CN111565290A

CN111565290A - LED power supply overvoltage protection circuit, LED drive power supply circuit and television

Info

Publication number: CN111565290A
Application number: CN202010473872.5A
Authority: CN
Inventors: 桂远斌
Original assignee: Shenzhen Dingsheng Photoelectric Co ltd
Current assignee: Shenzhen Dingsheng Photoelectric Co ltd
Priority date: 2020-05-29
Filing date: 2020-05-29
Publication date: 2020-08-21

Abstract

An LED power supply overvoltage protection circuit, an LED drive power supply circuit and a television are provided, wherein the LED power supply overvoltage protection circuit detects a drive voltage output by the LED power supply circuit through a first voltage detection circuit to generate a first voltage detection signal; the primary protection trigger circuit is conducted to generate a first protection trigger signal when the first voltage detection signal is larger than a first preset reference voltage value; the switch circuit closes the LED power supply circuit according to the first protection trigger signal, the LED power supply circuit is turned off in time when the driving voltage is overvoltage, an overvoltage protection mechanism is started on a power chip and a related circuit module in the LED power supply circuit, potential safety hazards of explosion, spark emission and the like caused by overvoltage of the LED power supply circuit on the TV plate are reduced, the safety reliability of the LED power supply circuit of the TV plate is improved, the safety performance of the TV plate is also improved, the maintenance cost and the replacement cost of the TV plate are reduced, and the safety reliability and the practicability of the LED power supply overvoltage protection circuit are high.

Description

LED power supply overvoltage protection circuit, LED drive power supply circuit and television

Technical Field

The application belongs to the technical field of power supplies, and particularly relates to an LED power supply overvoltage protection circuit, an LED driving power supply circuit and a television.

Background

At present, LED power modules of traditional TV integrated circuit boards all correspond to a certain overvoltage protection mechanism, and when overvoltage appears in the output of the LED power modules, the LED power modules on the TV integrated circuit boards can be triggered to perform overvoltage protection, so that the output voltage is fixed, the LED power modules can be protected, and meanwhile, the safety of the whole TV set is improved.

The performance in the aspect of use safety needs to be continuously improved regardless of the independent power supply board card or the TV complete machine. In a traditional design scheme, when the LED power module outputs overvoltage, a chip starting protection mechanism in the LED power module can only be guaranteed, the LED power module is protected to a certain extent, but other related modules on the TV board card cannot be timely started, so that other modules related to the LED power module on the TV board card are possibly damaged, and even the whole TV set safety hazard can be caused to a great extent. In a TV complete machine, the situation of overvoltage of voltage output by an LED power supply module can occur in different links and different occasions, so that potential safety hazards of electricity utilization such as explosion, spark and the like of other modules on a TV board card can occur; and once overvoltage abnormity occurs, a plurality of modules on the TV board card need to be maintained or replaced simultaneously, the inventory of the TV board card is increased, and the maintenance and replacement cost of the TV board card is high.

Therefore, the traditional overvoltage protection scheme for the LED power supply of the TV board card has the problems that only the overvoltage protection can be performed on the LED power supply module, and other related modules on the TV board card cannot be started in time to start an overvoltage protection mechanism, so that certain potential safety hazards exist, the safety and reliability are low, and the maintenance and replacement cost of the TV board card is high.

Disclosure of Invention

An object of the application is to provide an LED power supply overvoltage protection circuit, an LED drive power supply circuit and a television, and aims to solve the problems that the traditional TV board card LED power supply overvoltage protection scheme can only play overvoltage protection for an LED power supply module and can not timely enable other relevant modules on a TV board card to start an overvoltage protection mechanism, so that certain potential safety hazards exist, the safety and reliability are low, and the TV board card is high in maintenance and replacement cost.

The first aspect of the embodiment of the present application provides an LED power supply overvoltage protection circuit, which is connected to an LED power supply circuit, and the LED power supply overvoltage protection circuit includes:

the first voltage detection circuit is connected with the LED power supply circuit and is configured to detect the driving voltage output by the LED power supply circuit so as to generate a first voltage detection signal;

the primary protection trigger circuit is connected with the first voltage detection circuit and is configured to be conducted to generate a first protection trigger signal when the first voltage detection signal is larger than a first preset reference voltage value;

and the switch circuit is connected with the primary protection trigger circuit and is configured to close the LED power supply circuit according to the first protection trigger signal.

In one embodiment, the LED power supply overvoltage protection circuit further includes:

a second voltage detection circuit connected to the LED power supply circuit and configured to detect the driving voltage to generate a second voltage detection signal;

and the secondary protection trigger circuit is connected with the second voltage detection circuit and is configured to generate a second protection trigger signal when the second voltage detection signal is greater than a second preset reference voltage value, wherein the second protection trigger signal is used for fixing the driving voltage output by the LED power supply circuit.

In one embodiment, the LED power circuit includes:

a rectification transformation circuit connected with the switching circuit and the secondary protection trigger circuit and configured to generate a first power supply signal according to the input alternating current and the second direct current;

an LED driving circuit connected to the rectifying and transforming circuit, the first voltage detection circuit, and the second voltage detection circuit, and configured to generate the driving voltage according to the first power signal; wherein the rectification transformation circuit is further configured to fix the generated first power supply signal according to the second protection trigger signal.

In one embodiment, the first voltage detection circuit includes: a first resistor and a second resistor; the first end of the first resistor is connected with the LED power circuit, the second end of the first resistor is connected with the first end of the second resistor and the primary protection trigger circuit, and the second end of the second resistor is connected with a power ground.

In one embodiment, the primary protection trigger circuit includes: the controllable switch tube and the first photoelectric coupler; the control end of the controllable switch tube is connected with the first voltage detection circuit, the first end of the controllable switch tube is connected with the cathode of the first photoelectric coupler, the second end of the controllable switch tube is connected with the power ground, the anode of the first photoelectric coupler is connected with the first direct current end, the collector of the first photoelectric coupler is connected with the second direct current end, and the emitter of the first photoelectric coupler is connected with the switch circuit.

In one embodiment, the switching circuit includes: a first triode; the base electrode of the first triode is connected with the primary protection trigger circuit, the collector electrode of the first triode is connected with the second direct current end, and the emitting electrode of the first triode is connected with the LED power circuit.

In one embodiment, the switching circuit further comprises: a self-locking switch circuit; the input end of the self-locking switch circuit is connected with the primary protection trigger circuit, and the output end of the self-locking switch circuit is connected with the base electrode of the first triode.

In one embodiment, the self-locking switch circuit comprises: a second triode and a third triode; the base electrode of the second triode is connected with the collector electrode of the third triode, the emitting electrode of the second triode is connected with the power ground, the collector electrode of the second triode is connected with the base electrode of the third triode, and the emitting electrode of the third triode is connected with the base electrode of the first triode.

A third aspect of the embodiments of the present application provides an LED driving power supply circuit, which includes an LED power supply overvoltage protection circuit as described in any one of the above.

A third aspect of the embodiments of the present application provides a television set, where the television set includes the LED power supply overvoltage protection circuit described in any one of the above and the LED driving power supply circuit described above.

Compared with the prior art, the embodiment of the invention has the following beneficial effects: the LED power supply overvoltage protection circuit detects the driving voltage output by the LED power supply circuit through the first voltage detection circuit to generate a first voltage detection signal; the primary protection trigger circuit is conducted to generate a first protection trigger signal when the first voltage detection signal is larger than a first preset reference voltage value; the switch circuit closes the LED power supply circuit according to the first protection trigger signal, and the LED power supply circuit is turned off in time when the driving voltage is overvoltage, so that a power chip in the LED power supply circuit and a circuit module associated with the power chip all start an overvoltage protection mechanism, potential safety hazards that other circuit modules associated with the power chip on the TV board cannot start the overvoltage protection mechanism in time to cause explosion, sparks and the like are reduced when the overvoltage occurs, the safety and reliability of the LED power supply circuit on the TV board are improved, the safety performance of the TV board is also improved, the maintenance cost and the replacement cost of the TV board due to overvoltage are reduced, and the safety, reliability and practicability of the LED power supply overvoltage protection circuit are high.

Drawings

Fig. 1 is a schematic structural diagram of an overvoltage protection circuit for an LED power supply according to an embodiment of the present disclosure;

fig. 2 is a schematic structural diagram of an overvoltage protection circuit of an LED power supply according to an embodiment of the present disclosure;

fig. 3 is a schematic structural diagram of an overvoltage protection circuit for an LED power supply according to an embodiment of the present disclosure;

fig. 4 is a schematic structural diagram of an overvoltage protection circuit of an LED power supply according to an embodiment of the present application;

FIG. 5 is a schematic diagram of an example circuit of an overvoltage protection circuit for an LED power supply according to an embodiment of the present application;

fig. 6 is another schematic circuit diagram of an example of an overvoltage protection circuit for an LED power supply according to an embodiment of the present application.

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 will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or be indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or be indirectly connected to the other element.

It will be understood that the terms "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," and the like, refer to an orientation or positional relationship illustrated in the drawings for convenience in describing the present application and to simplify description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and thus should not be construed as limiting the present application.

Furthermore, the terms "first", "second" and "first" 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 shows a schematic structural diagram of an overvoltage protection circuit of an LED power supply provided in a first embodiment of the present application, and for convenience of description, only the parts related to this embodiment are shown, which are detailed as follows:

the utility model provides a LED power supply overvoltage crowbar, is connected with LED power supply circuit 01, and LED power supply overvoltage crowbar includes: a first voltage detection circuit 11, a primary protection trigger circuit 12, and a switching circuit 13.

A first voltage detection circuit 11 connected to the LED power supply circuit 01, and configured to detect a driving voltage output by the LED power supply circuit 01 to generate a first voltage detection signal; the primary protection trigger circuit 12 is connected with the first voltage detection circuit 11 and is configured to be conducted to generate a first protection trigger signal when the first voltage detection signal is greater than a first preset reference voltage value; and the switch circuit 13 is connected with the primary protection trigger circuit 12 and is configured to turn off the LED power supply circuit 01 according to the first protection trigger signal.

In specific implementation, optionally, the LED power supply circuit 01 is a driving power supply of the LED light source module, the LED power supply overvoltage protection circuit and the LED power supply circuit 01 can be integrated on the TV board card, and the LED light source module is a backlight source of the TV liquid crystal display screen. The LED power circuit 01 is connected with the LED power overvoltage protection circuit and the LED light source module, and the LED power circuit 01 outputs driving voltage to drive the LED light source module to emit light. Optionally, the LED power circuit 01 includes a power chip and an associated peripheral circuit, and can perform voltage conversion and voltage stabilization on input ac power, such as mains power, to generate a driving voltage to supply power to the LED light source module. The first voltage detection sampling circuit 11 detects a driving voltage output from the LED power circuit 01 to the LED light source module to generate a first voltage detection signal, and outputs the first voltage detection signal to the primary protection trigger circuit 12. When the voltage value corresponding to the first voltage detection signal is compared with a first preset reference voltage value and the first voltage detection signal is smaller than or equal to the first preset reference voltage value, the primary protection trigger circuit 12 does not conduct a first direct current and does not generate a first protection trigger signal, so that the switch circuit 13 keeps conducting a second direct current to the LED power supply circuit 01, and the LED power supply circuit 01 specifically performs voltage conversion, voltage stabilization and other processing on the input alternating current according to the second direct current to generate and output a driving voltage to the LED light source module; when the voltage value corresponding to the first voltage detection signal is greater than the first preset reference voltage value, the primary protection trigger circuit 12 is turned on, so that the first direct current is turned on to generate a first protection trigger signal, the switch circuit 13 is turned off according to the first protection trigger signal, so that the second direct current is turned off, the driving voltage output by the LED power supply circuit is turned off, and the LED light source module does not emit light when the power failure occurs. The second direct current supplies power to the associated peripheral circuit, and the second direct current is turned off to supply power to the peripheral circuit, so that the LED power supply circuit 01 does not output driving voltage according to the condition that the second direct current is not accessed, the second direct current is turned off to stop the power supply chip and the associated peripheral circuit, and overvoltage protection is performed on the power supply chip and the associated circuit in the LED power supply circuit 01. In specific implementation, the second direct current can be turned off to supply power to the peripheral circuit, so that the LED power supply circuit 01 outputs a driving voltage with a small voltage value (for example, close to zero voltage), thereby implementing overvoltage protection on the power chip and the associated circuit in the LED power supply circuit 01.

According to the embodiment of the application, when overvoltage protection can be carried out on the power chip on the TV board card, other related circuit modules on the TV board card are enabled to start an overvoltage protection mechanism, the safety and reliability of a driving power supply of the LED light source module of the TV board card are improved, the risk that other circuit modules on the TV board card explode due to overvoltage and spark is generated is reduced, the safety performance of the TV board card is improved, the maintenance cost and the replacement cost of the TV board card due to overvoltage damage are reduced, and the safety, reliability and practicability of the LED power supply overvoltage protection circuit are high.

In one embodiment, when the primary protection trigger circuit 12 generates the first protection trigger signal to control the switch circuit 13 to turn off the second direct current, the primary protection trigger circuit 12 can also feed back the overvoltage condition of the driving voltage to the power chip of the LED power circuit 01, so that the power chip stops working and stops outputting the driving voltage; or the first voltage detection signal generated correspondingly is fed back to the power chip through the first voltage detection circuit 11, so that the overvoltage condition of the driving voltage is fed back to the power chip, the power chip stops outputting the driving voltage, further, the situation that the related circuit module and the power chip of the power chip start an overvoltage protection mechanism when the driving voltage is overvoltage is further reached, the potential safety hazards such as explosion, spark and the like caused by the fact that other related circuit modules on the TV board card cannot start the overvoltage protection mechanism in time when the driving voltage is overvoltage are reduced, the safety reliability of the LED power circuit of the TV board card is improved, and the reliability and the practicability of the TV board card are also improved.

Referring to fig. 2, in one embodiment, the LED power over-voltage protection circuit includes: a second voltage detection circuit 14 and a secondary protection trigger circuit 15.

A second voltage detection circuit 14 connected to the LED power supply circuit 01, and configured to detect the driving voltage to generate a second voltage detection signal; and the secondary protection trigger circuit 15 is connected to the second voltage detection circuit 14, and is configured to generate a second protection trigger signal according to the second voltage detection signal being greater than a second preset reference voltage value, where the second protection trigger signal is used to fix the driving voltage output by the LED power supply circuit 01.

In specific implementation, when the primary protection trigger circuit 12 fails and does not generate the first protection trigger signal timely and effectively to control the switch circuit 13 to turn off the LED power circuit 01, that is, when the primary protection trigger circuit 12 does not generate the first protection trigger signal timely and effectively to control the switch circuit 13 to cut off the second direct current or does not feed back an overvoltage condition to the power chip timely or the switch circuit 13 fails and fails to effectively cut off the second direct current according to the first protection trigger signal, the driving voltage output by the LED power circuit 01 continuously increases, and the second voltage detection circuit 14 detects the driving voltage to generate the second voltage detection signal. The voltage value of the second voltage detection signal changes with the voltage value of the driving voltage to form positive correlation change, when the voltage value corresponding to the second voltage detection signal is larger than a second preset reference voltage value, the secondary protection trigger circuit 15 generates a second protection trigger signal according to the second voltage detection signal, the LED power circuit 01 stabilizes the output driving voltage value at the current voltage value according to the second protection trigger signal, so that the driving voltage value output to the LED light source module by the LED power circuit 01 is not increased any more, and secondary overvoltage protection of the LED power circuit 01 is realized.

The embodiment of the application can carry out dual overvoltage protection to the LED power supply circuit when the overvoltage occurs to the driving voltage of output, and make power chip and other relevant circuit module on the TV integrated circuit board all start the overvoltage protection mechanism, further improve the fail safe nature of the LED light source module's of TV integrated circuit board drive power supply, other circuit module appear exploding because of the overvoltage on having reduced the TV integrated circuit board, the risk of sending the spark, the TV integrated circuit board security performance has been improved, the quantity that the overvoltage damage appears in the TV integrated circuit board has been reduced, thereby maintenance cost and replacement cost have been reduced, LED power supply overvoltage protection circuit's fail safe nature and practicality are high.

Referring to fig. 3, in one embodiment, the LED power circuit 01 includes: a rectifier transformer circuit 011 and an LED drive circuit 012.

A rectification transformation circuit 011, connected to the switching circuit 13 and the secondary protection trigger circuit 15, configured to generate a first power supply signal from the input ac power and the second dc power; an LED drive circuit 012, which is connected to the rectification/transformation circuit 011, the first voltage detection circuit 11, and the second voltage detection circuit 14, and configured to generate a drive voltage from a first power supply signal; the rectification and transformation circuit 011 is also configured to fixedly generate the first power supply signal according to the second protection trigger signal.

In specific implementation, the LED driving circuit 012 is connected to the LED light source module, and the LED driving circuit 012 includes a power chip, and can generate a driving voltage according to the first power signal to drive the LED light source module to emit light. When the voltage value corresponding to the first voltage detection signal is less than or equal to the first preset reference voltage value, the primary protection trigger circuit 12 turns off the first direct current, and does not generate the first protection trigger signal, so that the switch circuit 13 keeps turning on the second direct current to the rectification transformation circuit 011, and the rectification transformation circuit 011 performs voltage conversion and voltage stabilization processing on the input alternating current (e.g., mains supply) according to the second direct current to generate a first power supply signal, and outputs the first power supply signal to the LED driving circuit 012; when the voltage value corresponding to the first voltage detection signal is greater than the first preset reference voltage value, the primary protection trigger circuit 12 is turned on to turn on the first direct current to generate the first protection trigger signal, the switch circuit 13 is turned off according to the first protection trigger signal to turn off the second direct current to the rectification transformation circuit 011, the rectification transformation circuit 011 stops working and does not output the first power signal, the LED driving circuit 012 stops outputting the driving voltage without receiving the first power signal, primary overvoltage protection is performed on the LED power circuit 01, and simultaneously the power chip in the LED driving circuit 012 and the rectification transformation circuit 011 at the previous stage are controlled to both start an overvoltage protection mechanism.

Further, when the primary overvoltage protection fails, the rectifier transformer circuit 011 continuously outputs a first power signal, and the LED driving circuit 012 continuously generates a driving voltage according to the first power signal. When the driving voltage value continuously becomes high, the second voltage detection circuit detects and samples the driving voltage to generate a second voltage detection signal, and when the voltage value of the second voltage detection signal is greater than a second preset reference voltage value, the secondary protection trigger circuit 15 generates a second protection trigger signal and feeds the second protection trigger signal back to the rectification transformation circuit 011. Rectification vary voltage circuit 011 fixes the first power signal who will generate at a certain magnitude of voltage according to second protection trigger signal to make LED drive circuit 012 carry out the magnitude of voltage to the drive voltage of output fixed, and then make the drive voltage value no longer grow, realize carrying out secondary overvoltage protection to LED power circuit 01, and the power chip in the control LED drive circuit 012 and preceding stage rectification vary voltage circuit 011 all start the overvoltage protection mechanism simultaneously, prevent effectively that the drive voltage of output is excessive pressure and damage circuit components and parts and power chip.

Referring to fig. 4, in one embodiment, the rectification and transformation circuit 011 includes: the power supply comprises a rectifying unit 0111, a power correction unit 0112 and a flyback transformation unit 0113.

A rectification unit 0111 configured to generate a rectified power supply signal from an input alternating current; a power correction unit 0112, connected to the rectification transformation circuit 011 and the switch circuit 13, configured to perform power factor correction on the rectified power supply signal according to the second direct current to generate a corrected power supply signal; the flyback transformer unit 0113 is connected to the power correction unit 0112, the switch circuit 13, and the secondary protection trigger circuit 15, and is configured to perform voltage conversion on the correction power supply signal according to the second direct current to generate a first power supply signal, and generate the first power supply signal fixedly according to the second protection trigger signal.

In specific implementation, the LED driving circuit 012 is connected to the flyback transformer unit 0113, and generates a driving voltage according to the first power signal to drive the LED light source module to emit light. When the voltage value corresponding to the first voltage detection signal generated by the first voltage detection circuit 11 detecting the driving voltage is less than or equal to the first preset reference voltage value, the primary protection trigger circuit 12 does not generate the first protection trigger signal, so that the switch circuit 13 keeps conducting the second direct current to the power correction unit 0112 and the flyback transformer unit 0113. The power correction unit 0112 and the flyback transformer unit 0113 perform power factor correction, voltage conversion and other processing on the rectified power supply signal generated by the rectifier unit 0111 according to the second direct current, and then output a first power supply signal to the LED driving circuit 012, and the LED driving circuit 012 keeps generating a driving voltage according to the first power supply signal; when the voltage value corresponding to the first voltage detection signal is greater than the first preset reference voltage value, the primary protection trigger circuit 12 generates a first protection trigger signal to control the switch circuit 13 to be turned off, so that the second direct current is not conducted to the power correction unit 0112 and the flyback transformer unit 0113, the power correction unit 0112 and the flyback transformer unit 0113 stop working according to the turning off of the second direct current (i.e., according to the fact that the second direct current is not received), and the first power signal is not output, so that the LED driving circuit 012 stops outputting the driving voltage, primary overvoltage protection of the LED power circuit 01 is realized, and the LED driving circuit 012 and the previous power correction unit 0112 and flyback transformer unit 0113 are simultaneously controlled to start an overvoltage protection mechanism.

Further, when the primary overvoltage protection fails, the switch circuit 13 cannot timely cut off the second direct current, the input alternating current is processed by the rectifier unit 0111, the power correction unit 0112 and the flyback transformer unit 0113 and then continuously outputs the first power signal, the LED driving circuit 012 continuously generates the driving voltage according to the first power signal, the second voltage detection circuit 14 detects the driving voltage with the continuously increased voltage value to generate the second voltage detection signal, when the voltage value of the second voltage detection signal is greater than the second preset reference voltage value, the secondary protection trigger circuit 15 generates the second protection trigger signal and feeds the second protection trigger signal back to the flyback transformer unit 0113, the flyback transformer unit 0113 processes the corrected power signal according to the second protection trigger signal, so as to fix the generated first power signal at a certain voltage value, and further fix the voltage value of the output driving voltage by the LED driving circuit 012, the realization carries out secondary overvoltage protection to LED power supply circuit, and controls LED drive circuit 012 and preceding flyback transformer unit 0113 all to start the overvoltage protection mechanism simultaneously, prevents that drive voltage excessive pressure from damaging circuit components and parts and power chip.

In specific implementation, the first direct current and the second direct current can be generated and output by the first voltage conversion circuit performing voltage conversion, voltage stabilization and the like on the input alternating current, and can also be generated and output by the second voltage conversion circuit according to the first power supply signal output by the rectification transformation circuit 011, so as to meet the power consumption requirements in the LED power supply circuit 01 and the LED power supply overvoltage protection circuit.

Referring to fig. 5, in one embodiment, the first voltage detecting circuit 11 includes: a first resistor R1 and a second resistor R2; the first end of the first resistor R1 is connected with the LED power circuit 01, the second end of the first resistor R1 is connected with the first end of the second resistor R2 and the primary protection trigger circuit 12, and the second end of the second resistor R2 is connected with the power ground.

In a specific implementation, the driving voltage is output by the LED power circuit 01, and the voltage value is LED + OUT. The first resistor R1 and the second resistor R2 divide the driving voltage (LED + OUT). A first end of the second resistor R2 is a first voltage detection signal output end of the first voltage detection circuit 11, and outputs a first voltage detection signal to the primary protection trigger circuit 12. Optionally, the first voltage detection circuit 11 may further include a voltage division network formed by a plurality of (three or more) resistors, so as to detect and sample the driving voltage to generate the first voltage detection signal.

Referring to fig. 5, in one embodiment, the primary protection trigger circuit 12 includes: a controllable switching tube U1 and a first photoelectric coupler PU 5; wherein, controllable switch tube U1's control end 1 is connected with first voltage detection circuit 11, controllable switch tube U1's first end 2 is connected with first photocoupler PU 5's negative pole, controllable switch tube U1's second end 3 is connected with power ground, first photocoupler PU 5's positive pole and first direct current end are connected, first photocoupler PU 5's collecting electrode and second direct current end are connected, first photocoupler PU 5's projecting pole and switch circuit are connected.

In an embodiment, referring to fig. 5, the primary protection trigger circuit 12 further includes a first capacitor C1, a second capacitor C2, a third resistor R3 and a fourth resistor R4; the first end of the first capacitor C1 is connected to the first voltage detection circuit 11, the second end of the first capacitor C1 is connected to the first end of the controllable switch tube U1, the second end of the third resistor R3 and the cathode of the first photocoupler PU5, the control end 1 of the controllable switch tube U1 is connected to the first end of the second capacitor C2 and the first voltage detection circuit 11, the second end of the controllable switch tube U1 and the second end of the second capacitor C2 are connected to the ground, the first end of the third resistor R3 is connected to the second end of the fourth resistor R4 and the anode of the first photocoupler PU5, the first end of the fourth resistor R4 is connected to the first dc end, the collector of the first photocoupler PU5 is connected to the second dc end, and the emitter of the first photocoupler PU5 is connected to the switch circuit 13. The first capacitor C1 and the second capacitor C2 are both filter capacitors, and perform filtering and noise reduction processing on the first voltage detection signal. The third resistor R3 and the fourth resistor R4 may be current limiting protection resistors, and divide and shunt the first direct current to perform voltage division and current limiting protection on the first photocoupler PU5 and the controllable switching tube U1.

The first direct current end outputs a first direct current, and the voltage value of the first direct current is +12 VOUT. The second direct current terminal outputs a second direct current, and the voltage value of the second direct current is VCC 1.

In one embodiment, referring to fig. 6, the controllable switching tube U1 employs a controllable regulator U1A, the reference terminal of the controllable regulator U1A is configured as the control terminal 1 of the controllable switching tube U1, the negative terminal of the controllable regulator U1A is configured as the first terminal 2 of the controllable switching tube U1, and the positive terminal of the controllable regulator U1A is configured as the second terminal 3 of the controllable switching tube U1.

Optionally, the first predetermined reference voltage is a reference voltage at a reference terminal of the controllable voltage regulator U1A, and the voltage value is Vfb 1. The reference terminal of the controllable voltage regulator U1A is the first voltage detection signal input terminal of the primary protection trigger circuit 12, and when the voltage value corresponding to the first voltage detection signal is greater than the first preset reference voltage value Vfb1, the controllable voltage regulator U1A is turned on, and the first protection trigger signal is output from the emitter of the first photocoupler PU5 to the switching circuit 13.

Optionally, the controllable voltage stabilizer U1A adopts a controllable precise voltage stabilizing source with model TL431, has good thermal stability, and is fast in on-state response speed, low in output noise, low in price, capable of meeting voltage stabilization and overvoltage triggering application requirements, and high in cost performance.

Referring to fig. 5, in one embodiment, the switch circuit 13 includes: a first transistor Q3; the base of the first triode Q3 is connected with the primary protection trigger circuit 12, the collector of the first triode Q3 is connected with the second direct current end, and the emitter of the first triode Q3 is connected with the LED power circuit 01.

In this embodiment, the first triode Q3 is a PNP type triode, and the first protection trigger signal according to the high level is cut off, so as to cut off the power correction unit 0112 of the second direct current output to the LED power circuit 01, and thus the power correction unit 0112 does not work to stop outputting the correction power signal, and further the LED driving circuit 012 stops outputting the driving voltage value LED light source module.

Optionally, the switch circuit 13 may also be at least one of an MOS transistor, a relay, and a diode, and can cut off the second direct current that is normally conducted to the LED power supply circuit 01 according to the first protection trigger signal.

In one embodiment, the switching circuit 13 further includes: a self-locking switch circuit 131; the input end of the self-locking switch circuit 131 is connected with the primary protection trigger circuit 12, and the output end of the self-locking switch circuit 131 is connected with the base electrode of the first triode Q3.

In specific implementation, the self-locking switch circuit 131 can generate and output a first switch control signal according to the first protection trigger signal to continuously and stably pull down the voltage level of the base of the first triode Q3, so that the first triode Q3 is stably and reliably cut off when the driving voltage is over-voltage, thereby cutting off the second direct current output to the power correction unit 0112 and the flyback transformer unit 0113 in the LED power circuit 01, and further enabling the LED driving circuit 012 to stop outputting the driving voltage value LED light source module.

Referring to fig. 6, in one embodiment, the self-locking switch circuit 131 includes: a second transistor Q1 and a third transistor Q2; the base of the second triode Q1 is connected with the collector of the third triode Q2, the emitter of the second triode Q1 is connected with the power ground, the collector of the second triode Q1 is connected with the base of the third triode Q2, and the emitter of the third triode Q2 is connected with the base of the first triode Q3.

In a specific implementation, the base of the second transistor Q1 is configured as the input of the latching switch circuit 131, and the emitter of the third transistor Q2 is configured as the output of the latching switch circuit 131.

In an embodiment, referring to fig. 6, the switch circuit 13 further includes: a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3 and a fourth capacitor C4; a first end of the fifth resistor R5 is connected to the primary protection trigger circuit 12, a second end of the fifth resistor R5 is connected to a first end of the third capacitor C3, a first end of the seventh resistor R7, a base of the second transistor Q1, and a collector of the third transistor Q2, a second end of the third capacitor C3, a second end of the seventh resistor R7, and an emitter of the second transistor Q1 are connected to the power ground, a collector of the second transistor Q1 is connected to a first end of the fourth capacitor C4, a first end of the sixth resistor R6, and a base of the third transistor Q2, and an emitter of the third transistor Q2, a second end of the fourth capacitor C4, and a second end of the sixth resistor R6 are connected to a base of the first transistor Q3.

In this embodiment, the first transistor Q3 is an NPN transistor, the second transistor Q1 is an NPN transistor, and the third transistor Q2 is a PNP transistor. The base of the second transistor Q1 is connected to the first protection trigger signal through the fifth resistor R5, and the optional first protection trigger signal is a high level signal. The self-locking switch circuit 131 generates a low-level first switch control signal according to the high-level first protection trigger signal, and outputs the low-level first switch control signal from the emitter of the third transistor Q2 in the self-locking switch circuit 131, so as to continuously and reliably pull down the base voltage level of the first transistor Q3 when the driving voltage output by the LED power circuit 01 is over-voltage. Optionally, the third capacitor C3 and the fourth capacitor C4 are both filter capacitors, and the sixth resistor R6 and the seventh resistor R7 are voltage-dividing current-limiting resistors, so that voltage-dividing current-limiting protection can be performed on corresponding triodes.

In one embodiment, referring to fig. 5 and 6, the second voltage detecting circuit 14 includes: an eighth resistor R19, a ninth resistor R20, a tenth resistor R21 and a fifth capacitor C01; the first end of the eighth resistor R19 and the first end of the fifth capacitor C01 are connected to the LED power circuit 01, the second end of the eighth resistor R19 and the second end of the fifth capacitor C01 are connected to the first end of the ninth resistor R20, the second end of the ninth resistor R20 is connected to the first end of the tenth resistor R21 and the secondary protection trigger circuit 15, and the second end of the tenth resistor R21 is connected to the power ground.

In a specific implementation, the fifth capacitor C01 performs filtering and noise reduction processing on the driving voltage output by the LED power circuit 01 to reduce noise interference of the driving voltage input to the second voltage detection circuit 14, and improve voltage detection accuracy. The first terminal of the tenth resistor R21 outputs the second voltage detection signal to the secondary protection trigger circuit 15.

In one embodiment, referring to fig. 5 and 6, the secondary protection trigger circuit 15 includes: a second photo-coupler PU3, a power management chip U3, and a peripheral circuit composed of an eleventh resistor R16, a twelfth resistor R17, a thirteenth resistor R18, a fourteenth resistor R22, a fifteenth resistor R23, a sixteenth resistor R24, a seventeenth resistor R25, a sixth capacitor C8, a seventh capacitor C9, an eighth capacitor C10, a ninth capacitor C11, a tenth capacitor C12, and an eleventh capacitor C13; wherein, the first end of the eleventh resistor R16 is connected to the first dc terminal, the second end of the eleventh resistor R16 is connected to the first end of the twelfth resistor R17 and the first end of the sixth capacitor C8, the second end of the sixth capacitor C8 is connected to the power ground, the second end of the twelfth resistor R17 is connected to the anode of the second photo coupler PU3, the cathode of the second photo coupler PU3 is connected to the first end of the thirteenth resistor R18, the power output terminal OUT of the power management chip U3 and the first end of the eleventh capacitor C13, the second end of the thirteenth resistor R18 is connected to the first end of the seventh capacitor C9, the second end of the seventh capacitor C9 is connected to the first end of the eighth capacitor C10 and the second voltage detection circuit 14, the second end of the eighth capacitor C10 and the ground terminal of the power management chip U3 are connected to the power ground, the voltage input terminal V-GND of the power management chip U3 is connected to the second voltage detection circuit 14, a second end of the eleventh capacitor C13 is connected to a first end of the fifteenth resistor R23, a second end of the fifteenth resistor R23 is connected to the current inverting input terminal VI-of the power management chip U3 and a first end of the sixteenth resistor R24, a second end of the sixteenth resistor R24 is connected to a first end of the tenth capacitor C12, a current non-inverting input terminal VI + of the power management chip U3 is connected to a second end of the tenth capacitor C12 and a first end of the seventeenth resistor R25, a second end of the seventeenth resistor R25 is connected to the potential ground, a power supply voltage terminal VCC of the power management chip U3 is connected to a first end of the ninth capacitor C11 and a second end of the fourteenth resistor R22, a second end of the ninth capacitor C11 is connected to the power ground, a first end of the fourteenth resistor R22 is connected to the first dc terminal, a collector of the second photocoupler PU3 is connected to the second dc terminal, and an emitter of the second photocoupler PU3 outputs a second rectified protection signal to the rectified protection circuit 011.

In a specific implementation, the voltage inverting input terminal V of the power management chip U3 inputs the second voltage detection signal. The second predetermined reference voltage is a reference voltage inside the power management chip U3, and the voltage value of the optional second predetermined reference voltage is Vfb 2. When the voltage value corresponding to the second voltage detection signal is greater than the second preset reference voltage value Vfb2, the second photoelectric coupler PU3 is turned on, and the second protection trigger signal is generated through the second photoelectric coupler PU3 to the flyback transformer unit 0113 in the rectification transformer circuit 011, so that the first power signal fixedly generated by the flyback transformer unit 0113 is controlled, the driving voltage fixedly generated by the LED driving circuit 012 is further controlled, and the driving voltage with a fixed voltage value is output to the LED light source module. Optionally, the power management chip U3 adopts a power control chip with a model number of iP 7700.

The working principle of the overvoltage protection circuit of the LED power supply will be briefly described with reference to fig. 6 as follows:

the first voltage detection circuit 11 (including the first resistor R1 and the second resistor R2) detects the driving voltage (LED + OUT), and generates a first voltage detection signal at a first terminal of the second resistor R2. When the voltage value corresponding to the first voltage detection signal is less than or equal to a first preset reference voltage value (i.e. the reference voltage Vfb1 at the reference end of the controllable voltage regulator U1A), the controllable voltage regulator U1A in the primary protection trigger circuit 12 is not turned on, the first photocoupler PU5 is not turned on the first direct current (+12VOUT), so that the primary protection trigger circuit 12 does not generate the first protection trigger signal, the second transistor Q1 and the third transistor Q2 in the control switch circuit 13 are kept off, the first transistor Q3 defaults to turn on the second direct current (VCC1) to the power correction unit 0112 and the flyback transformation unit 0113 in the rectification transformation circuit 01, the power correction unit 0112 and the flyback transformation unit 0113 perform power factor correction and voltage transformation on the rectified power signal generated by the rectification unit 0111 according to the second direct current (VCC1), and then output the first power signal to the LED driving circuit 012, the LED driving circuit 012 generates a driving voltage according to the first power signal to drive the LED light source module to emit light; when the voltage value corresponding to the first voltage detection signal is greater than the first preset reference voltage value, the controllable voltage regulator U1A in the primary protection trigger circuit 12 is turned on, so that the first photocoupler PU5 turns on the first direct current (+12VOUT) to generate a first protection trigger signal, the first protection trigger signal with high level is output to the base of the second triode Q1 in the switching circuit 13 through the fifth resistor R5, the second triode Q1 is controlled to be turned on, so that the third triode Q2 is turned on, the emitter of the third triode Q2 outputs the first switching control signal with low level, the first triode Q3 is turned off according to the first switching control signal with low level, so that the second direct current (VCC1) is turned off and output to the power correction unit 0112 and the flyback transformation unit 0113, the power correction unit 0112 and the flyback transformation unit 3 stop working according to the second direct current not being received, the first power signal is not output, so that the LED driving circuit 012 stops outputting the driving voltage, and the LED power circuit 01 is turned off to perform primary overvoltage protection on the LED power circuit 01.

Further, when the primary overvoltage protection fails, the first transistor Q3 fails to cut off the second dc power (VCC1), the first power signal is continuously output after the input ac power is processed by the rectifying unit 0111, the power correcting unit 0112 and the flyback transforming unit 0113, the LED driving circuit 012 continuously generates the driving voltage (LED + OUT) according to the first power signal, the eighth resistor R19, the ninth resistor R20 and the tenth resistor R21 in the second voltage detecting circuit 14 detect and sample the driving voltage (LED + OUT) whose voltage value continuously increases to generate the second voltage detecting signal, when the voltage value of the second voltage detecting signal is greater than the second preset reference voltage value (i.e. the reference voltage Vfb2 inside the power management chip U3), the second photocoupler PU3 in the secondary protection triggering circuit 15 turns on the first dc power (+ 12) VOUT, the second protection trigger signal is output from the emitter of the second photocoupler PU3 to the flyback transformer unit 0113 in the rectifier transformer circuit 011, so that the flyback transformer unit 0113 generates a first power signal fixedly, the LED driving circuit 012 outputs a driving voltage fixedly, the voltage value of the driving voltage is fixed at a certain voltage value (for example, the current output voltage value) and is not increased, secondary overvoltage protection is performed on the LED power circuit 01, and the LED driving circuit 012 in the LED power circuit 01, the previous power correction unit 0112 and the flyback transformer unit 0113 are controlled to start an overvoltage protection mechanism, so as to prevent overvoltage from damaging circuit components and power chips.

The second scheme of this application provides a LED drive power supply circuit, and LED drive power supply circuit includes as above LED power supply overvoltage crowbar.

In specific implementation, the LED driving power circuit is used as a driving power supply of the LED light source module, the LED driving power circuit is integrated on the TV board card, driving voltage is output through the LED driving power circuit to drive the LED light source module to emit light, and the LED power overvoltage protection circuit performs double reliable overvoltage protection on the LED driving power circuit.

The embodiment of the application can carry out dual overvoltage to the LED drive power supply circuit on the TV integrated circuit board when taking place the excessive pressure and include, include and carry out overvoltage protection to the power chip, make other circuit module associated with the power chip start the overvoltage protection mechanism simultaneously, the fail safe nature of LED drive power supply circuit and TV integrated circuit board has been improved, the machine of exploding appears because of the excessive pressure in other circuit modules on having reduced the TV integrated circuit board, the risk of sparkling, TV integrated circuit board security performance has been improved, the quantity that the TV integrated circuit board appears the excessive pressure damage has been reduced, thereby cost of maintenance and replacement cost have been reduced.

A third aspect of the application provides a television set comprising an LED power supply overvoltage protection circuit as described in any one of the above and an LED driving power supply circuit as described above.

In specific implementation, the television comprises a TV board card, and the LED power circuit on the TV board card can drive the backlight source (namely the LED light source module) to emit light, so that the liquid crystal screen is lightened, and video display is realized.

According to the embodiment of the application, the power chip and other related circuit modules on the TV board card can be subjected to double overvoltage protection when overvoltage occurs, the safety and reliability of the driving power supply of the liquid crystal screen backlight source of the television are further improved, the potential safety hazard of electricity utilization is reduced, the safety performance of the television is improved, and the maintenance cost and the replacement cost of the television caused by overvoltage damage of the TV board card are reduced.

It will be apparent to those skilled in the art that, for convenience and brevity of description, only the functional units, modules and circuits described above are illustrated as being divided into different functional units, modules and circuits, and in practical applications, the functions may be divided into different functional units, modules and circuits according to different requirements, that is, the internal structure of the device may be divided into different functional units, modules or circuits to complete all or part of the functions described above. In the embodiments, each functional unit, module, and circuit may be integrated into one processing unit, or each unit may exist alone physically, or two or more units are integrated into one unit, and the integrated unit may be implemented in a form of hardware, or in a form of software functional unit. In addition, specific names of the functional units, modules and circuits are only used for distinguishing one from another, and are not used for limiting the protection scope of the present application.

In the above embodiments, the descriptions of the respective embodiments have respective emphasis, and reference may be made to the related descriptions of other embodiments for parts that are not described or illustrated in a certain embodiment. 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 embodiments are only used to illustrate the technical solutions of the present application, and not to limit 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. The utility model provides a LED power supply overvoltage crowbar, with LED power supply circuit connection, its characterized in that, LED power supply overvoltage crowbar includes:

2. The LED power supply overvoltage protection circuit of claim 1, wherein said LED power supply overvoltage protection circuit further comprises:

3. The LED power supply overvoltage protection circuit of claim 2, wherein said LED power supply circuit comprises:

4. The LED power supply overvoltage protection circuit of claim 1, wherein said first voltage detection circuit comprises: a first resistor and a second resistor; the first end of the first resistor is connected with the LED power circuit, the second end of the first resistor is connected with the first end of the second resistor and the primary protection trigger circuit, and the second end of the second resistor is connected with a power ground.

5. The LED power supply overvoltage protection circuit of claim 1, wherein said primary protection trigger circuit comprises: the controllable switch tube and the first photoelectric coupler; the control end of the controllable switch tube is connected with the first voltage detection circuit, the first end of the controllable switch tube is connected with the cathode of the first photoelectric coupler, the second end of the controllable switch tube is connected with the power ground, the anode of the first photoelectric coupler is connected with the first direct current end, the collector of the first photoelectric coupler is connected with the second direct current end, and the emitter of the first photoelectric coupler is connected with the switch circuit.

6. The LED power supply overvoltage protection circuit of claim 1, wherein said switching circuit comprises: a first triode; the base electrode of the first triode is connected with the primary protection trigger circuit, the collector electrode of the first triode is connected with the second direct current end, and the emitting electrode of the first triode is connected with the LED power circuit.

7. The LED power supply overvoltage protection circuit of claim 6, wherein said switching circuit further comprises: a self-locking switch circuit; the input end of the self-locking switch circuit is connected with the primary protection trigger circuit, and the output end of the self-locking switch circuit is connected with the base electrode of the first triode.

8. The LED power supply overvoltage protection circuit of claim 7, wherein said self-latching switch circuit comprises: a second triode and a third triode; the base electrode of the second triode is connected with the collector electrode of the third triode, the emitting electrode of the second triode is connected with the power ground, the collector electrode of the second triode is connected with the base electrode of the third triode, and the emitting electrode of the third triode is connected with the base electrode of the first triode.

9. An LED driving power circuit, characterized in that the LED driving power circuit comprises the LED power overvoltage protection circuit as claimed in any one of claims 1 to 8.

10. A television set, characterized in that it comprises a LED power supply overvoltage protection circuit according to any one of claims 1 to 8 and a LED driving power supply circuit according to claim 9.