodiment also can change to detect current controling signal to replace the judgement that dim signal carrys out whether to stop protection.In addition, at the present embodiment, represent light modulation ON with high level, but in some practical application example, may represent light modulation ON with low level, conducting pulsewidth now refers to low level pulsewidth.And output voltage detecting circuit 320 is auxiliary circuit at the present embodiment, can be omitted and affect advantage of the present invention.
During actual enforcement low light modulation protection blocking circuit of the present invention, jointly can form one chip with current regulating circuit.And resistance in dimming detection circuit in RC filter circuit or electric capacity are with external form design, dimming detection circuit can be adjusted according to practical application request to dim signal or the susceptibility of current controling signal or the setting of predetermined pulse width.
Last it is noted that above each embodiment is only in order to illustrate technical scheme of the present invention, be not intended to limit; Although with reference to foregoing embodiments to invention has been detailed description, those of ordinary skill in the art is to be understood that: it still can be modified to the technical scheme described in foregoing embodiments, or carries out equivalent replacement to wherein some or all of technical characteristic; And these amendments or replacement, do not make the essence of appropriate technical solution depart from the scope of various embodiments of the present invention technical scheme.
Claims (11)
1. a LED driving circuit, is characterized in that, comprises:
One change-over circuit, converts an input power to a driving voltage to drive a light-emitting diode (LED) module luminous in order to carry out an electric power conversion;
One current regulating circuit, in order to couple this light-emitting diode (LED) module to regulate the LED current flowing through this light-emitting diode (LED) module, wherein this current regulating circuit stops or this LED current of conducting according to a dim signal, this current regulating circuit has at least one current regulation unit, and each this current regulation unit comprises:
One transistor, couples a drive end corresponding in this light-emitting diode (LED) module, to regulate the electric current flowing through this transistor according to a current controling signal;
One control circuit, detects this electric current flowing through this transistor, produces this current controling signal accordingly; And
One protective circuit, detects the state of this transistor, to judge whether this light-emitting diode (LED) module exception occurs, if then this transistor is turned off;
One conversion control circuit, according to an electric power conversion of this change-over circuit of Automatic level control of at least one tie point of this light-emitting diode (LED) module and this current regulating circuit; And
One low light modulation protection blocking circuit, couples this current regulating circuit and this change-over circuit, and this low light modulation protection blocking circuit, when this driving voltage is lower than a scheduled voltage, stops this protective circuit.
2. LED driving circuit according to claim 1; wherein this protective circuit comprises a timing circuit; state in order to this light-emitting diode (LED) module of timing is an abnormal duration; this protective circuit this duration more than a predetermined period of time time; produce one and stop Continuity signal, this transistor is turned off.
3. LED driving circuit according to claim 1, wherein this low light modulation protection blocking circuit comprises:
One output voltage detecting circuit, couples this change-over circuit and produces a protection stop signal at this driving voltage lower than this scheduled voltage; And
One protection halt circuit, coupling this output voltage detecting circuit and this protective circuit, when receiving this protection stop signal, stopping this protective circuit.
4. a LED driving circuit, is characterized in that, comprises:
One change-over circuit, converts an input power to a driving voltage to drive a light-emitting diode (LED) module luminous in order to carry out an electric power conversion;
One current regulating circuit, in order to couple this light-emitting diode (LED) module to regulate the LED current flowing through this light-emitting diode (LED) module, wherein this current regulating circuit stops or this LED current of conducting according to a dim signal, this current regulating circuit has at least one current regulation unit, and each this current regulation unit comprises:
One transistor, couples a drive end corresponding in this light-emitting diode (LED) module, to regulate the electric current flowing through this transistor according to a current controling signal;
One control circuit, detects this electric current flowing through this transistor, produces this current controling signal accordingly; And
One protective circuit, detects the state of this transistor, to judge whether this light-emitting diode (LED) module exception occurs, if then this transistor is turned off;
One conversion control circuit, according to an electric power conversion of this change-over circuit of Automatic level control of at least one tie point of this light-emitting diode (LED) module and this current regulating circuit; And
One low light modulation protection blocking circuit, couples this current regulating circuit, and this low light modulation protection blocking circuit receives this dim signal, and stops this protective circuit when a conducting pulsewidth of this dim signal is less than a predetermined pulse width value.
5. LED driving circuit according to claim 4, wherein
This protective circuit comprises a timing circuit, and the state in order to this light-emitting diode (LED) module of timing is an abnormal duration, this protective circuit this duration more than a predetermined period of time time, produce one stop Continuity signal, this transistor is turned off.
6. LED driving circuit according to claim 4, wherein this low light modulation protection blocking circuit comprises:
One dimming detection circuit, receives this dim signal, when the ON time that this dim signal represents or a conducting duty ratio are less than a predetermined value, produces a protection stop signal; And
One protection halt circuit, coupling this dimming detection circuit and this protective circuit, when receiving this protection stop signal, stopping this protective circuit.
7. the LED driving circuit according to claim arbitrary in claim 5 to 6, wherein this dimming detection circuit comprises:
One RC filter circuit, in order to receive this dim signal;
One decision circuitry, couples this RC filter circuit, and the level according to this RC filter circuit determines whether produce this protection stop signal.
8. a LED driving circuit, is characterized in that comprising:
One change-over circuit, converts an input power to a driving voltage to drive a light-emitting diode (LED) module luminous in order to carry out an electric power conversion;
One current regulating circuit, in order to couple this light-emitting diode (LED) module to regulate the LED current flowing through this light-emitting diode (LED) module, wherein this current regulating circuit has at least one current regulation unit, and each this current regulation unit comprises:
One transistor, couples a drive end corresponding in this light-emitting diode (LED) module, to regulate the electric current flowing through this transistor according to a current controling signal;
One control circuit, detects this electric current flowing through this transistor, produces this current controling signal accordingly, and stops or this electric current of conducting according to a dim signal; And
One protective circuit, detects the state of this transistor, to judge whether this light-emitting diode (LED) module exception occurs, if then this transistor is turned off;
One conversion control circuit, according to an electric power conversion of this change-over circuit of Automatic level control of at least one tie point of this light-emitting diode (LED) module and this current regulating circuit; And
One low light modulation protection blocking circuit; couple this current regulating circuit; this low light modulation protection blocking circuit receives this at least one current controling signal, and when this at least one current controling signal arbitrary is less than a predetermined pulse width value, stops the protective circuit of this current regulating circuit.
9. LED driving circuit according to claim 8, wherein
This protective circuit comprises a timing circuit, and the state in order to this light-emitting diode (LED) module of timing is an abnormal duration, this protective circuit this duration more than a predetermined period of time time, produce one stop Continuity signal, this transistor is turned off.
10. LED driving circuit according to claim 8, wherein this low light modulation protection blocking circuit comprises:
One dimming detection circuit, receives this dim signal, when the ON time that this dim signal represents or a conducting duty ratio are less than a predetermined value, produces a protection stop signal; And
One protection halt circuit, coupling this dimming detection circuit and this protective circuit, when receiving this protection stop signal, stopping this protective circuit.
11. LED driving circuit according to claim arbitrary in claim 9 to 10, wherein this dimming detection circuit comprises:
One RC filter circuit, in order to receive this dim signal;
One decision circuitry, couples this RC filter circuit, and the level according to this RC filter circuit determines whether produce this protection stop signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210120292.3A CN103379697B (en) | 2012-04-23 | 2012-04-23 | LED driving circuit |
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| CN201210120292.3A CN103379697B (en) | 2012-04-23 | 2012-04-23 | LED driving circuit |
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| CN103379697B true CN103379697B (en) | 2015-08-19 |
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|---|---|---|---|---|
| CN103533721B (en) * | 2013-10-31 | 2015-08-26 | 矽力杰半导体技术(杭州)有限公司 | Pulse type current LED drive circuit |
| TWI749339B (en) * | 2019-07-04 | 2021-12-11 | 力林科技股份有限公司 | Light emitting diode backlight system and light emitting diode control circuit |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200844706A (en) * | 2007-02-17 | 2008-11-16 | Seiko Instr Inc | Voltage regulator |
| CN101400200A (en) * | 2007-09-25 | 2009-04-01 | 新巨企业股份有限公司 | AC electricity driving method for LED and working voltage thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20040004446A1 (en) * | 2002-07-05 | 2004-01-08 | Hun-Huang Liu | Drive circuit for an led lighting apparatus |
| US8502461B2 (en) * | 2010-05-25 | 2013-08-06 | Green Solution Technology Co., Ltd. | Driving circuit and control circuit |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| TW200844706A (en) * | 2007-02-17 | 2008-11-16 | Seiko Instr Inc | Voltage regulator |
| CN101400200A (en) * | 2007-09-25 | 2009-04-01 | 新巨企业股份有限公司 | AC electricity driving method for LED and working voltage thereof |
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| CN103379697A (en) | 2013-10-30 |
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