Circuit with dual mode protection function and LED driving power supply

Abstract

The utility model relates to a kind of circuit and LED driving power supply with dual-mode protection function, comprising: over-temperature protection module, undervoltage protection module, back difference module, execution module and control module;Over-temperature protection module is used to detect the real-time temperature of power supply and exports over-temperature detection signal based on real-time temperature;Undervoltage protection module is used to detect the real-time voltage of the output end of rectifier bridge and exports undervoltage detection signal based on real-time voltage;Back difference module and execution module are used to turn on when receiving over-temperature detection signal, and drive control module to execute over-temperature protection;Or, back difference module and execution module are used to turn on when receiving undervoltage detection signal, and drive control module to execute undervoltage protection.By the utility model, the circuit can be effectively simplified, and multi-mode protection with small size, high reliability and low cost is realized.Meanwhile, the problem of high temperature and large power loss caused by the existing parallel diode, which reduces the efficiency of the whole machine, is also solved.

Description

Technical Field

[0001] This utility model relates to the technical field of power supplies, and more specifically, to a circuit with dual-mode protection function and an LED driver power supply. Background Technology

[0002] Traditional single-voltage power supply designs shut off when the input voltage drops below the rated voltage. However, this can cause lights to go out, potentially leading to safety hazards, especially for highway lighting. To improve reliability and grid stability, a single-voltage input range power supply employs a redundant structure to mitigate grid instability. If the input voltage drops below the rated range, causing damage to the power board or output power overload, the system automatically protects the power board. This includes overload protection by reducing power consumption to OTP (Over-the-Pack) and reducing power consumption when the input voltage drops below the rated voltage, thus ensuring normal equipment operation.

[0003] Existing parallel redundancy structures employ two DC power modules, four MOSFETs, and two secondary controllers. This structure is complex, significantly increasing costs and introducing unreliable factors. Another structure uses a diode at the output for parallel redundancy, but this results in high power losses, high temperatures, and reduced overall system efficiency. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a circuit and LED driver power supply with dual-mode protection function, addressing the problems existing in the prior art.

[0005] The technical solution adopted by this utility model to solve its technical problem is: to construct a circuit with dual-mode protection function, including: an over-temperature protection module, an under-voltage protection module, a hysteresis module, an execution module, and a control module;

[0006] The input terminal of the over-temperature protection module is connected to the power supply line, and the output terminal of the over-temperature protection module is connected to the hysteresis module and the execution module. The input terminal of the under-voltage protection module is connected to the output terminal of the rectifier bridge, and the output terminal of the under-voltage protection module is connected to the hysteresis module. The control module is connected to the under-voltage protection module and the execution module respectively.

[0007] The over-temperature protection module is used to detect the real-time temperature of the power supply and output an over-temperature detection signal based on the real-time temperature.

[0008] The undervoltage protection module is used to detect the real-time voltage at the output terminal of the rectifier bridge and output an undervoltage detection signal based on the real-time voltage.

[0009] The hysteresis module and the execution module are configured to turn on when the over-temperature detection signal is received, and drive the control module to perform over-temperature protection; or, the hysteresis module and the execution module are configured to turn on when the under-voltage detection signal is received, and drive the control module to perform under-voltage protection.

[0010] In the circuit with dual-mode protection function described in this utility model, the over-temperature protection circuit includes: a temperature detection circuit, a first parallel circuit, and a hysteresis drive circuit;

[0011] The input terminal of the temperature detection circuit is connected to the power supply line, and the output terminal of the temperature detection circuit is connected to the hysteresis drive circuit. The input terminal of the first parallel circuit is connected to the temperature detection circuit, and the output terminal of the first parallel circuit is connected to the hysteresis module. The input terminal of the hysteresis drive circuit is connected to the power supply line, and the output terminal of the hysteresis drive circuit is connected to the hysteresis module.

[0012] In the circuit with dual-mode protection function described in this utility model, the temperature detection circuit includes: a forty-first resistor, a thirty-ninth resistor, and a temperature sensor.

[0013] The first end of the forty-first resistor is connected to the power supply line, the second end of the forty-first resistor is connected to the first end of the thirty-ninth resistor and the hysteresis drive circuit, and the second end of the thirty-ninth resistor is grounded through the temperature sensor.

[0014] In the circuit with dual-mode protection function described in this utility model, the temperature sensor is a thermistor with a negative temperature coefficient.

[0015] In the circuit with dual-mode protection function described in this utility model, the hysteresis drive circuit includes: a fourth resistor, a first controllable voltage regulator, a first Zener diode, and a sixth diode; the first parallel circuit includes: a first parallel resistor;

[0016] The first end of the fourth resistor is connected to the power supply line, the second end of the fourth resistor is connected to the cathode of the first controllable voltage regulator, the reference electrode of the first controllable voltage regulator is connected to the second end of the forty-first resistor and the first end of the thirty-ninth resistor, and the anode of the first controllable voltage regulator is grounded; the cathode of the first Zener diode is connected to the cathode of the first controllable voltage regulator, the anode of the first Zener diode is connected to the anode of the sixth diode, the cathode of the sixth diode is connected to the hysteresis module, the first end of the first parallel resistor is connected to the second end of the forty-first resistor and the first end of the thirty-ninth resistor, and the second end of the first parallel resistor is connected to the hysteresis module.

[0017] In the circuit with dual-mode protection function described in this utility model, the undervoltage protection module includes: a voltage divider circuit, an execution drive circuit, and a second parallel circuit;

[0018] The input terminal of the voltage divider circuit is connected to the output terminal of the rectifier bridge, the output terminal of the voltage divider circuit is connected to the input terminal of the execution drive circuit, the output terminal of the execution drive circuit is connected to the hysteresis module, the input terminal of the second parallel circuit is connected to the output terminal of the voltage divider circuit, and the output terminal of the second parallel circuit is connected to the hysteresis module.

[0019] In the circuit with dual-mode protection function described in this utility model, the voltage divider circuit includes: a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, a seventh diode, a fourth voltage divider resistor, and a fifth voltage divider resistor;

[0020] The first voltage divider resistor, the second voltage divider resistor, the third voltage divider resistor, the seventh diode, the fourth voltage divider resistor, and the fifth voltage divider resistor are sequentially connected between the output terminal of the rectifier bridge and ground. The connection terminals of the fourth voltage divider resistor and the fifth voltage divider resistor are connected to the input terminal of the execution drive circuit.

[0021] In the circuit with dual-mode protection function described in this utility model, the execution drive circuit includes: a fifteenth resistor, a second controllable voltage regulator, a third Zener diode, and a fifth diode; the second parallel circuit includes: a second parallel resistor;

[0022] The first end of the fifteenth resistor is connected to the power supply line, the second end of the fifteenth resistor is connected to the cathode of the second controllable voltage regulator, the reference electrode of the second controllable voltage regulator is connected to the connection terminal of the fourth voltage divider resistor and the fifth voltage divider resistor, the anode of the second controllable voltage regulator is grounded, the cathode of the second controllable voltage regulator is also connected to the cathode of the third voltage regulator, the anode of the third voltage regulator is connected to the anode of the fifth diode, the cathode of the fifth diode is connected to the hysteresis module, the first end of the second parallel resistor is connected to the connection terminal of the fourth voltage divider resistor and the fifth voltage divider resistor, and the second end of the second parallel resistor is connected to the hysteresis module.

[0023] In the circuit with dual-mode protection function described in this utility model, the hysteresis module includes: a hysteresis resistor and a fifth MOSFET; the execution module includes: a third resistor and a sixth MOSFET; and the control module includes: a PWM control chip.

[0024] The first end of the hysteresis resistor is connected to the gate of the fifth MOS transistor, the second end of the hysteresis resistor is grounded, the gate of the fifth MOS transistor is connected to the over-temperature protection module, the source of the fifth MOS transistor is grounded, and the drain of the fifth MOS transistor is connected to the over-temperature protection module and the under-voltage protection module.

[0025] The gate of the sixth MOS transistor is connected to the over-temperature protection module, the source of the sixth MOS transistor is grounded, the drain of the sixth MOS transistor is connected to the dimming pin of the PWM control chip through the third resistor, and the control pin of the PWM control chip is connected to the undervoltage protection module.

[0026] This utility model also provides an LED driver power supply, including: the circuit with dual-mode protection function described above.

[0027] The circuit and LED driver power supply with dual-mode protection function of this utility model have the following beneficial effects: It includes an over-temperature protection module, an under-voltage protection module, a hysteresis module, an execution module, and a control module. The over-temperature protection module is used to detect the real-time temperature of the power supply and output an over-temperature detection signal based on the real-time temperature. The under-voltage protection module is used to detect the real-time voltage at the output terminal of the rectifier bridge and output an under-voltage detection signal based on the real-time voltage. The hysteresis module and the execution module are used to conduct when an over-temperature detection signal is received, and drive the control module to perform over-temperature protection; or, the hysteresis module and the execution module are used to conduct when an under-voltage detection signal is received, and drive the control module to perform under-voltage protection. This utility model can effectively simplify the circuit and achieve multi-mode protection with small size, high reliability, and low cost. It also solves the problems of high power loss, high temperature, and reduced overall efficiency caused by existing parallel diodes. Attached Figure Description

[0028] The present invention will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings:

[0029] Figure 1 This is a schematic block diagram of an embodiment of the circuit with dual-mode protection function provided by this utility model;

[0030] Figure 2 This is a circuit schematic diagram of an embodiment of the circuit with dual-mode protection function provided by this utility model. Detailed Implementation

[0031] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0032] To address the problems existing in current single-voltage power supply designs, this invention provides a circuit with dual-mode protection. This circuit simplifies the circuit structure, significantly reduces costs, and effectively solves the problems of high losses and high temperatures that lead to reduced overall efficiency caused by parallel connection of a single diode.

[0033] refer to Figure 1 In a preferred embodiment, the circuit with dual-mode protection includes: an over-temperature protection module 11, an under-voltage protection module 12, a hysteresis module 13, an execution module 14, and a control module 15. The input terminal of the over-temperature protection module 11 is connected to the power supply line, and its output terminal is connected to the hysteresis module 13 and the execution module 14. The input terminal of the under-voltage protection module 12 is connected to the output terminal of the rectifier bridge, and its output terminal is connected to the hysteresis module 13. The control module 15 is connected to both the under-voltage protection module 12 and the execution module 14.

[0034] Specifically, the over-temperature protection module 11 is used to detect the real-time temperature of the power supply and output an over-temperature detection signal based on the real-time temperature; the under-voltage protection module 12 is used to detect the real-time voltage at the output terminal of the rectifier bridge and output an under-voltage detection signal based on the real-time voltage; the hysteresis module 13 and the execution module 14 are used to turn on when the over-temperature detection signal is received and drive the control module 15 to perform over-temperature protection; or, the hysteresis module 13 and the execution module 14 are used to turn on when the under-voltage detection signal is received and drive the control module 15 to perform under-voltage protection.

[0035] Specifically, the over-temperature protection module 11 detects the real-time temperature of the power supply and outputs a corresponding over-temperature detection signal when the power supply over-temperatures. This over-temperature detection signal activates the hysteresis module 13 and the execution module 14, thereby driving the control module 15 to perform over-temperature protection. Similarly, the under-voltage protection module 12 detects the real-time voltage at the output of the rectifier bridge and outputs an under-voltage detection signal when the input voltage is under-voltage. This under-voltage detection signal activates the hysteresis module 13 and the execution module 14, thereby driving the control module 15 to perform under-voltage protection. When there is an over-temperature condition, the under-voltage protection module 12 does not operate; when there is an under-voltage condition, the over-temperature protection module 11 does not operate. That is, during over-temperature protection, the under-voltage protection module 12 does not operate, thus not affecting the over-temperature protection. Likewise, during under-voltage protection, the over-temperature protection module 11 does not operate, thus not affecting the under-voltage protection.

[0036] Optionally, in some embodiments, the over-temperature protection circuit includes: a temperature detection circuit, a first parallel circuit, and a hysteresis drive circuit. The input terminal of the temperature detection circuit is connected to the power supply line, and the output terminal of the temperature detection circuit is connected to the hysteresis drive circuit. The input terminal of the first parallel circuit is connected to the temperature detection circuit, and the output terminal of the first parallel circuit is connected to the hysteresis module 13. The input terminal of the hysteresis drive circuit is connected to the power supply line, and the output terminal of the hysteresis drive circuit is connected to the hysteresis module 13.

[0037] This temperature detection circuit enables real-time monitoring of the power supply temperature. When the power supply overheats, the hysteresis drive circuit controls the hysteresis module 13 and the execution module 14 to conduct, and the control module 15 performs over-temperature protection. Simultaneously, the first parallel circuit is designed to connect in parallel with the temperature detection circuit when the hysteresis module 13 is on, thereby preventing repeated changes in the power supply output current due to temperature variations and avoiding lamp flickering.

[0038] Optionally, in some embodiments, the undervoltage protection module 12 includes: a voltage divider circuit, an execution drive circuit, and a second parallel circuit. The input terminal of the voltage divider circuit is connected to the output terminal of the rectifier bridge, the output terminal of the voltage divider circuit is connected to the input terminal of the execution drive circuit, the output terminal of the execution drive circuit is connected to the hysteresis module 13, the input terminal of the second parallel circuit is connected to the output terminal of the voltage divider circuit, and the output terminal of the second parallel circuit is connected to the hysteresis module 13.

[0039] The voltage divider circuit divides the output voltage of the rectifier bridge. When the power supply is undervoltage, the drive circuit controls the addition / subtraction module and the execution module 14 to conduct, so that the control module 15 performs undervoltage protection. Simultaneously, the second parallel circuit is designed to connect in parallel with the voltage divider circuit when the hysteresis module 13 is on, thereby avoiding repeated changes in the power supply output current due to input voltage variations and preventing lamp flickering.

[0040] The following is a specific embodiment for illustration.

[0041] For details, please refer to Figure 2 In some embodiments, the temperature detection circuit includes a forty-first resistor R41, a thirty-ninth resistor R39, and a temperature sensor RT1. The first terminal of the forty-first resistor R41 is connected to the power supply line, the second terminal of the forty-first resistor R41 is connected to the first terminal of the thirty-ninth resistor R39 and the hysteresis drive circuit, and the second terminal of the thirty-ninth resistor R39 is grounded through the temperature sensor RT1. Optionally, in some embodiments, the temperature sensor RT1 is a negative temperature coefficient thermistor. By using a negative temperature coefficient thermistor, the temperature of the power supply can be monitored using the characteristics of the negative temperature coefficient thermistor. The power supply line is the voltage output from the VCC power supply line, which is typically 18V.

[0042] like Figure 2 As shown, in some embodiments, the hysteresis drive circuit includes: a fourth resistor R4, a first controllable voltage regulator U4, a first Zener diode ZD1, and a sixth diode D6; the first parallel circuit includes: a first parallel resistor R317.

[0043] The first end of the fourth resistor R4 is connected to the power supply line, and the second end of the fourth resistor R4 is connected to the cathode of the first controllable voltage regulator U4. The reference electrode of the first controllable voltage regulator U4 is connected to the second end of the forty-first resistor R41 and the first end of the thirty-ninth resistor R39. The anode of the first controllable voltage regulator U4 is grounded. The cathode of the first Zener diode ZD1 is connected to the cathode of the first controllable voltage regulator U4. The anode of the first Zener diode ZD1 is connected to the anode of the sixth diode D6. The cathode of the sixth diode D6 is connected to the hysteresis module 13. The first end of the first parallel resistor R317 is connected to the second end of the forty-first resistor R41 and the first end of the thirty-ninth resistor R39. The second end of the first parallel resistor R317 is connected to the hysteresis module 13.

[0044] like Figure 2 As shown, in some embodiments, the voltage divider circuit includes: a first voltage divider resistor R31, a second voltage divider resistor R32, a third voltage divider resistor R34, a seventh diode D7, a fourth voltage divider resistor R35, and a fifth voltage divider resistor R305.

[0045] The first voltage divider resistor R31, the second voltage divider resistor R32, the third voltage divider resistor R34, the seventh diode D7, the fourth voltage divider resistor R35, and the fifth voltage divider resistor R305 are connected sequentially between the output terminal of the rectifier bridge and ground. The connection terminals of the fourth voltage divider resistor R35 and the fifth voltage divider resistor R305 are connected to the input terminal of the drive circuit. Figure 2 As shown, VAC is the output voltage of the rectifier bridge. Since there is a small capacitor after the rectifier bridge, it can quickly detect changes in the output voltage. In contrast, the electrolytic capacitor in the PFC module cannot detect changes in the input voltage. Therefore, by placing a capacitor at the output of the rectifier bridge, changes in the output voltage can be detected quickly.

[0046] like Figure 2 As shown, in some embodiments, the execution drive circuit includes: a fifteenth resistor R15, a second controllable voltage regulator U5, a third Zener diode ZD3, and a fifth diode D5; the second parallel circuit includes: a second parallel resistor R23.

[0047] The first end of the fifteenth resistor R15 is connected to the power supply line, and the second end of the fifteenth resistor R15 is connected to the cathode of the second controllable voltage regulator U5. The reference electrode of the second controllable voltage regulator U5 is connected to the connection terminal of the fourth voltage divider resistor R35 and the fifth voltage divider resistor R305. The anode of the second controllable voltage regulator U5 is grounded. The cathode of the second controllable voltage regulator U5 is also connected to the cathode of the third voltage regulator ZD3. The anode of the third voltage regulator ZD3 is connected to the anode of the fifth diode D5. The cathode of the fifth diode D5 is connected to the hysteresis module 13. The first end of the second parallel resistor R23 is connected to the connection terminal of the fourth voltage divider resistor R35 and the fifth voltage divider resistor R305. The second end of the second parallel resistor R23 is connected to the hysteresis module 13.

[0048] like Figure 2 As shown, in some embodiments, the hysteresis module 13 includes: a hysteresis resistor R306 and a fifth MOSFET Q5; the execution module 14 includes: a third resistor R3 and a sixth MOSFET Q6; and the control module 15 includes: a PWM control chip U2.

[0049] The first terminal of the hysteresis resistor R306 is connected to the gate of the fifth MOSFET Q5, and the second terminal of the hysteresis resistor R306 is grounded. The gate of the fifth MOSFET Q5 is connected to the over-temperature protection module 11 (i.e., as shown in the image). Figure 2 As shown, the gate of the fifth MOSFET Q5 is connected to the cathode of the fifth diode D5, the source of the fifth MOSFET Q5 is grounded, and the drain of the fifth MOSFET Q5 is connected to the over-temperature protection module 11 (i.e., as shown). Figure 2 As shown, the drain of the fifth MOSFET Q5 is connected to the second terminal of the first parallel resistor R317 and the undervoltage protection module 12 (i.e., as shown). Figure 2As shown, the drain of the fifth MOSFET Q5 is connected to the second terminal of the second parallel resistor R23; the gate of the sixth MOSFET Q6 is connected to the over-temperature protection module 11 (i.e., as shown). Figure 2 As shown, the gate of the sixth MOSFET Q6 is connected to the cathode of the fifth diode D5, the source of the sixth MOSFET Q6 is grounded, and the drain of the sixth MOSFET Q6 is connected to the dimming pin of the PWM control chip U2 through the third resistor R3. The control pin of the PWM control chip U2 is connected to the undervoltage protection module 12 (i.e., as shown). Figure 2 As shown, the control pin (CTRL pin) of the PWM control chip U2 is connected to the connection terminals of the fourth voltage divider resistor R35 and the fifth voltage divider resistor R305.

[0050] Figure 2 In the text, OTP stands for over-temperature protection, and UVP stands for under-voltage protection.

[0051] according to Figure 2 The specific working principle of this circuit with dual-mode protection function is as follows:

[0052] Under normal operating conditions, both the first controllable voltage regulator U4 and the second controllable voltage regulator U5 are controllable precision voltage regulators. During normal operation, the voltage at the reference electrodes of both U4 and U5 reaches their reference voltage, 2.5V. At this time, the anode and cathode of the first controllable voltage regulator U4 are conducting, and the cathode level is close to ground potential, i.e., a low level. VCC, the fourth resistor R4, the first controllable voltage regulator U4, and ground form a circuit, resulting in a low voltage at the gate of the fifth MOSFET Q5, which is in the off state. Similarly, when the anode and cathode of the second controllable voltage regulator U5 are conducting, VCC, the fifteenth resistor R15, the second controllable voltage regulator U5, and ground form a circuit, resulting in a low voltage at the gate of the sixth MOSFET Q6, which is in the off state. At this time, since the third resistor R3 cannot be grounded through the sixth MOSFET Q6, the third resistor R3 is not connected to the dimming pin (DIM pin, which is an analog dimming pin) of the control chip. It is equivalent to the DIM pin being floating. Therefore, the PWM control chip U2 does not perform internal control, and the power supply outputs the set current value normally. That is, the PWM control chip U2 does not perform over-temperature or under-voltage power protection.

[0053] Over-temperature protection state: As the power supply temperature rises, due to the characteristic that the resistance of the thermistor with negative temperature coefficient decreases with increasing temperature, the voltage across the temperature sensor RT1 in the voltage divider circuit composed of the forty-first resistor R41, the thirty-ninth resistor R39, and the temperature sensor RT1 decreases. When the temperature rises to the set value of the over-temperature protection point (e.g., 96℃), the voltage across the temperature sensor RT1 is less than 2.5V, which is lower than the reference voltage of 2.5V of the reference electrode of the first controllable voltage regulator U4. At this time, the anode and cathode of the first controllable voltage regulator U4 are disconnected, that is, the first controllable voltage regulator U4 is not conducting. VCC drives the fifth MOSFET Q5 and the sixth MOSFET Q6 through the first Zener diode ZD1, the sixth diode D6, and the hysteresis resistor R306 by limiting the current through the fourth resistor R4, making the fifth MOSFET Q5 and the sixth MOSFET Q6 fully conduct.

[0054] When the fifth MOSFET Q5 is turned on, the second parallel resistor R23 is connected to ground. At this time, it is equivalent to connecting the series circuit formed by the second parallel resistor R23, the thirty-ninth resistor R39, and the temperature sensor RT1 in parallel. This further reduces the voltage on the reference electrode of the first controllable voltage regulator U4 when the temperature sensor RT1 reaches its temperature protection point. This ensures that after the temperature on the temperature sensor RT1 reaches the protection point, small temperature fluctuations will not disrupt the operating state (i.e., the off state) of the first controllable voltage regulator U4, preventing repeated changes in the power supply output current due to temperature variations, which could cause the lamp to flicker. The first controllable voltage regulator U4 will only resume its conducting state when the temperature drops to a lower level. Simultaneously, with the sixth MOSFET Q6 conducting, the third resistor R3 is connected to the DIM pin of the PWM control chip U2, thereby changing the level of the DIM pin (when not dimming, the maximum level of the internal control DIM pin is 1.8V, and when an external resistor is connected, the voltage here will be divided). The PWM control chip U2 performs dimming action, changing the drive signal output by its drive pin (GATE pin), thereby changing the working state of the subsequent BUCK circuit (power circuit), reducing the output current, and thus reducing the heat generated when the power supply is working. This achieves the purpose of over-temperature protection by reducing the operating power and lowering the power supply temperature when the power supply is over-temperature.

[0055] The over-temperature protection point setting value can be achieved by comparing the series resistance of the 39th resistor R39 and temperature sensor RT1 with the total resistance of the 41st resistor R41, the 39th resistor R39, and temperature sensor RT1. The recovery point temperature can be achieved by the ratio of the parallel resistance of the 39th resistor R39, temperature sensor RT1 (connected in series) and the second parallel resistor R23 in the entire circuit. Adjusting the 39th resistor R39 individually allows for fine-tuning of the over-temperature protection point setting value and the recovery point temperature. During over-temperature protection, since the fifth diode D5 is in the cutoff state (during over-temperature protection, the cathode of the fifth diode D5 is at high voltage, and the anode is at low voltage), the undervoltage protection is not affected.

[0056] Undervoltage protection state: When the input voltage is lower than the set value, the voltage detected after the rectifier bridge passes through the first voltage divider resistor R31, the second voltage divider resistor R32, the third voltage divider resistor R34, and the fourth voltage divider resistor R35, and is rectified by the seventh diode D7. The voltage at the upper end of the fifth voltage divider resistor R305 decreases with the input voltage. At the same time, the upper end of the fifth voltage divider resistor R305 is directly connected to the control pin of the PWM control chip U2. When the voltage drops to less than the reference voltage of 2.5V on the reference electrode of the second controllable voltage regulator U5, the anode and cathode of the second controllable voltage regulator U5 are disconnected, and the voltage at the lower end of the fifteenth resistor R15 switches from low voltage to high voltage. That is, VCC enters the third Zener diode ZD3 through the fifteenth resistor R15 and drives the fifth MOSFET Q5 and the sixth MOSFET Q6 to conduct.

[0057] After the fifth MOSFET Q5 turns on, it pulls the second parallel resistor R23 to ground. At this point, it's equivalent to the second parallel resistor R23 being connected in parallel with the fifth voltage divider resistor R305. Then, through the first voltage divider resistor R31, the second voltage divider resistor R32, the third voltage divider resistor R34, the fourth voltage divider resistor R35, and the seventh diode D7, the voltage across the fifth voltage divider resistor R305 decreases further as the second parallel resistor R23 is connected in parallel to the fifth voltage divider resistor R305. This ensures that the voltage on the second controllable voltage regulator U5, after reaching the undervoltage protection level, will not be disrupted by input voltage fluctuations, preventing the second controllable voltage regulator U5 from operating in the off state (i.e., the disconnected state). This avoids repeated changes in the power supply output current caused by input voltage variations, which could lead to flickering of the lamps. Only when the input voltage rises to a level higher than the undervoltage protection voltage (i.e., the recovery voltage) can the second controllable voltage regulator U5 return to the on state, thus returning to normal operation. The undervoltage protection voltage can be adjusted by changing the ratio of the first voltage divider resistor R31, the second voltage divider resistor R32, the third voltage divider resistor R34, the fourth voltage divider resistor R35, the seventh diode D7, the fifth voltage divider resistor R305 to the total resistance. The recovery voltage can be achieved by adjusting the ratio of the fifth voltage divider resistor R305 to the second parallel resistor R23 in the entire voltage divider circuit.

[0058] The voltage division across the fifth voltage divider resistor R305, and the voltage division after the fifth voltage divider resistor R305 and the second parallel resistor R23 are in parallel, are greater than the operating voltage of CTRL. This protects the power supply from undervoltage input within a certain range; the power supply only reduces power and does not stop outputting. The power supply only stops outputting when the voltage exceeds the range. (CTRL is the control pin of the PWM control chip U2, which should normally be greater than 0.35V and is generally used for undervoltage protection during power supply operation.) During undervoltage protection, because the sixth diode D6 is in the off state (during undervoltage protection, the cathode of the sixth diode D6 is at high voltage and the anode is at low voltage), it does not affect the over-temperature protection.

[0059] Furthermore, this utility model also provides an LED driver power supply, which includes the circuit with dual-mode protection function disclosed in this utility model.

[0060] By implementing the dual-mode protection circuit of this invention, a small-size, highly reliable, and low-cost multi-mode protection function can be achieved. Simultaneously, if the input voltage is lower than the rated voltage, the power supply will automatically derating to 50%, ensuring that the LED light will not be turned off in an emergency. This method results in a simple and practical circuit, thereby reducing costs.

[0061] The above embodiments are only for illustrating the technical concept and features of this utility model, and are intended to enable those skilled in the art to understand the content of this utility model and implement it accordingly. They do not limit the scope of protection of this utility model. All equivalent changes and modifications made within the scope of the claims of this utility model should fall within the scope of the claims of this utility model.

Claims

1. A circuit having dual mode protection functionality, characterized by, include: Over-temperature protection module, under-voltage protection module, hysteresis module, execution module, and control module; The input terminal of the over-temperature protection module is connected to the power supply line, and the output terminal of the over-temperature protection module is connected to the hysteresis module and the execution module. The input terminal of the under-voltage protection module is connected to the output terminal of the rectifier bridge, and the output terminal of the under-voltage protection module is connected to the hysteresis module. The control module is connected to the under-voltage protection module and the execution module respectively. The over-temperature protection module is used to detect the real-time temperature of the power supply and output an over-temperature detection signal based on the real-time temperature. The undervoltage protection module is used to detect the real-time voltage at the output terminal of the rectifier bridge and output an undervoltage detection signal based on the real-time voltage. The hysteresis module and the execution module are configured to turn on when the over-temperature detection signal is received, and drive the control module to perform over-temperature protection; or, the hysteresis module and the execution module are configured to turn on when the under-voltage detection signal is received, and drive the control module to perform under-voltage protection. The hysteresis module includes a hysteresis resistor and a fifth MOSFET; the execution module includes a third resistor and a sixth MOSFET; the control module includes a PWM control chip. The first end of the hysteresis resistor is connected to the gate of the fifth MOS transistor, the second end of the hysteresis resistor is grounded, the gate of the fifth MOS transistor is connected to the over-temperature protection module, the source of the fifth MOS transistor is grounded, and the drain of the fifth MOS transistor is connected to the over-temperature protection module and the under-voltage protection module. The gate of the sixth MOS transistor is connected to the over-temperature protection module, the source of the sixth MOS transistor is grounded, the drain of the sixth MOS transistor is connected to the dimming pin of the PWM control chip through the third resistor, and the control pin of the PWM control chip is connected to the undervoltage protection module.

2. The circuit having dual mode protection function according to claim 1, characterized in that, The over-temperature protection circuit includes: a temperature detection circuit, a first parallel circuit, and a hysteresis drive circuit; The input terminal of the temperature detection circuit is connected to the power supply line, and the output terminal of the temperature detection circuit is connected to the hysteresis drive circuit. The input terminal of the first parallel circuit is connected to the temperature detection circuit, and the output terminal of the first parallel circuit is connected to the hysteresis module. The input terminal of the hysteresis drive circuit is connected to the power supply line, and the output terminal of the hysteresis drive circuit is connected to the hysteresis module.

3. The circuit having dual mode protection function according to claim 2, characterized in that, The temperature detection circuit includes: a forty-first resistor, a thirty-ninth resistor, and a temperature sensor; The first end of the forty-first resistor is connected to the power supply line, the second end of the forty-first resistor is connected to the first end of the thirty-ninth resistor and the hysteresis drive circuit, and the second end of the thirty-ninth resistor is grounded through the temperature sensor.

4. The circuit having dual mode protection function according to claim 3, characterized in that, The temperature sensor is a thermistor with a negative temperature coefficient.

5. The circuit having dual mode protection function according to claim 3, wherein, The hysteresis drive circuit includes: a fourth resistor, a first controllable voltage regulator, a first Zener diode, and a sixth diode; the first parallel circuit includes: a first parallel resistor; The first end of the fourth resistor is connected to the power supply line, the second end of the fourth resistor is connected to the cathode of the first controllable voltage regulator, the reference electrode of the first controllable voltage regulator is connected to the second end of the forty-first resistor and the first end of the thirty-ninth resistor, and the anode of the first controllable voltage regulator is grounded; the cathode of the first Zener diode is connected to the cathode of the first controllable voltage regulator, the anode of the first Zener diode is connected to the anode of the sixth diode, the cathode of the sixth diode is connected to the hysteresis module, the first end of the first parallel resistor is connected to the second end of the forty-first resistor and the first end of the thirty-ninth resistor, and the second end of the first parallel resistor is connected to the hysteresis module.

6. The circuit having dual mode protection function according to claim 1, wherein, The undervoltage protection module includes: a voltage divider circuit, an execution drive circuit, and a second parallel circuit; The input terminal of the voltage divider circuit is connected to the output terminal of the rectifier bridge, the output terminal of the voltage divider circuit is connected to the input terminal of the execution drive circuit, the output terminal of the execution drive circuit is connected to the hysteresis module, the input terminal of the second parallel circuit is connected to the output terminal of the voltage divider circuit, and the output terminal of the second parallel circuit is connected to the hysteresis module.

7. The circuit having dual mode protection function according to claim 6, characterized in that, The voltage divider circuit includes: a first voltage divider resistor, a second voltage divider resistor, a third voltage divider resistor, a seventh diode, a fourth voltage divider resistor, and a fifth voltage divider resistor; The first voltage divider resistor, the second voltage divider resistor, the third voltage divider resistor, the seventh diode, the fourth voltage divider resistor, and the fifth voltage divider resistor are sequentially connected between the output terminal of the rectifier bridge and ground. The connection terminals of the fourth voltage divider resistor and the fifth voltage divider resistor are connected to the input terminal of the execution drive circuit.

8. The circuit having dual mode protection functionality of claim 7, wherein, The execution drive circuit includes: a fifteenth resistor, a second controllable voltage regulator, a third Zener diode, and a fifth diode; the second parallel circuit includes: a second parallel resistor; The first end of the fifteenth resistor is connected to the power supply line, the second end of the fifteenth resistor is connected to the cathode of the second controllable voltage regulator, the reference electrode of the second controllable voltage regulator is connected to the connection terminal of the fourth voltage divider resistor and the fifth voltage divider resistor, the anode of the second controllable voltage regulator is grounded, the cathode of the second controllable voltage regulator is also connected to the cathode of the third voltage regulator, the anode of the third voltage regulator is connected to the anode of the fifth diode, the cathode of the fifth diode is connected to the hysteresis module, the first end of the second parallel resistor is connected to the connection terminal of the fourth voltage divider resistor and the fifth voltage divider resistor, and the second end of the second parallel resistor is connected to the hysteresis module.

9. An LED driving power supply, characterized by, include: The circuit with dual-mode protection function as described in any one of claims 1-8.

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