CN109274910A

CN109274910A - A kind of Switching Power Supply and TV

Info

Publication number: CN109274910A
Application number: CN201811317165.6A
Authority: CN
Inventors: 陈建忠; 杨寄桃; 沈思宽
Original assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Current assignee: Shenzhen Skyworth RGB Electronics Co Ltd
Priority date: 2018-11-07
Filing date: 2018-11-07
Publication date: 2019-01-25
Anticipated expiration: 2038-11-07
Also published as: WO2020094097A1; CN109274910B

Abstract

The embodiment of the invention discloses a kind of Switching Power Supply and TV, the Switching Power Supply includes: PFC control management constant pressure module, PFC control management constant flow module and linear constant pressure module；Wherein, PFC control management constant pressure module is used to improve the power factor of constant voltage output and exports constant voltage and powers to the host chip；PFC control management constant flow module is used to improve the power factor of constant current output and exports constant voltage powers to the Constant Current Load；The linear constant pressure module is used for during system is from the standby underloading to booting, the voltage of the voltage and the second input terminal that pass sequentially through first input end is that the power end of PFC control management constant flow module carries out relay power supply, so that the Constant Current Load normally starts.Be not in that the power end power supply capacity that controls management constant-current circuit because of PFC is insufficient by the Switching Power Supply, lead to the situation that LED backlight can not be normally-open, improve the stability of system.

Description

A kind of Switching Power Supply and TV

Technical field

The present embodiments relate to power supply control technology field more particularly to a kind of Switching Power Supply and TVs.

Background technique

With the high speed development of LED (Light Emitting Diode, light emitting diode) LCD TV, currently, LED liquid Brilliant TV has spread to huge numbers of families.

Existing LED liquid crystal television is all made of power panel+constant current plate design method, wherein power panel is responsible for constant current Plate and TV motherboard provide suitable input voltage, and constant current plate is responsible for LED backlight mould group and provides constant electric current, the electricity Source plate+constant current plate is referred to as Switching Power Supply.In whole set of television work, Switching Power Supply realizes constant pressure and flow output, should meet The constant current demand of LED backlight meets the constant pressure demand of TV motherboard (machine core) again.But existing power supply design scheme It is low, at high cost that there are power supply conversion efficiencies, machine core at light load, LED backlight can not it is normally-open, when LED backlight exception mistake After pressure, the defect that can not be protected.

Summary of the invention

The embodiment of the present invention provides a kind of Switching Power Supply and TV, during system is from the standby underloading to booting, leads to Crossing the Switching Power Supply may be implemented the normally-open of LED backlight, be not in because PFC controls the power supply of management constant-current circuit It holds power supply capacity insufficient, leads to the situation that LED backlight can not be normally-open, improve the stability of system.

To achieve the above object, the embodiment of the present invention adopts the following technical scheme that

In a first aspect, the Switching Power Supply includes: PFC (Power the embodiment of the invention provides a kind of Switching Power Supply Factor Correction, PFC) control management constant pressure module, PFC control management constant flow module and linear constant pressure Module；

Wherein, the input terminal of PFC control management constant pressure module is connected with power supply, the first output end and host chip phase Even, second output terminal is connected with linear constant pressure module, for improving the power factor of constant voltage output and exporting constant voltage to institute Host chip power supply is stated, while providing pretrigger voltage for the linear constant pressure module；

The input terminal of PFC control management constant flow module is connected with the output end of the linear constant pressure module, the first output end It is connected with Constant Current Load, second output terminal is connected with the linear constant pressure module, for improving the power factor of constant current output simultaneously It exports constant voltage to power to the Constant Current Load, while providing relay voltage for the linear constant pressure module；

The first input end of the linear constant pressure module controls the second output terminal phase of management constant pressure module with the PFC Even, the second input terminal is connected with the PFC second output terminal for controlling management constant flow module, and output end and PFC control are managed The input terminal for managing constant flow module is connected, for when system from shutdown to it is standby again to booting underloading during, pass sequentially through the The voltage of the voltage of one input terminal and the second input terminal is that the power end of PFC control management constant flow module carries out relay confession Electricity, so that the Constant Current Load normally starts.

Further, PFC control management constant pressure module include: PFC control management constant voltage circuit, constant pressure switching tube, Constant-voltage transformer and Isobarically Control loop；

Wherein, the first end of PFC control management constant voltage circuit is connected with power supply, and the 6th end and constant-voltage transformer assist The output end of winding is connected, and the 7th end is connected by constant pressure switching tube with the control terminal of constant-voltage transformer main winding, is used for basis The conducting and shutdown for the zero passage detection signal control constant pressure switching tube that the output end of constant-voltage transformer auxiliary winding provides, to improve The power factor of constant voltage output, the 4th end of the PFC control management constant voltage circuit and the output end of the Isobarically Control loop It is connected, the PFC control management constant voltage circuit, which is also used to control constant pressure according to the signal of the Isobarically Control loop output, to be opened The conducting and shutdown of pipe are closed, so that constant-voltage transformer exports constant voltage；

The input terminal of the constant-voltage transformer main winding is connected with power supply, and output end is connected with main unit movement, is used for Constant voltage is provided under the control that the PFC controls management constant voltage circuit for host chip；

The input terminal of the Isobarically Control loop is connected with the output end of the constant-voltage transformer main winding, for described The constant voltage of constant-voltage transformer main winding output is sampled, and sampled voltage is sent to the PFC control management constant pressure 4th end of circuit, so that PFC control management constant voltage circuit controls the conducting of constant pressure switching tube according to the sampled voltage With shutdown so that constant-voltage transformer export constant voltage.

Further, PFC control management constant flow module include: PFC control management constant-current circuit, constant current switch pipe, Constant-current transformer and over-voltage adjustment circuit,

Wherein, the power end of the PFC control management constant-current circuit is connected with the output end of the linear constant voltage circuit, the Six ends are connected with the output end of constant-current transformer auxiliary winding, and the 9th end passes through constant current switch pipe and constant-current transformer main winding Control terminal is connected, and the zero passage detection signal for being provided according to the output end of constant-current transformer auxiliary winding controls constant current switch pipe Conducting and shutdown, to improve the power factor of constant current output, the 4th end of the PFC control management constant-current circuit and the mistake The output end of adjustment circuit is pressed to be connected, the PFC control management constant-current circuit is also used to according to the defeated of the over-voltage adjustment circuit The conducting and shutdown of end signal control constant current switch pipe out, so that constant-current transformer exports constant voltage；

The input terminal of the constant-current transformer main winding is connected with power supply, and output end is connected with Constant Current Load, is used for Constant voltage is provided under the control that the PFC controls management constant-current circuit for the Constant Current Load；

The over-voltage adjustment circuit input terminal is connected with the output end of the Constant Current Load, for the Constant Current Load Output end voltage is sampled, and sampled voltage is sent to the 4th end of the PFC control management constant-current circuit, so that described PFC control management constant-current circuit controls the conducting and shutdown of constant current switch pipe according to the sampled voltage, so that constant-current transformer Export constant voltage.

Further, the linear constant pressure module includes linear constant voltage circuit, the first input of the linear constant voltage circuit End is connected with the output end of the constant-voltage transformer auxiliary winding, and the second input terminal is defeated with the constant-current transformer auxiliary winding Outlet is connected, and control terminal is connected with enable signal, and output end is connected with the PFC power end for controlling management constant-current circuit, uses In when system from shutdown to it is standby again to booting underloading during, pass sequentially through first input end voltage and second input The voltage at end is that the power end of PFC control management constant-current circuit carries out relay power supply, so that the Constant Current Load normally opens It is dynamic.Further, the Switching Power Supply further include: high pressure pretrigger circuit, the input terminal of the high pressure pretrigger circuit and friendship Power supply is flowed to be connected, the first end that output end and the PFC control manage constant voltage circuit is connected, for system by shut down to In standby process, management constant voltage circuit is controlled for the PFC, power supply is provided, so that PFC control management constant voltage circuit opens It moves and starts to work.

Further, the power end of PFC control management constant voltage circuit and the constant-voltage transformer auxiliary winding is defeated Outlet be connected, when the PFC control management constant voltage circuit starting after by the constant-voltage transformer auxiliary winding output end be its Power supply is provided, and controls the high pressure pretrigger circuit and closes.

Further, the high pressure pretrigger circuit includes: the 4th diode, the 5th diode, the 9th resistance, the tenth electricity Resistance, the first control pipe, wherein the 4th diode and the connection of the 5th diodes in parallel, anode are connected with power supply, cathode It is connected respectively with the first end of the first end of the 9th resistance and the tenth resistance, the second end of the 9th resistance and described the The second end of one control pipe is connected, the first end and the PFC of the second end of the tenth resistance and the first control pipe The tenth one end of control management constant voltage circuit is connected, the third end of the first control pipe and PFC control management constant pressure electricity The first end on road is connected.

Further, the Switching Power Supply further include: em filtering circuit and rectification circuit, wherein the em filtering The input terminal of circuit is connected with communication power supply, output end respectively with the input terminal of the high pressure pretrigger circuit and described The input terminal of rectification circuit is connected, the output end of the rectification circuit respectively with the input terminal of the constant-voltage transformer main winding with And the input terminal of the constant-current transformer main winding is connected.

Further, the Switching Power Supply further include: overvoltage crowbar, the input terminal of the overvoltage crowbar and institute The output end for stating constant-current transformer auxiliary winding is connected, and output end is connected with the PFC second end for controlling management constant-current circuit, When voltage for exporting when the constant-current transformer is more than setting value, the PFC control management constant-current circuit is made to pass through control The conducting and shutdown of the constant current switch pipe drop to the voltage of the constant-current transformer output in setting range.

Further, the 7th end of the PFC control management constant-current circuit passes through constant current switch pipe and the constant current transformation The output end of device main winding is connected, and the 7th end of the PFC control management constant-current circuit also passes through voltage sample resistance eutral grounding.

Further, the overvoltage crowbar includes: first capacitor, first resistor, second resistance, 3rd resistor and Four resistance, wherein the first end of the first capacitor respectively with the output end of constant-current transformer auxiliary winding and described first The first end of resistance is connected, and second of 3rd resistor described in the second end of the first capacitor, the second end of the first resistor End is grounded, and the first end of the first resistor is also connected with the first end of the second resistance, and the second of the second resistance It holds and is connected with the 3rd resistor respectively and the first end of the 4th resistance, the second end and PFC of the 4th resistance are controlled The second end that tubulation manages constant-current circuit is connected.

Further, the linear constant voltage circuit includes: first diode, the second diode, third diode, the 5th electricity Resistance, the 6th resistance, the 7th resistance, the 8th resistance, the second capacitor, the first zener diode, the first triode, the second triode and First optocoupler, wherein the anode of the first diode is connected with constant-current transformer auxiliary winding output end, the two or two pole The anode of pipe is connected with the output end of constant-voltage transformer auxiliary winding, the cathode of the first diode, second diode Cathode, the 5th resistance, first triode and second capacitor series connection after be grounded, first triode Base stage is connected by the 6th resistance with the third end of first optocoupler, and the base stage of first triode also passes through described First pressure stabilizing triode ground connection, the cathode of second diode also pass through the 4th of the 7th resistance and first optocoupler End is connected, and the first end of first optocoupler is connected by the 8th resistance with the output end of the constant-voltage transformer, described The second end of first optocoupler is grounded by second triode, and the base stage of second triode makes with what host chip provided Energy signal is connected, and the cathode of the third diode is connected with the base stage of first triode, and anode and PFC control are managed The power end for managing constant-current circuit is connected.

Second aspect, the embodiment of the present invention also provide a kind of TV, and the TV includes opening described in above-mentioned first aspect Powered-down source.

A kind of Switching Power Supply provided in an embodiment of the present invention, by be arranged the first input end of linear constant voltage circuit with it is described The output end of constant-voltage transformer auxiliary winding is connected, the output end phase of the second input terminal and the constant-current transformer auxiliary winding Even, control terminal is connected with enable signal, and output end is connected with the PFC power end for controlling management constant-current circuit, is for working as It unites during the standby underloading to booting, the voltage of the voltage and the second input terminal that pass sequentially through first input end is described The power end of PFC control management constant-current circuit carries out relay power supply, so that the Constant Current Load normally starts, realizes LED back Light lamp it is normally-open, be not in that the power end power supply capacity that controls management constant-current circuit because of PFC is insufficient, lead to LED backlight Lamp can not be normally-open situation, improve the stability of system, transformer controlled by single- stage PFC, directly carries out AC-DC Conversion, and export constant pressure, constant-current source respectively, improve power-efficient, reduce system cost, and the control and constant pressure of constant current Control independently of one another, so that constant pressure source and constant-current source are not interfere with each other when dynamic load, further improves the stability of system.

Detailed description of the invention

To describe the technical solutions in the embodiments of the present invention more clearly, institute in being described below to the embodiment of the present invention Attached drawing to be used is needed to be briefly described, it should be apparent that, the accompanying drawings in the following description is only some implementations of the invention Example, for those of ordinary skill in the art, without creative efforts, can also implement according to the present invention The content of example and these attached drawings obtain other attached drawings.

Fig. 1 is a kind of structural schematic diagram for Switching Power Supply that the embodiment of the present invention one provides；

Fig. 2 is the structural schematic diagram for another Switching Power Supply that the embodiment of the present invention one provides；

Fig. 3 is a kind of structural schematic diagram of Switching Power Supply provided by Embodiment 2 of the present invention；

Fig. 4 is a kind of electrical block diagram of Switching Power Supply provided by Embodiment 2 of the present invention；

Fig. 5 is a kind of structural schematic diagram of linear constant voltage circuit provided by Embodiment 2 of the present invention；

Fig. 6 is a kind of electrical block diagram of current constant control loop provided by Embodiment 2 of the present invention；

Fig. 7 is a kind of structural schematic diagram of overvoltage crowbar provided by Embodiment 2 of the present invention；

Fig. 8 is a kind of electrical block diagram of Isobarically Control loop provided by Embodiment 2 of the present invention.

Specific embodiment

To keep the technical problems solved, the adopted technical scheme and the technical effect achieved by the invention clearer, below It will the technical scheme of the embodiment of the invention will be described in further detail in conjunction with attached drawing, it is clear that described embodiment is only It is a part of the embodiment of the present invention, instead of all the embodiments.Based on the embodiments of the present invention, those skilled in the art exist Every other embodiment obtained under the premise of creative work is not made, shall fall within the protection scope of the present invention.

Embodiment one

Fig. 1 is a kind of structural schematic diagram for Switching Power Supply that the embodiment of the present invention one provides.The disclosed switch of the present embodiment Power supply can provide constant pressure source and constant-current source simultaneously, be particularly suitable for LCD TV field, while applying also for liquid crystal display, throwing The related fieldss such as shadow instrument, medical instrument and army's industrial equipment, the present embodiment is using the application scenarios of the Switching Power Supply as liquid crystal It is illustrated for TV, the Constant Current Load is LED light bar.Switching Power Supply provided in this embodiment can effectively improve power supply system The efficiency of system, that realizes TV stablizes booting, and at low cost and power factor is higher.Referring specifically to shown in Fig. 1, the Switching Power Supply packet It includes: PFC PFC control management constant pressure module 100, PFC control management constant flow module 300 and linear constant pressure module 500；

Wherein, the input terminal of PFC control management constant pressure module 100 is connected with power supply, the first output end and host core Piece is connected, and second output terminal is connected with linear constant pressure module 500, for improving the power factor of constant voltage output and exporting constant electricity It presses and powers to the host chip, while providing pretrigger voltage for the linear constant pressure module 500；

The input terminal of PFC control management constant flow module 300 is connected with the output end of linear constant pressure module 500, the first output End is connected with Constant Current Load, and second output terminal is connected with linear constant pressure module 500, for improving the power factor of constant current output simultaneously It exports constant voltage to power to the Constant Current Load, while providing relay voltage for linear constant pressure module 500；

The first input end of linear constant pressure module 500 is connected with the PFC output end for controlling management constant pressure module 100, and second Input terminal is connected with the PFC output end for controlling management constant flow module 300, and output end controls the defeated of management constant flow module 300 with PFC Enter end be connected, for when system from shutdown to it is standby again to booting underloading during, pass sequentially through the voltage of first input end And second input terminal voltage be PFC control management constant flow module 300 power end carry out relay power supply so that the constant current The normal starting of load.

Illustratively, the structural schematic diagram of another Switching Power Supply shown in Figure 2, PFC control management constant pressure module 100 include: PFC PFC control management constant voltage circuit 110, constant pressure switching tube Q17, constant-voltage transformer 120 and constant pressure Control loop 130, wherein the first end of PFC control management constant voltage circuit 110 is connected with power supply, the 4th end and constant pressure control The output end of loop 130 processed is connected, and the 6th end is connected with the output end of 120 auxiliary winding 121 of constant-voltage transformer, and the 7th end passes through Constant pressure switching tube Q17 is connected with the control terminal of 120 main winding 122 of constant-voltage transformer, for according to constant-voltage transformer 120 auxiliary around The conducting and shutdown for the zero passage detection signal control constant pressure switching tube Q17 that the output end of group 121 provides, to improve constant voltage output Power factor, PFC control management constant voltage circuit 110 are also used to be controlled according to the signal of 130 output end of Isobarically Control loop The conducting and shutdown of constant pressure switching tube Q17, so that constant-voltage transformer 120 exports constant voltage VDD；Constant-voltage transformer 120 it is main around The input terminal of group 122 is connected with power supply, and output end is connected with main unit movement, for controlling management constant voltage circuit 110 in PFC Control under for host chip provide constant voltage VDD；The input terminal of Isobarically Control loop 130 and the master of constant-voltage transformer 120 Winding output end is connected, and the constant voltage VDD for exporting to 120 main winding of constant-voltage transformer is sampled, and will sampling electricity Pressure is sent to the 4th end of PFC control management constant voltage circuit 110, so that PFC control management constant voltage circuit 110 is according to the sampling Voltage controls the conducting and shutdown of constant pressure switching tube Q17, and constant-voltage transformer 120 is made to export constant voltage.

Illustratively, PFC control management constant flow module 300 includes: PFC control management constant-current circuit 140, constant current switch pipe Q12, constant-current transformer 150 and over-voltage adjustment circuit 160；Wherein, the power end of PFC control management constant-current circuit 140 and linear The output end of constant voltage circuit 170 is connected, and the 4th end is connected with the output end of over-voltage adjustment circuit 160, the 6th end and constant current transformation The output end of device auxiliary winding 151 is connected, the control terminal phase of the 9th end constant current switch pipe Q12 and constant-current transformer main winding 152 Even, the zero passage detection signal for being provided according to the output end of constant-current transformer auxiliary winding 151 controls constant current switch pipe Q12's Conducting and shutdown, to improve the power factor of constant current output, PFC control management constant-current circuit 140 is also used to be adjusted according to over-voltage The conducting and shutdown of the output end signal control constant current switch pipe Q12 of circuit 160, so that constant-current transformer 150 exports constant electricity Pressure；The input terminal of constant-current transformer main winding 152 is connected with power supply, and output end is connected with Constant Current Load, for controlling in PFC Constant voltage is provided under the control of tubulation reason constant-current circuit 140 for the Constant Current Load；160 input terminal of over-voltage adjustment circuit and institute The output end for stating Constant Current Load is connected, and samples for the output end voltage to the Constant Current Load, and sampled voltage is sent out It send to PFC and controls the 4th end of management constant-current circuit 140, so that PFC control management constant-current circuit 140 is according to the sampled voltage The conducting and shutdown for controlling constant current switch pipe Q12 make constant-current transformer 150 export constant voltage；

Illustratively, linear constant pressure module 500 includes linear constant voltage circuit 170, the first input of linear constant voltage circuit 170 End VCC1 is connected with the output end of constant-voltage transformer auxiliary winding 121, the second input terminal VCC2 and constant-current transformer auxiliary winding 151 output end is connected, and control terminal is connected with enable signal BL-EN, the electricity of output end and PFC control management constant-current circuit 140 Source be connected, for when system from shutdown to it is standby again to booting underloading during, pass sequentially through the voltage of first input end The voltage VCC2 of VCC1 and the second input terminal is the power end progress relay power supply of PFC control management constant-current circuit 140, so that The Constant Current Load normally starts.

A kind of Switching Power Supply provided in this embodiment, first input end and the constant pressure by the linear constant voltage circuit of setting The output end of transformer auxiliary winding is connected, and the second input terminal is connected with the output end of the constant-current transformer auxiliary winding, control End processed is connected with enable signal, and the power end that output end and the PFC control management constant-current circuit is connected, for work as system to During machine to booting underloading, the voltage of the voltage and the second input terminal that pass sequentially through first input end is PFC control The power end of tubulation reason constant-current circuit, which carries out relay power supply, realizes LED backlight so that the Constant Current Load normally starts It is normally-open, it is not in during system is from the standby underloading to booting because PFC controls the power end of management constant-current circuit Power supply capacity is insufficient, leads to the situation that LED backlight can not be normally-open, improves the stability of system, pass through single- stage PFC control Transformer processed directly carries out the conversion of AC-DC, and exports constant pressure source and constant-current source respectively, improves power-efficient, reduces and is System cost, and the control of constant current and the control of constant pressure are independent of one another, so that constant pressure source and constant-current source are not done mutually when dynamic load It disturbs, further improves the stability of system.

Embodiment two

Fig. 3 is a kind of structural schematic diagram of Switching Power Supply provided by Embodiment 2 of the present invention.On the basis of above-described embodiment On, the present embodiment advanced optimizes the structure of the Switching Power Supply, by increasing high pressure pretrigger circuit, works as TV When standby to energization from power-off shutdown, realize and provide stable supply voltage for PFC control management constant voltage circuit, it can also be effective The stand-by power consumption of reduction system；By increasing overvoltage crowbar, realizing ensures that the output voltage of constant-current transformer will not mistake Greatly, it avoids damaging LED light bar because the output voltage of constant-current transformer is excessive.Referring specifically to shown in Fig. 3, the Switching Power Supply packet It includes:

PFC PFC control management constant voltage circuit 110, constant-voltage transformer 120, Isobarically Control loop 130, PFC Control management constant-current circuit 140, constant-current transformer 150, over-voltage adjustment circuit 160, linear constant voltage circuit 170, high pressure pretrigger Circuit 180, em filtering circuit 190, rectification circuit 200 and overvoltage crowbar 210.In order between clear each circuit of explanation Shown in connection relationship, referring also to Fig. 3 and Fig. 4: where the input terminal of em filtering circuit 190 and 1 phase of communication power supply Even, output end is connected with the input terminal of the input terminal of high pressure pretrigger circuit 180 and rectification circuit 200 respectively, rectification circuit The 200 output end input terminal phase with the input terminal of constant-voltage transformer main winding 122 and constant-current transformer main winding 152 respectively Even；The first end that the output end of high pressure pretrigger circuit 180 and PFC control management constant voltage circuit 110 is connected, be used for system by It shuts down to during standby, provides power supply for PFC control management constant voltage circuit 110, so that PFC control management constant voltage circuit 110 start and start to work, the power end of PFC control management constant voltage circuit 110 and the output of constant-voltage transformer auxiliary winding 121 End is connected, and is provided when PFC is controlled after management constant voltage circuit 110 starts by the output end of constant-voltage transformer auxiliary winding 121 for it Power supply, and control the closing of high pressure pretrigger circuit 180.The input terminal and constant-current transformer auxiliary winding of overvoltage crowbar 210 151 output end is connected, and output end is connected with the PFC second end for controlling management constant-current circuit 140, for working as constant-current transformer When the voltage of 150 outputs is more than setting value, make PFC control management constant-current circuit 140 by controlling the constant current switch pipe Q12's Conducting and shutdown, the voltage for exporting constant-current transformer 150 drop in setting range.PFC control management constant-current circuit 140 7th end is connected by constant current switch pipe Q12 with the output end of constant-current transformer main winding 152, PFC control management constant-current circuit 140 the 7th end also passes through voltage sample resistance R138 ground connection.PFC control management the 4th end of constant voltage circuit 110 and Isobarically Control The output end of loop 130 is connected, the 6th end be connected with the output end of 120 auxiliary winding 121 of constant-voltage transformer (in Fig. 4, PFC Route between the output end of 120 auxiliary winding 121 of the 6th end and constant-voltage transformer of control management constant voltage circuit 110 is expressed as ZCD1 in Fig. 3), the 7th end is connected by constant pressure switching tube Q17 with the output end of 120 main winding 122 of constant-voltage transformer, is used for Control constant pressure switching tube Q17Q17's according to the zero passage detection signal that the output end of 120 auxiliary winding 121 of constant-voltage transformer provides Conducting and shutdown, to improve the power factor of constant voltage output, PFC control management constant voltage circuit 110 is also used to according to the constant pressure The conducting and shutdown of the signal control constant pressure switching tube Q17Q17 of 130 output end of control loop, so that constant-voltage transformer 120 exports Constant voltage；The output end of constant-voltage transformer 120 is connected with main unit movement, for controlling the control of management constant voltage circuit 110 in PFC System is lower to provide constant voltage for host chip；The output end phase of the input terminal of Isobarically Control loop 130 and constant-voltage transformer 120 Even, the constant voltage VDD for exporting to constant-voltage transformer 120 is sampled, and sampled voltage is sent to PFC control management 4th end of constant voltage circuit 110, so that PFC control management constant voltage circuit 110 controls constant pressure switching tube according to the sampled voltage The conducting and shutdown of Q17Q17, so that constant-voltage transformer exports constant voltage；The power end of PFC control management constant-current circuit 140 It is connected with the output end VCC-LED of linear constant voltage circuit 170, the 4th end is connected with the output end of over-voltage adjustment circuit 160, and the 6th End is connected with the output end of constant-current transformer auxiliary winding 151, and (in Fig. 4, PFC control manages the 6th end of constant-current circuit 140 Route between the output end of 150 auxiliary winding 121 of constant-current transformer is expressed as the ZCD2 in Fig. 3), the 9th end passes through constant current Switching tube Q12 is connected with the output end of constant-current transformer main winding 152, for according to the defeated of constant-current transformer auxiliary winding 151 The conducting and shutdown for the zero passage detection signal control constant current switch pipe Q12 that outlet provides, to improve the power factor of constant current output, PFC control management constant-current circuit 140 is also used to control constant current switch pipe Q12 according to the output end signal of over-voltage adjustment circuit 160 Conducting and shutdown so that constant-current transformer 150 export constant voltage；The output end of constant-current transformer is connected with Constant Current Load 2, For being that the Constant Current Load 2 provides constant voltage under the control that PFC controls management constant-current circuit 140；Over-voltage adjustment circuit 160 input terminals are connected with the output end of the Constant Current Load 2, sample for the output end voltage to the Constant Current Load 2, And sampled voltage is sent to the 4th end of PFC control management constant-current circuit 140, so that PFC control management constant-current circuit 140 According to the conducting and shutdown of sampled voltage control constant current switch pipe Q12, so that constant-current transformer 150 exports constant voltage；Line The first input end VCC1 of property constant voltage circuit 170 is connected with the output end of constant-voltage transformer auxiliary winding 121, the second input terminal VCC2 is connected with the output end of constant-current transformer auxiliary winding 151, and control terminal is connected with enable signal BL-EN, output end and PFC The power end of control management constant-current circuit 140 is connected, for passing sequentially through the during system is from the standby underloading to booting The voltage VCC2 of the voltage VCC1 of one input terminal and the second input terminal be PFC control management constant-current circuit 140 power end into Row relay power supply, so that the Constant Current Load normally starts.

As shown in connection with fig. 3, be illustrated to the working principle of the Switching Power Supply: communication power supply 1 is through em filtering Constant-voltage transformer 120 and constant-current transformer 150, constant-voltage transformer 120 and perseverance are conveyed after circuit 190 and rectification circuit 200 respectively (i.e. PFC control management constant voltage circuit 110 and PFC control management are permanent under the control management of respective single- stage PFC for convertor transformer 150 Current circuit 140), constant pressure switching tube and constant current switch pipe are further controlled, so that constant pressure source and constant-current source that output is stable.In this way Design architecture be not necessarily to high-voltage electrolytic capacitor, save PCB surface product and cost.AC exchange 1 powers on, television system by shutdown to When machine, em filtering circuit 190 controls management constant voltage circuit 110 to PFC by high pressure pretrigger circuit 180 and provides starting voltage VCC1, after PFC, which controls the management starting of constant voltage circuit 110, to start to work, the auxiliary winding output voltage of constant-voltage transformer 120 VCC1 is that PFC control management constant voltage circuit 110 provides stable operating voltage, and high pressure pretrigger circuit 180 is closed, and can basis Payload size situation adjusts working frequency, stand-by power consumption is reduced, so that the output of constant-voltage transformer 120 is after DC-DC pressure stabilizing Machine core provides stable operating voltage.The auxiliary winding output voltage VCC1 of constant-voltage transformer 120 is connected to linear constant pressure electricity simultaneously The first input end on road 170 provides pretrigger voltage for subsequent PFC control management constant-current circuit 140.

As further described above, the auxiliary winding output of constant-voltage transformer 120 is by ZCD1 circuit, for PFC control management Constant voltage circuit 110 provides zero passage detection signal, to improve the power factor of PFC.

Further, when television system by it is standby to booting at light load, LED backlight open signal BL-EN pass through the first light Coupling opens linear constant voltage circuit 170, the power supply of the output termination PFC control management constant-current circuit 140 of linear constant voltage circuit 170 End provides pretrigger operating voltage for it, and after PFC control management constant-current circuit 140 is started to work, constant-current transformer 150 is exported Voltage VCC2, while 150 output voltage VCC2 of constant-current transformer is connected to the second input terminal of linear constant voltage circuit 170, by perseverance VCC2 after pressure is PFC control management 140 relay of constant-current circuit power supply, is realized when mainboard machine core work just starts to make, because VCC1 voltage is lower, and management constant-current circuit 140 can be controlled by PFC and controls the voltage VCC2 warp that constant-current transformer 150 generates Property constant pressure after provide that energy is sufficient and stable operating voltage for PFC control management constant-current circuit 140, avoid in mainboard machine core When just starting to work, due to the starting undertension problem that causes system boot unstable.

As further described above, the output of constant-current transformer 150 is by ZCD2 circuit, for PFC control management constant-current circuit 140 provide zero passage detection signal, to improve the power factor of PFC.

As further described above, rectified 1 output of filtering of the output of constant-current transformer 150 exists respectively to LED1 and LED2 Under constant-current circuit 1 and constant-current circuit 2 control, constant current is exported.

As further described above, the rectified filtering 2 of the output of constant-current transformer 150 exports perseverance by the linear constant pressure 2 of DC-DC Constant voltage, as reference voltage, constant current assists IC voltage and optocoupler supply voltage.

As further described above, LED1 and LED2 passes through over-voltage adjustment circuit 160 respectively, connects the second optocoupler, then controls PFC control management constant-current circuit 140.

As further described above, because the constant pressure source of output and constant-current source respectively control, so that permanent in machine core dynamic load Pressure and constant current output are not interfere with each other, and constant pressure improves the stability of system not by the cross influence of LED light deviation.

When LED backlight open signal BL-EN low level is closed, by the first optocoupler, linear constant voltage circuit is fed back to 170, cut off its output voltage, PFC control management constant-current circuit 140 stops working, then does not have electric current to pass through in LED, LED is It goes out, so that stand-by power consumption is low.When LED backlight open signal BL-EN is opened, then by the first optocoupler, linear constant pressure is fed back to Circuit 170 opens its output voltage, and PFC control management constant-current circuit 140 is started to work, and has electric current to pass through in LED, and lead to Cross constant-current circuit 1, constant-current circuit 2 control LED in electric current it is constant.The bright dark degree of LED by mainboard conveying come pwm signal It is adjusted, when PWM duty cycle is big, LED light is brighter, and when PWM duty cycle is small, LED light is darker.

As further described above, when LED light bar voltage is smaller than the output voltage of constant-current transformer 150, pass through over-voltage tune Whole the second optocoupler of circuit 160-, control single- stage PFC control management constant-current circuit 140, adjusts the working frequency or duty ratio of PFC, Further control constant current switch pipe, make flyback transformer export voltage become smaller so that constant-current transformer 150 export voltage and The matching of LED light bar operating voltage, and then the temperature rise of over-voltage adjustment circuit 160 can be reduced.Solves the identical screen body LED in volume production The big problem of output voltage difference caused by the voltage deviation of lamp is larger.

As further described above, under the control that PFC controls management constant voltage circuit 110, constant-voltage transformer is further controlled 120, stable constant pressure source is exported by DC-DC pressure stabilizing after rectifying and wave-filtering 2.Its Isobarically Control loop 130 by sampling by The output of constant-voltage transformer 120 controls third optocoupler by the voltage after rectifying and wave-filtering 2, by sampling circuit of pressure-stabilizing, and then controls The voltage that PFC control management constant voltage circuit 110 processed exports constant-voltage transformer 120 is constant.It, can be with when requiring lower to ripple The Voltage stabilizing module of DC-DC is saved in output, to reduce power supply cost.

The electrical block diagram of Switching Power Supply shown in Figure 4, AC power source AC is after EMI filtering and rectifying and wave-filtering It is conveyed to constant-current transformer T1 and constant-voltage transformer T2 respectively, is filtered without big electrolytic capacitor, constant pressure switching tube Q17 and constant current control Switching tube Q12 processed further controls constant-voltage transformer T2 and constant current under control chip U14 and the U13 control of respective single- stage PFC Transformer T1, so that giving LED backlight and main board power supply after the rectified filtering of transformer secondary output output.It is above-mentioned to use single-stage PFC control switch module, and further control switch transformer, such design architecture are not necessarily to high-voltage electrolytic capacitor, have compared with High power factor output, and save PCB surface product and cost.

With further reference to shown in Fig. 4, high pressure pretrigger circuit 180 include: the 4th diode D36, the 5th diode D37, 9th resistance R164, the tenth resistance R165, the first control pipe Q21, wherein the 4th diode D36 and the 5th diode D37 are in parallel Connection, anode is connected with power supply, the cathode first end with the first end of the 9th resistance R164 and the tenth resistance R165 respectively It is connected, the second end of the 9th resistance R164 is connected with the second end of the first control pipe Q21, the second end of the tenth resistance R165 and institute The tenth one end of the first end and PFC control management constant voltage circuit U14 of stating the first control pipe Q21 is connected, the first control pipe Q21 Third end and PFC control the first end of management constant voltage circuit U14 and be connected.When television system is standby to being powered by power-off shutdown When, AC exchange passes through EMI filter circuit after powering on, then passes through the 4th diode D36 in high pressure pretrigger circuit, the five or two pole Pipe D37, the 9th resistance R164, first control pipe Q21,1 foot of PFC control management constant voltage circuit IC U14, the tenth resistance R165 The pole the G level of first control pipe Q21 is set into height, the first control pipe Q21 conducting, and then management constant voltage circuit IC is controlled by PFC 1 foot of U14 provides voltage to the capacitor C88 connected at its 10 foot VCC, when the voltage of capacitor C88 reaches PFC control management module When the starting voltage of U14, PFC control management module U14 starts and starts to work, and PFC controls 9 feet of management module U14 at this time Output pwm signal control switch pipe Q17, and then constant-voltage transformer T2 concussion is controlled, the 5 feet output of constant-voltage transformer T2 is (i.e. auxiliary Help winding output end 121) the output voltage VCC1 after the 5th diode D27 rectification and capacitor C86 filtering, for PFC control management 10 feet of module U14 are powered, and 11 feet that then PFC controls management module U14 export low level, and the first control pipe Q21 is closed, So that when television system is standby by the voltage VCC1 of low pressure to PFC control management module IC U14 power supply, and can be according to load Size cases adjust working frequency, reduce the stand-by power consumption of system.

As further described above, the voltage VCC1 of the 5 feet output of constant-voltage transformer T2 is that PFC manages constant voltage circuit IC U14 Stable operating voltage is provided, so that the output of constant-voltage transformer T2 is filtered through the 6th diode D30 rectification and the 4th capacitor CE10 After wave, then by providing stable operating voltage after DC-DC pressure stabilizing for main trigger core.Linear constant pressure referring also to shown in fig. 5 The electrical block diagram of circuit 170, linear constant voltage circuit 170 include: first diode D407, the second diode D406, Three diode D405, the 5th resistance R162, the 6th resistance R168, the 7th resistance R160, the 8th resistance R159, the second capacitor C1D62, the first zener diode ZD403, the first triode QP9, the second triode QP7 and the first optocoupler U15, wherein first The anode of diode D407 is connected with 151 output end of constant-current transformer auxiliary winding, the anode and constant pressure of the second diode D406 The output end of transformer auxiliary winding 121 is connected, the cathode of first diode D407, the cathode of the second diode D406, the 5th It is grounded after resistance R162, the first triode QP9 and the second capacitor C1D62 series connection, the base stage of the first triode QP9 passes through the 6th Resistance R168 is connected with the third end of the first optocoupler U15, and the base stage of the first triode QP9 also passes through the first pressure stabilizing triode ZD403 ground connection, the cathode of the second diode D406 also pass through the 7th resistance R160 and are connected with the 4th end of the first optocoupler U15, the The first end of one optocoupler U15 is connected by the 8th resistance R159 with the output end of constant-voltage transformer 120, and the of the first optocoupler U15 Two ends are grounded by the second triode QP7, the enable signal BL-EN phase that the base stage of the second triode QP7 is provided with host chip Even, the cathode of third diode D405 is connected with the base stage of the first triode QP9, anode and PFC control management constant-current circuit 140 Power end be connected.The first input end of the voltage VCC1 wiring constant voltage circuit 170 of the 5 feet output of constant-voltage transformer T2, i.e., By the second diode triode of D406, the 5th resistance R162, first QP9, the second capacitor C1D62, output voltage VCC- is generated LED, the PFC control management constant-current circuit U13 after opening for subsequent LED backlight open signal BL-EN provide pretrigger voltage.It is permanent Second input terminal of the voltage VCC2 wiring constant voltage circuit 170 of 5 foot of the auxiliary winding output of convertor transformer T1, by linear Second input terminal of constant voltage circuit 170 controls management constant-current circuit U13 for PFC and provides relay voltage, specifically: work as television system By standby to being switched at light load, LED backlight open signal BL-EN is high level, the second triode QP7 conducting, the first optocoupler U15 1-2 foot conducting, and then 3-4 foot be connected, linear constant voltage circuit is opened by the first triode QP9 and exports first voltage VCC_LED (i.e. VCC1), the output of linear constant voltage circuit connect 10 feet of PFC control management constant-current circuit IC U13, provide for it Pretrigger operating voltage, after PFC control management constant-current circuit IC U13 starts to work, 5 foot of auxiliary winding of constant-current transformer T1 Output through diode D1D3, generate voltage VCC2 after first capacitor C3D14 filtering, voltage VCC2 passes through first diode D407, the 5th resistance R162, the first triode QP9, the second capacitor C1D62 generate the second output voltage VCC_LED (i.e. VCC2), the second output voltage VCC_LED is that PFC control management constant-current circuit IC U13 carries out relay power supply, to solve When mainboard machine core work just starts to make, because of light load, voltage VCC1 energy is smaller, and voltage is lower, and can not light LED backlight Problem.Management constant-current circuit IC U13 is controlled by PFC and controls constant current switch pipe Q12, and then is controlled constant-current transformer T1 and generated Management constant-current circuit IC U13 continuous power is controlled for PFC after the linear constant voltage circuit of voltage VCC2, voltage VCC2, and energy abundance is provided Stable operating voltage again.

Further, the voltage of the 5 feet output of constant-voltage transformer T2 passes through the R148 and R147 of ZCD1 circuit, after sampled 6 feet of PFC control management constant voltage circuit IC U14 are connect, management constant voltage circuit U14 is controlled for PFC and zero passage detection signal is provided, with Improve the PFC power factor of constant voltage output.The voltage of the 5 feet output of constant-current transformer T1 passes through ZCD2 circuit, i.e. resistance R149 With resistance R150, sampled 6 feet for being followed by PFC control management constant-current circuit IC U13 control management constant-current circuit for PFC and provide Zero passage detection signal, to improve the power factor of the PFC of constant current output.

Further, the output voltage of constant-current transformer T1 is exported after diode D20 rectification and capacitor CE1 filtering and is connect LED1 ... LED1n and LED2 ... LED2n export constant current respectively under the control of constant-current circuit 1 and constant-current circuit 2. The particular circuit configurations of constant-current circuit 1 and constant-current circuit 2 may refer to electrical block diagram shown in fig. 6, while constant current becomes The 10 foot output voltages of depressor T1 are rectified through the 5th diode D408 in Fig. 6, the 5th capacitor C4B9 filtering, then through the 17th electricity R428 is hindered, exports constant voltage SVCC after the linear constant voltage circuit of DC-DC of third transistor Q0B20, the 6th capacitor C414 composition, Reference voltage of the constant voltage SVCC as constant-current circuit, constant current assist the supply voltage of IC voltage and the second optocoupler U2.

Further, referring to the particular circuit configurations schematic diagram of over-voltage adjustment circuit 160 in Fig. 6, LED1 passes through over-voltage tune The 4th diode D22 in whole circuit, the 18th resistance R65, third capacitor CE6 and the 19th resistance R64, LED2 pass through two The second optocoupler U2 is connect by second adjustment pipe U16 after pole pipe D35, resistance R158, capacitor CE11 and resistance R157, is then controlled PFC control management constant-current circuit IC U13, the final output voltage for realizing constant-current transformer T1 and voltage phase needed for LED light bar Matching.

Further, it because of the respective independent control of the constant pressure source of output and constant-current source, realizes in mainboard machine core dynamic load When constant pressure and the output of constant current do not interfere with each other, and constant pressure source improves the stabilization of system not by the cross influence of LED light deviation Property.

Further, referring to fig. 4 and electrical block diagram shown in fig. 5, when television system by standby to when booting, When starting-up signal, that is, LED backlight open signal BL-EN becomes high level, the second triode QP7 conducting passes through the first optocoupler The first triode QP9 is connected in U15, passes through the second diode D406, the 5th resistance R162, the one or three pole by voltage VCC1 first Pipe QP9, the second capacitor C1D62 generate output voltage VCC_LED, for PFC control management constant-current circuit U13 power supply, control PFC Tubulation manages constant-current circuit U13 and starts to work, then has electric current to pass through in LED, and LED is bright state.In addition, the bright dark degree of LED By mainboard conveying come brightness control signal BL-ADJ control the turn-on time of the 4th triode Q8, and then adjust LED light Brightness, when PWM duty cycle is big, LED light is brighter, and when PWM duty cycle is small, LED light is darker.As LED backlight open signal BL- When EN is low level, by control the second triode QP7 cut-off, and then the first optocoupler U15 is controlled, made by the first optocoupler U15 First triode QP9 cut-off, output voltage VCC_LED cutting, the supply voltage cutting of PFC control management constant-current circuit U13, The 10 foot VCC no-voltages of PFC control management constant-current circuit U13, PFC control management constant-current circuit U13 stop working, constant current flyback Power supply stops working, so that stand-by power consumption is lower.

Further, the electrical block diagram of current constant control loop shown in Figure 6, current constant mode are permanent using series connection A reference source control is flowed, pipe U4 is adjusted by third, the 5th triode Q2, the 20th resistance R51 form constant current a reference source, third adjustment Reference voltage of the pipe U4 as constant current controls the 5th triode Q2, so that the both end voltage of the 20th resistance R51 is constant, in turn So that the electric current for flowing through lamp bar is constant.When constant-current transformer T1 output ripple voltage is larger, because the 5th triode Q2 work exists Amplification region, a reference source control the 5th triode Q2 can the pole adjust automatically C-E partial pressure so that electric current is more accurate, reduce electric current line Wave.When lamp bar voltage is less than normal, because constant-current transformer T1 output winding is constant, then the C pole tension of the 5th triode Q2 increases, and leads to It crosses by the 19th resistance R64, the over-voltage adjustment circuit of third capacitor CE6, the 18th resistance R65, the 4th diode D22 composition, Second adjustment pipe U16 is controlled to control the electric current for flowing through the second optocoupler U2, and then controls PFC control management constant-current circuit ICU13 The working frequency or duty ratio of primary side, and then the voltage of constant-current transformer T1 output winding output is reduced, so that constant-current source two The voltage at end reduces.By the 6th triode Q16, another constant-current source of the 7th triode Q20, the 21st resistance R154 composition with 5th triode Q2, the 20th resistance R51, it is current mirror ontology that third, which adjusts pipe U4, so that the 6th triode Q16, the seven or three The constant-current source of pole pipe Q20, the 21st resistance R154 composition is identical as current mirror ontology electric current, and rear class reproducible any identical Constant-current source so that the constant current output can match the lamp bar in any channel.Further, constant-current circuit can be according to the channel of lamp bar Quantity arbitrary extension realizes large scale electricity so that this programme realizes the demand that can match any number of channels of backlight lamp bar Low cost and High Power Factor depending on power supply design.

Further, structural schematic diagram shown in Figure 4 passes through the electricity after rectifying and wave-filtering after alternating current AC is powered on For pressure by the 4th diode D36, the 5th diode D37 and the 9th resistance R164, it is permanent that the first control pipe Q21 controls management to PFC The 1 foot pretrigger of volt circuit IC U14, so that the VCC voltage of PFC control management 10 foot of constant voltage circuit U14 reaches cut-in voltage, Constant-voltage transformer ICT2 starts oscillatory work, and after stablizing, 5 feet, that is, auxiliary winding output voltage of constant-voltage transformer T2 is via the 5th Diode D27, capacitor C86 control management constant voltage circuit IC U14 for PFC and provide stable operating voltage, then PFC control pipe 11 feet for managing constant voltage circuit IC U14 export low level, control the first control pipe Q21 cut-off, so that PFC control management constant pressure electricity The power supply of road U14 becomes the VCC1 of transformer auxiliary winding output.3 feet of the management of PFC control simultaneously constant voltage circuit U14 pass through inspection The exchange sample circuit that the 22nd resistance R166 and the 23rd resistance R167 is constituted is surveyed, sampling ac voltage signal is as ginseng Signal is examined, the electricity of primary winding is detected by current sampling resistor the 15th resistance R148 and the 16th resistance R147 Stream, compares with reference signal, and then controls the working frequency and duty ratio of constant pressure switching tube Q17, when full wave voltage is big, work Working frequency is high, and duty ratio is small；When full wave voltage is small, working frequency is low, and duty ratio is big, so that full-wave voltage signal and flowing through perseverance The current in phase position of pressure transformer T2 armature winding, finally improves power factor, while also achieving AC-DC AC-DC Transformation.

Further, by that will be the constant-current source of LED backlight power supply and be that the constant pressure source that chip main board is powered separates individually Control, both reduced constant-current transformer T1 and constant-voltage transformer T2 operating temperature rise and constant current switch pipe Q12 and constant pressure switch The operating temperature rise of pipe Q17 also improves the stability of system independent control.

Further, when LED light bar voltage is smaller than the voltage of constant-current transformer T1 output winding, pass through current constant control ring The second optocoupler U2 control single- stage PFC in road manages constant-current circuit IC U13, and the working frequency and duty ratio for adjusting PFC become smaller, Constant current switch pipe Q12 is further controlled, the voltage for exporting flyback constant-current transformer T1 becomes smaller, so that constant-current transformer T1 is exported Voltage and the operating voltage of LED light bar match, and then the temperature rise of constant-current control circuit can be reduced, solve the phase in volume production The big problem of output voltage difference caused by the voltage deviation of same screen body LED light is larger.

Further, referring to the electrical block diagram of overvoltage crowbar 210 shown in fig. 7, overvoltage crowbar 210 include: first capacitor C3D14, first resistor R3B101, second resistance R3B102,3rd resistor R3B103 and the 4th resistance R3B104, wherein the first end of first capacitor C3D14 respectively with the output end of constant-current transformer T1 auxiliary winding (5 feet of T1) And the first end of first resistor C3D14 is connected, the second of the second end of first capacitor C3D14, the first resistor C3D14 End, 3rd resistor R3B103 second end be grounded, the first end of the first resistor C3D14 is also with second resistance R3B102's First end is connected, the second end of second resistance R3B102 and respectively 3rd resistor R3B103's and the 4th resistance R3B104 First end is connected, and the second end of the 4th resistance R3B104 is connected with the PFC second end for controlling management constant-current circuit U13.It crosses Voltage protection circuit 210 is used to protect the overcurrent of LED backlight and over-voltage output, working principle specifically: current-limiting resistance R28 As the current-limiting resistance of the second optocoupler U2, current sampling resistor thirteenth resistor R138 sampling is followed by PFC controlling management constant current 7 feet of IC circuit U13, when output power is excessive, it is permanent that the voltage of thirteenth resistor R138 sampling can be greater than PFC control management The internal reference voltage of 7 feet of current circuit IC U13 makes PFC control management constant-current circuit IC U13 overload protection and stops work Make.Voltage of the sampling resistor second resistance R3B102 and 3rd resistor R3B103 to the auxiliary winding output of constant-current transformer T1 VCC2 is sampled, when the overtension of constant-voltage transformer T1 output, the output of constant-voltage transformer T1 primary side auxiliary winding Voltage similarly also will increase, and 2 feet of PFC control management constant-current circuit IC U13 pass through sampling resistor second resistance R3B102 and the Three resistance R3B103 detect the voltage of VCC2, and the output voltage of the auxiliary winding of constant-voltage transformer T1 is made to be limited in safe range, LED light bar is damaged to avoid the voltage for exporting constant-voltage transformer T1 secondary windings excessive.

Further, constant pressure switching tube Q17 single- stage PFC control PFC control management constant voltage circuit IC U14 control under, Constant-voltage transformer T2 is further controlled, is rectified by the 6th diode D30, exports stable constant pressure after the 4th capacitor CE10 filtering Source.The electrical block diagram of Isobarically Control loop 130 shown in Figure 8, Isobarically Control loop 130 pass through sampling resistor the The 1-2 foot of third optocoupler U1D1 is controlled after 24 resistance R9D4 and the 25th resistance R9D3 by the first adjustment pipe U3D1 Electric current, and then the 4 foot voltages of PFC control management constant voltage circuit U14 are controlled, then make PFC control management constant voltage circuit U14 control The switch operating frequency or duty ratio of constant pressure switching tube Q17 keeps the voltage of output constant, can be with when more demanding to ripple Increase the Voltage stabilizing module of DC-DC in the output end of constant-voltage transformer T2, keeps the voltage ripple of output smaller.

Further, single- stage PFC management constant-current circuit IC U13 and single- stage PFC management constant voltage circuit IC U14 can be used Each pin function is arranged by software in the JP0010 digit chip of JPX, and it is standby at light load, can be automatically controled power switch Frequency is transferred to the working method of hop cycle, improves standby light-load efficiency, is not necessarily to standby transformer, saves cost, and standby When close constant-current transformer T1, reduce stand-by power consumption.

A kind of Switching Power Supply provided in this embodiment, on the basis of the above embodiment 1, by increasing high pressure pretrigger Circuit, when TV is PFC control management constant voltage circuit from power-off shutdown to high pressure pretrigger circuit when being powered standby, is preferably passed through The end VCC power supply, when PFC control management constant voltage circuit starting start to work after, close high pressure pretrigger circuit, be changed to pass through perseverance The voltage of the auxiliary winding output end of pressure transformer is the end the VCC power supply of PFC control management constant voltage circuit, is realized as PFC control Tubulation reason constant voltage circuit provides stable supply voltage, and can adjust working frequency according to payload size situation, reduces standby function Consumption, while the auxiliary winding output end voltage of constant-voltage transformer passes through the first input end of wiring constant voltage circuit, realizes and works as Management constant-current circuit is controlled for PFC when booting, pretrigger voltage is provided, improve the stability of system；By increasing overvoltage protection Circuit, realizing ensures that the output voltage of constant-current transformer is not too big, avoids due to the output voltage of constant-current transformer is excessive Damage LED light bar.

By the description above with respect to embodiment, it is apparent to those skilled in the art that, the present invention It can be realized by software and required common hardware, naturally it is also possible to which by hardware realization, but in many cases, the former is more Good embodiment.Based on this understanding, technical solution of the present invention substantially in other words contributes to the prior art Part can be embodied in the form of software products, which can store in computer readable storage medium In, floppy disk, read-only memory (Read-Only Memory, ROM), random access memory (Random such as computer Access Memory, RAM), flash memory (FLASH), hard disk or CD etc., including some instructions are with so that a computer is set Standby (can be personal computer, storage medium or the network equipment etc.) executes described in each embodiment of the present invention.

Note that the above is only a better embodiment of the present invention and the applied technical principle.It will be appreciated by those skilled in the art that The invention is not limited to the specific embodiments described herein, be able to carry out for a person skilled in the art it is various it is apparent variation, It readjusts and substitutes without departing from protection scope of the present invention.Therefore, although being carried out by above embodiments to the present invention It is described in further detail, but the present invention is not limited to the above embodiments only, without departing from the inventive concept, also It may include more other equivalent embodiments, and the scope of the invention is determined by the scope of the appended claims.

Claims

1. a kind of Switching Power Supply, which is characterized in that the power supply includes: PFC control management constant pressure module, PFC control management perseverance Flow module and linear constant pressure module；

Wherein, the input terminal of PFC control management constant pressure module is connected with power supply, and the first output end is connected with host chip, Second output terminal is connected with linear constant pressure module, for improving the power factor of constant voltage output and exporting constant voltage to the master The power supply of machine core piece, while pretrigger voltage is provided for the linear constant pressure module；

The input terminal of PFC control management constant flow module is connected with the output end of the linear constant pressure module, the first output end and perseverance Current load is connected, and second output terminal is connected with the linear constant pressure module, for improving power factor and the output of constant current output Constant voltage is powered to the Constant Current Load, while providing relay voltage for the linear constant pressure module；

The first input end of the linear constant pressure module is connected with the PFC second output terminal for controlling management constant pressure module, the Two input terminals are connected with the PFC second output terminal for controlling management constant flow module, output end and PFC control management constant current The input terminal of module is connected, for when system from shutdown to it is standby again to booting underloading during, pass sequentially through the first input The voltage of the voltage at end and the second input terminal is that the power end of PFC control management constant flow module carries out relay power supply, with Start the Constant Current Load normally.

2. Switching Power Supply according to claim 1, which is characterized in that the PFC control management constant pressure module includes: PFC Control management constant voltage circuit, constant pressure switching tube, constant-voltage transformer and Isobarically Control loop；

Wherein, the first end of PFC control management constant voltage circuit is connected with power supply, the 6th end and constant-voltage transformer auxiliary winding Output end be connected, the 7th end is connected by constant pressure switching tube with the control terminal of constant-voltage transformer main winding, is used for according to constant pressure The conducting and shutdown for the zero passage detection signal control constant pressure switching tube that the output end of transformer auxiliary winding provides, to improve constant pressure 4th end of the power factor of output, the PFC control management constant voltage circuit is connected with the output end of the Isobarically Control loop, The PFC control management constant voltage circuit is also used to control constant pressure switching tube according to the signal of the Isobarically Control loop output Conducting and shutdown, so that constant-voltage transformer exports constant voltage；

The input terminal of the constant-voltage transformer main winding is connected with power supply, and output end is connected with main unit movement, in institute It states and provides constant voltage under the control of PFC control management constant voltage circuit for host chip；

The input terminal of the Isobarically Control loop is connected with the output end of the constant-voltage transformer main winding, for the constant pressure The constant voltage of transformer main winding output is sampled, and sampled voltage is sent to the PFC control management constant voltage circuit The 4th end so that the PFC control management constant voltage circuit according to the sampled voltage control constant pressure switching tube conducting and pass It is disconnected, so that constant-voltage transformer exports constant voltage.

3. Switching Power Supply according to claim 2, which is characterized in that the PFC control management constant flow module includes: PFC Control management constant-current circuit, constant current switch pipe, constant-current transformer and over-voltage adjustment circuit,

Wherein, the power end of the PFC control management constant-current circuit is connected with the output end of the linear constant voltage circuit, the 6th end It is connected with the output end of constant-current transformer auxiliary winding, the 9th end passes through the control of constant current switch pipe and constant-current transformer main winding End is connected, and the zero passage detection signal control constant current switch pipe for being provided according to the output end of constant-current transformer auxiliary winding is led Logical and shutdown, to improve the power factor of constant current output, the 4th end of the PFC control management constant-current circuit and the over-voltage tune The output end of whole circuit is connected, and the PFC control management constant-current circuit is also used to the output end according to the over-voltage adjustment circuit Signal controls the conducting and shutdown of constant current switch pipe, so that constant-current transformer exports constant voltage；

The input terminal of the constant-current transformer main winding is connected with power supply, and output end is connected with Constant Current Load, in institute It states and provides constant voltage under the control of PFC control management constant-current circuit for the Constant Current Load；

The over-voltage adjustment circuit input terminal is connected with the output end of the Constant Current Load, for the output to the Constant Current Load End voltage is sampled, and sampled voltage is sent to the 4th end of the PFC control management constant-current circuit, so that the PFC Control management constant-current circuit controls the conducting and shutdown of constant current switch pipe according to the sampled voltage, so that constant-current transformer exports Constant voltage.

4. Switching Power Supply according to claim 3, which is characterized in that the linear constant pressure module includes linear constant pressure electricity Road, the first input end of the linear constant voltage circuit are connected with the output end of the constant-voltage transformer auxiliary winding, the second input End is connected with the output end of the constant-current transformer auxiliary winding, and control terminal is connected with enable signal, and output end and the PFC are controlled Tubulation manage constant-current circuit power end be connected, for when system from shutdown to it is standby again to booting underloading during, successively lead to The voltage of the voltage and the second input terminal of crossing first input end is that the power end of PFC control management constant-current circuit is connect Power power supply, so that the Constant Current Load normally starts.

5. Switching Power Supply according to claim 3, which is characterized in that further include: high pressure pretrigger circuit, the high pressure are pre- The input terminal of start-up circuit is connected with communication power supply, and output end controls the first end phase of management constant voltage circuit with the PFC Even, for system by shutdown to it is standby during, for the PFC control manage constant voltage circuit power supply is provided so that described PFC control management constant voltage circuit starts and starts to work.

6. Switching Power Supply according to claim 5, which is characterized in that the power end of the PFC control management constant voltage circuit It is connected with the output end of the constant-voltage transformer auxiliary winding, by the perseverance after PFC controls management constant voltage circuit starting The output end of pressure transformer auxiliary winding provides power supply for it, and controls the high pressure pretrigger circuit and close.

7. Switching Power Supply according to claim 5, which is characterized in that the high pressure pretrigger circuit includes: the four or two pole Pipe, the 5th diode, the 9th resistance, the tenth resistance, the first control pipe, wherein the 4th diode and the 5th diode are simultaneously Connection connection, anode is connected with power supply, the cathode first end phase with the first end of the 9th resistance and the tenth resistance respectively Even, the second end of the 9th resistance is connected with the second end of the first control pipe, the second end of the tenth resistance and institute The tenth one end of the first end and PFC control management constant voltage circuit of stating the first control pipe is connected, the first control pipe Third end and the PFC control the first end of management constant voltage circuit and be connected.

8. Switching Power Supply according to claim 5, which is characterized in that further include: em filtering circuit and rectification circuit, In, the input terminal of the em filtering circuit is connected with communication power supply, output end respectively with the high pressure pretrigger circuit Input terminal and the rectification circuit input terminal be connected, the output end of the rectification circuit respectively with the constant-voltage transformer The input terminal of the input terminal of main winding and the constant-current transformer main winding is connected.

9. Switching Power Supply according to claim 1, which is characterized in that further include: overvoltage crowbar, the overvoltage protection The input terminal of circuit is connected with the output end of the constant-current transformer auxiliary winding, output end and PFC control management constant current The second end of circuit is connected, and when the voltage for exporting when the constant-current transformer is more than setting value, makes the PFC control management Constant-current circuit drops to the voltage of the constant-current transformer output and is set by the conducting and shutdown of the control constant current switch pipe Determine in range.

10. a kind of TV, which is characterized in that including the described in any item Switching Power Supplies of the claims 1-9.