An LED power overvoltage protection circuit, an LED driving power circuit and a television set

Abstract

An LED power overvoltage protection circuit, an LED driving power circuit and a television, wherein the LED power overvoltage protection circuit detects a driving voltage output by the LED power circuit through a first voltage detection circuit to generate a first voltage detection signal; a primary protection trigger circuit is turned on to generate a first protection trigger signal when the first voltage detection signal is greater than a first preset reference voltage value; and a switch circuit turns off the LED power circuit according to the first protection trigger signal, so that the LED power circuit is turned off in time when the driving voltage is overvoltage, the power chip and the associated circuit module in the LED power circuit start the overvoltage protection mechanism, the safety hazards such as explosion and spark caused by overvoltage of the LED power circuit on the TV board are reduced, the safety and reliability of the LED power circuit of the TV board are improved, the safety performance of the TV board is improved, the maintenance cost and replacement cost of the TV board are reduced, and the safety and reliability and practicability of the LED power overvoltage protection circuit are high.

Description

Technical Field

[0001] This application belongs to the field of power supply technology, and in particular relates to an LED power supply overvoltage protection circuit, an LED driver power supply circuit, and a television set. Background Technology

[0002] Currently, traditional TV board LED power modules have corresponding overvoltage protection mechanisms. When an overvoltage occurs in the output of the LED power module, it will trigger the LED power module chip on the TV board to perform overvoltage protection, thereby fixing the output voltage. This can protect the LED power module and also improve the safety of the entire TV.

[0003] Whether it's a standalone power supply board or the entire TV set, the performance in terms of safety needs continuous improvement. In traditional designs, when the LED power module outputs overvoltage, only the chip in the LED power module can activate its protection mechanism, providing some protection. However, it cannot promptly activate the protection mechanisms of other related modules on the TV board. This could potentially damage other modules connected to the LED power module, and even pose a significant safety hazard to the entire TV set. In reality, overvoltage situations can occur at different stages and in different situations within a TV set, leading to electrical safety hazards such as explosions or sparks in other modules on the TV board. Furthermore, once an overvoltage anomaly occurs, multiple modules on the TV board need to be repaired or replaced simultaneously, increasing the inventory of repairable TV boards and resulting in high maintenance and replacement costs.

[0004] Therefore, traditional TV board LED power supply overvoltage protection solutions can only protect the LED power module from overvoltage, but cannot promptly activate the overvoltage protection mechanism of other related modules on the TV board. This results in certain safety hazards, low safety and reliability, and high maintenance and replacement costs for the TV board. Summary of the Invention

[0005] The purpose of this application is to provide an LED power supply overvoltage protection circuit, an LED driver power supply circuit, and a television set, which aims to solve the problems of traditional TV board LED power supply overvoltage protection schemes, which can only provide overvoltage protection for the LED power supply module but cannot promptly activate the overvoltage protection mechanism for other related modules on the TV board, resulting in certain safety hazards, low safety and reliability, and high maintenance and replacement costs for the TV board.

[0006] A first aspect of this application provides an LED power supply overvoltage protection circuit, connected to an LED power supply circuit, the LED power supply overvoltage protection circuit comprising:

[0007] A first voltage detection circuit is connected to the LED power supply circuit and configured to detect the driving voltage output by the LED power supply circuit to generate a first voltage detection signal.

[0008] A primary protection trigger circuit is connected to the first voltage detection circuit and is configured to turn on when the first voltage detection signal is greater than a first preset reference voltage value to generate a first protection trigger signal.

[0009] A switching circuit, connected to the primary protection trigger circuit, is configured to turn off the LED power supply circuit according to the first protection trigger signal.

[0010] In one embodiment, the LED power supply overvoltage protection circuit further includes:

[0011] The second voltage detection circuit is connected to the LED power supply circuit and is configured to detect the driving voltage to generate a second voltage detection signal.

[0012] The secondary protection trigger circuit is connected to 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. The second protection trigger signal is used to fix the driving voltage output by the LED power supply circuit.

[0013] In one embodiment, the LED power supply circuit includes:

[0014] A rectifier transformer circuit, connected to the switching circuit and the secondary protection trigger circuit, is configured to generate a first power signal based on the input AC and second DC power.

[0015] The LED driving circuit is connected to the rectifier transformer circuit, the first voltage detection circuit, and the second voltage detection circuit, and is configured to generate the driving voltage according to the first power supply signal; wherein, the rectifier transformer circuit is further configured to fix the first power supply signal generated according to the second protection trigger signal.

[0016] In one embodiment, the first voltage detection circuit includes a first resistor and a second resistor; wherein a first end of the first resistor is connected to the LED power supply circuit, a second end of the first resistor is connected to the first end of the second resistor and the primary protection trigger circuit, and a second end of the second resistor is connected to power ground.

[0017] In one embodiment, the primary protection trigger circuit includes: a controllable switch and a first optocoupler; wherein, the control terminal of the controllable switch is connected to the first voltage detection circuit, the first terminal of the controllable switch is connected to the cathode of the first optocoupler, the second terminal of the controllable switch is connected to the power ground, the anode of the first optocoupler is connected to a first DC terminal, the collector of the first optocoupler is connected to a second DC terminal, and the emitter of the first optocoupler is connected to the switching circuit.

[0018] In one embodiment, the switching circuit includes a first transistor; wherein the base of the first transistor is connected to the primary protection trigger circuit, the collector of the first transistor is connected to a second DC terminal, and the emitter of the first transistor is connected to the LED power supply circuit.

[0019] In one embodiment, the switching circuit further includes a self-locking switching circuit; the input terminal of the self-locking switching circuit is connected to the primary protection trigger circuit, and the output terminal of the self-locking switching circuit is connected to the base of the first transistor.

[0020] In one embodiment, the self-locking switch circuit includes a second transistor and a third transistor; wherein the base of the second transistor is connected to the collector of the third transistor, the emitter of the second transistor is connected to power ground, the collector of the second transistor is connected to the base of the third transistor, and the emitter of the third transistor is connected to the base of the first transistor.

[0021] A third aspect of this application provides an LED driver power supply circuit, the LED driver power supply circuit including the LED power supply overvoltage protection circuit as described in any of the preceding claims.

[0022] A third aspect of this application provides a television set, the television set including the LED power supply overvoltage protection circuit and the LED driving power supply circuit as described in any of the preceding claims.

[0023] The beneficial effects of the embodiments of the present invention compared with the prior art are as follows: The above-mentioned LED power supply overvoltage protection circuit detects the driving 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 conducts when the first voltage detection signal is greater than a first preset reference voltage value to generate a first protection trigger signal; the switching circuit shuts down the LED power supply circuit according to the first protection trigger signal, thereby realizing timely shutdown of the LED power supply circuit when the driving voltage is overvoltaged. This allows the power chip in the LED power supply circuit and the circuit modules associated with the power chip to activate the overvoltage protection mechanism, reducing the safety hazards such as device explosion or sparking caused by the inability to activate the overvoltage protection mechanism of other circuit modules associated with the power chip on the TV board in time during overvoltage. This improves the safety and reliability of the LED power supply circuit on the TV board, enhances the safety performance of the TV board, and reduces the maintenance and replacement costs of the TV board due to overvoltage. The LED power supply overvoltage protection circuit has high safety, reliability, and practicality. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of an LED power supply overvoltage protection circuit provided in an embodiment of this application;

[0025] Figure 2 This is a schematic diagram of another structure of an LED power supply overvoltage protection circuit provided in an embodiment of this application;

[0026] Figure 3 This is a schematic diagram of another structure of an LED power supply overvoltage protection circuit provided in an embodiment of this application;

[0027] Figure 4 This is a schematic diagram of another structure of an LED power supply overvoltage protection circuit provided in an embodiment of this application;

[0028] Figure 5 An example circuit schematic diagram of an LED power supply overvoltage protection circuit provided in an embodiment of this application;

[0029] Figure 6 This is another example circuit diagram of an LED power supply overvoltage protection circuit provided in an embodiment of this application. Detailed Implementation

[0030] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0031] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0032] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0033] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying 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 this application, "multiple" means two or more, unless otherwise explicitly specified.

[0034] Figure 1 A schematic diagram of the LED power supply overvoltage protection circuit provided in the first embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0035] An LED power supply overvoltage protection circuit is connected to an LED power supply circuit 01. The LED power supply overvoltage protection circuit includes: a first voltage detection circuit 11, a primary protection trigger circuit 12, and a switching circuit 13.

[0036] The first voltage detection circuit 11 is connected to the LED power supply circuit 01 and is configured to detect the 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 to the first voltage detection circuit 11 and is configured to turn on when the first voltage detection signal is greater than a first preset reference voltage value to generate a first protection trigger signal; the switch circuit 13 is connected to 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.

[0037] In a specific implementation, optionally, the LED power supply circuit 01 serves as the driving power supply for the LED light source module. The LED power supply overvoltage protection circuit and the LED power supply circuit 01 can be integrated onto the TV board. The LED light source module serves as the backlight for the TV LCD display. The LED power supply circuit 01 is connected to the LED power supply overvoltage protection circuit and the LED light source module. The LED power supply circuit 01 outputs a driving voltage to drive the LED light source module to emit light. Optionally, the LED power supply circuit 01 includes a power chip and related peripheral circuits, capable of voltage conversion and regulation of the input AC power, such as mains power, to generate a driving voltage to power the LED light source module. The first voltage detection sampling circuit 11 detects the driving voltage output from the LED power supply 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 less than or equal to the first preset reference voltage value, the primary protection trigger circuit 12 does not conduct the first DC power and does not generate the first protection trigger signal. This allows the switching circuit 13 to maintain the second DC power supply to the LED power supply circuit 01, so that the LED power supply circuit 01 can specifically perform voltage conversion and voltage regulation on the input AC power according to the second DC power supply to generate and output the 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 conducts, thereby conducting the first DC power supply to generate the first protection trigger signal. The switching circuit 13 cuts off according to the first protection trigger signal, thereby turning off the second DC power supply to realize the shutdown of the driving voltage output by the LED power supply circuit, so that the LED light source module does not emit light when powered off. Since the second DC power supply powers the associated peripheral circuits, turning off the second DC power supply to the peripheral circuits causes the LED power supply circuit 01 to stop outputting a drive voltage because the second DC power supply is not connected. This shuts off the second DC power supply, causing the power chip and associated peripheral circuits to stop working, thus providing overvoltage protection for the power chip and associated circuits in the LED power supply circuit 01. In a specific implementation, turning off the second DC power supply to the peripheral circuits can also cause the LED power supply circuit 01 to output a very small drive voltage (e.g., close to zero voltage), thereby achieving overvoltage protection for the power chip and associated circuits in the LED power supply circuit 01.

[0038] This application embodiment can simultaneously provide overvoltage protection for the power chip on the TV board and activate the overvoltage protection mechanism for other related circuit modules on the TV board. This improves the safety and reliability of the driving power supply for the LED light source module of the TV board, reduces the risk of other circuit modules on the TV board exploding or sparking due to overvoltage, improves the safety performance of the TV board, and reduces the repair and replacement costs caused by overvoltage damage to the TV board. The LED power supply overvoltage protection circuit has high safety, reliability, and practicality.

[0039] In one embodiment, when the primary protection trigger circuit 12 generates a first protection trigger signal to control the switching circuit 13 to turn off the second DC power, the primary protection trigger circuit 12 can also feed back the overvoltage situation 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 circuit 11 feeds back the corresponding generated first voltage detection signal to the power chip, thereby feeding back the overvoltage situation of the driving voltage to the power chip, so that the power chip stops outputting the driving voltage. This further achieves that when the driving voltage is overvoltage, the associated circuit modules of the power chip and the power chip itself will activate the overvoltage protection mechanism, reducing the safety hazards such as explosion or sparks caused by the failure to activate the overvoltage protection mechanism of other related circuit modules on the TV board in time when overvoltage occurs. This improves the safety and reliability of the LED power circuit of the TV board, and also improves the reliability and practicality of the TV board.

[0040] Please see Figure 2 In one embodiment, the LED power supply overvoltage protection circuit includes a second voltage detection circuit 14 and a secondary protection trigger circuit 15.

[0041] The second voltage detection circuit 14 is connected to the LED power supply circuit 01 and is configured to detect the driving voltage to generate a second voltage detection signal; 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 when the second voltage detection signal is greater than a second preset reference voltage value. The second protection trigger signal is used to fix the driving voltage output by the LED power supply circuit 01.

[0042] In specific implementation, when the primary protection trigger circuit 12 fails and fails to generate the first protection trigger signal in a timely and effective manner to control the switching circuit 13 to shut down the LED power circuit 01, that is, when the primary protection trigger circuit 12 fails to generate the first protection trigger signal in a timely and effective manner to control the switching circuit 13 to cut off the second DC power, or fails to promptly feedback the overvoltage situation to the power chip, or when the switching circuit 13 fails and fails to effectively cut off the second DC power according to the first protection trigger signal, the driving voltage output by the LED power circuit 01 continues to rise. The second voltage detection circuit 14 detects the driving voltage to generate a second voltage detection signal. The voltage value of the second voltage detection signal changes positively with the voltage value of the driving voltage. When the voltage value corresponding to the second voltage detection signal is greater than the 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 by the LED power circuit 01 to the LED light source module no longer rises, thereby realizing secondary overvoltage protection for the LED power circuit 01.

[0043] This application embodiment can provide dual overvoltage protection for the LED power supply circuit when the output driving voltage is overvoltaged, and also enables the power chip and other related circuit modules on the TV board to activate the overvoltage protection mechanism, further improving the safety and reliability of the driving power supply of the LED light source module of the TV board, reducing the risk of other circuit modules on the TV board exploding or sparking due to overvoltage, improving the safety performance of the TV board, reducing the number of TV boards damaged by overvoltage, thereby reducing maintenance and replacement costs. The LED power supply overvoltage protection circuit has high safety, reliability and practicality.

[0044] Please see Figure 3 In one embodiment, the LED power supply circuit 01 includes a rectifier transformer circuit 011 and an LED driver circuit 012.

[0045] The rectifier transformer circuit 011 is connected to the switching circuit 13 and the secondary protection trigger circuit 15, and is configured to generate a first power supply signal based on the input AC and second DC power. The LED driver circuit 012 is connected to the rectifier transformer circuit 011, the first voltage detection circuit 11 and the second voltage detection circuit 14, and is configured to generate a drive voltage based on the first power supply signal. The rectifier transformer circuit 011 is also configured to generate the first power supply signal based on the second protection trigger signal.

[0046] In a specific implementation, the LED driver circuit 012 is connected to the LED light source module. The LED driver circuit 012 includes a power chip that 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 cuts off the first DC power and does not generate the first protection trigger signal, so that the switching circuit 13 keeps conducting the second DC power to the rectifier transformer circuit 011. The rectifier transformer circuit 011 performs voltage conversion and voltage regulation on the input AC power (e.g., mains power) according to the second DC power to generate the first power signal and outputs it to the LED driver 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, thereby conducting the first DC power to generate the first protection trigger signal. The switching circuit 13 is turned off according to the first protection trigger signal and does not conduct the second DC power to the rectifier transformer circuit 011. The rectifier transformer circuit 011 stops working and does not output the first power signal. The LED driver circuit 012 does not receive the first power signal and stops outputting the driving voltage, thereby realizing primary overvoltage protection for the LED power circuit 01 and simultaneously controlling the power chip in the LED driver circuit 012 and the upstream rectifier transformer circuit 011 to start the overvoltage protection mechanism.

[0047] Furthermore, when the primary overvoltage protection fails, the rectifier-transformer circuit 011 continuously outputs the first power signal, and the LED driver circuit 012 continuously generates a driving voltage based on the first power signal. As the driving voltage continuously increases, the second voltage detection circuit detects and samples the driving voltage to generate a second voltage detection signal. When the voltage value of the second voltage detection signal exceeds the second preset reference voltage value, the secondary protection trigger circuit 15 generates a second protection trigger signal and feeds it back to the rectifier-transformer circuit 011. The rectifier-transformer circuit 011 fixes the generated first power signal at a certain voltage value based on the second protection trigger signal, thereby fixing the output driving voltage value of the LED driver circuit 012 and preventing the driving voltage value from increasing further. This achieves secondary overvoltage protection for the LED power supply circuit 01, and simultaneously controls the power chip in the LED driver circuit 012 and the preceding rectifier-transformer circuit 011 to activate the overvoltage protection mechanism, effectively preventing damage to circuit components and the power chip due to overvoltage of the output driving voltage.

[0048] Please see Figure 4 In one embodiment, the rectifier-transformer circuit 011 includes: a rectifier unit 0111, a power correction unit 0112, and a flyback transformer unit 0113.

[0049] The rectifier unit 0111 is configured to generate a rectified power supply signal based on the input AC power; the power correction unit 0112 is connected to the rectifier transformer circuit 011 and the switching circuit 13, and is configured to perform power factor correction on the rectified power supply signal based on the second DC power to generate a correction power supply signal; the flyback transformer unit 0113 is connected to the power correction unit 0112, the switching circuit 13 and the secondary protection trigger circuit 15, and is configured to perform voltage transformation on the correction power supply signal based on the second DC power to generate a first power supply signal, and to fix the first power supply signal generated based on the second protection trigger signal.

[0050] In specific implementation, the LED driving circuit 012 is connected to the flyback transformer unit 0113 and generates a driving voltage based on 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 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 switching circuit 13 keeps the second DC power to the power correction unit 0112 and the flyback transformer unit 0113 conducting. After the power correction unit 0112 and flyback transformer unit 0113 process the rectified power signal generated by the rectifier unit 0111 according to the second DC power, they output the first power signal to the LED driver circuit 012. The LED driver circuit 012 maintains the generation of driving voltage according to the first power 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 the first protection trigger signal to control the switch circuit 13 to be cut off, thereby preventing the second DC power from being conducted to the power correction unit 0112 and flyback transformer unit 0113. The power correction unit 0112 and flyback transformer unit 0113 stop working according to the cutoff of the second DC power (that is, according to the absence of the second DC power), and do not output the first power signal, so that the LED driver circuit 012 stops outputting the driving voltage, thereby realizing primary overvoltage protection for the LED power circuit 01, and simultaneously controlling the LED driver circuit 012 and the preceding power correction unit 0112 and flyback transformer unit 0113 to start the overvoltage protection mechanism.

[0051] Furthermore, when the primary overvoltage protection fails, the switching circuit 13 fails to cut off the second DC power in time. After processing the input AC power through the rectifier unit 0111, power correction unit 0112, and flyback transformer unit 0113, it continuously outputs the first power signal. The LED driver circuit 012 continuously generates a driving voltage based on the first power signal. The second voltage detection circuit 14 detects the continuously increasing driving voltage to generate a 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 is triggered. Circuit 15 generates a second protection trigger signal and feeds it back to flyback transformer unit 0113. Flyback transformer unit 0113 processes the correction power supply signal according to the second protection trigger signal, thereby fixing the generated first power supply signal at a certain voltage value. This causes LED driver circuit 012 to fix the output driving voltage value, realizing secondary overvoltage protection for LED power supply circuit. At the same time, it controls both LED driver circuit 012 and the preceding flyback transformer unit 0113 to start the overvoltage protection mechanism to prevent overvoltage of driving voltage from damaging circuit components and power supply chip.

[0052] In specific implementation, the first DC power and the second DC power can be generated and output by the first voltage conversion circuit through voltage conversion and voltage regulation of the input AC power, or they can be generated and output by the second voltage conversion circuit based on the first power signal output by the rectifier transformer circuit 011, so as to meet the power demand of the LED power supply circuit 01 and the LED power supply overvoltage protection circuit.

[0053] Please see Figure 5 In one embodiment, the first voltage detection circuit 11 includes a first resistor R1 and a second resistor R2; wherein, the first end of the first resistor R1 is connected to the LED power supply circuit 01, the second end of the first resistor R1 is connected to 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 to the power supply ground.

[0054] In specific implementation, the driving voltage is output by the LED power supply circuit 01, and the voltage value is LED+OUT. The first resistor R1 and the second resistor R2 divide the driving voltage (LED+OUT). The first terminal of the second resistor R2 is the first voltage detection signal output terminal of the first voltage detection circuit 11, which outputs the first voltage detection signal to the primary protection trigger circuit 12. Optionally, the first voltage detection circuit 11 may also include a voltage divider network composed of multiple (three or more) resistors to detect and sample the driving voltage to generate the first voltage detection signal.

[0055] Please see Figure 5In one embodiment, the primary protection trigger circuit 12 includes: a controllable switch U1 and a first optocoupler PU5; wherein, the control terminal 1 of the controllable switch U1 is connected to the first voltage detection circuit 11, the first terminal 2 of the controllable switch U1 is connected to the cathode of the first optocoupler PU5, the second terminal 3 of the controllable switch U1 is connected to the power ground, the anode of the first optocoupler PU5 is connected to the first DC terminal, the collector of the first optocoupler PU5 is connected to the second DC terminal, and the emitter of the first optocoupler PU5 is connected to the switching circuit.

[0056] For specific implementation details, please refer to [link / reference]. Figure 5 The primary protection trigger circuit 12 also includes a first capacitor C1, a second capacitor C2, a third resistor R3, and a fourth resistor R4. The first terminal of the first capacitor C1 is connected to the first voltage detection circuit 11. The second terminal of the first capacitor C1 is connected to the first terminal of the controllable switch U1, the second terminal of the third resistor R3, and the cathode of the first optocoupler PU5. The control terminal 1 of the controllable switch U1 is connected to the first terminal of the second capacitor C2 and the first voltage detection circuit 11. The second terminals of the controllable switch U1 and the second terminals of the second capacitor C2 are connected to the power ground. The first terminal of the third resistor R3, the second terminal of the fourth resistor R4, and the anode of the first optocoupler PU5 are connected. The first terminal of the fourth resistor R4 is connected to the first DC power terminal. The collector of the first optocoupler PU5 is connected to the second DC power terminal. The emitter of the first optocoupler PU5 is connected to the switching circuit 13. Both the first capacitor C1 and the second capacitor C2 are filter capacitors, used for filtering and noise reduction of the first voltage detection signal. The third resistor R3 and the fourth resistor R4 can be current-limiting protection resistors to divide and shunt the first DC current in order to provide voltage-dividing and current-limiting protection for the first optocoupler PU5 and the controllable switch U1.

[0057] The first DC terminal outputs a first DC voltage, with a voltage value of +12VOUT. The second DC terminal outputs a second DC voltage, with a voltage value of VCC1.

[0058] In one embodiment, please refer to Figure 6 The controllable switch U1 adopts a controllable voltage regulator U1A. The reference terminal of the controllable voltage regulator U1A is configured as the control terminal 1 of the controllable switch U1. The negative terminal of the controllable voltage regulator U1A is configured as the first terminal 2 of the controllable switch U1. The positive terminal of the controllable voltage regulator U1A is configured as the second terminal 3 of the controllable switch U1.

[0059] Optionally, the first preset reference voltage is the reference voltage of the reference terminal of the controllable voltage regulator U1A, with a voltage value of Vfb1. The reference terminal of the controllable voltage regulator U1A is the first voltage detection signal input terminal of the primary protection trigger circuit 12. 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 optocoupler PU5 to the switching circuit 13.

[0060] Optionally, the controllable voltage regulator U1A uses the TL431 controllable precision voltage regulator, which has good thermal stability, fast on-state response speed, low output noise, and low price. It can meet the needs of voltage regulation and overvoltage triggering applications, and has a high cost performance.

[0061] Please see Figure 5 In one embodiment, the switching circuit 13 includes a first transistor Q3; wherein the base of the first transistor Q3 is connected to the primary protection trigger circuit 12, the collector of the first transistor Q3 is connected to the second DC terminal, and the emitter of the first transistor Q3 is connected to the LED power supply circuit 01.

[0062] In this embodiment, the first transistor Q3 is a PNP transistor. It is cut off according to the high-level first protection trigger signal, thereby cutting off the second DC power output to the power correction unit 0112 in the LED power supply circuit 01. This causes the power correction unit 0112 to stop working and stop outputting the correction power signal, which in turn causes the LED driving circuit 012 to stop outputting the driving voltage value of the LED light source module.

[0063] Optionally, the switching circuit 13 may also be at least one of a MOSFET, a relay, and a diode, capable of being cut off according to the first protection trigger signal, thereby cutting off the second DC power supply to the LED power supply circuit 01 under normal conditions.

[0064] In one embodiment, the switching circuit 13 further includes a self-locking switching circuit 131; the input terminal of the self-locking switching circuit 131 is connected to the primary protection trigger circuit 12, and the output terminal of the self-locking switching circuit 131 is connected to the base of the first transistor Q3.

[0065] 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 transistor Q3, so that the first transistor Q3 can be stably and reliably cut off when the driving voltage is overvoltage, thereby cutting off the second DC power output to the power correction unit 0112 and the flyback transformer unit 0113 in the LED power supply circuit 01, and thus causing the LED driving circuit 012 to stop outputting the driving voltage value of the LED light source module.

[0066] Please see Figure 6 In one embodiment, the self-locking switch circuit 131 includes a second transistor Q1 and a third transistor Q2; wherein the base of the second transistor Q1 is connected to the collector of the third transistor Q2, the emitter of the second transistor Q1 is connected to the power supply ground, the collector of the second transistor Q1 is connected to the base of the third transistor Q2, and the emitter of the third transistor Q2 is connected to the base of the first transistor Q3.

[0067] In a specific implementation, the base of the second transistor Q1 is configured as the input terminal of the self-locking switch circuit 131, and the emitter of the third transistor Q2 is configured as the output terminal of the self-locking switch circuit 131.

[0068] For specific implementation details, please refer to [link / reference]. Figure 6 The switching 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; wherein, the first end of the fifth resistor R5 is connected to the primary protection trigger circuit 12, the second end of the fifth resistor R5 is connected to the first end of the third capacitor C3, the first end of the seventh resistor R7, the base of the second transistor Q1, and the collector of the third transistor Q2, the second end of the third capacitor C3, the second end of the seventh resistor R7, and the emitter of the second transistor Q1 are connected to the power supply ground, the collector of the second transistor Q1 is connected to the first end of the fourth capacitor C4, the first end of the sixth resistor R6, and the base of the third transistor Q2, and the emitter of the third transistor Q2, the second end of the fourth capacitor C4, and the second end of the sixth resistor R6 are connected to the base of the first transistor Q3.

[0069] 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. The first protection trigger signal can be a high-level signal. The self-locking switch circuit 131 generates a low-level first switch control signal based on the high-level first protection trigger signal, which is output from the emitter of the third transistor Q2 in the self-locking switch circuit 131. This signal continuously and reliably pulls down the base voltage level of the first transistor Q3 when the driving voltage output by the LED power supply circuit 01 is overvoltage. 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 divider and current limiting resistors, which can provide voltage divider and current limiting protection for the corresponding transistors.

[0070] In one embodiment, please refer to Figure 5 and Figure 6The second voltage detection circuit 14 includes: an eighth resistor R19, a ninth resistor R20, a tenth resistor R21, and a fifth capacitor C01; wherein, the first end of the eighth resistor R19 and the first end of the fifth capacitor C01 are connected to the LED power supply 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 and the first end of the tenth resistor R21 are connected to the secondary protection trigger circuit 15, and the second end of the tenth resistor R21 is connected to the power ground.

[0071] In specific implementation, the fifth capacitor C01 filters and reduces the noise of the driving voltage output by the LED power supply 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.

[0072] In one embodiment, please refer to Figure 5 and Figure 6The secondary protection trigger circuit 15 includes: a second optocoupler PU3 and a power management chip U3, as well as an external 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, and the second end of the eleventh resistor R16... The first terminal of the twelfth resistor R17 and the first terminal of the sixth capacitor C8 are connected. The second terminal of the sixth capacitor C8 is connected to the power ground. The second terminal of the twelfth resistor R17 is connected to the anode of the second optocoupler PU3. The cathode of the second optocoupler PU3 is connected to the first terminal of the thirteenth resistor R18, the power output terminal OUT of the power management chip U3, and the first terminal of the eleventh capacitor C13. The second terminal of the thirteenth resistor R18 is connected to the first terminal of the seventh capacitor C9. The second terminal of the seventh capacitor C9 is connected to the first terminal of the eighth capacitor C10 and the second voltage detection circuit 1. 4. Connections: The second terminal of the eighth capacitor C10 and the ground terminal GND of the power management chip U3 are connected to the power supply ground. The voltage inverting input terminal V- of the power management chip U3 is connected to the second voltage detection circuit 14. The second terminal of the eleventh capacitor C13 is connected to the first terminal of the fifteenth resistor R23. The second terminal of the fifteenth resistor R23 is connected to the current inverting input terminal VI- of the power management chip U3 and the first terminal of the sixteenth resistor R24. The second terminal of the sixteenth resistor R24 ​​is connected to the first terminal of the tenth capacitor C12. The current non-inverting input terminal VI- of the power management chip U3... + Connect the second terminal of the tenth capacitor C12 and the first terminal of the seventeenth resistor R25. The second terminal of the seventeenth resistor R25 is connected to the potential ground. The power supply voltage terminal VCC of the power management chip U3 is connected to the first terminal of the ninth capacitor C11 and the second terminal of the fourteenth resistor R22. The second terminal of the ninth capacitor C11 is connected to the power supply ground. The first terminal of the fourteenth resistor R22 is connected to the first DC power terminal. The collector of the second optocoupler PU3 is connected to the second DC power terminal. The emitter of the second optocoupler PU3 outputs the second protection trigger signal to the rectifier transformer circuit 011.

[0073] In specific implementation, the voltage inverting input terminal V- of the power management chip U3 receives a second voltage detection signal. The second preset reference voltage is an internal reference voltage of the power management chip U3, and the selectable value of the second preset reference voltage is Vfb2. When the voltage value corresponding to the second voltage detection signal is greater than the second preset reference voltage value Vfb2, the second optocoupler PU3 is turned on, generating a second protection trigger signal through the second optocoupler PU3 to the flyback transformer unit 0113 in the rectifier transformer circuit 011. This controls the flyback transformer unit 0113 to fix the first power supply signal generated, thereby controlling the LED driver circuit 012 to fix the driving voltage generated, resulting in a fixed output driving voltage value to the LED light source module. Optionally, the power management chip U3 uses a power control chip of model iP7700.

[0074] The following will combine Figure 6 A brief explanation of the working principle of the LED power supply overvoltage protection circuit:

[0075] The first voltage detection circuit 11 (including a first resistor R1 and a second resistor R2) detects the driving voltage (LED+OUT) and generates a first voltage detection signal at the first terminal of the second resistor R2. When the voltage value corresponding to the first voltage detection signal is less than or equal to the first preset reference voltage value (i.e., the reference voltage Vfb1 at the reference terminal of the controllable regulator U1A), the controllable regulator U1A in the primary protection trigger circuit 12 is not turned on, and the first optocoupler PU5 is not turned on to the first DC current (+12VOUT), so that the primary protection trigger circuit 12 does not generate the first protection trigger signal, and the second transistor Q1 and the third transistor Q2 in the control switch circuit 13 remain off, while the first transistor Q3 is turned on by default. The direct current (VCC1) is supplied to the power correction unit 0112 and flyback transformer unit 0113 in the rectifier-transformer circuit 01. The power correction unit 0112 and flyback transformer unit 0113 process the rectified power signal generated by the rectifier unit 0111 according to the second direct current (VCC1), performing power factor correction and voltage conversion, and then outputting a first power signal to the LED driver circuit 012. The LED driver circuit 012 generates a driving voltage based on the first power signal to drive the LED light source module to emit light; and when the first voltage... When the voltage value corresponding to the detection signal is greater than the first preset reference voltage value, the controllable regulator U1A in the primary protection trigger circuit 12 is turned on, thereby causing the first optocoupler PU5 to conduct the first DC power (+12VOUT) to generate the first protection trigger signal. The high-level first protection trigger signal is output to the base of the second transistor Q1 in the switching circuit 13 after passing through the fifth resistor R5, controlling the second transistor Q1 to conduct, thereby causing the third transistor Q2 to conduct. The emitter of the third transistor Q2 outputs a low-level first switch control signal. The first transistor Q3 is turned off according to the low-level first switch control signal, thereby cutting off the output of the second DC power (VCC1) 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 because they do not receive the second DC power and do not output the first power signal, thereby causing the LED driver circuit 012 to stop outputting the drive voltage, realizing the shutdown of the LED power supply circuit 01, so as to perform primary overvoltage protection on the LED power supply circuit 01.

[0076] Furthermore, when the primary overvoltage protection fails, the first transistor Q3 fails to cut off the second DC power (VCC1) in time. After processing the input AC power through the rectifier unit 0111, power correction unit 0112, and flyback transformer unit 0113, it continuously outputs the first power signal. The LED driver circuit 012 continuously generates a drive voltage (LED+OUT) based on the first power signal. The eighth resistor R19, the ninth resistor R20, and the tenth resistor R21 in the second voltage detection circuit 14 detect and sample the continuously increasing drive voltage (LED+OUT) to generate a second voltage detection signal. When the voltage value of the second voltage detection signal is greater than the second preset reference voltage value (i.e., the reference voltage value Vfb2 inside the power management chip U3), the secondary protection is activated. The second optocoupler PU3 in the trigger circuit 15 conducts the first DC power (+12VOUT), and outputs the second protection trigger signal from the emitter of the second optocoupler PU3 to the flyback transformer unit 0113 in the rectifier transformer circuit 011. This causes the flyback transformer unit 0113 to fix the first power supply signal generated, thereby fixing the output driving voltage of the LED driver circuit 012. The driving voltage value is fixed at a certain voltage value (e.g., the current output voltage value) and no longer increases, thus realizing secondary overvoltage protection for the LED power supply circuit 01. At the same time, it controls the LED driver circuit 012 in the LED power supply circuit 01, as well as the power correction unit 0112 and the flyback transformer unit 0113 in the previous stage, to start the overvoltage protection mechanism to prevent overvoltage damage to circuit components and power chips.

[0077] The second aspect of this application provides an LED driver power supply circuit, which includes the LED power supply overvoltage protection circuit as described above.

[0078] In specific implementation, the LED driver power supply circuit serves as the driving power supply for the LED light source module. The LED driver power supply circuit is integrated on the TV board. The LED driver power supply circuit outputs a driving voltage to drive the LED light source module to emit light. The LED power supply overvoltage protection circuit provides double reliable overvoltage protection for the LED driver power supply circuit.

[0079] This application embodiment can provide dual overvoltage protection for the LED driver power supply circuit on the TV board when overvoltage occurs. This includes overvoltage protection for the power chip and simultaneously activating overvoltage protection mechanisms for other circuit modules associated with the power chip. This improves the safety and reliability of the LED driver power supply circuit and the TV board, reduces the risk of other circuit modules on the TV board exploding or generating sparks due to overvoltage, improves the safety performance of the TV board, and reduces the number of TV boards damaged by overvoltage, thereby reducing maintenance and replacement costs.

[0080] A third aspect of this application provides a television set, which includes an LED power supply overvoltage protection circuit as described in any of the preceding claims and an LED driver power supply circuit as described in the preceding claims.

[0081] In practice, the television set includes a TV board, which can drive the backlight (i.e., the LED light source module) to emit light through the LED power circuit on the TV board, thereby illuminating the LCD screen and enabling video display.

[0082] The embodiments of this application can provide dual overvoltage protection for the power chip and other related circuit modules on the TV board when overvoltage occurs, further improving the safety and reliability of the driving power supply of the TV LCD screen backlight, reducing electrical safety hazards, improving the safety performance of the TV, and reducing the repair and replacement costs caused by overvoltage damage to the TV board.

[0083] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units, modules, and circuits is merely an example. In practical applications, the above functions can be assigned to different functional units, modules, and circuits as needed, that is, the internal structure of the device can be divided into different functional units, modules, or circuits to complete all or part of the functions described above. The functional units, modules, and circuits in the embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit. Furthermore, the specific names of the functional units, modules, and circuits are only for easy distinction and are not intended to limit the scope of protection of this application.

[0084] In the above embodiments, the descriptions of each embodiment have their own emphasis. Parts not described in detail in a particular embodiment can be referred to in the relevant descriptions of other embodiments. Furthermore, the displayed or discussed couplings, direct couplings, or communication connections can be indirect couplings or communication connections through interfaces, devices, or units, and can be electrical, mechanical, or other forms.

[0085] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. An LED power supply overvoltage protection circuit, connected to an LED power supply circuit, characterized in that, The LED power supply overvoltage protection circuit includes: A first voltage detection circuit is connected to the LED power supply circuit and configured to detect the driving voltage output by the LED power supply circuit to generate a first voltage detection signal. A primary protection trigger circuit is connected to the first voltage detection circuit and is configured to conduct a first DC current to generate a first protection trigger signal when the first voltage detection signal is greater than a first preset reference voltage value. A switching circuit, connected to the primary protection trigger circuit, is configured to turn off the LED power supply circuit according to the first protection trigger signal; the switching circuit is used to turn off the second DC power according to the first protection trigger signal, stop supplying power to the peripheral circuits and power chips in the LED power supply circuit, and turn off the driving voltage output by the LED power supply circuit. The LED power supply circuit performs voltage conversion and regulation on the input AC power based on the second DC power to generate and output a driving voltage to the LED light source component.

2. The LED power supply overvoltage protection circuit as described in claim 1, characterized in that, The LED power supply overvoltage protection circuit also includes: The second voltage detection circuit is connected to the LED power supply circuit and is configured to detect the driving voltage to generate a second voltage detection signal. The secondary protection trigger circuit is connected to 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. The second protection trigger signal is used to fix the driving voltage output by the LED power supply circuit.

3. The LED power supply overvoltage protection circuit as described in claim 2, characterized in that, The LED power supply circuit includes: A rectifier transformer circuit, connected to the switching circuit and the secondary protection trigger circuit, is configured to generate a first power signal based on the input AC and second DC power. The LED driving circuit is connected to the rectifier transformer circuit, the first voltage detection circuit, and the second voltage detection circuit, and is configured to generate the driving voltage according to the first power supply signal; wherein, the rectifier transformer circuit is further configured to fix the first power supply signal generated according to the second protection trigger signal.

4. The LED power supply overvoltage protection circuit as described in claim 1, characterized in that, The first voltage detection circuit includes a first resistor and a second resistor; wherein, the first end of the first resistor is connected to the LED power supply circuit, the second end of the first resistor is connected to the first end of the second resistor and the primary protection trigger circuit, and the second end of the second resistor is connected to the power ground.

5. The LED power supply overvoltage protection circuit as described in claim 1, characterized in that, The primary protection trigger circuit includes a controllable switch and a first optocoupler; wherein, the control terminal of the controllable switch is connected to the first voltage detection circuit, the first terminal of the controllable switch is connected to the cathode of the first optocoupler, the second terminal of the controllable switch is connected to the power ground, the anode of the first optocoupler is connected to the first DC terminal, the collector of the first optocoupler is connected to the second DC terminal, and the emitter of the first optocoupler is connected to the switching circuit.

6. The LED power supply overvoltage protection circuit as described in claim 1, characterized in that, The switching circuit includes a first transistor; wherein the base of the first transistor is connected to the primary protection trigger circuit, the collector of the first transistor is connected to the second DC terminal, and the emitter of the first transistor is connected to the LED power supply circuit.

7. The LED power supply overvoltage protection circuit as described in claim 6, characterized in that, The switching circuit further includes a self-locking switch circuit; the input terminal of the self-locking switch circuit is connected to the primary protection trigger circuit, and the output terminal of the self-locking switch circuit is connected to the base of the first transistor.

8. The LED power supply overvoltage protection circuit as described in claim 7, characterized in that, The self-locking switch circuit includes a second transistor and a third transistor; wherein the base of the second transistor is connected to the collector of the third transistor, the emitter of the second transistor is connected to the power supply ground, the collector of the second transistor is connected to the base of the third transistor, and the emitter of the third transistor is connected to the base of the first transistor.

9. An LED driver power supply circuit, characterized in that, The LED driver power supply circuit includes the LED power supply overvoltage protection circuit as described in any one of claims 1 to 8.

10. A television set, characterized in that, The television set includes an LED power supply overvoltage protection circuit as described in any one of claims 1 to 8 and an LED driving power supply circuit as described in claim 9.

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