CN211859717U

CN211859717U - Power supply control circuit and television

Info

Publication number: CN211859717U
Application number: CN202020717133.1U
Authority: CN
Inventors: 郭军; 钟振亮
Original assignee: Shenzhen Dingsheng Photoelectric Co ltd
Current assignee: Shenzhen Dingsheng Photoelectric Co ltd
Priority date: 2020-04-30
Filing date: 2020-04-30
Publication date: 2020-11-03
Anticipated expiration: 2030-04-30

Abstract

A starting circuit works when receiving a starting instruction, converts a first power supply signal into a switch control signal and outputs the switch control signal to a first switch circuit to enable the first switch circuit to work. When the first switch circuit works, the second power supply signal is transmitted to the PFC circuit and the second switch circuit, and the PFC circuit is powered on to work. The voltage division circuit samples the direct current working voltage output by the PFC circuit, and the second switch circuit works only when the sampling voltage reaches a preset threshold value, so that the received second power supply signal is output to the flyback backlight driving circuit to control the flyback backlight driving circuit to work. Through the power supply control circuit, the flyback backlight driving circuit is powered on to work only when the PFC circuit works normally, otherwise, when the PFC circuit breaks down, if the direct-current working voltage cannot be output or cannot climb to a target value, the second switching circuit cannot work, and therefore the TV power supply is guaranteed to work only in a normal PF value range, and safety is high.

Description

Power supply control circuit and television

Technical Field

The application belongs to the technical field of TV (Television) power supply control, and particularly relates to a power supply control circuit and a Television.

Background

The topological structure of the TV Power supply mainly comprises a PFC (Power Factor Correction), a flyback backlight driving circuit and a Power supply control circuit. At present, when a traditional power control circuit receives a starting signal, the traditional power control circuit controls a PFC circuit to work, a capacitor of the traditional power control circuit slowly charges, and when the capacitor finishes charging, the flyback backlight driving circuit is controlled to work, so that after the PFC circuit works normally, a certain time is delayed, and the flyback backlight driving circuit works again. However, the control processes of the conventional Power control circuit for the PFC circuit and the flyback backlight driving circuit are independent from each other, and when the PFC circuit fails, the Power control circuit still controls the flyback backlight circuit to operate after a certain time delay, which results in a low PF (Power Factor) value of the TV Power supply, and is liable to damage a Power device inside the TV Power supply.

Therefore, in the conventional power control technical scheme, when the control processes of the PFC circuit and the flyback backlight driving circuit are independent to each other and the PFC circuit fails, the power control circuit still controls the flyback backlight circuit to operate after a certain time delay, which causes a problem that the PF value of the TV power supply is low and a power device inside the TV power supply is easily damaged.

SUMMERY OF THE UTILITY MODEL

The application aims to provide a Power supply control circuit and a television, and aims to solve the problems that when the control processes of a PFC circuit and a flyback backlight driving circuit are mutually independent and the PFC circuit fails, the Power supply control circuit still controls the flyback backlight circuit to work after a certain time delay, so that the PF (Power Factor) value of the TV Power supply is low, and a Power device in the TV Power supply is easily damaged.

The first aspect of the embodiment of the present application provides a power control circuit for be connected with power supply circuit, PFC circuit and flyback backlight drive circuit, power supply circuit is used for exporting first power supply signal and second power supply signal, the PFC circuit is used for obtaining direct current operating voltage and export after carrying out rectification and vary voltage processing with the commercial power, and its characterized in that, power control circuit includes:

the starting circuit is connected with the power supply circuit, is configured to work when receiving a starting instruction, and converts the first power supply signal into a switch control signal and then outputs the switch control signal;

the first switch circuit is connected with the starting circuit, the power supply circuit and the PFC circuit and is configured to be conducted when receiving the switch control signal so as to transmit the second power supply signal and control the PFC circuit to work;

the voltage division circuit is connected with the PFC circuit and is configured to receive the direct-current working voltage, divide the direct-current working voltage to obtain a sampling voltage and output the sampling voltage; and

and the second switch circuit is connected with the voltage division circuit, the flyback backlight driving circuit and the first switch circuit and is configured to be conducted when the sampling voltage reaches a preset threshold value, so that the second power supply signal output by the first switch circuit is transmitted to the flyback backlight driving circuit and the flyback backlight driving circuit is controlled to work.

Specifically, the dc working voltage output by the PFC circuit has a climbing process, that is, the dc working voltage continuously rises during the voltage transformation process, and the voltage dividing circuit continuously samples the dc working voltage until the sampling voltage reaches a preset threshold, and the second switching circuit does not operate. When the PFC circuit fails, the dc working voltage may not be output, or the output dc working voltage may not climb to a target value, so that the sampling voltage may not reach the preset threshold all the time, and under these circumstances, the second switching circuit may not operate, so that the flyback backlight driving circuit may not operate.

A second aspect of the embodiments of the present application provides a television, including a backlight panel, further including:

a power supply circuit configured to output a first power supply signal and a second power supply signal;

the PFC circuit is configured to rectify and transform the mains supply to obtain direct-current working voltage and output the direct-current working voltage;

a flyback backlight driving circuit configured to drive the backlight plate to operate;

a master control circuit configured to output a start instruction; and

the power supply control circuit is provided.

Compared with the prior art, the embodiment of the utility model beneficial effect who exists is: according to the power control circuit and the television, the voltage division circuit and the second switch circuit work in a matched mode, the voltage division circuit samples the direct-current working voltage output by the PFC circuit, and only when the sampled voltage reaches the preset threshold value, the second switch circuit works to output the second power supply signal to the flyback backlight driving circuit, so that the flyback backlight driving circuit works. Therefore, the flyback backlight driving circuit can be powered to work only when the PFC circuit works normally, otherwise, when the PFC circuit breaks down, if the direct-current working voltage cannot be output or cannot climb to a target value, the second switching circuit cannot work, and therefore the TV power supply can only work within a normal PF value range, and safety is high.

Drawings

Fig. 1 is a schematic block diagram of a power control circuit according to an embodiment of the present disclosure;

fig. 2 is a schematic block diagram of a power control circuit according to an embodiment of the present disclosure;

fig. 3 is an exemplary circuit schematic of the power control circuit shown in fig. 2.

Detailed Description

In order to make the technical problems, technical solutions and advantageous effects to be solved by the present application clearer, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the present application and are not intended to limit the present application.

It should be noted that the terms "first" and "second" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present application, "a plurality" means two or more unless specifically limited otherwise.

Fig. 1 is a schematic block diagram of a power control circuit 100 according to an embodiment of the present disclosure, which only shows parts related to the embodiment for convenience of description, and the details are as follows:

a power control circuit 100 is used for being connected with a power supply circuit 200, a PFC circuit 300 and a flyback backlight driving circuit 400, wherein the power supply circuit 200 is used for outputting a first power supply signal and a second power supply signal VCC1, and the PFC circuit 300 is used for rectifying and transforming mains supply to obtain direct-current working voltage and outputting the direct-current working voltage.

The power control circuit 100 includes a start circuit 10, a first switch circuit 20, a voltage dividing circuit 30, and a second switch circuit 40.

The start circuit 10 is connected to the power supply circuit 200, the first switch circuit 20 is connected to the start circuit 10, the power supply circuit 200 and the PFC circuit 300, the voltage dividing circuit 30 is connected to the PFC circuit 300, and the second switch circuit 40 is connected to the voltage dividing circuit 30, the flyback backlight driving circuit 400 and the first switch circuit 20.

The start circuit 10 is configured to operate when receiving the start instruction BK, and convert the first power supply signal into the switch control signal and output the switch control signal.

Specifically, the first power supply signal is a 12V dc signal. The conversion process of the starting circuit 10 to the first power supply signal is an electrical-optical-electrical process, that is, the first power supply signal is converted into an optical signal for transmission, the optical signal is converted into an electrical signal again and then output, and the output electrical signal is a switch control signal.

The first switching circuit 20 is configured to operate upon receiving the switching control signal, transmit the second power supply signal VCC1, and control the PFC circuit 300 to operate.

Specifically, the first switch circuit 20 transmits the second power supply signal VCC1 to the PFC circuit 300 and the second switch circuit 40, the PFC circuit operates after receiving the second power supply signal VCC1, and the second switch circuit 40 transmits the received second power supply signal VCC1 to the flyback backlight driving circuit 400 when operating, so as to control the flyback backlight driving circuit 400 to operate.

The voltage dividing circuit 30 is configured to receive the dc working voltage, divide the dc working voltage to obtain a sampling voltage, and output the sampling voltage.

Specifically, in the actual working process, the ratio of the sampling voltage to the dc voltage can be changed by setting the characteristic parameters of the internal components of the voltage divider circuit 30.

The dc working voltage output by the PFC circuit 300 has a climbing process, that is, the dc working voltage continuously rises during the transformation process, and the voltage dividing circuit 30 continuously samples the dc working voltage until the sampled voltage reaches the preset threshold, and the second switching circuit 40 does not operate. When the PFC circuit 300 fails, the dc working voltage may not be output, or the output dc working voltage may not climb to a target value, so that the sampling voltage may not reach the preset threshold all the time, and under these circumstances, the second switch circuit 40 may not operate, so that the flyback backlight driving circuit 400 may not operate.

Meanwhile, the power control circuit 100 provided in this embodiment skillfully utilizes the process of the dc working voltage climbing as a method for controlling the flyback backlight driving circuit 400 to operate in a delayed manner, so that after the PFC circuit 300 operates in a power receiving manner, the second switching circuit 40 is turned on to operate only when the dc working voltage climbs to a target value, thereby controlling the flyback backlight driving circuit 400 to operate.

The second switch circuit 40 is configured to operate when the sampled voltage reaches a preset threshold, receive the second power supply signal VCC1 transmitted by the first switch circuit 20 to the flyback backlight driving circuit 400, and control the flyback backlight driving circuit 400 to operate.

Specifically, the specific value of the preset threshold value can be adjusted according to actual needs, and the specific adjustment mode is realized by changing the characteristic parameters of the internal components of the divider resistor.

Through the power control circuit 100, the flyback backlight driving circuit 400 is powered on to work only when the PFC circuit 300 normally works, otherwise, when the PFC circuit 300 fails, if the dc working voltage cannot be output or cannot climb to a target value, the second switch circuit 40 cannot work, so that it is ensured that the TV power supply only works in a normal PF value range, that is, more than 0.9, and interference to the power grid is avoided, and the problems of explosion and the like caused by damage of long-time high-temperature work of a power device on a live wire and a power device in the flyback backlight driving circuit due to a low PF value when low-voltage commercial power is input are avoided, and the safety is high.

Fig. 2 is a schematic block diagram of another power control circuit 100 according to an embodiment of the present disclosure, which only shows parts related to the embodiment for convenience of description, and the details are as follows:

in an alternative embodiment, the power control circuit 100 further includes a first filter circuit 50. In another alternative embodiment, the power control circuit 100 further includes a second filter circuit 60.

The first filter circuit 50 is connected to the first switch circuit 20 and the start circuit 10. The second filter circuit 60 is connected to the first switch circuit 20 and the second switch circuit 40.

The first filter circuit 50 is configured to filter and stabilize the switching control signal and output the filtered switching control signal to the first switch circuit 20. The second filter circuit 60 is configured to filter the second power supply signal VCC1 transmitted by the first switch circuit 20 and output the filtered second power supply signal VCC1 to the second switch circuit 40.

Specifically, the switch control signal is filtered by the first filter circuit 50, and then the high-frequency interference signal is filtered; the second power supply signal VCC1 is processed by the second filter circuit 60 to filter out high frequency interference signals therein. By providing the first filter circuit 50 and the second filter circuit 60, safety is further improved.

Fig. 3 is a schematic diagram of an exemplary circuit of the power control circuit 100 shown in fig. 2, which only shows the relevant parts of the present embodiment for convenience of explanation, and the details are as follows:

in an optional embodiment, the starting circuit 10 includes a first resistor SR1, a second resistor SR2, a third resistor SR3, a first capacitor SC1, a first switch tube SQ1, and an optical coupler PU 2. The optocoupler PU2 includes a light emitting diode and a phototransistor inside.

A first end of the first resistor SR1 is connected to the power supply circuit 200, and a second end of the first resistor SR1 is connected to the anode of the light emitting diode; a first end of the second resistor SR2 is connected with a start instruction BK, a second end of the second resistor SR2, a first end of the third resistor SR3, a first end of the first capacitor SC1 and a controlled end of the first switch tube SQ1 are connected in common, an input end of the first switch tube SQ1 is connected with a cathode of the light emitting diode, and an output end of the first switch tube SQ1 is grounded; the collector and emitter of the phototransistor are both connected to a first switching circuit 20.

Specifically, the start instruction BK is a high-level signal, the high-level signal is transmitted to the controlled end of the first switch tube SQ1 through the second resistor SR2, and the first switch tube SQ1 is controlled to be turned on, so that the first power supply signal is transmitted to the light emitting diode inside the optocoupler PU2 through the first resistor SR1, and the first power supply signal is converted into an optical signal inside the optocoupler PU2 and is converted into a switch control signal to be output after being received by the phototriode.

The optocoupler PU2 isolates the first switch circuit 20 from a circuit outputting a start instruction BK, mutual influence between a circuit at the front end and a circuit at the rear end is avoided, and the overall stability and safety of the power control circuit 100 are improved.

Optionally, the first switch tube SQ1 is implemented by using an NPN triode, and the controlled terminal, the input terminal, and the output terminal of the first switch tube SQ1 are a base, a collector, and an emitter of the NPN triode, respectively. The first capacitor SC1 and the third resistor SR3 form a filter loop for filtering the start command BK.

In an alternative embodiment, the first switch circuit 20 includes a fourth resistor PR11, a fifth resistor PR10, a first diode PD2, a second diode PD1, and a second switch tube PQ 2.

A first end of the fourth resistor PR11 and a controlled end of the second switching tube PQ2 are both connected to the starting circuit 10, and a second end of the second switching tube PQ2 is used for receiving a switching control signal; a node where the second end of the fourth resistor PR11, the cathode of the first diode PD2 and the input end of the second diode PD2 are connected to the power supply circuit 200, and a node where the anode of the first diode PD2, the output end of the second diode PD2 and the anode of the second diode PD1 are connected to the second switch circuit 40; the cathode of the second diode PD1 is connected to the first terminal of the fifth resistor PR10, and the second terminal of the fifth resistor PR10 is connected to the power supply terminal PFC _ VCC of the PFC circuit 300.

Specifically, a first end of the fourth resistor PR11 is connected to a collector of a phototransistor inside the optocoupler PU2, a controlled end of the second switching tube PQ2 is connected to an emitter of the phototransistor, and a switching control signal is transmitted to the controlled end of the second switching tube PQ2 through the emitter of the phototransistor, so as to control the conduction of the second switching tube PQ 2.

After the second switching tube PQ2 is turned on, the second power supply voltage is transmitted to the output terminal of the second switching tube PQ2, the anode of the second diode PD1, the cathode of the second diode PD1, the first end of the fifth resistor PR10, and the second end of the fifth resistor PR10 via the input terminal of the second switching tube PQ2, and is finally transmitted to the power supply terminal PFC _ VCC of the PFC circuit 300, so that the PFC circuit 300 receives power for operation.

The first diode PD2 is used to prevent current from flowing backward, and the first diode PD2 is connected in parallel between the input terminal and the output terminal of the second switch tube PQ2 by using the unidirectional conduction characteristic of the diode, and the cathode of the first diode PD2 is connected to the power supply circuit 200, thereby preventing the current from flowing backward into the power supply circuit 200 and damaging the power supply circuit 200. Similarly, the second diode PD1 also plays a role of preventing backflow.

Optionally, the second switching tube PQ2 is implemented by an NPN triode, and the controlled end, the input end, and the output end of the second switching tube PQ2 are a base, a collector, and an emitter of the NPN triode, respectively.

In an alternative embodiment, the voltage divider circuit 30 includes a sixth resistor PR2, a seventh resistor PR3, an eighth resistor PR4, and a ninth resistor PR 6.

The first end of the sixth resistor PR2 is connected with a direct-current working voltage, the second end of the sixth resistor PR2 is connected with the first end of the seventh resistor PR3 in a common mode, the second end of the seventh resistor PR3 is connected with the first end of the eighth resistor PR4 in a common mode, a node, connected with the first end of the ninth resistor PR6 in a common mode, of the second end of the eighth resistor PR4 is connected with the second switch circuit 40, and the second end of the ninth resistor PR6 is connected with the ground.

The direct-current working voltage is input to a first end of the sixth resistor PR2 from a 400V port of the PFC circuit 300; it should be noted that the 400V port does not represent that the output dc operating voltage is 400V, but is an output port of a power grid in the voltage transformation unit inside the PFC circuit 300.

The conversion formula between the direct current working voltage and the sampling voltage is as follows:

where Vin is the value of the dc working voltage, and Vsm is the value of the sampling voltage.

Optionally, the resistances of the sixth resistor PR2, the seventh resistor PR3, the eighth resistor PR4, and the ninth resistor PR6 are set to 2000K Ω, and 47K Ω, respectively, so that the conversion formula between the dc working voltage and the sampling voltage is:

In actual operation, the resistances of the sixth resistor PR2, the seventh resistor PR3, the eighth resistor PR4 and the ninth resistor PR6 can be adjusted according to actual needs, so as to change the ratio coefficient of the dc operating voltage to the sampling voltage.

In an alternative embodiment, the second switch circuit 40 includes a tenth resistor PR5, an eleventh resistor PR7, a twelfth resistor PR1, a second capacitor PC1, a third switch tube PQ1, and a voltage reference chip PU 1.

The first end of the second capacitor PC1, the first end of the tenth resistor PR5 and the reference end of the voltage reference chip PU1 are connected in common; a second end of the second capacitor PC1 is grounded with an anode end of the voltage reference chip PU 1; the cathode end of the voltage reference chip PU1 is connected with the first end of the eleventh resistor PR7, and the second end of the eleventh resistor PR7 is connected with the controlled end of the third switching tube PQ 1; an input end of the third switching tube PQ1 is connected to the first switching circuit 20, an output end of the third switching tube PQ1, a second end of the tenth resistor PR5 and a first end of the twelfth resistor PR1 are commonly connected, and a second end of the twelfth resistor PR1 is connected to the flyback backlight driving circuit 400.

Specifically, the reference terminal of the voltage reference chip PU1 is connected to the second terminal of the eighth resistor PR 4. The voltage reference chip PU1 is model AZ431, and the cathode terminal and the anode terminal of the voltage reference chip PU1 are turned on only when the voltage value of the reference terminal reaches the reference value. The reference value was 2.5V. Since the sampling voltage of the voltage divider circuit 30 is output to the reference terminal of the voltage reference chip PU1, when the sampling voltage is 2.5V, the cathode terminal and the anode terminal of the voltage reference chip PU1 are turned on, so that the controlled terminal of the third switching tube PQ1 is pulled down by the eleventh resistor PR7, and the third switching tube PQ1 is turned on.

Taking the resistance values of the sixth resistor PR2, the seventh resistor PR3, the eighth resistor PR4 and the ninth resistor PR6 as 2000K Ω, 2000K Ω and 47K Ω respectively, and the reference value is 2.5V as an example, it can be known through calculation that the dc working voltage

The cathode terminal and the anode terminal of the voltage reference chip PU1 are turned on. If the PFC circuit 300 is abnormal, no dc operating voltage may be output, or the output dc operating voltage may not reach 321.6V when it climbs to the maximum value, so that the second switching circuit 40 may not be operated.

After the third switching tube PQ1 is turned on, the second power supply signal VCC1 is finally output to the power supply terminal LED _ VCC of the flyback backlight driving circuit 400 through the input terminal of the second switching tube PQ2, the output terminal of the second switching tube PQ2, the input terminal of the third switching tube PQ1, the output terminal of the third switching tube PQ1, the first terminal of the twelfth resistor PR1, and the second terminal of the twelfth resistor PR1, and the flyback backlight driving circuit 400 starts to operate when receiving power.

Optionally, the third switching tube PQ1 is implemented by a PNP triode, and the controlled end, the input end, and the output end of the third switching tube PQ1 are respectively a base, an emitter, and a collector of the PNP triode.

In an alternative embodiment, the first filter circuit 50 includes a zener diode PZ1, a thirteenth resistor PR12, and a third capacitor PC 4.

A node where the first end of the third capacitor PC4, the first end of the thirteenth resistor PR12 and the cathode of the zener diode PZ1 are connected together is connected with the controlled end of the second switching tube PQ 2; the second terminal of the third capacitor PC4, the second terminal of the thirteenth resistor PR12, and the anode of the zener diode PZ1 are grounded.

Specifically, the third capacitor PC4 and the thirteenth resistor PR12 form a filtering loop, and filter a switch control signal output by the optocoupler PU 2.

In an alternative embodiment, the second filter circuit 60 includes a fourteenth resistor PR8, a fifteenth resistor PR9, a fourth capacitor PC2, and a fifth capacitor PC 3.

The first end of the fourth capacitor PC2, the first end of the fourteenth resistor PR8, the first end of the fifth capacitor PC3, the first end of the fifteenth resistor PR9 and the input end of the third switching tube PQ1 are connected in common; the second end of the fourth capacitor PC2, the second end of the fourteenth resistor PR8 and the controlled end of the third switching tube PQ1 are connected in common; the second terminal of the fifth capacitor PC3, the second terminal of the fifteenth resistor PR9 and the cathode terminal of the voltage reference chip PU1 are connected in common.

Specifically, the fourth capacitor PC2 and the fourteenth resistor PR8 form a filter loop, the fifth capacitor PC3 and the fifteenth resistor PR9 form another filter loop, and the second power supply signal VCC1 is filtered by the two filter loops and then transmitted to the emitter of the third switching tube PQ1, so that the flyback backlight driving circuit 400 at the rear end is prevented from being damaged by a high-frequency interference signal.

A second aspect of the embodiment of the present application provides a television, which includes a backlight panel, and further includes a power supply circuit 200, a PFC circuit 300, a flyback backlight driving circuit 400, and a main control circuit.

The power control circuit 100 is connected to the power supply circuit 200, the PFC circuit 300, the flyback backlight driving circuit 400, and the main control circuit.

The power supply circuit 200 is configured to output a first power supply signal and a second power supply signal VCC 1.

The PFC circuit 300 is configured to rectify and transform the commercial power to obtain a dc operating voltage and output the dc operating voltage. Specifically, in the voltage transformation process, the dc working voltage climbs according to a certain rate of increase, and if the dc working voltage still cannot reach the target value when climbing to the maximum value, the sampling voltage sampled by the voltage dividing circuit 30 in the power control circuit 100 cannot reach the preset threshold, and the second switch circuit 40 is not turned on, so that the flyback backlight driving circuit 400 does not operate.

The flyback backlight driving circuit 400 is configured to drive the backlight panel to operate.

The master control circuit is configured to output a start instruction BK, which is a high level signal. Optionally, the main control circuit is implemented by using a secondary chip of a secondary side of a transformer in a TV power supply of the TV set.

To sum up, the application provides a power control circuit and a television, realizes only when the PFC circuit normally works, and the flyback backlight drive circuit just receives the electric work, otherwise, when the PFC circuit breaks down, if unable output direct current operating voltage, perhaps direct current operating voltage fails to climb to the target value, the unable work of second switch circuit to guarantee that the TV power only works in normal PF value scope, the security is high.

In the embodiments provided in the present application, it should be understood that the disclosed apparatus/terminal device and method may be implemented in other ways. For example, the above-described embodiments of the apparatus/terminal device are merely illustrative, and for example, the division of the modules or units is only one logical division, and there may be other divisions when actually implemented, for example, a plurality of units or components may be combined or integrated into another system, or some features may be omitted, or not executed. In addition, the shown or discussed mutual coupling or direct coupling or communication connection may be an indirect coupling or communication connection through some interfaces, devices or units, and may be in an electrical, mechanical or other form.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present application, and not for limiting the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; such modifications and substitutions do not substantially depart from the spirit and scope of the embodiments of the present application and are intended to be included within the scope of the present application.

Claims

1. A power control circuit is used for being connected with a power supply circuit, a PFC circuit and a flyback backlight drive circuit, wherein the power supply circuit is used for outputting a first power supply signal and a second power supply signal, and the PFC circuit is used for rectifying and transforming mains supply to obtain direct-current working voltage and outputting the direct-current working voltage, and the power control circuit is characterized by comprising:

2. The power control circuit of claim 1, wherein the start-up circuit comprises:

the circuit comprises a first resistor, a second resistor, a third resistor, a first capacitor, a first switch tube and an optocoupler; the optical coupler comprises a light emitting diode and a phototriode;

the first end of the first resistor is connected with the power supply circuit, and the second end of the first resistor is connected with the anode of the light-emitting diode; the first end of the second resistor is connected to the starting instruction, the second end of the second resistor, the first end of the third resistor, the first end of the first capacitor and the controlled end of the first switch tube are connected in common, the input end of the first switch tube is connected with the cathode of the light emitting diode, and the output end of the first switch tube is grounded; and the collector and the emitter of the phototriode are both connected with the first switching circuit.

3. The power supply control circuit of claim 1, wherein the first switching circuit comprises:

the fourth resistor, the fifth resistor, the first diode, the second diode and the second switch tube;

the first end of the fourth resistor and the controlled end of the second switch tube are both connected with the starting circuit, and the second end of the second switch tube is used for receiving the switch control signal; the power supply circuit is connected with a node where the second end of the fourth resistor, the cathode of the first diode and the input end of the second switch tube are connected in common, and a node where the anode of the first diode, the output end of the second switch tube and the anode of the second diode are connected in common is connected with the second switch circuit; the cathode of the second diode is connected with the first end of the fifth resistor, and the second end of the fifth resistor is connected with the PFC circuit.

4. The power supply control circuit of claim 1, wherein the voltage divider circuit comprises:

a sixth resistor, a seventh resistor, an eighth resistor, and a ninth resistor;

the first end of the sixth resistor is connected to the direct-current working voltage, the second end of the sixth resistor and the first end of the seventh resistor are connected in common, the second end of the seventh resistor and the first end of the eighth resistor are connected in common, a node where the second end of the eighth resistor and the first end of the ninth resistor are connected in common is connected to the second switch circuit, and the second end of the ninth resistor is grounded.

5. The power supply control circuit of claim 1, wherein the second switching circuit comprises:

the voltage reference circuit comprises a tenth resistor, an eleventh resistor, a twelfth resistor, a second capacitor, a third switching tube and a voltage reference chip;

the first end of the second capacitor, the first end of the tenth resistor and the reference end of the voltage reference chip are connected in common; the second end of the second capacitor is grounded with the anode end of the voltage reference chip; the cathode end of the voltage reference chip is connected with the first end of the eleventh resistor in common, and the second end of the eleventh resistor is connected with the controlled end of the third switching tube; the input end of the third switching tube is connected with the first switching circuit, the output end of the third switching tube, the second end of the tenth resistor and the first end of the twelfth resistor are connected in common, and the second end of the twelfth resistor is connected with the flyback backlight driving circuit.

6. The power control circuit of claim 3, further comprising:

and the first filter circuit is connected with the first switch circuit and the starting circuit and is configured to output the switch control signal to the first switch circuit after filtering processing and voltage stabilization processing are carried out on the switch control signal.

7. The power control circuit of claim 5, further comprising:

and the second filter circuit is connected with the first switch circuit and the second switch circuit and is configured to filter the second power supply signal transmitted by the first switch circuit and output the second power supply signal to the second switch circuit.

8. The power control circuit of claim 6, wherein the first filter circuit comprises:

a voltage stabilizing diode, a thirteenth resistor and a third capacitor;

a node where the first end of the third capacitor, the first end of the thirteenth resistor and the cathode of the voltage stabilizing diode are connected in common is connected with the controlled end of the second switching tube; and the second end of the third capacitor, the second end of the thirteenth resistor and the anode of the voltage stabilizing diode are grounded.

9. The power control circuit of claim 7, wherein the second filter circuit comprises:

a fourteenth resistor, a fifteenth resistor, a fourth capacitor and a fifth capacitor;

a first end of the fourth capacitor, a first end of the fourteenth resistor, a first end of the fifth capacitor, a first end of the fifteenth resistor and an input end of the third switching tube are connected in common; a second end of the fourth capacitor, a second end of the fourteenth resistor and a controlled end of the third switching tube are connected in common; the second end of the fifth capacitor, the second end of the fifteenth resistor and the cathode end of the voltage reference chip are connected in common.

10. A television set comprises a backlight plate and is characterized by further comprising:

a master control circuit configured to output a start instruction; and

a power control circuit as claimed in any one of claims 1 to 9.