Summary of the invention
Place in view of above-mentioned deficiencies of the prior art, the purpose of the present invention is to provide one kind to be applied to LLC resonance frameworkAdaptive backlight power circuit, be suitable for the backlighting parameters that cover without replacing backlight transformer more, improve the simultaneous of circuitCapacitive simultaneously reduces development cost.
In order to achieve the above object, this invention takes following technical schemes:
A kind of adaptive backlight power circuit applied to LLC resonance framework comprising power factor correction module, LLC resonanceThe direct current of module, backlight module and backlight Voltage Feedback adjustment module, input power factor correction module passes through power factorOutput power factor correction voltage to LLC resonance modules, PFC voltage carry out humorous by LLC resonance modules after correctionBacklight voltage is exported after vibration to backlight module, backlight Voltage Feedback adjustment module samples the value and feedback adjustment signal of backlight voltageTo power factor correction module, power factor correction module makes according to the PFC voltage of adjustment signal adjustment outputLLC resonance modules adjust the working frequency or duty ratio of itself according to the variation of PFC voltage.
In the adaptive backlight power circuit applied to LLC resonance framework, the power factor correction module packetInclude PFC control chip, PFC inductance, PFC voltage output unit and PFC feedback voltage sampling unit, the first of the PFC inductanceHold input dc power, the end ZCD of the second end connection PFC control chip of the PFC inductance, the third end point of the PFC inductanceNot Lian Jie PFC feedback voltage sampling unit and PFC voltage output unit, the 4th end ground connection of the PFC inductance, PFC electricityPressure output unit is also connected with LLC resonance modules, and the PFC feedback voltage sampling unit is also connected with the end INV of PFC control chip.
In the adaptive backlight power circuit applied to LLC resonance framework, the backlight Voltage Feedback adjusts mouldBlock includes backlight feedback voltage sampling unit and feedback regulation unit, and the feedback regulation unit is separately connected PFC feedback voltageSampling unit and backlight feedback voltage sampling unit, the backlight feedback voltage sampling unit connect LLC resonance modules.
In the adaptive backlight power circuit applied to LLC resonance framework, the PFC feedback voltage sampling unitIncluding first resistor, second resistance, 3rd resistor and the 4th resistance, one end of the first resistor is separately connected PFC inductanceThird end and PFC voltage output unit, one end of the other end connection second resistance of the first resistor, the second resistanceThe other end connects one end of 3rd resistor, and the other end of the 3rd resistor is separately connected one end and the PFC control of the 4th resistanceThe other end at the end INV of chip, the 4th resistance connects feedback regulation unit.
In the adaptive backlight power circuit applied to LLC resonance framework, the feedback regulation unit includes anti-Fiducial chip, feedback optocoupler, first capacitor, the 5th resistance and the 6th resistance are presented, the first end of the feedback optocoupler is separately connectedOne end of 5th resistance and one end of the 6th resistance, it is described feedback optocoupler second end be separately connected the 6th resistance the other end andThe reference pole of the cathode of feedback reference chip, the feedback reference chip connects backlight feedback voltage sampling unit, the feedbackThe plus earth of fiducial chip, the other end of the 5th resistance input 12V voltage, and the third end of the feedback optocoupler is grounded,4th end of the feedback optocoupler is separately connected one end of PFC feedback voltage sampling unit and first capacitor, first capacitor it is anotherOne end ground connection.
In the adaptive backlight power circuit applied to LLC resonance framework, the feedback regulation unit further includesSecond capacitor and the 7th resistance, one end of the 7th resistance are separately connected the other end of the 6th resistance, feedback reference chipThe second end of cathode and feedback optocoupler, the other end of the 7th resistance connect one end of the second capacitor, the second capacitor it is anotherEnd is separately connected reference pole and the PFC feedback voltage sampling unit of feedback reference chip.
In the adaptive backlight power circuit applied to LLC resonance framework, the feedback reference chip is selected as essenceClose controllable source of stable pressure TL431.
In the adaptive backlight power circuit applied to LLC resonance framework, the backlight feedback voltage sampling is singleMember includes the 8th resistance, the 9th resistance, the tenth resistance and eleventh resistor, and one end of the 8th resistance connects LLC resonant modeBlock, the other end of the 8th resistance connect one end of the 9th resistance, and the other end of the 9th resistance connects the tenth resistanceOne end, the other end of the tenth resistance are separately connected one end and the feedback regulation module of eleventh resistor, the 11st electricityThe other end of resistance is grounded.
In the adaptive backlight power circuit applied to LLC resonance framework, the model of the PFC control chipNCP1608B。
In the adaptive backlight power circuit applied to LLC resonance framework, the PFC voltage output unit includesThird capacitor and the 4th capacitor, one end of the third capacitor be separately connected the third end of PFC inductance, the 4th capacitor one end,PFC feedback voltage sampling unit and LLC resonance modules.
Compared to the prior art, a kind of adaptive backlight power circuit applied to LLC resonance framework provided by the invention,It includes power factor correction module, LLC resonance modules, backlight module and backlight Voltage Feedback adjustment module, input power becauseThe direct current of number correction modules after PFC output power factor correction voltage to LLC resonance modules, power becauseNumber correction voltage output backlight voltage to backlight module, backlight Voltage Feedback after LLC resonance modules carry out resonance adjusts mouldBlock samples the value of backlight voltage and feedback adjustment signal is to power factor correction module, and power factor correction module is believed according to adjustingNumber adjustment output PFC voltage, so that LLC resonance modules is adjusted itself according to the variation of PFC voltageWorking frequency or duty ratio or duty ratio.The present invention is by backlight Voltage Feedback adjustment module, so that backlight electric power circuit canMore set backlighting parameters are adapted to without replacing backlight transformer, the compatibility of circuit is improved and reduces development cost.
Specific embodiment
The present invention provides a kind of adaptive backlight power circuit applied to LLC resonance framework, it is suitable for cover more and carries on the backOptical parameter improves the compatibility of circuit and reduces development cost without replacing backlight transformer.Also, to make the present inventionPurpose, technical solution and effect it is clearer, clear, as follows in conjunction with drawings and embodiments further specifically to the present inventionIt is bright.It should be appreciated that described herein, specific examples are only used to explain the present invention, is not intended to limit the present invention.
Referring to Fig. 2, being the preferred embodiment of the adaptive backlight circuit provided by the invention applied to LLC resonance frameworkCircuit diagram, the adaptive backlight circuit applied to LLC resonance framework includes power factor correction module 100, LLCResonance modules 200, backlight module 300 and backlight Voltage Feedback adjustment module 400, input power factor correction module 100 it is straightGalvanic electricity output power factor correction voltage to LLC resonance modules 200, PFC voltage after PFC pass throughCrossing output backlight voltage after LLC resonance modules 200 carry out resonance, to backlight module 300, backlight Voltage Feedback adjustment module 400 is adoptedThe value and feedback adjustment signal of sample backlight voltage are to power factor correction module 100, and power factor correction module 100 is according to adjustingThe PFC voltage of signal adjustment output, adjusts LLC resonance modules 200 according to the variation of PFC voltageThe working frequency or duty ratio of itself, so that steady operation is in resonant state.
Wherein, the backlight module 300 uses LED backlight, and the adaptive backlight electricity applied to LLC resonance frameworkThe automatic adjusument process on road are as follows: when backlight voltage improves, backlight Voltage Feedback adjustment module 400 samples backlight voltage, andFeedback adjustment signal is to power factor correction module 100, so that the PFC electricity that power factor correction module 100 exports(below with the replacement of PFC voltage) is pressed to rise, and after the PFC voltage rising of the input of LLC resonance modules 200, LLC resonance modules 200The gain needed reduces, and the working frequency of LLC resonance modules 200 improves；
When backlight voltage reduces, backlight Voltage Feedback adjustment module 400 samples backlight voltage, and feedback adjustment signal is to powerFactor correcting module 100, so that PFC voltage (PFC voltage) decline that power factor correction module 100 exports, andAfter the PFC voltage decline that LLC resonance modules 200 input, the gain that LLC resonance modules 200 need increases, LLC resonance modules 200Working frequency reduce.
Therefore the present invention passes through in existing power factor correction module 100, LLC resonance modules 200 and backlight module 300On the basis of, backlight Voltage Feedback adjustment module 400 is increased, to realize that PFC voltage is adjusted according to backlight voltage adaptive, is made200 constant operation of LLC resonance modules is near resonance point, the final automatic adjusument for realizing backlight circuit.
In the particular embodiment, the power factor correction module 100 include PFC control chip U1, PFC inductance L1,PFC voltage output unit 110 and PFC feedback voltage sampling unit 120, the first end input dc power of the PFC inductance L1, instituteThe end ZCD of the second end connection PFC control chip U1 of PFC inductance L1 is stated, the third end of the PFC inductance L1 is separately connected PFCFeedback voltage sampling unit 120 and PFC voltage output unit 110, the 4th end ground connection of the PFC inductance L1, the PFC voltageOutput unit 110 is also connected with LLC resonance modules 200, and the PFC feedback voltage sampling unit 120 is also connected with PFC control chip U1The end INV.
Wherein, the PFC inductance L1 is used to provide energy to PFC voltage output unit 110, and the PFC feedback voltage is adoptedSample unit 120 is used to sample the PFC voltage of the output of PFC voltage output unit 110 and feeds back to PFC control chip U1, and by PFCThe working frequency (or duty ratio of adjustment driving signal) that chip U1 adjusts driving signal is controlled, power factor correction module is madeThe PFC voltage of 110 output of PFC voltage output unit is a steady state value when 100 normal work.Preferably, the PFC controls chipThe model of U1 is selected as NCP1608B, certainly in other embodiments, other unlike signals but with the same function also may be selectedPFC controls chip.
More specifically, the PFC voltage output unit 110 includes third capacitor C3 and the 4th capacitor C4, the third electricityThe one end for holding C3 is separately connected the third end of PFC inductance L1, one end of the 4th capacitor C4,120 and of PFC feedback voltage sampling unitLLC resonance modules 200.The third capacitor C3 and the 4th capacitor C4 is big electrolytic capacitor, may be implemented energy storage andRelease.Meanwhile the power factor correction module 100 further includes driving metal-oxide-semiconductor Q1, sustained diode 1 and other periphery membersPart and circuit, because those skilled in the art can be designed according to actual needs, therefore details are not described herein by the present invention.
Further, the backlight Voltage Feedback adjustment module 400 includes backlight feedback voltage sampling unit 410 and feedbackUnit 420 is adjusted, the feedback regulation unit 420 is separately connected PFC feedback voltage sampling unit 120 and backlight feedback voltage is adoptedSample unit 410, the backlight feedback voltage sampling unit 410 connect LLC resonance modules 200.The backlight feedback voltage samplingThe backlight voltage that unit 410 can export LLC module samples, and the feedback regulation unit 420 can be to the back of samplingPhotovoltage carry out benchmark judgement simultaneously adjust PFC feedback voltage sampling unit 120 sampling PFC voltage value, and then adjust power becauseThe PFC voltage value that number correction module 100 exports.
More specifically, the PFC feedback voltage sampling unit 120 includes first resistor R1, second resistance R2,3rd resistorR3 and the 4th resistance R4, one end of the first resistor R1 are separately connected third end and the PFC voltage output unit of PFC inductance L1110(, that is, one end of third capacitor C3 and one end of the 4th capacitor C4), the other end of the first resistor R1 connects second resistanceOne end of R2, one end of the other end connection 3rd resistor R3 of the second resistance R2, the other end point of the 3rd resistor R3Not Lian Jie the 4th resistance R4 one end and PFC control chip U1 the end INV, the 4th resistance R4 the other end connection feedback adjustSave unit 420.Pass through the sampling point of the sampling resistors such as first resistor R1, second resistance R2,3rd resistor R3 and the 4th resistance R4Pressure, the PFC voltage that can be exported to power factor correction module 100 sample.Certainly, it is also selected in other embodimentsThe sampling resistor of its quantity carries out PFC voltage sample.
The backlight feedback voltage sampling unit 410 includes the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and theOne end of 11 resistance R11, the 8th resistance R8 connects LLC resonance modules 200, the other end connection of the 8th resistance R8One end of 9th resistance R9, the other end of the 9th resistance R9 connect one end of the tenth resistance R10, the tenth resistance R10The other end be separately connected one end and the feedback regulation module of eleventh resistor R11, another termination of the eleventh resistor R11Ground.It is divided by the sampling of the sampling resistors such as the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and eleventh resistor R11,The backlight voltage that can be exported to 200 module of LLC resonance modules samples.Certainly, it also selects in other embodiments otherThe sampling resistor of quantity carries out backlight voltage sample.
In a still further embodiment, the feedback regulation unit 420 includes feedback reference chip U2, feedback optocouplerThe first end of OC, first capacitor C1, the 5th resistance R5 and the 6th resistance R6, the feedback optocoupler OC are separately connected the 5th resistance R5One end and the 6th resistance R6 one end, the second end of the feedback optocoupler OC is separately connected the other end of the 6th resistance R6 and anti-The cathode of fiducial chip U2 is presented, the reference pole of the feedback reference chip U2 connects backlight feedback voltage sampling unit 410, describedThe plus earth of feedback reference chip U2, the other end of the 5th resistance R5 input 12V voltage, and the of the feedback optocoupler OC4th end of three ends ground connection, the feedback optocoupler OC is separately connected the one of PFC feedback voltage sampling unit 120 and first capacitor C1End, the other end ground connection of first capacitor C1.
Preferably, the feedback regulation unit 420 further includes the second capacitor C2 and the 7th resistance R7, the 7th resistance R7One end be separately connected the other end of the 6th resistance R6, feedback reference chip U2 cathode and feed back optocoupler OC second end, instituteThe other end for stating the 7th resistance R7 connects one end of the second capacitor C2, and the other end of the second capacitor C2 is separately connected feedback reference coreThe reference pole of piece U2 and PFC feedback voltage sampling unit 120.It, can be with Compensation Feedback by the second capacitor C2 and the 7th resistance R7Loop reduces interference, so that circuit work is more stable.
At this point, the first end of the feedback optocoupler OC is separately connected the 5th electricity in backlight Voltage Feedback adjustment module 400One end of R5 and one end of the 6th resistance R6 are hindered, the second end of the feedback optocoupler OC is separately connected the another of the 6th resistance R6The cathode at end, one end of the 7th resistance R7 and feedback reference chip U2, the reference pole of the feedback reference chip U2 is separately connectedThe other end, the other end of the tenth resistance R10 and one end of eleventh resistor R11 of second capacitor C2, the feedback reference chipThe plus earth of U2, the other end of the 5th resistance R5 input 12V voltage, the other end connection second of the 7th resistance R74th end of one end of capacitor C2, the third end ground connection of the feedback optocoupler OC, the feedback optocoupler OC is separately connected the 4th electricityHinder the other end of R4 and one end of first capacitor C1, the other end ground connection of first capacitor C1.
Preferably, feedback reference chip U2 is preferably that accurate controllable source of stable pressure TL431, TL431 can carry out 2.5V to 36VIt is continuously adjustable, with the low characteristic of good temp characteristic, quick response, leakage current within the scope of total temperature.Also, first electricityHold C1 for filtering, the 5th resistance R5 is used for current limliting, and the 6th resistance R6 is used to avoid shining in feedback optocoupler OCDiode misleads.
The course of work of the backlight Voltage Feedback adjustment module 400 are as follows:
When backlight voltage improves, after the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and eleventh resistor R11 samplingVoltage is greater than the reference voltage 2.5V of TL431, to make to feed back optocoupler OC conducting, so that first resistor R1, second resistanceThe sampled value for the PFC voltage that R2,3rd resistor R3 and the 4th resistance R4 are sampled reduces, and PFC control chip U1 is caused to increaseThe working frequency of driving signal or the duty ratio for increasing driving signal, and then the big electrolytic capacitor of PFC control chip U1 adjustment (theThree capacitor C3 and the 4th capacitor C4) voltage rise；After the voltage of big electrolytic capacitor increases, what LLC resonance modules 200 inputtedPFC voltage value increases, and the gain that LLC resonance modules 200 need reduces, so that the frequency of the work of LLC module improves；
When backlight voltage reduces, after the 8th resistance R8, the 9th resistance R9, the tenth resistance R10 and eleventh resistor R11 samplingVoltage is less than the reference voltage 2.5V of TL431, to make to feed back optocoupler OC cut-off, so that first resistor R1, second resistanceThe sampled value for the PFC voltage that R2,3rd resistor R3 and the 4th resistance R4 are sampled increases, and PFC control chip U1 is caused to reduceThe working frequency of driving signal or the duty ratio for reducing driving signal, and then PFC control chip U1 adjusts big electrolytic capacitorVoltage decline；After the voltage of big electrolytic capacitor reduces, the PFC voltage value that LLC resonance modules 200 input is reduced, LLC resonant modeThe gain that block 200 needs increases, so that the frequency of the work of LLC resonance modules 200 reduces；To pass through backlight Voltage Feedback tuneModule 400 is saved, big decomposition voltage is realized and is adaptively adjusted according to backlight voltage, finally make LLC resonance modules 200 constantIt works near resonance point.
Therefore, the present invention is by the designs of above-mentioned innovative circuits, the adaptive more sets of no replacement is required backlight transformer and circuitBacklighting parameters improve compatibility compared to traditional power circuit, reduce development cost, be suitable for backlighting parameters change it is big andSwitching Power Supply using LLC framework as LED backlight circuit.
In conclusion the present invention provides a kind of adaptive backlight power circuits applied to LLC resonance framework comprisingPower factor correction module, LLC resonance modules, backlight module and backlight Voltage Feedback adjustment module, input power factor correctionThe direct current of module after PFC output power factor correction voltage to LLC resonance modules, PFCVoltage output backlight voltage to backlight module, backlight Voltage Feedback adjustment module after LLC resonance modules carry out resonance samplesTo power factor correction module, power factor correction module adjusts the value and feedback adjustment signal of backlight voltage according to adjustment signalThe PFC voltage of output, make LLC resonance modules according to the variation of PFC voltage to steady operation inResonant state.The present invention by backlight Voltage Feedback adjustment module so that backlight electric power circuit be suitable for cover backlighting parameters andNo replacement is required backlight transformer, improves the compatibility of circuit and reduces development cost.
It, can according to the technique and scheme of the present invention and its hair it is understood that for those of ordinary skillsBright design is subject to equivalent substitution or change, and all these changes or replacement all should belong to the guarantor of appended claims of the inventionProtect range.