CN107592704B - A kind of constant-current circuit for LCD TV - Google Patents
A kind of constant-current circuit for LCD TV Download PDFInfo
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- CN107592704B CN107592704B CN201710897090.2A CN201710897090A CN107592704B CN 107592704 B CN107592704 B CN 107592704B CN 201710897090 A CN201710897090 A CN 201710897090A CN 107592704 B CN107592704 B CN 107592704B
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Abstract
The invention discloses a kind of constant-current circuits for LCD TV.The circuit includes: current rectifying and wave filtering circuit, provides the first DC voltage for reception exchange input and after carrying out rectifying and wave-filtering；Pfc circuit, for receiving the first DC voltage and carrying out power factor correcting to export the second DC voltage；LLC circuit, for receiving the second DC voltage and exporting corresponding continuous current respectively in multiple output channels under the driving of the second DC voltage；Feed circuit, for when continuous current fluctuates, adjusting the output duty cycle of LLC controller in LLC circuit to keep continuous current constant.By the above-mentioned means, the present invention can realize constant-current circuit in a relatively simple manner, be conducive to the productivity effect for improving LCD TV.
Description
Technical field
The present invention relates to LCD TV fields, more particularly to a kind of constant-current circuit for LCD TV.
Background technique
In LCD TV, certain driving circuits such as LED drive circuit needs to drive using constant current, in order to realize constant current
Driving, the way of the prior art is: constant current driving is provided using external constant-current driven chip and its peripheral circuit.
Constant current driving is provided in this way, is needed using additional chip, circuit complexity and higher cost.
Summary of the invention
The invention mainly solves the technical problem of providing a kind of constant-current circuits for LCD TV, can be with relatively simple
Single mode provides constant current driving.
In order to solve the above technical problems, one technical scheme adopted by the invention is that: a kind of constant current for liquid crystal is provided
Circuit, the circuit include: current rectifying and wave filtering circuit, provide the first direct current for reception exchange input and after carrying out rectifying and wave-filtering
Pressure；Pfc circuit, for receiving the first DC voltage and carrying out power factor correcting to export the second DC voltage；LLC circuit,
For receiving the second DC voltage and exporting corresponding constant current respectively in multiple output channels under the driving of the second DC voltage
Electric current；Feed circuit, for when continuous current fluctuates, adjusting the output duty cycle of LLC controller in LLC circuit to protect
It is constant to hold continuous current.
The beneficial effects of the present invention are: the constant-current circuit for LCD TV of the invention passes through on the basis of available circuit
Upper increase feed circuit, wherein feed circuit is used for when continuous current fluctuates, and adjusts LLC controller in LLC circuit
Output duty cycle is to keep continuous current constant.By the above-mentioned means, the present invention can realize constant current in a relatively simple manner
Circuit, circuit is simple, low in cost, is conducive to improve productivity effect.
Detailed description of the invention
Fig. 1 is the structural schematic diagram of the constant-current circuit for LCD TV of the embodiment of the present invention；
Fig. 2 is the circuit theory of current rectifying and wave filtering circuit in Fig. 1；
Fig. 3 is the circuit diagram of pfc circuit in Fig. 1；
Fig. 4 is the circuit diagram of LLC circuit and feed circuit in Fig. 1.
Specific embodiment
Following will be combined with the drawings in the embodiments of the present invention, and technical solution in the embodiment of the present invention carries out clear, complete
Site preparation description, it is clear that the described embodiments are merely a part of the embodiments of the present invention, instead of all the embodiments.It is based on
Embodiment in the present invention, it is obtained by those of ordinary skill in the art without making creative efforts every other
Embodiment shall fall within the protection scope of the present invention.
Fig. 1 is the structural schematic diagram of the constant-current circuit for LCD TV of the embodiment of the present invention.As shown in Figure 1, constant current
Circuit 10 includes current rectifying and wave filtering circuit 11, pfc circuit 12, LLC circuit 13 and feed circuit 14.
Current rectifying and wave filtering circuit 11 provides the first DC voltage for reception exchange input and after carrying out rectifying and wave-filtering；
Pfc circuit 12 is connect with current rectifying and wave filtering circuit 11, for receiving the first DC voltage and carrying out power factor correcting
To export the second DC voltage；
LLC circuit 13 is connect with pfc circuit 12, for receiving the second DC voltage and under the driving of the second DC voltage
Corresponding continuous current is exported respectively in multiple output channels；
Feed circuit 14 is connect with LLC circuit 13, for when continuous current fluctuates, adjusting LLC control in LLC circuit
The output duty cycle of device processed is to keep continuous current constant.
Fig. 2 is the circuit diagram of current rectifying and wave filtering circuit in Fig. 1.As shown in Fig. 2, current rectifying and wave filtering circuit 11 includes the six or two
Pole pipe D6, the 7th diode D7, the 8th diode D8, the 9th diode D9 and third capacitor C3.
Wherein, GND, the 6th diode D6 are grounded after the connection of the anode of the anode of the 6th diode D6 and the 7th diode D7
Cathode and the 8th diode D8 anode connection after with exchange input AC one end such as zero line connect, the 7th diode D7
Cathode and the 9th diode D9 anode connection after with exchange input AC the other end such as zero line side connect, the 8th diode
It is connect after the connection of the cathode of the cathode of D8 and the 9th diode D9 with one end of third capacitor C3, another termination of third capacitor C3
Ground.In the present embodiment, the capacitance of third capacitor C3 is 1uF.
The commonly connected place of the cathode of the cathode and the 9th diode D9 of 8th diode D8 exports the first DC voltage U1.
It is the circuit diagram of pfc circuit in Fig. 1 please also refer to Fig. 3, Fig. 3.As shown in figure 3, pfc circuit 12 includes
Pfc controller PFC IC, common mode inductance LF1, second transistor Q2, first diode D1 and first capacitor C1.
Pfc controller PFC IC includes zero current detection input pin ZCD, door driving output pin GATE and current detecting
Input pin CS.
Zero current detection input pin ZCD is connect with the second Same Name of Ends of common mode inductance LF1, and door drives output pin GATE
Connect with the grid of second transistor Q2, the drain electrode of second transistor Q2 respectively with the first Same Name of Ends of common mode inductance LF1 and the
The anode of one diode D1 connects, and current detecting input pin CS is connect with the source electrode of second transistor Q2, first diode D1
Cathode connect with one end of first capacitor C1, the other end of first capacitor C1 is grounded GND, the first different name of common mode inductance LF1
End is connect with the common end of third capacitor C3 and the 9th diode D9 in Fig. 2 to receive the first DC voltage U1, common mode inductance
The second different name end of LF1 is grounded GND.In the present embodiment, the capacitance of first capacitor C1 is 390uF.
Wherein, the cathode of first diode D1 exports the second DC voltage U2.
It is the circuit diagram of LLC circuit and feed circuit in Fig. 1 please also refer to Fig. 4, Fig. 4.As shown in figure 4, LLC is electric
Road 13 includes LLC controller LLC IC, first resistor R1, second resistance R2, the first transistor Q1, third transistor Q3, transformation
Device T1, the second diode D2, third diode D3, the 4th diode D4, the 5th diode D5, the first inductance L1, the second capacitor
C2, the 5th capacitor C5.
LLC controller LLC IC include first driving pin GATE1, second driving pin GATE2, delay pin DELAY,
Control pin CF and feedback pin FB.
Wherein, the first driving pin GATE1 is connect with the grid of the first transistor Q1, and second drives pin GATE2 and the
The grid of three transistor Q3 connects, and the drain electrode of the first transistor Q1 receives the second DC voltage U2, the source electrode of the first transistor Q1
It is connect with the drain electrode of third transistor Q3, the source electrode ground connection of third transistor Q3, the one of delay pin DELAY and first resistor R1
End connection, the other end of first resistor R1 are grounded GND, and control pin CF is connect with one end of second resistance R2, second resistance R2
The other end be grounded GND, feedback pin FB connect with feed circuit 14.
Transformer T1 includes primary side winding and vice-side winding, and the Same Name of Ends of primary side winding is brilliant by the first inductance L1 and first
The source electrode of body pipe Q1 connects, and the different name end of primary side winding is grounded GND by the 5th capacitor C5, and vice-side winding passes through the second capacitor
It is formed between C2, the second diode D2, third diode D3, the 4th diode D4, the 5th diode D5 and feed circuit 14 more
A output channel.
Specifically, when multiple output channels are two, one end of the Same Name of Ends of vice-side winding and the second capacitor C2 connect
It connects, the other end of the second capacitor C2 is connect with the anode of the cathode of the second diode D2, third diode D3 respectively, the three or two pole
Form the first output channel between the cathode and feed circuit 14 of pipe D3, the plus earth of the second diode D2, vice-side winding
Different name end is connect with the anode of the cathode of the 4th diode D4, the 5th diode D5 respectively, the cathode of the 5th diode D5 and anti-
The second output channel, the plus earth of the 4th diode D4 are formed between current feed circuit 14.
In the present embodiment, first resistor R1, second resistance R2 resistance value be respectively 470R, 10K.The electricity of first inductance L1
Inductance value is 150uH.Second capacitor C2, the 5th capacitor C5 capacitance be respectively 1uF, 22nF.
Preferably, LLC circuit 13 further comprises the 4th capacitor C4, the 6th capacitor C6 and the 7th capacitor C7, the 4th capacitor
One end of C4 is connect with the cathode of third diode D3, and the other end of the 4th capacitor C4 is grounded GND.One end of 6th capacitor C6 with
The cathode of 5th diode D5 connects, and the other end of the 6th capacitor C6 is grounded GND.One end of 7th capacitor C7 and delay pin
DELAY connection, the other end ground connection of the 7th capacitor C7.In the present embodiment, the 4th capacitor C4, the 6th capacitor C6 and the 7th capacitor
The capacitance of C7 is respectively 1uF, 1uF and 0.1uF (104).
Feed circuit 14 includes operational amplifier IC2, voltage reference chip IC3, optoelectronic isolating element PC1, the 9th capacitor
C9, the 4th resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, the 11st electricity
Hinder R11 and twelfth resistor R12.
Wherein, the first end of the 9th resistance R9 is connect with one end of the 8th resistance R8, the second end ground connection of the 9th resistance R9
The other end of GND, the 8th resistance R8 are connect with the inverting input terminal of one end of the 9th capacitor C9 and operational amplifier IC2 respectively,
The other end of 9th capacitor C9 is connect with one end of the 7th resistance R7, the other end of the 7th resistance R7 respectively with operational amplifier
The cathode connection of the output end of IC2, one end of the 6th resistance R6, optoelectronic isolating element PC1, the other end and light of the 6th resistance R6
It is connect after being electrically isolated the anode connection of element PC1 with one end of the 5th resistance R5, the other end of the 5th resistance R5 is respectively with first
The connection of one end of power supply V0 and the 4th resistance R4, the other end of the 4th resistance R4 are connect with the cathode of voltage reference chip IC3, electricity
The plus earth GND of fiducial chip IC3 is pressed, the adjustable end of voltage reference chip IC3 is connect with one end of eleventh resistor R11,
The other end of eleventh resistor R11 connects with the non-inverting input terminal of one end of twelfth resistor R12 and operational amplifier IC2 respectively
It connects, the other end of twelfth resistor R12 is grounded GND, and the emitter of optoelectronic isolating element PC1 is grounded, optoelectronic isolating element PC1's
Collector is connect with the feedback pin FB of LLC controller LLC IC.
In the present embodiment, the first end of the cathode of third diode D3 and the 9th resistance R9 form the first output channel,
The second output channel is formed between the cathode of 5th diode D5 and the first end of the 9th resistance R9.In the first output channel and
Two output channels are respectively arranged with the first LED light string 15 and the second LED light string 16, wherein the anode and the of the first LED light string 15
The cathode of three diode D3 connects, and the cathode of the first LED light string 15 is connect with the first end of the 9th resistance R9, the second LED light string
16 anode is connect with the cathode of the 5th diode D5, and the cathode of the second LED light string 16 is connect with the first end of the 9th resistance R9.
Wherein, the first LED light string 15 is identical with model with the quantity of LED light in the second LED light string 16.Flow through the electricity of the first output channel
Stream is denoted as the first continuous current I1, and the electric current for flowing through the second output channel is denoted as the second continuous current I2.
It will be understood to those skilled in the art that being only in the first output channel and the second output channel setting LED light string
Citing, invention is not limited thereto, in other embodiments, may be arranged as other loads.
In the present embodiment, the capacitance of the model AZ431, the 9th capacitor C9 of voltage reference chip IC3 are 0.1uF, the
Four resistance R4, the 5th resistance R5, the 6th resistance R6, the 7th resistance R7, the 8th resistance R8, the 9th resistance R9, eleventh resistor
R11, twelfth resistor R12 resistance value be 560R, 470R, 1K, 47K, 470R, 2R, 12K, 3K.
Preferably, feed circuit 14 further comprises third capacitor C3, the tenth capacitor C10 and the 11st capacitor C11, third
The both ends of capacitor C3 are connect with the emitter and collector for being electrically isolated element PC1 respectively, and one end of the tenth capacitor C10 is put with operation
The positive input connection of big device IC2, the other end ground connection of the tenth capacitor C10, one end of the 11st capacitor C11 and the 8th resistance
The public connecting end connection of R8, the 9th resistance R9, the other end of the 11st capacitor C11 are grounded GND.In the present embodiment, third
The capacitance of capacitor C3, the tenth capacitor C10 and the 11st capacitor C11 are respectively 1uF (105), 1uF (105), 1uF.
The working principle of constant-current circuit is illustrated below with reference to circuit diagram, specific as follows shown:
After exchange input AC access current rectifying and wave filtering circuit, current rectifying and wave filtering circuit 11 receives exchange input AC and is rectified
First DC voltage U1, the first DC voltage U1 is provided after filtering and exports second after pfc circuit 12 carries out power factor correcting
DC voltage U2.
After LLC circuit 13 receives the second DC voltage U2, LLC controller LLC IC controls the first transistor Q1 and third is brilliant
The service time of body pipe Q3 is to form primary current Ip in the primary side winding of transformer T1, wherein primary current Ip is positive and negative half
Axis amplitude is identical, and frequency respectively accounts for 50% sine wave, and then secondary current Is is formed on vice-side winding.Those skilled in the art
Member is it is appreciated that since the relationship of primary current Ip and secondary current Is meet: Is=Ip*N, wherein N is primary side winding and pair
The turn ratio of side winding, therefore the secondary current Is on vice-side winding is also that frequency is identical, positive and negative semiaxis amplitude is identical just
String wave.
When secondary current Is flow through vice-side winding so that vice-side winding Same Name of Ends be high level when, secondary current Is
The first continuous current I1, which is formed, after third diode D3 rectification, the 4th capacitor C4 filtering flows through the first of the first output channel
LED light string 15, and pass through the different name end of the 4th diode D4 return vice-side winding.Similarly, when secondary current Is flow through secondary side around
Group is so that when the different name end of vice-side winding is high level, and secondary current Is is by the 5th diode D5 rectification, the 6th capacitor
The second LED light string 16 that the second continuous current I2 flows through the second output channel is formed after C6 filtering, and passes through the second diode D2
Return to the Same Name of Ends of vice-side winding.
Wherein, the first continuous current I1 is the electric current of secondary current Is positive axis, and the second continuous current I2 is secondary current
The electric current of the negative semiaxis of Is, therefore, the size of the first continuous current I1 are equal to the size of the second continuous current I2, are denoted as continuous current
I0。
In the present embodiment, as the first continuous current I1, the second continuous current I2 is equal in magnitude and remains continuous current
When I0, the voltage of the inverting input terminal of operational amplifier IC2 is equal to the voltage of positive input.
Wherein, the voltage of the positive input of operational amplifier IC2 meets following formula:
Ua=VREF/ (r11+r12) * r12；
Wherein, Ua is the voltage of the positive input of operational amplifier, and VREF is the reference voltage of voltage reference chip,
R11 is the resistance value of eleventh resistor R11, and r12 is the resistance value of twelfth resistor R12.
Wherein, the voltage of the inverting input terminal of operational amplifier IC2 meets following formula:
Ub=I0*r9；
Wherein, Ub is the voltage of the reverse input end of operational amplifier, and I0 is the first perseverance flowed through in the first output channel
Galvanic electricity stream flows through the second continuous current in the second output channel, and r9 is the resistance value of the 9th resistance R9.
It changes for an angle, since operational amplifier IC2 work is in closed loop states, and the forward direction of operational amplifier IC2 is defeated
The voltage Ua for entering end is a reference voltage, so that the voltage Ub of inverting input terminal is fixed on the reference voltage, so that
First continuous current I1, the second continuous current I2 are fixed on same continuous current I0.
In the present embodiment, when the first continuous current I1 or the second continuous current I2 such as external load for some reason
When changing and increasing, then the voltage Ub of the inverting input terminal of operational amplifier IC2 increases, so that operational amplifier
The output voltage of IC2 is reduced, so that increasing from the electric current that the anode of optoelectronic isolating element PC1 flows to cathode.When photoelectricity every
When the electric current that anode from element PC1 flows to cathode increases, the light emission luminance of optoelectronic isolating element PC1 enhances so that photoelectricity
The electric current that the collector of isolation element PC1 flows to emitter increases, so that the voltage of feedback pin FB increases.When LLC is controlled
After the voltage that device LLC IC processed detects feedback pin FB increases, the first driving pin GATE1, the second driving pin are reduced
The duty ratio of the pulse signal of GATE2 output is to reduce the first transistor Q1, the service time of third transistor Q3 makes just
Grade electric current Ip becomes smaller, and then reaches the increase for inhibiting the first continuous current I1 or the second continuous current I2, keeps the first Constant Electric Current
Flow the constant effect of I1, the second continuous current I2.
Similarly, when the first continuous current I1 or the second continuous current I2 reduce for some reason, then operation amplifier
The voltage Ub of the inverting input terminal of device IC2 reduces, so that the output voltage of operational amplifier IC2 increases, so that from
The electric current that the anode of optoelectronic isolating element flows to cathode reduces.When the electric current that the anode of optoelectronic isolating element flows to cathode reduces
When, the light emission luminance of optoelectronic isolating element weakens so that the electric current that the collector of optoelectronic isolating element flows to emitter subtracts
It is small, so that the voltage of feedback pin FB reduces.When the voltage that LLC controller LLC IC detects feedback pin FB reduces
Afterwards, increase the duty ratio of the first driving pin GATE1, the pulse signal that the second driving pin GATE2 is exported to increase by first
Transistor Q1, third transistor Q3 service time make primary current Ip increase, and then reach inhibit the first continuous current I1
Or second continuous current I2 reduction, keep the first continuous current I1, the second continuous current I2 constant effect.
It will be understood to those skilled in the art that multiple output channels include that two output channels namely first are defeated in Fig. 4
Channel and the second output channel are only for example out, and present invention could apply to be different from two multiple output channels.
Specifically, when multiple output channels include four output channels namely the first output channel, the second output channel,
Third output channel and the 4th output channel, wherein the first LED light string, the setting of the second output channel is arranged in the first output channel
The 4th LED light string is arranged in second LED light string, third output channel setting third LED light string, the 4th output channel, wherein first
The anode of LED light string is connect with the cathode of third diode, and the cathode of the first LED light string is connect with the anode of the second LED light string
It is connect afterwards with the first end of the 9th resistance, the cathode of the second LED light string is connect with the anode of the second diode, third LED light string
Anode connect with the cathode of the 5th diode, the cathode of third LED light string and the 4th LED light string it is positive connect after with the 9th
The first end of resistance connects, and the cathode of the 4th LED light string is connect with the anode of the 4th diode, at this point, the sun of the second diode
Pole, the anode of the 4th diode are earth-free, and the cathode of the first LED light string, the cathode of third LED light string are grounded.That is, the
One output channel and the second output channel are in a current loop, and third output channel and the 4th output channel are in another electricity
It flows back in road.It will be understood to those skilled in the art that when multiple output channels include three output channels, by the 4th LED
Lamp string is taken away, and the cathode of third LED light string is directly connect with the anode of the 4th diode, at this point, the first output channel and
Second output channel is in a current loop, and third output channel is in another current loop.
The beneficial effects of the present invention are: the constant-current circuit for LCD TV of the invention passes through on the basis of available circuit
Upper increase feed circuit, wherein feed circuit is used for when continuous current fluctuates, and adjusts LLC controller in LLC circuit
Output duty cycle is to keep continuous current constant.By the above-mentioned means, the present invention can realize constant current in a relatively simple manner
Circuit, circuit is simple, low in cost, is conducive to improve productivity effect.
Mode the above is only the implementation of the present invention is not intended to limit the scope of the invention, all to utilize this
Equivalent structure or equivalent flow shift made by description of the invention and accompanying drawing content, it is relevant to be applied directly or indirectly in other
Technical field is included within the scope of the present invention.
Claims (6)
1. a kind of constant-current circuit for LCD TV, which is characterized in that the circuit includes:
Current rectifying and wave filtering circuit provides the first DC voltage for reception exchange input and after carrying out rectifying and wave-filtering；
Pfc circuit, for receiving first DC voltage and carrying out power factor correcting to export the second DC voltage；
LLC circuit, for receiving second DC voltage and leading under the driving of second DC voltage in multiple outputs
Road exports corresponding continuous current respectively；
Feed circuit, for when the continuous current fluctuates, the output for adjusting LLC controller in the LLC circuit to be accounted for
Sky is than to keep the continuous current constant；
Wherein, the LLC circuit includes LLC controller, first resistor, second resistance, the first transistor, third transistor, change
Depressor, the second diode, third diode, the 4th diode, the 5th diode, the first inductance, the second capacitor, the 5th capacitor,
Wherein, the LLC controller includes the first driving pin, the second driving pin, delay pin, control pin and feedback pin；
The grid of the first driving pin and the first transistor connects, the second driving pin and the third transistor
Grid connection, the drain electrode of the first transistor receive second DC voltage, the source electrode of the first transistor with it is described
The drain electrode of third transistor connects, the source electrode ground connection of the third transistor, and the one of the delay pin and the first resistor
End connection, the other end ground connection of the first resistor, the control pin are connect with one end of the second resistance, and described second
The other end of resistance is grounded, and the feedback pin is connect with the feed circuit；
The transformer includes primary side winding and vice-side winding, and the Same Name of Ends of the primary side winding passes through first inductance and institute
The source electrode connection of the first transistor is stated, the different name end of the primary side winding passes through the 5th capacity earth, the vice-side winding
Pass through second capacitor, second diode, the third diode, the 4th diode, the 5th diode
Multiple output channels are formed with the feed circuit；
Wherein, when multiple output channels are two, the Same Name of Ends of the vice-side winding is connect with one end of the second capacitor,
The other end of second capacitor is connect with the anode of the cathode of second diode, the third diode respectively, described
The cathode of third diode and the feed circuit form the first output channel, and the plus earth of second diode is described
The different name end of vice-side winding is connect with the anode of the cathode of the 4th diode, the 5th diode respectively, and the described 5th
The cathode of diode and the feed circuit form the second output channel, the plus earth of the 4th diode；
Wherein, the electric current for flowing through first output channel is denoted as the first continuous current, flows through the electricity of second output channel
Stream is denoted as the second continuous current；
Wherein, the first continuous current is the electric current of the positive axis of the secondary current formed on the vice-side winding, the second Constant Electric Current
Stream is the electric current of the negative semiaxis of the secondary current formed on the vice-side winding；
The feed circuit includes operational amplifier, voltage reference chip, optoelectronic isolating element, the 9th capacitor, the 4th resistance,
Five resistance, the 6th resistance, the 7th resistance, the 8th resistance, the 9th resistance, eleventh resistor and twelfth resistor；
The first end of 9th resistance is electric with one end of the 8th resistance and the LLC circuit connection, the described 9th respectively
The second end of resistance is grounded, the other end of the 8th resistance reverse phase with one end of the 9th capacitor and the operational amplifier respectively
Input terminal connection, the other end of the 9th capacitor connect with one end of the 7th resistance, the other end of the 7th resistance respectively with institute
State the cathode connection of the output end of operational amplifier, one end of the 6th resistance, the optoelectronic isolating element, the 6th electricity
It is connect after the connection of the anode of the other end of resistance and the optoelectronic isolating element with one end of the 5th resistance, the 5th resistance
The other end connect respectively with one end of the first power supply and the 4th resistance, the other end of the 4th resistance and the voltage
The cathode of fiducial chip connects, the plus earth of the voltage reference chip, the adjustable end and the tenth of the voltage reference chip
One end of one resistance connects, and the other end of the eleventh resistor is put with one end of the twelfth resistor and the operation respectively
The non-inverting input terminal connection of big device, the other end ground connection of the twelfth resistor, the emitter ground connection of the optoelectronic isolating element,
The collector of the optoelectronic isolating element PC1 is connect with the feedback pin FB of LLC controller LLC IC.
2. circuit according to claim 1, which is characterized in that the voltage of the inverting input terminal of the operational amplifier meets
Following formula:
Ub=I0*r9；
Wherein, Ub is the voltage of the reverse input end of the operational amplifier, and I0 is the flowed through in first output channel
One continuous current flows through the second continuous current in second output channel, and r9 is the resistance value of the 9th resistance.
3. circuit according to claim 2, which is characterized in that when first continuous current, second continuous current
When keeping constant, the voltage of the inverting input terminal of the operational amplifier is equal to the voltage of positive input.
4. circuit according to claim 1, which is characterized in that the voltage of the positive input of the operational amplifier meets
Following formula:
Ua=VREF/ (r11+r12) * r12；
Wherein, Ua is the voltage of the positive input of the operational amplifier, and VREF is the benchmark electricity of the voltage reference chip
Pressure, r11 are the resistance value of the eleventh resistor, and r12 is the resistance value of the twelfth resistor.
5. circuit according to claim 1, which is characterized in that the current rectifying and wave filtering circuit includes the 6th diode, the 7th
Diode, the 8th diode, the 9th diode and third capacitor, wherein the anode and the described 7th 2 of the 6th diode
Be grounded after the anode connection of pole pipe, after the anode connection of the cathode of the 6th diode and the 8th diode with the friendship
After the anode connection of one end connection of stream input, the cathode of the 7th diode and the 9th diode with it is described exchange it is defeated
After the cathode connection of the other end connection entered, the cathode of the 8th diode and the 9th diode with the third capacitor
One end connection, the third capacitor the other end ground connection；
Wherein, the cathode of the 8th diode exports first direct current after connecting with the cathode of the 9th diode
Pressure.
6. circuit according to claim 1, which is characterized in that the PFC circuit include pfc controller, common mode inductance,
Second transistor, first diode and first capacitor, wherein the pfc controller includes zero current detection input pin, door drive
Dynamic output pin and current detecting input pin；
The zero current detection input pin is connect with the second Same Name of Ends of the common mode inductance, door driving output pin with
The grid of the second transistor connects, the drain electrode of the second transistor respectively with the first Same Name of Ends of the common mode inductance and
The anode of the first diode connects, and the current detecting input pin is connect with the source electrode of the second transistor, described
The cathode of first diode is connect with one end of the first capacitor, the other end ground connection of the first capacitor, the common mode electricity
First different name end of sense receives first DC voltage, the second different name end ground connection of the common mode inductance；
Wherein, the cathode of the first diode exports second DC voltage.
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| CN201710897090.2A CN107592704B (en) | 2017-09-29 | 2017-09-29 | A kind of constant-current circuit for LCD TV |
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| CN201710897090.2A CN107592704B (en) | 2017-09-29 | 2017-09-29 | A kind of constant-current circuit for LCD TV |
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| CN107592704B true CN107592704B (en) | 2019-09-20 |
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| CN109151351B (en) * | 2018-09-25 | 2021-06-01 | 深圳创维－Rgb电子有限公司 | Power panel and television |
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| CN103813589A (en) * | 2014-01-24 | 2014-05-21 | 东南大学 | Isolation type high-power light emitting diode (LED) driving power source with multi-output current sharing |
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| CN107592704A (en) | 2018-01-16 |
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