CN104253960A - Low-power-consumption stable voltage backlight control circuit and television - Google Patents

Low-power-consumption stable voltage backlight control circuit and television Download PDF

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CN104253960A
CN104253960A CN201410476693.1A CN201410476693A CN104253960A CN 104253960 A CN104253960 A CN 104253960A CN 201410476693 A CN201410476693 A CN 201410476693A CN 104253960 A CN104253960 A CN 104253960A
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voltage
circuit
power supply
output
resistance
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CN104253960B (en
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吴永芳
刘威河
廖武
杨达富
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Guangzhou Kun Electronic Technology Co. Ltd.
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Guangzhou Shiyuan Electronics Thecnology Co Ltd
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B20/00—Energy efficient lighting technologies, e.g. halogen lamps or gas discharge lamps
    • Y02B20/40—Control techniques providing energy savings, e.g. smart controller or presence detection

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Abstract

The invention discloses a low-power-consumption stable voltage backlight control circuit. The low-power-consumption stable voltage backlight control circuit comprises a front-end power supply circuit, a DC-DC (Direct Current-Direct Current) voltage adjusting circuit, a rear end linear constant current circuit and a voltage detection circuit, wherein the front-end power supply circuit comprises a power supply circuit, a first power supply output end, a second power supply output end and a feedback circuit; the feedback circuit is used for controlling the power supply circuit to adjust voltage values of the first power supply output end and the second power supply output end according to a voltage value of a control signal input end; the DC-DC voltage adjusting circuit is used for adjusting a voltage signal output by the second power supply output end to a fixed voltage signal; the voltage detection circuit is used for switching off current passing through an LED lamp cluster when the LED lamp cluster is closed. The invention further provides a self-adapted power supply adjustable television. According to the technical scheme disclosed by the invention, the output voltage is controlled according to the voltage change of the LED lamp cluster, supply voltage of a main board is stabilized and a phenomenon that an LED has micro-light when backlight is closed is prevented.

Description

A kind of voltage stabilizing backlight control circuit of low-power consumption and television set
Technical field
The present invention relates to Energy control technical field, the television set that the voltage stabilizing backlight control circuit particularly relating to a kind of low-power consumption regulates with the adaptation power supply of the voltage stabilizing backlight control circuit comprising this low-power consumption.
Background technology
In TV set power control technology field, often employing one-level linear constant-current modulation circuit realizes the power supply simultaneously to mainboard and LED-backlit.
Linear constant-current modulation circuit is widely used a kind of element circuit in analog integrated circuit, multiple-channel output transformer is provided with in it is usual, by this multiple-channel output transformer, draw a road and export and to power output as LED-backlit, then draw another road and export power supply output as mainboard.Carrying out in integration process to television components, mainboard and backlight lamp bar need to form a complete production network usually, and the different backlight LED light bars of quantity exports different magnitudes of voltage by needing linear constant-current modulation circuit adaptability.Adopt in prior art one and TV SKD to power the feedback loop that output is connected, the change in voltage of timely monitoring television main board power supply output.
As shown in Figure 1, be the schematic diagram of a kind of linear constant-current modulation circuit that prior art provides, provide LED power supply signal and main board power supply signal by power circuit 10.When the output voltage of main board power supply output raises, be linked in the reference input R0 of voltage-stabiliser tube UB102 by the voltage signal after resistance RB135 and resistance RB134 dividing potential drop, and the reference voltage (as 2.5V) of this voltage signal and voltage-stabiliser tube UB102 inside is made comparisons, voltage between voltage-stabiliser tube UB102 anode and cathode is reduced, and then the ER effect of optocoupler diode PCB101A is large, dynamic electric resistor between collector electrode and emitter diminishes, the voltage step-down between collector electrode and emitter; By output terminals A DJ/Vs-ON the variable quantity of voltage signal fed back to the internal transformer in power circuit 10; Internal transformer output voltage thereupon in power circuit 10 is reduced to the voltage of setting.Therefore, along with the increase of resistance RB134 resistance, LED power output and main board power supply output output voltage reduce, otherwise voltage raise.
Due to the difference of application scenario, at LED (Light Emitting Diode, light-emitting diode) television set actual production process in often need linear constant current circuit to export different magnitudes of voltage, and the feeder ear exporting TV SKD and backlight to is all under the jurisdiction of same transformer usually, when output of powering to wherein any road is modulated, will inevitably have an impact to the power supply output on another road.Such as, often need the number change according to backlight LED in practice and adjust the supply power voltage exporting LED string to, and the supply power voltage of TV SKD is relatively fixing, therefore, prior art cannot meet adjustment LED power output output voltage values while, keep the demand of voltage stabilization of supply TV SKD adaptively.
In addition, prior art is when improving linear constant current circuit, often make when turning off the power supply of backlight LED, one end of backlight LED is still connected with electricity consumption device and there is weak current, this weak current is played a reversed role and makes backlight LED conducting to backlight LED and send faint light, this is unallowed in tv mechanism technology for making field.
Summary of the invention
Technical problem to be solved by this invention is, provides a kind of voltage stabilizing backlight control circuit of low-power consumption, can turn off backlight of television LED completely, avoids the useful life of unnecessary power consumption penalty and raising backlight LED.
For solving above technical problem, on the one hand, embodiments provide a kind of voltage stabilizing backlight control circuit of low-power consumption, comprising: front end power circuit, DC-DC voltage regulator circuit, rear end linear constant current circuit and voltage detecting circuit;
Described front end power circuit comprises power supply circuits, the first power supply output, the second power supply output and feedback circuit; Described first power supply output is connected with the anode of LED string, for electric to described LED statements based on collusion;
The input and described second of described DC-DC voltage regulator circuit output of powering is connected, and after the voltage signal for being exported by described second power supply output being adjusted to fixing voltage signal, exporting mainboard to and powering;
Described rear end linear constant current circuit comprises constant-current control circuit and a switching tube (QB1), is constant current signal for controlling to export to the electric current of described LED string; When described switching tube (QB1) is for triode, described constant-current control circuit is connected with the negative electrode of described LED string by the collector electrode of described triode; When described switching tube (QB1) is for field-effect transistor, described constant-current control circuit is connected with the negative electrode of described LED string by the drain electrode of described field-effect transistor;
Draw a road voltage acquisition output at described constant-current control circuit and described LED string junction, be connected with described voltage detecting circuit; Described voltage detecting circuit comprises diode (DB2) and resistance (RB18); Wherein, the negative electrode of diode (DB2) is connected on the negative electrode of described LED string; The anode of diode (DB2) is connected on one end of resistance (RB18), the other end access high level of resistance (RB18);
When described LED string is opened, diode (DB2) conducting, described voltage detecting circuit detects the operating voltage of described LED string by diode (DB2), thus controls the output voltage of the described first power supply output of described feedback circuit adjustment, the second power supply output; When described LED string is closed, diode (DB2) oppositely ends, and turns off the electric current flowing through described LED string.
Further, described voltage detecting circuit also comprises resistance (RB16); One end of resistance (RB16) is connected with the anode of diode (DB2), and the other end is as described voltage acquisition output.
Further, described voltage detecting circuit also comprises diode (DB3);
The anode of described diode (DB3) is connected with the anode of diode (DB2); The negative electrode of described diode (DB3) is as described voltage acquisition output.
Preferably, described voltage detecting circuit also comprises resistance (RB17); One end ground connection of described resistance (RB17), the other end is connected on described voltage detecting output.
Further, described voltage detecting circuit also comprises voltage stabilizing didoe (D1), electric capacity (CB7); And the negative electrode of voltage stabilizing didoe (D1) is connected as voltage detecting output with one end of electric capacity (CB7) jointly; The anode of voltage stabilizing didoe (D1) and the other end common ground of electric capacity (CB7).
Further, described feedback circuit comprises feedback input end, control signal input and feedback signal output;
Described feedback input end and described second output of powering is connected, and described feedback signal output is connected with described power supply circuits; Described feedback circuit, according to the magnitude of voltage of described control signal input, to described power supply circuits output feedback signal, adjusts to control the magnitude of voltage of described power supply circuits to described first power supply output and described second power supply output.
Further, in the power circuit of described front end, described feedback circuit is also provided with optocoupler (PCB101), pressurizer (UB102);
Described optocoupler (PCB101) comprises the light-emitting diode being positioned at former limit and the optical signal converter being positioned at secondary;
The control signal that described control signal input inputs is accessed to the light-emitting diode being positioned at former limit of described optocoupler (PCB101) by described pressurizer (UB102); Described light-emitting diode is passed to the optical signal converter being positioned at secondary of described optocoupler (PCB101) after control signal is converted to light signal; Described optical signal converter exports described feedback signal output to after light signal is converted to the signal of telecommunication.
Preferably, described pressurizer (UB102) adopts adjustable precision shunt pressurizer, comprises negative electrode (K), anode (A) and reference input (R), and in have reference voltage;
Wherein, anode (A) ground connection of described adjustable precision shunt pressurizer, negative electrode (K) is connected with the light-emitting diode being positioned at former limit of described optocoupler (PCB101); Reference input (R) is for accessing the control signal of described control signal input.
Further, the reference input (R) of described adjustable precision shunt pressurizer is connected with described control signal input by a voltage divider, and preferably, described voltage divider is a resistance (RB150).
Again further, described DC-DC voltage regulator circuit is boosting regulating circuit or reduction regulation circuit.
On the other hand, present invention also offers the television set that a kind of adaptation power supply regulates, comprising: TV SKD, backlight LED light string, and the voltage stabilizing backlight control circuit of the low-power consumption described in any one as above;
Described voltage stabilizing backlight control circuit is connected respectively with described TV SKD and described backlight LED light string, for when turning on the power supply of described television set, according to the operating voltage of described backlight LED light string, Automatic adjusument supplies the voltage signal of described TV SKD, described backlight LED light string.
Implement technical scheme provided by the invention, can provide duplex feeding output by front end power circuit, the first power supply output is used for powering to LED backlight; Second power supply output is connected with DC-DC voltage regulator circuit, after the voltage signal that the second power supply output exports is adjusted to fixing voltage signal, exports mainboard to and powers, ensure that the voltage stability being supplied to mainboard; It is constant current signal through the electric current of backlight LED light string that rear end linear constant current circuit is used for control flow check; Voltage detecting circuit is contacted by diode (DB2) and backlight LED light and is connect, when LED string is opened, diode (DB2) conducting, voltage detecting circuit detects the operating voltage of LED string, thus can control the output voltage of the described first power supply output of described feedback circuit adjustment, the second power supply output; When described LED string is closed, diode (DB2) oppositely ends, turn off the electric current flowing through described LED string completely, therefore the present invention can when backlight open, the operating voltage of normal acquisition LED string, thus regulate the voltage signal values to mainboard and LED statements based on collusion electricity adaptively; When receiving the order of closing backlight LED, LED string two ends are equivalent to open circuit, and LED, without glimmer phenomenon, avoids the useful life of unnecessary power consumption penalty and raising backlight LED.
Accompanying drawing explanation
Fig. 1 is the schematic diagram of a kind of linear constant-current modulation circuit that prior art provides.
Fig. 2 is the structural representation of the constant current of low-power consumption provided by the invention and an embodiment of controlling circuit of voltage regulation.
Fig. 3 is that a kind of of front end provided by the invention power circuit can the physical circuit schematic diagram of implementation.
Fig. 4 is a kind of physical circuit schematic diagram of front end provided by the invention power circuit.
A kind of circuit theory diagrams during Fig. 5 to be DC-DC voltage regulator circuit provided by the invention be boosting regulating circuit.
Fig. 6 is that a kind of of rear end provided by the invention linear constant current circuit can the circuit theory diagrams of implementation.
Fig. 7 is the structural representation of an embodiment of the voltage stabilizing backlight control circuit of low-power consumption provided by the invention.
Fig. 8 is that a kind of of voltage detecting circuit provided by the invention can the physical circuit figure of implementation.
Fig. 9 is that the another kind of voltage detecting circuit provided by the invention can the physical circuit figure of implementation.
Figure 10 is the structural representation of another embodiment of the voltage stabilizing backlight control circuit of low-power consumption provided by the invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is clearly and completely described.
The present invention is described concrete execution mode for LED television mainboard and LED backlight, it should be noted that, the various circuit itself that the invention provides or improve are applicable to various mainboard to be powered and LED.
See Fig. 2, it is the structural representation of the constant current of low-power consumption provided by the invention and an embodiment of controlling circuit of voltage regulation.
In the present embodiment, the constant current of described low-power consumption and controlling circuit of voltage regulation comprise front end power circuit 101, DC-DC voltage regulator circuit 102 and rear end linear constant current circuit 103.
Described front end power circuit 101 comprises power supply circuits 1011, first power supply output OUT1, the second power supply output OUT2 and feedback circuit 1012;
Wherein, described feedback circuit 1012 comprises feedback input end A_in, control signal input Cont and feedback signal output B_out; Described feedback input end A_in and the described second output OUT2 that powers is connected, and described feedback signal output B_out is connected with described power supply circuits 1011; Described feedback circuit 1012 is according to the magnitude of voltage of described control signal input Cont, to described power supply circuits 1011 output feedback signal, adjust to control the magnitude of voltage of described power supply circuits 1011 to described first power supply output OUT1 and described second power supply output OUT2.
During concrete enforcement, the LED string that the present embodiment provides is preferably backlight of television LED string, and is powered by the first power supply output OUT1; Described mainboard is preferably TV SKD, and is powered by the second power supply output OUT2.
Referring to Fig. 3, be that a kind of of front end provided by the invention power circuit can the physical circuit schematic diagram of implementation.
Can in implementation in one, as shown in Figure 3, feedback circuit 1012 can be provided with optocoupler PCB101, pressurizer UB102 and peripheral circuit thereof.Wherein, described optocoupler PCB101 comprises the light-emitting diode (i.e. the pin 1 of optocoupler PCB101 and the assembly of pin 2) being positioned at former limit and the optical signal converter (i.e. the pin 3 of optocoupler PCB101 and the assembly of pin 4) being positioned at secondary.
The control signal that described control signal input inputs is accessed to the light-emitting diode being positioned at former limit of optocoupler PCB101 by pressurizer UB102; Described light-emitting diode is passed to the optical signal converter being positioned at secondary of described optocoupler PCB101 after control signal is converted to light signal; Described optical signal converter exports described feedback signal output to after light signal is converted to the signal of telecommunication.
Further, described feedback circuit 1012 is also provided with resistance RB131 and resistance RB132; One end of described resistance RB131 is described feedback input end, and the other end is connected with the anode being positioned at the light-emitting diode on former limit of optocoupler PCB101; One end of described resistance RB132 is connected to the anode of described light-emitting diode, and the other end is connected on the negative electrode of described light-emitting diode.
Wherein, the input (pin 1) being positioned at the light-emitting diode on former limit is connected as feedback input end A_in and the second output OUT2 that powers by resistance RB131, and the two ends, former limit of optocoupler PCB101 (pin 1 and pin 2) is in parallel with resistance RB132; The output (pin 4) being positioned at the optical signal converter of the secondary of optocoupler PCB101 connects and is connected with the FEEDBACK CONTROL end feedback of power supply circuits 1011 as feedback signal output B_out, the other end (pin 3) ground connection of optical signal converter.It should be noted that, resistance RB132 is not the necessary electronic component in the feedback circuit in the present embodiment.
Pressurizer UB102 preferably adopts adjustable precision shunt pressurizer, comprises negative electrode K, anode A and reference input R, and the reference voltage of built-in 2.5V (volt), preferably, model can be adopted to be that the pressurizer of TL431 realizes.Wherein, the anode A ground connection of described adjustable precision shunt pressurizer, negative electrode K is connected with the light-emitting diode being positioned at former limit of described optocoupler PCB101; Reference input R is for accessing the control signal of described control signal input Cont.
Further, described feedback circuit 1012 is also provided with voltage stabilizing feedback circuit.
In the attainable mode of one, described voltage stabilizing feedback circuit comprises electric capacity CB109 and resistance RB133; One end of described electric capacity CB109 is connected on the negative electrode K of described adjustable precision shunt pressurizer, and the other end is connected with one end of resistance RB133; The other end of resistance RB133 is connected on the reference input R of described adjustable precision shunt pressurizer.
In the attainable mode of another kind, described voltage stabilizing feedback circuit comprises electric capacity CB110; One end of described electric capacity CB110 is connected on the negative electrode K of described adjustable precision shunt pressurizer, and the other end is connected on the reference input R of described adjustable precision shunt pressurizer.
Further, above two kinds of implementations can combine by the present embodiment, to realize described voltage stabilizing feedback circuit.Namely described voltage stabilizing feedback circuit is provided with electric capacity CB109, resistance RB133 and electric capacity CB110 simultaneously.
As shown in Figure 3, the negative electrode K of pressurizer UB102 is connected with light-emitting diode 2 pin on the former limit of optocoupler PCB101, the anode A ground connection of pressurizer UB102; One end of resistance RB134 is connected with the reference input R of pressurizer UB102, other end ground connection; One end of electric capacity CB109 is connected on the negative electrode K of described adjustable precision shunt pressurizer, and the other end is connected with one end of resistance RB133; The other end of resistance RB133 is connected on the reference input R of described adjustable precision shunt pressurizer; One end of described electric capacity CB110 is connected on the negative electrode K of described adjustable precision shunt pressurizer, and the other end is connected on the reference input R of described adjustable precision shunt pressurizer.
Further, the reference input R of described adjustable precision shunt pressurizer is connected with described control signal input by a voltage divider.In the present embodiment, preferably, described voltage divider is a resistance RB150.
As shown in Figure 3, electric capacity CB109 one end is connected with 2 pin of optocoupler PCB101, and be connected with one end of resistance RB150 after the other end and resistance RB133 connect, the other end of resistance RB150 is as described control signal input Cont; One end of electric capacity CB110 is connected with the negative electrode K of pressurizer UB102, and the other end is connected with the reference input R of pressurizer UB102; One end of resistance RB135 is connected with feedback input end A_in, and the other end is connected with the reference input R of pressurizer UB102.Thus, a kind of concrete execution mode of feedback circuit 1012 is constituted.
In the present embodiment, the reference input R of pressurizer UB102 increases a resistance RB150, introduce the output voltage values of a control signal to the negative electrode K of pressurizer UB102 by control signal input Cont simultaneously and carry out Automated condtrol, thus the adjustment to power supply circuits 1011 and output voltage thereof can be realized.
Referring to Fig. 4, it is a kind of physical circuit schematic diagram of front end provided by the invention power circuit.
Wherein, described power supply circuits 1011 comprise power supply input circuit 11, switching power circuit 12, multiple-channel output transformer TB101, LED power output circuit 13 and main board power supply output circuit 14.
The power supply signal of access is transferred to described multiple-channel output transformer TB101 by described power supply input circuit 11 under the control of described switching power circuit 12; As shown in Figure 4, described multiple-channel output transformer TB101 comprises main winding and auxiliary winding.Wherein, the coil of 9 pin ~ 11 pin of multiple-channel output transformer TB101 forms elementary main winding, and the coil of 1 pin ~ 2 pin of multiple-channel output transformer TB101 forms secondary main winding; The coil of 7 pin ~ 8 pin of multiple-channel output transformer TB101 forms elementary auxiliary winding, the coil of 1 pin ~ 6 pin of multiple-channel output transformer TB101 forms secondary auxiliary winding, wherein, the coil of 1 pin ~ 2 pin is the shared winding of main winding and time winding, it should be noted that, can common sparing winding between secondary main winding and auxiliary winding, also can adopt independently winding.During concrete enforcement, described main winding transfers to described main board power supply output circuit 14 by after described power supply signal transformation, and is exported by described second power supply output OUT2; Described auxiliary winding to be powered transferring to described LED after synchronous for described power supply signal transformation output circuit 13, and is exported by described first power supply output OUT1; Therefore, the multiple-channel output transformer TB101 in Fig. 4 has two output voltage.
Especially, in technical field of television sets, the first power supply output OUT1 is preferably the power supply output of supply LED backlight, and the second power supply output OUT2 is preferably the power supply output of supply TV SKD.
In the present embodiment, the output voltage of multiple-channel output transformer TB101 every circle coil is identical, and when changing the output voltage on a wherein road, so the output voltage on another road also synchronously will follow change.Such as, the coil of main winding is 2 circles, and output voltage is 12V, and namely the output voltage of every circle coil is 6V; Suppose that the output voltage of auxiliary winding is 120V, then the coil turn of auxiliary winding is 20 circles.And the coil turn of main winding and auxiliary winding can adjust according to practical application, namely the coil ratio of described main winding and described auxiliary winding is 1:N, N > 0, namely when the output voltage of main winding is V1, the output voltage of auxiliary winding is V2=N*V1.
It should be noted that, the feedback input end A_in of feedback circuit 1012 can connect the first power supply output OUT1 or second power supply output OUT2 of described power supply circuits 1011, does not affect the enforcement of the present embodiment.
The size of the external control signal that the present invention accesses by the control signal input Cont of linear regulation feedback circuit 1012, thus the magnitude of voltage controlling the first power supply output OUT1 or second power supply output OUT2.Particularly, be connected to the second power supply output OUT2 of described power supply circuits 1011 for the feedback input end A_in of described feedback circuit 1012, the basic functional principle of the present embodiment is mainly:
When the output voltage of power supply circuits 1011 raises (the first power supply output OUT1 and second power supply output OUT2 raises) simultaneously, the control signal of the control signal input Cont voltage transmission after resistance RB135 and resistance RB134, resistance RB150 dividing potential drop compares to the reference input R of pressurizer UB102, pressurizer UB102 with reference to the signal value of input R and its internal reference voltage.When the signal value of reference input R is greater than reference voltage, voltage between pressurizer UB102 anode and cathode reduces, and then the electric current of optocoupler PCB101 increases, between optocoupler PCB101 collector electrode and emitter, dynamic electric resistor diminishes (4 pin of the current collection of optocoupler PCB101 very optocoupler, launch 3 pin of very optocoupler), the voltage step-down between collector electrode and emitter; PWM (the Pulse Width Modulation thereupon connected, pulse width modulation) the level step-down of feedback pin COMP of control chip UB101, pwm chip UB101 output duty cycle reduces, thus the output voltage of multiple-channel output transformer TB101 is reduced.Otherwise, when the signal value of reference input R is less than reference voltage, the output voltage of multiple-channel output transformer TB101 (comprising the output voltage of the first power supply output OUT1 and second power supply output OUT2) can be made to raise.Therefore, the magnitude of voltage of the reference input R of pressurizer UB102 determines the output voltage of multiple-channel output transformer TB101.
Therefore, based on above principle, for reaching the size of voltage signal thus the object of the output voltage of control transformer TB101 that the reference input R that regulates pressurizer UB102 accesses, the present invention is by increasing resistance RB150 and realizing at the side incoming control signal of resistance RB150.Particularly, to power the output voltage of output OUT2 when needing modulation second, and the internal reference voltage of pressurizer UB102 is when being 2.5V, the output voltage values computing formula of the second power supply output is: Vout2=reference voltage * (1+R135/R134), wherein, reference voltage is preferably 2.5V.Preferably, export a PWM_12V signal to described control signal input Cont by external control chip, via resistance RB150 by PWM_12V Signal transmissions to series connection point between resistance RB134 and resistance RB135 (i.e. the reference input R of pressurizer UB102).
During concrete enforcement, the PWM_12V signal of control signal input Cont can adopt any one constant voltage values in 0-3.3V, or, adopt PWM (Pulse Width Modulation, the pulse width modulation) ripple of certain waveform.Output voltage values computing formula according to the second power supply output: Vout2=reference voltage * (1+R135/R134), under any circumstance, when being 3.3V (maximum) by external control chip to the control signal that the control signal input Cont of feedback circuit 1012 inputs, the output voltage of the second power supply output OUT2 is minimum, because the input voltage (3.3V) of control signal input Cont is greater than the reference voltage 2.5V (when circuit stability work the 1 pin voltage of pressurizer UB102 and reference voltage almost equal) of pressurizer UB102, so be the equal of now that resistance RB150 receives on the power supply of 3.3V, resistance RB150 is namely equivalent to be connected in parallel on resistance RB135, according to the voltage equation of Vout2, due to resistance RB135 resistance RB150 in parallel, the equivalent resistance being equivalent to resistance RB135 reduces, thus output voltage Vout2 is reduced.When being 0V (minimum) by external control chip to the control signal that the control signal input Cont of feedback circuit 1012 inputs, the output voltage of the second power supply output OUT2 is maximum, because the control signal that control signal input Cont inputs is equivalent to ground connection when being 0V, at this moment resistance RB150 is equivalent to be connected in parallel on resistance RB134, according to above-mentioned voltage computing formula, due to resistance RB134 resistance RB150 in parallel, the equivalent resistance being equivalent to resistance RB135 diminishes, thus output voltage Vout2 is raised.
Visible, the control signal (constant voltage signal of 0V ~ 3.3V as escribed above or PWM ripple) inputted by the control signal input Cont of linear regulation feedback circuit 1012, the output voltage of the second power supply output OUT2 can be made to carry out regulating (Vout2_max=12.5V between actual common voltage scope 11.5V ~ 12.5V, Vout2_min=11.5V), thus realize fine setting; In like manner, under the effect of multiple-channel output transformer TB101, the output voltage of the first power supply output OUT1 also will realize synchronous automatic adaptation and regulate, especially, the output voltage of supply TV motherboard circuit often changes 0.01V, and the output voltage of supply LED string will change 0.1V.
In embody rule occasion, under product ideal case (power supply circuits export and reduce), the control signal inputted to the control signal input Cont of feedback circuit 1012 by linear regulation external control chip is high level (as 3.3V), thus the voltage that second of power supply circuits 1011 the power supply output OUT2 can be made to export is minimum output voltage, can reduce the stand-by power consumption of TV SKD.
In addition, described LED string to be powered is in series by multiple LED, along with the increasing of quantity of LED string to be powered, after multiple LED strip connection, required supply power voltage constantly increases, therefore, require that the output voltage of the first power supply output OUT1 can respond the number change of LED adaptively, automatically regulate its output voltage values.
The first power supply output OUT1 and the second output OUT2 that powers provided due to the present embodiment belongs to a transformer TB101, when regulating the output voltage of the first power supply output OUT1, will inevitably have an impact to the output voltage of the second power supply output OUT2, vice versa.And the supply power voltage of TV SKD usually comparatively fixing (about 12V), if the output voltage amplitude fluctuation of the second power supply output OUT2 is excessive, will affect the overall performance of TV SKD, and too high supply power voltage even may burn TV SKD.
As shown in Figure 2, the constant current of low-power consumption provided by the invention and controlling circuit of voltage regulation are also provided with DC-DC voltage regulator circuit 102.Particularly, the input and described second of the described DC-DC voltage regulator circuit 102 output OUT2 that powers is connected, after voltage signal for being exported by described second power supply output OUT2 being adjusted to fixing voltage signal, exporting TV SKD to and powering.
For supply power voltage needed for TV SKD for 12V, the present embodiment increases one-level DC-DC voltage regulator circuit 102 between front end power circuit 101 and TV SKD, responded the change of the output voltage of the second power supply output OUT2 by DC-DC voltage regulator circuit 102, automatically adjust the output to the voltage value of TV SKD.DC-DC voltage regulator circuit 102 can be greater than or less than the situation of 12V according to the output voltage of the second power supply output OUT2, adopt reduction regulation circuit or boosting regulating circuit.
See Fig. 5, a kind of circuit theory diagrams during to be DC-DC voltage regulator circuit provided by the invention be boosting regulating circuit.Particularly, when described DC-DC voltage regulator circuit 102 is for boosting regulating circuit, comprise: to power inductor LB801, switching circuit 1021, voltage conversion chip UB801 and the peripheral circuit 1022 thereof that output OUT2 is connected and output filter circuit 1023 with described second.In the present embodiment, obtain 12.5Vout after the output voltage by powering output OUT2 by second adopts the boosting regulating circuit of Fig. 5 to boost to power to TV SKD.
Described switching circuit 1021 is connected with inductor LB801 output, is transferred in voltage conversion chip UB801 by the voltage signal of described second power supply output OUT2 and is adjusted to stable voltage signal; Stable voltage signal after regulating transferred to after described output filter circuit 1023 filters by described switching circuit 1021 again, be supplied to TV SKD and power.
To power the output voltage of output OUT1 to realize Automatic adjusument first, ensure the stability of the voltage signal of supply TV SKD simultaneously, the present embodiment after with the addition of DC-DC voltage regulator circuit 102, then achieves the adjustability of the output voltage of the second power supply output OUT2.The operating voltage range that TV SKD allows is generally 11.5V ~ 12.5V, then DC-DC voltage regulator circuit 102 starts rear effect is the voltage signal exporting 11.5V ~ 12.5V after being regulated by the output voltage of the second power supply output OUT2 at 12.5Vout output, thus the first output voltage of powering output OUT1 that making contacts with LED connects can regulate according to the LED lamp bar quantity of reality, improves the scope of application and the flexibility of the control circuit that the present embodiment provides.
Described constant current and controlling circuit of voltage regulation are also provided with rear end linear constant current circuit 103, and particularly, as shown in Figure 2, described rear end linear constant current circuit 103 comprises comparison circuit 1031 and constant-current control circuit 1032; Described comparison circuit 1031 is provided with reference signal input PWM_REF, to access constant current reference voltage V rEF; Described constant-current control circuit 1032 is connected with one end LED-of LED string to be powered under the adjustment of described comparison circuit 1031, and the other end LED+ and described first of the described LED string to be powered output OUT1 that powers is connected;
A road voltage acquisition output (the output terminals A DC_12V as in Fig. 2) is drawn with described LED string junction P to be powered at described constant-current control circuit 1032, with the change in voltage according to described LED string to be powered, described front end power circuit adjusts the magnitude of voltage of described control signal input Cont, thus controls the output voltage of described first power supply output OUT1, the second power supply output OUT2.
Referring to Fig. 6, be that a kind of of rear end provided by the invention linear constant current circuit can the circuit theory diagrams of implementation.
During concrete enforcement, in the rear in linear constant-current circuit 103, described comparison circuit 1031 also comprises operational amplifier UB1A, and the inverting input of described operational amplifier UB1A is connected with described reference signal input PWM_REF by a resistance RB12; The normal phase input end of described operational amplifier UB1A is connected with current feedback circuit.Particularly, as shown in Figure 6, this current feedback circuit comprises multiple constant current and detects resistance, is respectively resistance RB5, resistance RB6, resistance RB7, resistance RB8, resistance RB9; Wherein, resistance RB6, resistance RB7, resistance RB8 and resistance RB9 form parallel circuits, and one end of described parallel circuits is connected on one end of resistance RB5, the other end ground connection of described parallel circuits; The other end of resistance RB5 is connected on the normal phase input end of described operational amplifier.Further, described current feedback circuit also comprises electric capacity CB5; One end ground connection of described electric capacity CB5, the other end is connected on the normal phase input end of described operational amplifier.The circuit that wherein resistance RB5 and electric capacity CB5 forms can carry out filtering to the signal of the normal phase input end being input to operational amplifier UB1A.
Preferably, described comparison circuit 1031 also comprises a clamp diode DB1, to protect the normal work of described comparison circuit 1031.
Described rear end linear constant current circuit 103 also comprises a switching tube QB1.Switching tube QB1 can be triode or MOS (Metal-Oxid-Semiconductor, metal-oxide semiconductor (MOS)) field-effect transistor, is called for short metal-oxide-semiconductor or field-effect transistor.Wherein, the conduction and cut-off state of switching tube QB1 follows the physical characteristic of himself to be associated.Such as, when switching tube QB1 is triode, according to the volt-ampere characteristic of triode, there is saturation region, amplification region and cut-off region, respectively from the voltage signal between collector electrode, different impacts is produced to the emitter of triode, as when triode operation is in saturation region, between the emitter of triode and collector electrode, be equivalent to short circuit (conducting state).
In the present embodiment, when described switching tube QB1 is triode, described constant-current control circuit 1032 is connected with one end (LED-) of described LED string to be powered by the collector electrode of described triode; The emitter of described triode is connected with the anode of described clamp diode DB1; When described switching tube QB1 is field-effect transistor, described constant-current control circuit 1032 is connected with one end (LED-) of described LED string to be powered by the drain electrode of described field-effect transistor; The source electrode of described field-effect transistor is connected with the anode of described clamp diode DB1.
During concrete enforcement, the minus earth of clamp diode DB1, anode is connected to the normal phase input end of operational amplifier UB1A by resistance RB5.After rear end linear constant current circuit 103 starts, through the adjustment of operational amplifier UB1A, its normal phase input end institute connects the constant current detection magnitude of voltage got of resistance and it oppositely inputs the constant current reference voltage V accessed rEFequal, then as constant current reference voltage V rEFduring turn-on voltage (about 0.7V) higher than clamp diode DB1; clamp diode DB1 will conducting ground connection; namely the magnitude of voltage that the constant current that composed in parallel by resistance RB6, resistance RB7, resistance RB8 and resistance RB9 detects resistance two ends limit by clamp diode DB1; therefore, clamp diode DB1 serves certain protective effect.
And, because the emitter (switching tube QB1 is triode) of switching tube QB1 or source electrode (switching tube QB1 is metal-oxide-semiconductor) are connected with the anode of clamp diode DB1, the constant current value of the switching tube QB1 that therefore circulates can pass through following formulae discovery:
As constant current reference voltage V rEFduring turn-on voltage higher than clamp diode DB1, the constant current signal of circulation switching tube QB1 is: I constant currentturn-on voltage/the constant current of=DB1 detects the resistance of resistance; As constant current reference voltage V rEFduring turn-on voltage lower than clamp diode DB1, the constant current signal of circulation switching tube QB1 is: I constant current=constant current reference voltage V rEF/ constant current detects the resistance of resistance.Usually, the turn-on voltage of clamp diode DB1 is 0.7V, and the resistance of constant current detection resistance is the equivalent resistance after resistance RB6, resistance RB7, resistance RB8 and resistance RB9 parallel connection.
In the present embodiment, first power supply output is connected to the positive pole LED+ of LED string, by the current constant control of switching tube QB1, be connected in series constant current again and detect resistance (parallel resistance of resistance RB6, resistance RB7, resistance RB8 and resistance RB9) to ground, the size of current of LED string is converted to voltage signal and is linked into operational amplifier UB1A and constant current reference voltage V by constant current detection resistance rEF(controlled by outside master chip, or access fixed voltage, if the constant current value I that fixed voltage then exports constant currentbe then fixed value, the adjustment of constant current size can not be carried out) compare and amplify, thus control switch pipe QB1 adjusts the constant current hold of LED string.
During concrete enforcement, LED string generally can be connected plurality of LEDs lamp, and wherein the operating voltage of single LEDs is generally 2.8V ~ 3.4V, and the operating voltage after the series connection of plurality of LEDs lamp is by corresponding increase.For switching tube QB1 for metal-oxide-semiconductor, the voltage between the drain electrode of switching tube QB1 and source electrode is: V dS=V oUT1-LED string operating voltage-constant current reference voltage V rEF.Therefore, after rear end linear constant current circuit 103 enters operating state, the voltage V between the drain electrode of switching tube QB1 and source electrode dSthe impact of the operating voltage size of LED string will be subject to, the impact of the cross modulation (general range is 7%) of multiple-channel output transformer TB101 may be subject in addition.
Along with the change of LED crosstalk pressure, the drain-source voltage V of switching tube QB1 dSvoltage also synchronously changes, this part power (V of switching tube QB1 dS* constant current value I constant current) form that will convert heat to comes out, V dSvoltage is larger, and the power consumption of switching tube QB1 is larger, and temperature is higher.Therefore the switching tube QB1 that power consumption is excessive can reduce power-efficient and causes switching tube QB1 overheated and easily damage.In order to reduce power consumption and the temperature of switching tube QB1, multiple metal-oxide-semiconductor or triode parallel connection can be adopted to use as switching tube QB1, but this technical scheme result in the increase of cost.For this reason, the present embodiment makes further improvement to rear end linear constant current circuit 103.
Embodiment of the present invention composition graphs 2 ~ Fig. 6, provides a kind of constant current and controlling circuit of voltage regulation of low-power consumption, can solve the power problems of above-described switching tube QB1.Particularly, the present embodiment is by drawing a road voltage acquisition output terminals A DC_12V at described constant-current control circuit 1032 with described LED string junction P to be powered, to detect the change in voltage of LED string to be powered in real time, for the pressure drop between voltage acquisition output terminals A DC_12V and reference signal input PWM_REF sets a threshold value, or the output voltage for voltage acquisition output terminals A DC_12V sets a steady state value (the voltage V of reference signal input PWM_REF rEFgeneral less), pressure drop between voltage acquisition output terminals A DC_12V and reference signal input PWM_REF is greater than described threshold value, or when the output voltage of voltage acquisition output terminals A DC_12V is greater than described steady state value, by the control signal PWM_12V of the control signal input Cont in adjustment front end power circuit 101, control optocoupler PCB101 and the situation of change (i.e. the change in voltage situation of the first power supply output OUT1) of the operating voltage of LED string is fed back to pwm chip UB101, pwm chip UB101 control switch pipe QB101 changes duty ratio, thus the magnitude of voltage making the magnitude of voltage of voltage acquisition output terminals A DC_12V deduct reference signal input PWM_REF equals or close to the described threshold value (or the magnitude of voltage of voltage acquisition output terminals A DC_12V equals or close to described steady state value) preset, therefore, the present embodiment can by the control signal PWM_12V of control signal input Cont, stop voltage gathers the pressure drop between output terminals A DC_12V and reference signal input PWM_REF, thus reduce the drain-source voltage V of switching tube QB1 dSbe subject to the impact of the change in voltage of LED string, reduce the power consumption of switching tube QB1 and ensure that power-efficient.
In the present embodiment, because the output voltage of the first power supply output OUT1 and second power supply output OUT2 exported by multiple-channel output transformer TB101, while reducing the power consumption of switching tube QB1 by the control signal PWM_12V of control signal input Cont then, the voltage of all output windings of multiple-channel output transformer TB101 will inevitably be made to change (second output voltage of powering output OUT2 of namely powering to TV SKD also will change), but, because the present embodiment is provided with DC-DC voltage regulator circuit 102 between the second power supply output OUT2 and TV SKD, therefore the present embodiment can prevent because to the output voltage adjustment of front end power circuit is excessive, situation that is that cause the excursion of TV SKD power supply excessive occurs, and DC-DC voltage regulator circuit 102 can adopt step-down or booster circuit according to actual conditions.
The constant current of a kind of low-power consumption provided by the invention and controlling circuit of voltage regulation, be provided with front end power circuit, DC-DC voltage regulator circuit and rear end linear constant current circuit, front end power circuit is utilized to regulate the supply power voltage of two-way output, and feedback circuit is set up in the power circuit of front end, and be provided with control signal input in a feedback circuit, to realize controlling the front end power circuit voltage at the first power supply output and the second power supply output, voltage signal due to control signal input will affect the output voltage of the first power supply output and the second output simultaneously, and therefore the present invention ensures the stable of the voltage signal exporting motherboard circuit to further by DC-DC voltage regulator circuit, and the change by setting up rear end linear constant current circuit automatically to adapt to the LED backlight quantity of connecting, the magnitude of voltage of described control signal input can be adjusted according to the magnitude of voltage after LED backlight series connection, thus control described first power supply output by front end power circuit and feedback circuit thereof, the output voltage of the second power supply output, and the first power supply output is connected to LED backlight and powers, achieve the voltage automation adapted with LED backlight quantity to regulate, reduce the power consumption of circuit switch element, and ensure that the stability of the supply power voltage of motherboard circuit.
In the present embodiment, when the LED operating voltage (analog signal) collected is delivered to external control devices as analog to digital converter by the voltage acquisition output terminals A DC_12V drawn due to the tie point of backlight LED light string and constant-current control circuit, the voltage of voltage acquisition output terminals A DC often higher (being greater than 3.3V), does not mate directly can not be connected with it with the voltage of analog to digital converter.Therefore, between voltage acquisition output terminals A DC_12V and analog to digital converter, be usually serially connected with one or more resistance extremely greatly, the voltage signal after dividing potential drop exports the input port of analog to digital converter again to.But, when closing television machine backlight electric power, the resistance generation current signal that the magnitude of voltage of voltage acquisition output terminals A DC_12V will make it be connected in series, this current signal moves back in LED string through voltage acquisition output terminals A DC_12V, because LED string is very responsive to electric current, as long as just energy conducting is luminous faint electric current, therefore, adopt the mode of the large resistance of serial connection to make backlight LED can not turn off completely and send faint light, this phenomenon is unallowed for television set manufactures index request.Therefore need to do further improvement to backlight of television control circuit.
For this reason, the embodiment of the present invention is in the constant current of previously described low-power consumption and the basis of controlling circuit of voltage regulation, further, by setting up a kind of voltage detecting circuit 104 be connected with rear end linear constant current circuit 103, to set up into a kind of voltage stabilizing backlight control circuit of low-power consumption.
See Fig. 7, it is the structural representation of an embodiment of the voltage stabilizing backlight control circuit of a kind of low-power consumption provided by the invention.
The voltage stabilizing backlight control circuit of the low-power consumption that the present embodiment provides, in the constant current of above-described low-power consumption and the basis of stabilization control circuit, further, also be provided with voltage detecting circuit 104, namely comprise: front end power circuit 101, DC-DC voltage regulator circuit 102, rear end linear constant current circuit 103 and voltage detecting circuit 104.
Particularly, described front end power circuit 101, DC-DC voltage regulator circuit 102, rear end linear constant current circuit 103 with above and the front end power circuit 101 of embodiment described in Fig. 2 ~ Fig. 6, DC-DC voltage regulator circuit 102, rear end linear constant current circuit 103 basic structure identical with principle one_to_one corresponding, detailed content please refer to above, does not repeat them here.
Preferably, described first power supply output OUT1 is connected with the anode of LED string, for powering to television set LED backlight; The input and described second of the described DC-DC voltage regulator circuit 102 output OUT2 that powers is connected, and after the voltage signal for being exported by described second power supply output OUT2 being adjusted to fixing voltage signal, exporting TV SKD to and powering; During concrete enforcement, adding DC-DC voltage regulator circuit 102 makes the voltage adjustable extent supplying backlight LED light string wider, but still the voltage signal exporting TV SKD to can be kept relatively fixing, therefore the present embodiment can mate with the television set of the scopes such as 32 cun ~ 42 cun and uses when without the need to revising hardware circuit.
Described rear end linear constant current circuit 103 comprises constant-current control circuit 1032 and a switching tube QB1, is constant current signal for controlling to export to the electric current of described LED string; When described switching tube QB1 is triode, described constant-current control circuit 1032 is connected with the negative electrode of described LED string by the collector electrode of described triode; When described switching tube QB1 is field-effect transistor, described constant-current control circuit 1032 is connected with the negative electrode of described LED string by the drain electrode of described field-effect transistor;
Draw a road voltage acquisition voltage output end ADC_12V at described constant-current control circuit 1032 with LED string junction (i.e. switching tube QB1 and LED string), be connected with described voltage detecting circuit 104; Described voltage detecting circuit 104 comprises diode DB2 and resistance RB18; Wherein, the negative electrode of diode DB2 is connected on the negative electrode of described LED string; The anode of diode DB2 is connected on one end of resistance RB18, other end access high level VCC (being preferably 3.3V) of resistance RB18.During concrete enforcement, the constant-current control circuit 1032 that high level VCC can be controlled by the control end identical with switching tube QB1 provides.
When described LED string is opened, diode DB2 conducting, described voltage detecting circuit 104 detects the operating voltage of described LED string by diode DB2, thus controls the output voltage that described feedback circuit 1012 adjusts described first power supply output OUT1, the second power supply output OUT2; When described LED string is closed, diode DB2 oppositely ends, and turns off the electric current flowing through described LED string.
The present embodiment is provided with detector 1041 further, for deriving the voltage signal of voltage acquisition output terminals A DC_12V.Wherein, the input of described detector 1041 is connected with the anode of diode DB2, and the output of described detector 1041 is as " new voltage acquisition output terminals A DC_12V " (now or be called voltage detecting output terminals A DC).
As shown in Figure 7, draw a road output terminals A DC_12V at constant-current control circuit 1032 with the junction P of LED string negative electrode to be connected with diode DB2 negative electrode, when described LED string is opened, diode DB2 conducting, described voltage detecting circuit 104 detects the operating voltage of described LED string by diode DB2, thus controls the output voltage that described feedback circuit 1012 adjusts described first power supply output OUT1, the second power supply output OUT2; When described LED string is closed, diode DB2 oppositely ends, and turns off the electric current flowing through described LED string.
Particularly, the main operational principle of the voltage stabilizing backlight control circuit of low-power consumption that the present embodiment provides is:
When opening backlight of television power supply, switching tube QB1 conducting enters operating state, be limited in collector electrode (when switching tube QB1 is triode) by with the contact voltage of the P point connect of LED or drain on the magnitude of voltage (being usually less than 3.3V) of (when switching tube QB1 is field-effect transistor), meanwhile, the access of high level VCC makes the voltage V of the tie point of diode DB2 and resistance RB18 ahigher than the voltage of P point, therefore, diode DB2 conducting, circuit carries out work by resistance RB18, diode DB2 and switching tube QB1 loop.Now, the voltage V of the tie point of diode DB2 and resistance RB18 a=V dB2+ V qB1; When closing television machine backlight electric power, switching tube QB1 enters cut-off state, LED string two ends keep constant voltage and there is the high level much larger than 3.3V at LED-end, therefore diode DB2 oppositely ends, open circuit is equivalent between LED string and voltage detecting circuit 104, namely LED string will pass through without weak current, thus can not produce glimmer phenomenon.
Preferably, the described voltage detecting circuit 104 that the present embodiment provides also comprises a filter circuit of pressure-stabilizing 1042; Described filter circuit of pressure-stabilizing 1042 is connected with described detector 1041 output, for when diode DB2 conducting, exports after the output signal of described detector 1041 is carried out filtering.
Particularly, described voltage detecting circuit 104, in described filter circuit of pressure-stabilizing 1042, also comprises resistance RB17; One end ground connection of described resistance RB17, the other end is connected on described voltage detecting output terminals A DC.
Further, described voltage detecting circuit 104 also comprises voltage stabilizing didoe D1, electric capacity CB7; And the negative electrode of voltage stabilizing didoe D1 is connected as voltage detecting output terminals A DC with one end of electric capacity CB7 jointly; The anode of voltage stabilizing didoe D1 and the other end common ground of electric capacity CB7.Wherein, the Main Function of voltage stabilizing didoe D1 prevents voltage detecting circuit 104 from causing the output voltage of port ADC excessive at operation irregularity or when switching tube QB1 turns off because high level VCC voltage is greater than 3.3V, thus the situation of burning the device that voltage detecting output terminals A DC connects occurs.
See Fig. 8, be that a kind of of voltage detecting circuit provided by the invention can the physical circuit figure of implementation.
In the attainable mode of one, described voltage detecting circuit 104 also comprises resistance RB16; One end of resistance RB16 is connected with the anode of diode DB2, and the other end is as described voltage detecting output terminals A DC.Now, the output voltage of voltage acquisition output terminals A DC is: V aDC=V a* RB17/ (RB16+RB17).
See Fig. 9, be that the another kind of voltage detecting circuit provided by the invention can the physical circuit figure of implementation.
In the attainable mode of another kind, described voltage detecting circuit 104 also comprises diode DB3 (namely described detector 1041 is diode DB3), and the anode of described diode DB3 is connected with the anode of diode DB2; The negative electrode of described diode DB3 is as described voltage acquisition output terminals A DC, and now, the output voltage of voltage acquisition output terminals A DC is: V aDC=V a-V dB3.
The output voltage V of voltage detecting output terminals A DC aDCexternal control devices will be transferred to and carry out Treatment Analysis, to control the operating state of front end power circuit 101 according to analysis result, thus control the output voltage of the first power supply output OUT1 and second power supply output OUT2.
Referring to Figure 10, it is the structural representation of the another embodiment of the voltage stabilizing backlight control circuit of low-power consumption provided by the invention.
The distinctive points of the present embodiment and previously described embodiment is, on the basis of previously described embodiment, further, the present embodiment also comprises a control master chip 105.Wherein, front end power circuit 101, DC-DC voltage regulator circuit 102, rear end linear constant current circuit 103 are identical with previously described embodiment with operation principle with the essential structure of voltage detecting circuit 104, do not repeat them here.
Described control master chip 105 connects respectively with described control signal input Cont, described reference signal input PWM_REF and described voltage acquisition output terminals A DC_12V (when control circuit comprises voltage detecting circuit 104, the voltage detecting output terminals A DC for after overvoltage detection circuit 104 detection).
Described control master chip 105 is according to the change in voltage of described voltage detecting output terminals A DC, adjust the output to the signal magnitude of described control signal input Cont, to control the first power supply output OUT1 of described front end power circuit 101, the output voltage values of the second power supply output OUT2; And input described constant current reference voltage V by described reference signal input PWM_REF to described rear end linear constant current circuit 103 rEF.
Particularly, when described control master chip 105 detects that the voltage difference of described voltage detecting output terminals A DC and described reference signal input PWM_REF is greater than default threshold value, the voltage signal duty ratio exporting described control signal input Cont to reduces by described control master chip 105.During concrete enforcement, described control master chip 105 is built-in with analog to digital converter, is converted to digital signal for the voltage signal accessed by described control master chip 105.Gather the voltage signal that obtains first after the conversion of analog to digital converter from voltage detecting output terminals A DC, obtain corresponding digital signal, then by controlling the process of other processing unit in master chip 105.Because too high input voltage value can affect the normal work of analog to digital converter, and the magnitude of voltage of P point easily makes the resistance between the connection mode number converter in original technology produce low current signal when closing LED string, thus LED backlight is made to produce glimmer phenomenon.Because the present embodiment is provided with voltage detecting circuit 104, when turning off backlight electric power, can move back in LED string by controlling diode DB2 thus effectively cutting off the current signal of voltage detecting circuit 104, avoiding the generation of " glimmer phenomenon ".
The present embodiment processes owing to have employed the signal of same control master chip to control signal input Cont, described reference signal input PWM_REF and described voltage detecting output terminals A DC tri-terminals, therefore on the basis of previously described effective effect, further can in real time according to the signal intensity of reference signal input PWM_REF and voltage acquisition output terminals A DC, and send corresponding control signal to control signal input Cont, therefore can reach the beneficial effect rapidly to the response for changing of LED string operating voltage.
Further, the embodiment of the present invention additionally provides the television set that a kind of adaptation power supply regulates, and comprising: TV SKD, backlight LED light string, and the voltage stabilizing backlight control circuit of low-power consumption described in above any one.
Described voltage stabilizing backlight control circuit is connected respectively with described TV SKD and described backlight LED light string, for when turning on the power supply of described television set, according to the operating voltage of described backlight LED light string, Automatic adjusument supplies the voltage signal of described TV SKD, described backlight LED light string; When closing the power supply of described television set, turn off the electric current flowing through described backlight LED light string.Wherein, the basic comprising of voltage stabilizing backlight control circuit, does not repeat them here with described identical above with operation principle.
The above is the preferred embodiment of the present invention; it should be pointed out that for those skilled in the art, under the premise without departing from the principles of the invention; can also make some improvements and modifications, these improvements and modifications are also considered as protection scope of the present invention.

Claims (24)

1. a voltage stabilizing backlight control circuit for low-power consumption, is characterized in that, comprising: front end power circuit, DC-DC voltage regulator circuit, rear end linear constant current circuit and voltage detecting circuit;
Described front end power circuit comprises power supply circuits, the first power supply output, the second power supply output and feedback circuit; Described first power supply output is connected with the anode of LED string, for electric to described LED statements based on collusion;
The input and described second of described DC-DC voltage regulator circuit output of powering is connected, and after the voltage signal for being exported by described second power supply output being adjusted to fixing voltage signal, exporting mainboard to and powering;
Described rear end linear constant current circuit comprises constant-current control circuit and a switching tube (QB1), is constant current signal for controlling to export to the electric current of described LED string; When described switching tube (QB1) is for triode, described constant-current control circuit is connected with the negative electrode of described LED string by the collector electrode of described triode; When described switching tube (QB1) is for field-effect transistor, described constant-current control circuit is connected with the negative electrode of described LED string by the drain electrode of described field-effect transistor;
Draw a road voltage acquisition output at described constant-current control circuit and described LED string junction, be connected with described voltage detecting circuit; Described voltage detecting circuit comprises diode (DB2) and resistance (RB18); Wherein, the negative electrode of diode (DB2) is connected on the negative electrode of described LED string; The anode of diode (DB2) is connected on one end of resistance (RB18), the other end access high level of resistance (RB18);
When described LED string is opened, diode (DB2) conducting, described voltage detecting circuit detects the operating voltage of described LED string by diode (DB2), thus controls the output voltage of the described first power supply output of described feedback circuit adjustment, the second power supply output; When described LED string is closed, diode (DB2) oppositely ends, and turns off the electric current flowing through described LED string.
2. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 1, it is characterized in that, described voltage detecting circuit also comprises resistance (RB16); One end of resistance (RB16) is connected with the anode of diode (DB2), and the other end is as described voltage acquisition output.
3. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 1, it is characterized in that, described voltage detecting circuit also comprises diode (DB3);
The anode of described diode (DB3) is connected with the anode of diode (DB2); The negative electrode of described diode (DB3) is as described voltage acquisition output.
4. the voltage stabilizing backlight control circuit of the low-power consumption as described in any one of claims 1 to 3, is characterized in that, described voltage detecting circuit also comprises resistance (RB17);
One end ground connection of described resistance (RB17), the other end is connected on described voltage detecting output.
5. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 4, it is characterized in that, described voltage detecting circuit also comprises voltage stabilizing didoe (D1), electric capacity (CB7); And the negative electrode of voltage stabilizing didoe (D1) is connected as voltage detecting output with one end of electric capacity (CB7) jointly; The anode of voltage stabilizing didoe (D1) and the other end common ground of electric capacity (CB7).
6. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 5, it is characterized in that, described feedback circuit comprises feedback input end, control signal input and feedback signal output;
Described feedback input end and described second output of powering is connected, and described feedback signal output is connected with described power supply circuits; Described feedback circuit, according to the magnitude of voltage of described control signal input, to described power supply circuits output feedback signal, adjusts to control the magnitude of voltage of described power supply circuits to described first power supply output and described second power supply output.
7. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 6, is characterized in that, in the power circuit of described front end, described feedback circuit is also provided with optocoupler (PCB101), pressurizer (UB102);
Described optocoupler (PCB101) comprises the light-emitting diode being positioned at former limit and the optical signal converter being positioned at secondary;
The control signal that described control signal input inputs is accessed to the light-emitting diode being positioned at former limit of described optocoupler (PCB101) by described pressurizer (UB102); Described light-emitting diode is passed to the optical signal converter being positioned at secondary of described optocoupler (PCB101) after control signal is converted to light signal; Described optical signal converter exports described feedback signal output to after light signal is converted to the signal of telecommunication.
8. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 7, it is characterized in that, described pressurizer (UB102) adopts adjustable precision shunt pressurizer, comprise negative electrode (K), anode (A) and reference input (R), and in have reference voltage;
Wherein, anode (A) ground connection of described adjustable precision shunt pressurizer, negative electrode (K) is connected with the light-emitting diode being positioned at former limit of described optocoupler (PCB101); Reference input (R) is for accessing the control signal of described control signal input.
9. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 8, is characterized in that, described feedback circuit is also provided with voltage stabilizing feedback circuit.
10. the voltage stabilizing backlight control circuit of low-power consumption as claimed in claim 9, is characterized in that, described voltage stabilizing feedback circuit comprises electric capacity (CB109) and resistance (RB133);
One end of described electric capacity (CB109) is connected on the negative electrode (K) of described adjustable precision shunt pressurizer, and the other end is connected with the one end of resistance (RB133); The other end of resistance (RB133) is connected on the reference input (R) of described adjustable precision shunt pressurizer.
The voltage stabilizing backlight control circuit of 11. low-power consumption as claimed in claim 9, it is characterized in that, described voltage stabilizing feedback circuit comprises electric capacity (CB110);
One end of described electric capacity (CB110) is connected on the negative electrode (K) of described adjustable precision shunt pressurizer, and the other end is connected on the reference input (R) of described adjustable precision shunt pressurizer.
The voltage stabilizing backlight control circuit of 12. low-power consumption as claimed in claim 9, it is characterized in that, described voltage stabilizing feedback circuit comprises electric capacity (CB109), resistance (RB133) and electric capacity (CB110);
One end of described electric capacity (CB109) is connected on the negative electrode (K) of described adjustable precision shunt pressurizer, and the other end is connected with the one end of resistance (RB133); The other end of resistance (RB133) is connected on the reference input (R) of described adjustable precision shunt pressurizer;
One end of described electric capacity (CB110) is connected on the negative electrode (K) of described adjustable precision shunt pressurizer, and the other end is connected on the reference input (R) of described adjustable precision shunt pressurizer.
The voltage stabilizing backlight control circuit of 13. low-power consumption as claimed in claim 9, it is characterized in that, described feedback circuit is also provided with resistance (RB131) and resistance (RB132);
One end of described resistance (RB131) is described feedback input end, and the other end is connected with the anode being positioned at the light-emitting diode on former limit of optocoupler (PCB101); One end of described resistance (RB132) is connected to the anode of described light-emitting diode, and the other end is connected on the negative electrode of described light-emitting diode.
The voltage stabilizing backlight control circuit of 14. low-power consumption as claimed in claim 9, it is characterized in that, the reference input (R) of described adjustable precision shunt pressurizer is connected with described control signal input by a voltage divider.
The voltage stabilizing backlight control circuit of 15. low-power consumption as claimed in claim 14, it is characterized in that, described voltage divider is a resistance (RB150).
The voltage stabilizing backlight control circuit of 16. low-power consumption as claimed in claim 7, it is characterized in that, be also provided with comparison circuit in linear constant-current circuit in the rear, described comparison circuit is provided with reference signal input, to access constant current reference voltage;
Described comparison circuit is also provided with operational amplifier, and the inverting input of described operational amplifier is connected with described reference signal input by a resistance (RB12); The normal phase input end of described operational amplifier is connected with current feedback circuit.
The voltage stabilizing backlight control circuit of 17. low-power consumption as claimed in claim 16, it is characterized in that, described current feedback circuit comprises multiple constant current and detects resistance, is respectively resistance (RB5), resistance (RB6), resistance (RB7), resistance (RB8), resistance (RB9);
Wherein, resistance (RB6), resistance (RB7), resistance (RB8) and resistance (RB9) form parallel circuits, one end of described parallel circuits is connected on one end of resistance (RB5), the other end ground connection of described parallel circuits; The other end of resistance (RB5) is connected on the normal phase input end of described operational amplifier.
The voltage stabilizing backlight control circuit of 18. low-power consumption as claimed in claim 17, it is characterized in that, described current feedback circuit also comprises electric capacity (CB5); One end ground connection of described electric capacity (CB5), the other end is connected on the normal phase input end of described operational amplifier.
The voltage stabilizing backlight control circuit of 19. low-power consumption as claimed in claim 16, it is characterized in that, described comparison circuit also comprises a clamp diode;
The minus earth of described clamp diode; The anode of described clamp diode is connected with described switching tube (QB1), comprising: when described switching tube (QB1) is for triode, the anode of described clamp diode is connected with the emitter of described triode; When described switching tube (QB1) is for field-effect transistor, the anode of described clamp diode is connected with the source electrode of described field-effect transistor.
The voltage stabilizing backlight control circuit of 20. low-power consumption as claimed in claim 16, is characterized in that, also comprise a control master chip;
Described control master chip is connected respectively with described control signal input, described reference signal input and described voltage acquisition output;
Described control master chip, according to the change in voltage of described voltage acquisition output, adjusts the output to the signal magnitude of described control signal input, to control the first power supply output of described front end power circuit, the output voltage values of the second power supply output; And input described constant current reference voltage by described reference signal input to described rear end linear constant current circuit.
The voltage stabilizing backlight control circuit of 21. low-power consumption as claimed in claim 20, it is characterized in that, when described control master chip detects that the voltage difference of described voltage acquisition output and described reference signal input is greater than default threshold value, the voltage signal duty ratio exporting described control signal input to reduces by described control master chip.
The voltage stabilizing backlight control circuit of 22. low-power consumption as claimed in claim 21, is characterized in that, described power supply circuits comprise power supply input circuit, switching power circuit, multiple-channel output transformer, LED power output circuit and main board power supply output circuit;
The power supply signal of access is transferred to described multiple-channel output transformer by described power supply input circuit under the control of described switching power circuit;
Described multiple-channel output transformer comprises main winding and auxiliary winding; Described main winding transfers to described main board power supply output circuit by after described power supply signal transformation, and is exported by described second power supply output; Described auxiliary winding to be powered transferring to described LED after synchronous for described power supply signal transformation output circuit, and is exported by described first power supply output; The coil ratio of described main winding and described auxiliary winding is 1:N, N > 0.
The voltage stabilizing backlight control circuit of 23. low-power consumption as claimed in claim 1, is characterized in that, described DC-DC voltage regulator circuit is boosting regulating circuit or reduction regulation circuit.
The television set that 24. 1 kinds of adaptation power supplies regulate, is characterized in that, comprising: TV SKD, backlight LED light string, and the voltage stabilizing backlight control circuit of low-power consumption as described in any one of claim 1 ~ 23;
Described voltage stabilizing backlight control circuit is connected respectively with described TV SKD and described backlight LED light string, for when turning on the power supply of described television set, according to the operating voltage of described backlight LED light string, Automatic adjusument supplies the voltage signal of described TV SKD, described backlight LED light string; When closing the power supply of described television set, turn off the electric current flowing through described backlight LED light string.
CN201410476693.1A 2014-09-17 2014-09-17 The voltage stabilizing backlight control circuit and television set of a kind of low-power consumption Active CN104253960B (en)

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