LED driving power supply with over-temperature protection

Abstract

The embodiment of the utility model discloses an LED driving power supply with over-temperature protection. The LED driving power supply comprises an input rectification filter circuit, a voltage transformation circuit, a master control circuit, a feedback circuit, a temperature control circuit and an auxiliary power supply circuit. The voltage transformation circuit is used for converting the primary direct-current voltage output by the input rectification filter circuit into load direct-current voltage and outputting the load direct-current voltage to an LED load; the feedback circuit is connected with the voltage transformation circuit and is used for receiving the load direct current voltage and generating feedback voltage; the main control circuit is used for controlling the voltage transformation circuit to adjust the size of the load direct current voltage according to the feedback voltage; the temperature control circuit comprises a negative temperature coefficient resistor and is used for reducing the feedback voltage through the negative temperature coefficient resistor when the environment temperature rises, so that the main control circuit controls the transformation circuit to reduce the load direct current voltage; therefore, when the environment temperature is abnormally high or the power supply is in overload use, the DC voltage of the load can be reduced in time, and the over-temperature protection function is realized.

Description

Technical Field

[0001] This utility model relates to the field of LED driving technology, and in particular to an LED driving power supply with over-temperature protection. Background Technology

[0002] LED lights boast advantages such as low energy consumption, long lifespan, energy efficiency, environmental friendliness, and rich colors, making them widely used in lighting, displays, transportation, and the automotive industry. The driver power supply, as a crucial component of LED lighting fixtures, plays a vital role in their lifespan and performance. LED driver power supplies generate heat during operation, especially under overload conditions, which can significantly increase the temperature and lead to abnormally high ambient temperatures. Excessive temperatures can adversely affect many electronic components, such as electrolytic capacitors and semiconductor devices, even causing them to fail or burn out. Currently, over-temperature protection circuits in LED driver power supplies typically employ temperature-controlled switches. These switches directly shut off the LED output when the temperature is too high and restore output when the temperature drops. However, this method causes the LED to flicker repeatedly, reducing its lifespan. Utility Model Content

[0003] This utility model provides an LED driver power supply with over-temperature protection, which can promptly reduce the output load DC voltage when the ambient temperature is abnormally high or the power supply is overloaded, thereby reducing the load output power and ensuring that the power supply is not damaged, thus achieving the over-temperature protection function.

[0004] To achieve the above objectives, this utility model provides an LED driver power supply with over-temperature protection, including an input rectifier and filter circuit, a transformer circuit, a main control circuit, a feedback circuit, a temperature control circuit, and an auxiliary power supply circuit.

[0005] The input rectifier and filter circuit is used to convert the input AC voltage into a primary DC voltage;

[0006] The auxiliary power supply circuit is connected to the input rectifier and filter circuit and is used to provide operating voltage to the main control circuit.

[0007] The transformer circuit is connected to the input rectifier and filter circuit to convert the primary DC voltage into the load DC voltage and output it to the LED load.

[0008] The feedback circuit is connected to the transformer circuit and is used to receive the DC voltage of the load and generate a feedback voltage; the main control circuit is connected to the feedback circuit and the transformer circuit and is used to control the transformer circuit to adjust the magnitude of the DC voltage of the load according to the feedback voltage.

[0009] The temperature control circuit includes a negative temperature coefficient resistor. The temperature control circuit is connected to a feedback circuit. The temperature control circuit is used to reduce the feedback voltage through the negative temperature coefficient resistor when the ambient temperature rises, thereby enabling the main control circuit to control the transformer circuit to reduce the DC voltage of the load.

[0010] Furthermore, the main control circuit includes chip U1, power switch Q2, resistors R11, R13, R17, R18, RS1, RS2, diode D5, capacitor C5, and capacitor C6.

[0011] The GND pin of chip U1 is connected to the power supply ground. The FB pin of chip U1 is connected to the feedback circuit. The DEM pin of chip U1 is connected to the power supply ground through capacitor C5. The GATE pin of chip U1 is connected to one end of resistor R13. The other end of resistor R13 is connected to one end of resistor R11 and the cathode of diode D5. The other end of resistor R11, the anode of diode D5, and one end of resistor R17 are all connected to the gate of power switch Q2. The drain of power switch Q2 is connected to the transformer circuit. The source of power switch Q2 is connected to the other end of resistor R17, one end of resistor R18, one end of resistor RS1, and one end of resistor RS2. The other ends of resistors RS1 and RS2 are both connected to the power supply ground. The other end of resistor R18 and one end of capacitor C6 are both connected to the CS pin of chip U1. The other end of capacitor C6 is connected to the power supply ground. The VCC pin of chip U1 is connected to the auxiliary power supply circuit.

[0012] Furthermore, the feedback circuit includes an optocoupler, a chip U3, resistors RJ1, R19, R20, R21, R23, R28, RN1, a Zener diode DN1, capacitors C3, C7, C9, and C10.

[0013] The first end of the optocoupler is connected to the positive terminal of the Zener diode DN1 through resistor R19. The negative terminal of the Zener diode DN1 and one end of resistor RN1 are connected to the output terminal of the transformer circuit. The other end of resistor RN1 is connected to one end of resistor R20. The other end of resistor R20 is connected to one end of capacitor C7, one end of capacitor C10, one end of capacitor C9, one end of resistor R28, and the reference terminal of chip U3. The other end of resistor R28, the other end of capacitor C9, and the positive terminal of chip U3 are all connected to signal ground. The other end of capacitor C7 is connected to the second end of the optocoupler through resistor R23. The other end of capacitor C10 and the negative terminal of chip U3 are both connected to the second end of the optocoupler. Resistor R21 is connected in parallel between the first and second ends of the optocoupler. The third end of the optocoupler is connected to power ground. The fourth end of the optocoupler is connected to the FB pin of chip U1 through resistor RJ1. One end of capacitor C3 is connected to the FB pin of chip U1, and the other end is connected to power ground.

[0014] Furthermore, the temperature control circuit includes a first temperature control branch and / or a second temperature control branch;

[0015] The first temperature control branch is connected between the FB pin of chip U1 and the power ground. The first end of the second temperature control branch is connected to the output terminal of the transformer circuit. The second end of the second temperature control branch is connected to the signal ground. The third end of the second temperature control branch is connected to the reference ground of chip U3.

[0016] Furthermore, the first temperature control branch includes a negative temperature coefficient resistor R7, a resistor R8, and a resistor R16. One end of the negative temperature coefficient resistor R7 is connected to the FB pin of the chip U1, and the other end of the negative temperature coefficient resistor R7 is connected to one end of the resistor R8 and one end of the resistor R16. The other ends of the resistor R8 and the other ends of the resistor R16 are both connected to the power supply ground.

[0017] Furthermore, the second temperature control branch includes a negative temperature coefficient resistor R30, a resistor R31, a resistor R32, and a diode D8;

[0018] One end of the negative temperature coefficient resistor R30 is connected to the output terminal of the transformer circuit, the other end of the negative temperature coefficient resistor R30 is connected to one end of resistor R31, the other end of resistor R31 is connected to the positive terminal of diode D8 and one end of resistor R32, the negative terminal of diode D8 is connected to the reference ground of chip U3, and the other end of resistor R32 is connected to signal ground.

[0019] Furthermore, the transformer circuit includes a transformer, resistors R1, R2, R3, R4, R5, and R6, capacitors C1, C2, and C1A, and diodes D1, D2, D3, D4, and D7; the transformer includes a first primary coil, a second primary coil, and a secondary coil.

[0020] The first end of the first primary coil is connected to the input rectifier filter circuit, and the second end of the first primary coil is connected to the drain of the power switch Q2. Resistors R2, R3, R4, R5, capacitor C1, and capacitor C1A are all connected in parallel between the first end of the first primary coil and the cathode of diode D3. The cathodes of diodes D4 and D7 are both connected to the cathode of diode D3. The anodes of diodes D3, D4, and D7 are all connected to the second end of the first primary coil. The first end of the secondary coil is connected to one end of resistor R1, one end of resistor R6, the anode of diode D1, and the anode of diode D2. The other end of resistor R1 is connected to the other end of resistor R6 and one end of capacitor C2. The other end of capacitor C2 is connected to the cathodes of diodes D1 and D2, and the connection node is the output terminal of the transformer circuit. The second end of the secondary coil is connected to signal ground. The first end of the second primary coil is connected to the auxiliary power supply circuit, and the second end of the second primary coil is connected to power ground.

[0021] Furthermore, the auxiliary power supply circuit includes resistors R24, R25, R29, and R22, capacitor C8, capacitor CE7, and diode D6;

[0022] Resistors R24, R25, and R29 are connected in series, with one end connected to the input rectifier filter circuit and the other end connected to the VCC pin of chip U1. One end of capacitor C8, one end of capacitor CE7, and one end of resistor R22 are all connected to the VCC pin of chip U1. The other ends of capacitor C8 and capacitor CE7 are connected to the power supply ground. The other end of resistor R22 is connected to the negative terminal of diode D6, and the positive terminal of diode D6 is connected to the first end of the second primary coil.

[0023] Furthermore, the circuit also includes an output filter circuit, which includes capacitors CE2, CE3, CE4, and CE5; capacitors CE2, CE3, CE4, and CE5 are all connected in parallel between the output terminal of the transformer circuit and the second terminal of the secondary coil.

[0024] Furthermore, it also includes an input protection circuit and an EMI filter circuit. The input AC power is transmitted to the input rectifier filter circuit in sequence through the input protection circuit and the EMI filter circuit.

[0025] The input rectifier and filter circuit includes a rectifier bridge DB1, a capacitor CE1, and a capacitor CE6. The first and second input terminals of the rectifier bridge DB1 are connected to the EMI filter circuit, the first output terminal of the rectifier bridge DB1 is connected to the transformer circuit and the auxiliary power supply circuit, the second output terminal of the rectifier bridge DB1 is connected to the power supply ground, and both capacitors CE1 and CE6 are connected in parallel between the first and second output terminals of the rectifier bridge DB1.

[0026] Beneficial Effects: This utility model provides an LED driver power supply with over-temperature protection, comprising an input rectifier and filter circuit, a transformer circuit, a main control circuit, a feedback circuit, a temperature control circuit, and an auxiliary power supply circuit. The input rectifier and filter circuit converts the input AC voltage into a primary DC voltage. The auxiliary power supply circuit is connected to the input rectifier and filter circuit and provides the operating voltage to the main control circuit. The transformer circuit is connected to the input rectifier and filter circuit and converts the primary DC voltage into a load DC voltage, outputting it to the LED load. The feedback circuit is connected to the transformer circuit and receives the load DC voltage and generates a feedback voltage. The main control circuit and the feedback circuit... The circuit and transformer circuit are connected to control the transformer circuit to adjust the magnitude of the load DC voltage according to the feedback voltage; the temperature control circuit includes a negative temperature coefficient resistor, and the temperature control circuit is connected to the feedback circuit. When the ambient temperature rises, the temperature control circuit reduces the feedback voltage through the negative temperature coefficient resistor, thereby enabling the main control circuit to control the transformer circuit to reduce the load DC voltage. Thus, through the above method, the LED driver power supply of this utility model can promptly reduce the output load DC voltage when the ambient temperature is abnormally high or the power supply is overloaded, thereby reducing the load output power and ensuring that the power supply is not damaged, realizing the over-temperature protection function. Attached Figure Description

[0027] The technical solution and beneficial effects of this utility model will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0028] Figure 1 This is a schematic diagram of the structure of the LED driver power supply with over-temperature protection provided by this utility model;

[0029] Figure 2 This is a circuit diagram of a portion of the structure of the LED driver power supply provided by this utility model;

[0030] Figure 3 This is a circuit schematic diagram of the input rectifier filter circuit, input protection circuit, and EMI filter circuit provided by this utility model;

[0031] Figure 4 This is another circuit diagram of a partial structure of the LED driver power supply provided by this utility model;

[0032] Figure 5 This is another circuit diagram of a partial structure of the LED driver power supply provided by this utility model;

[0033] Figure 6 This is a circuit diagram of the load module of the LED driver power supply provided by this utility model. Detailed Implementation

[0034] Please refer to the diagram, where the same component symbols represent the same components. The principle of this utility model is illustrated by example in a suitable computing environment. The following description is based on the illustrated specific embodiments of this utility model, and should not be considered as limiting other specific embodiments not detailed herein.

[0035] See Figure 1 An embodiment of the present invention provides an LED driver power supply 100 with over-temperature protection, comprising an input rectifier and filter circuit 10, a transformer circuit 20, a main control circuit 30, a feedback circuit 40, a temperature control circuit 50, and an auxiliary power supply circuit 60.

[0036] The input rectifier and filter circuit 10 is used to convert the input AC voltage into a primary DC voltage. The AC voltage can be AC ​​mains power. The input rectifier and filter circuit 10 rectifies and filters the AC mains power and outputs the primary DC voltage.

[0037] The auxiliary power supply circuit 60 is connected to the input rectifier and filter circuit 10 and is used to provide operating voltage to the main control circuit 30.

[0038] The transformer circuit 20 is connected to the input rectifier and filter circuit 10, and is used to convert the primary DC voltage into the load DC voltage and output it to the LED load. The primary DC voltage is a high voltage, and the load DC voltage is a low voltage.

[0039] The feedback circuit 40 is connected to the transformer circuit 20 and is used to receive the DC voltage of the load and generate a feedback voltage. The main control circuit 30 is connected to the feedback circuit 40 and the transformer circuit 20 and is used to control the transformer circuit 20 to adjust the magnitude of the DC voltage of the load according to the feedback voltage provided by the feedback circuit 40, thereby achieving constant output power.

[0040] The temperature control circuit 50 includes a negative temperature coefficient resistor. The temperature control circuit 50 is connected to the feedback circuit 40. The temperature control circuit 50 is used to reduce the feedback voltage through the negative temperature coefficient resistor when the ambient temperature rises, thereby enabling the main control circuit 30 to control the transformer circuit 20 to reduce the DC voltage of the load.

[0041] Therefore, through the above method, the LED driver power supply of this utility model can reduce the output load DC voltage in a timely manner when the ambient temperature is abnormally high or the power supply is overloaded, thereby reducing the load output power, ensuring that the power supply is not damaged, and realizing the over-temperature protection function.

[0042] See Figure 2 In one embodiment of this utility model, the main control circuit 30 includes a chip U1, a power switch Q2, resistors R11, R13, R17, R18, RS1, RS2, a diode D5, a capacitor C5, and a capacitor C6.

[0043] The GND pin of chip U1 is connected to the power supply ground. The FB pin of chip U1 is connected to the feedback circuit. The DEM pin of chip U1 is connected to the power supply ground through capacitor C5. The GATE pin of chip U1 is connected to one end of resistor R13. The other end of resistor R13 is connected to one end of resistor R11 and the cathode of diode D5. The other end of resistor R11, the anode of diode D5, and one end of resistor R17 are all connected to the gate of power switch Q2. The drain of power switch Q2 is connected to the transformer circuit. The source of power switch Q2 is connected to the other end of resistor R17, one end of resistor R18, one end of resistor RS1, and one end of resistor RS2. The other ends of resistors RS1 and RS2 are both connected to the power supply ground. The other end of resistor R18 and one end of capacitor C6 are both connected to the CS pin of chip U1. The other end of capacitor C6 is connected to the power supply ground. The VCC pin of chip U1 is connected to auxiliary power supply circuit 60.

[0044] The current sampling and detection circuit consists of resistor R18, resistor RS1, resistor RS2, and capacitor C6.

[0045] Furthermore, the feedback circuit 40 includes an optocoupler, chip U3, resistors RJ1, R19, R20, R21, R23, R28, RN1, Zener diode DN1, capacitors C3, C7, C9, and C10. The optocoupler is divided into two parts, optocoupler U2A and optocoupler U2B, as shown in the figure. Chip U3 can be a TL431 chip.

[0046] The first terminal of optocoupler U2B is connected to the positive terminal of Zener diode DN1 through resistor R19. The negative terminal of Zener diode DN1 and one end of resistor RN1 are connected to the output terminal Vout of transformer circuit 20. The other end of resistor RN1 is connected to one end of resistor R20. The other end of resistor R20 is connected to one end of capacitor C7, one end of capacitor C10, one end of capacitor C9, one end of resistor R28, and the reference terminal (pin 1) of chip U3. The other end of resistor R28 is connected to the other end of capacitor C9 and chip U3. The positive terminal (pin 3) of chip U3 is connected to signal ground. The other end of capacitor C7 is connected to the second terminal of optocoupler U2B through resistor R23. The other end of capacitor C10 and the negative terminal (pin 2) of chip U3 are both connected to the second terminal of optocoupler U2B. Resistor R21 is connected in parallel between the first and second terminals of optocoupler U2B. The third terminal of optocoupler U2A is connected to power ground. The fourth terminal of optocoupler U2A is connected to the FB pin of chip U1 through resistor RJ1. One end of capacitor C3 is connected to the FB pin of chip U1, and the other end is connected to power ground.

[0047] The main control circuit 30 and feedback circuit 40 enable the LED driver power supply 100 to achieve constant power output. Specifically, chip U1 outputs a PWM control signal through its GATE pin to control the on / off state of power switch Q2. When the duty cycle of the PWM control signal increases, the load DC voltage output by transformer circuit 20 increases; when the duty cycle of the PWM control signal decreases, the load DC voltage output by transformer circuit 20 decreases. Feedback circuit 40 provides feedback on the load DC voltage to chip U1 through optocouplers U2B and U2A. If the load DC voltage increases, the feedback voltage output by optocoupler U2A to the FB pin of chip U1 decreases, thereby decreasing the duty cycle of the PWM control signal and thus lowering the load DC voltage. Conversely, if the load DC voltage decreases, the feedback voltage output by optocoupler U2A to the FB pin of chip U1 increases, thereby increasing the duty cycle of the PWM control signal and thus increasing the load DC voltage. This achieves constant power output from the LED driver power supply 100.

[0048] Continue reading Figure 2 In this embodiment, the temperature control circuit 50 includes a first temperature control branch, which is connected between the FB pin of chip U1 and the power supply ground. Specifically, the first temperature control branch includes a negative temperature coefficient resistor R7, a resistor R8, and a resistor R16. One end of the negative temperature coefficient resistor R7 is connected to the FB pin of chip U1, and the other end of the negative temperature coefficient resistor R7 is connected to one end of resistor R8 and one end of resistor R16. The other ends of resistor R8 and resistor R16 are both connected to the power supply ground.

[0049] The ambient temperature is detected by the negative temperature coefficient resistor R7. When the ambient temperature around the negative temperature coefficient resistor R7 rises, the resistance of the negative temperature coefficient resistor R7 decreases, which causes the feedback voltage received by the FB pin to decrease. This causes the duty cycle of the PWM control signal output by the GATE pin of chip U1 to decrease, thereby controlling the load DC voltage to decrease. At this time, chip U1 is in constant power mode. By adjusting the load DC voltage to decrease when the temperature rises, the output can be automatically adjusted to protect the power supply from damage, thus achieving the over-temperature protection function.

[0050] like Figure 2 As shown, the transformer circuit 20 includes a transformer, resistors R1, R2, R3, R4, R5, and R6, capacitors C1, C2, and C1A, and diodes D1, D2, D3, D4, and D7. The transformer is divided into two parts, transformer T1A and transformer T1B, as shown in the figure. Transformer T1A includes a first primary coil and a secondary coil, and transformer T1B includes a second primary coil.

[0051] The first end of the first primary coil (pin 1 of transformer T1A in the figure) is connected to the output terminal of the input rectifier filter circuit 10. The second end of the first primary coil (pin 3 of transformer T1A in the figure) is connected to the drain of the power switch Q2. Resistors R2, R3, R4, R5, capacitor C1, and capacitor C1A are all connected in parallel between the first end of the first primary coil and the cathode of diode D3. The cathodes of diodes D4 and D7 are both connected to the cathode of diode D3. The anodes of diodes D3, D4, and D7 are all connected to the second end of the first primary coil. The first end of the secondary coil (in the figure) is connected to the output terminal of the input rectifier filter circuit 10. The transformer T1A shown in the figure has its pin 10 connected to one end of resistor R1, one end of resistor R6, the positive terminal of diode D1, and the positive terminal of diode D2. The other end of resistor R1 is connected to the other end of resistor R6 and one end of capacitor C2. The other end of capacitor C2 is connected to the negative terminals of diode D1 and diode D2, and the connection node is the output terminal Vout of transformer circuit 20. The second end of the secondary coil (pin 6 of transformer T1A shown in the figure) is connected to signal ground. The first end of the second primary coil (pin 4 of transformer T1B shown in the figure) is connected to auxiliary power supply circuit 60. The second end of the second primary coil (pin 5 of transformer T1B shown in the figure) is connected to power supply ground.

[0052] Among them, resistors R2, R3, R4, R5, capacitors C1 and C1A, diodes D3, D4, and D7 can form an RCD snubber circuit. When the power switch Q2 is turned off, the transformer T1A will generate a very high reverse voltage. The RCD snubber circuit can release and absorb this reverse voltage to prevent the power switch Q2 from being damaged.

[0053] The auxiliary power supply circuit 60 includes resistors R24, R25, R29, and R22, capacitors C8 and CE7, and diode D6.

[0054] Resistors R24, R25, and R29 form the starting resistor. These three resistors are connected in series, with one end connected to the output of the input rectifier filter circuit 10 and the other end connected to the VCC pin of chip U1. One end of capacitor C8, one end of capacitor CE7, and one end of resistor R22 are all connected to the VCC pin of chip U1. The other ends of capacitor C8 and capacitor CE7 are connected to the power supply ground. The other end of resistor R22 is connected to the negative terminal of diode D6, and the positive terminal of diode D6 is connected to the first end of the second primary coil.

[0055] Furthermore, the LED driver power supply 100 also includes an output filter circuit, which includes capacitors CE2, CE3, CE4, and CE5. These capacitors are connected in parallel between the output terminal Vout of the transformer circuit 20 and the second terminal of the secondary coil. The output filter circuit filters the DC voltage output from the transformer circuit 20 and outputs it to the LED load.

[0056] See Figure 3 In this embodiment, the LED driver power supply 100 further includes an input protection circuit and an EMI filter circuit. The input AC power is transmitted to the input rectifier filter circuit through the input protection circuit and the EMI circuit in sequence. The input rectifier filter circuit 10 includes a rectifier bridge DB1, a capacitor CE1, and a capacitor CE6. The input protection circuit includes a fuse F1, a varistor RV1, and a thermistor NTC1. The EMI filter circuit includes capacitors CY4, CY5, and CX1, a resistor R26, a resistor R27, and a common-mode inductor LF1.

[0057] One end of fuse F1 is connected to the live wire L of AC voltage, and the other end is connected to one end of the thermistor NTC1. The other end of the thermistor NTC1 is connected to one end of the varistor RV1, one end of the capacitor CX1, one end of the resistor R27, the first input terminal of the common mode inductor LF1, and one end of the capacitor CY4. The other end of the resistor R27 is connected to one end of the resistor R26. The other end of the resistor R26, the second input terminal of the common mode inductor LF1, the other end of the capacitor CX1, the other end of the varistor RV1, and one end of the capacitor CY5 are all connected to the neutral wire N of AC voltage. The other ends of the capacitors CY4 and CY5 are both connected to ground PE.

[0058] The first input terminal (pin 2) and the second input terminal (pin 3) of the rectifier bridge DB1 are connected to the first output terminal and the second output terminal of the common mode inductor LF1, respectively. The first output terminal (pin 1) of the rectifier bridge DB1 is connected to the transformer circuit 20 and the auxiliary power supply circuit 60. Specifically, the first output terminal of the rectifier bridge DB1 is connected to the first end of the first primary coil (pin 1 of the transformer T1A shown in the figure). The second output terminal (pin 4) of the rectifier bridge DB1 is connected to the power supply ground. Capacitors CE1 and CE6 are connected in parallel between the first output terminal and the second output terminal of the rectifier bridge DB1.

[0059] See Figure 4 In another embodiment of this utility model, unlike the above embodiment, the temperature control circuit 50 of this embodiment includes a second temperature control branch, which includes a negative temperature coefficient resistor R30, a resistor R31, a resistor R32, and a diode D8. One end of the negative temperature coefficient resistor R30 is connected to the output terminal of the transformer circuit, the other end of the negative temperature coefficient resistor R30 is connected to one end of the resistor R31, the other end of the resistor R31 is connected to the positive terminal of the diode D8 and one end of the resistor R32, the negative terminal of the diode D8 is connected to the reference ground of the chip U3, and the other end of the resistor R32 is connected to the signal ground. The resistance value of resistor R28 is greater than the resistance value of resistor R32.

[0060] In this embodiment, the ambient temperature is detected by the negative temperature coefficient resistor R30. When the ambient temperature around the negative temperature coefficient resistor R30 gradually increases, the resistance of the negative temperature coefficient resistor R30 gradually decreases. At this time, the voltage at point A gradually increases until the voltage increases to the point that the diode D8 conducts. At this time, the detection circuit of the output load DC voltage changes from the original detection circuit composed of resistor RN1, resistor R20, resistor R28 and chip U3 to the detection circuit composed of negative temperature coefficient resistor R30, resistor R31, diode D8 and resistor R28. Since the reference voltage of chip U3 remains constant, after diode D8 conducts, as the voltage at point A increases, the voltage at the reference terminal (pin 1) of chip U3 increases. When this voltage exceeds the reference voltage of chip U3, the current flowing through optocoupler U2B increases. Consequently, through optocoupler U2A, the feedback voltage fed back to chip U1 gradually decreases, causing the duty cycle of the PWM control signal output from the GATE pin of chip U1 to gradually decrease. This controls the DC voltage of the load to continuously decrease, thus achieving a continuous decrease in the load power of the LED driver power supply when the ambient temperature rises, achieving a better protection effect for the power supply. Therefore, with the LED driver power supply 100 of this utility model, when the power supply suddenly malfunctions, resulting in a high temperature or overload, the temperature control circuit 50 can detect the temperature rise in time, thereby reducing the load power output, preventing damage to the LED driver power supply 100, and also avoiding situations such as fire caused by the LED driver power supply 100 being used in abnormal environments.

[0061] See Figure 5 In another embodiment of the LED driver power supply 100 of this utility model, the temperature control circuit 50 may simultaneously include a first temperature control branch and a second temperature control branch. The first temperature control branch and... Figure 2 The structure of the first temperature control branch shown is the same as that of the second temperature control branch. Figure 4 The second temperature control branch shown is the same. Through the function of the first and second temperature control branches, the DC voltage of the output load can be reduced when the temperature rises, thereby reducing the output power, preventing the power supply from being damaged, and achieving the function of over-temperature protection.

[0062] See Figure 6 In this embodiment of the present invention, an LED driver power supply is also provided, which further includes a load module. The load module includes resistors R9, R10, R12, R14, and R15, and a light-emitting diode LED1. The light-emitting diode LED1 is the LED load. Resistors R9, R10, R12, and R14 are all connected in parallel between the output terminal Vout of the transformer circuit 20 and the signal ground. One end of resistor R15 is connected to the output terminal Vout of the transformer circuit 20, and the other end is connected to the positive terminal of the light-emitting diode LED1. The negative terminal of the light-emitting diode LED1 is connected to the signal ground.

[0063] This document uses specific examples to illustrate the principles and implementation methods of this utility model. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of this utility model. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this utility model. Therefore, the content of this specification should not be construed as a limitation of this utility model.

Claims

1. An LED driver power supply with over-temperature protection, characterized in that, It includes an input rectifier and filter circuit, a transformer circuit, a main control circuit, a feedback circuit, a temperature control circuit, and an auxiliary power supply circuit; The input rectifier and filter circuit is used to convert the input AC voltage into a primary DC voltage; The auxiliary power supply circuit is connected to the input rectifier and filter circuit and is used to provide operating voltage to the main control circuit. The transformer circuit is connected to the input rectifier and filter circuit to convert the primary DC voltage into the load DC voltage and output it to the LED load. The feedback circuit is connected to the transformer circuit and is used to receive the DC voltage of the load and generate a feedback voltage; the main control circuit is connected to the feedback circuit and the transformer circuit and is used to control the transformer circuit to adjust the magnitude of the DC voltage of the load according to the feedback voltage. The temperature control circuit includes a negative temperature coefficient resistor. The temperature control circuit is connected to a feedback circuit. The temperature control circuit is used to reduce the feedback voltage through the negative temperature coefficient resistor when the ambient temperature rises, thereby enabling the main control circuit to control the transformer circuit to reduce the DC voltage of the load.

2. The LED driver power supply according to claim 1, characterized in that, The main control circuit includes chip U1, power switch Q2, resistors R11, R13, R17, R18, RS1, RS2, diode D5, capacitor C5, and capacitor C6. The GND pin of chip U1 is connected to the power supply ground. The FB pin of chip U1 is connected to the feedback circuit. The DEM pin of chip U1 is connected to the power supply ground through capacitor C5. The GATE pin of chip U1 is connected to one end of resistor R13. The other end of resistor R13 is connected to one end of resistor R11 and the cathode of diode D5. The other end of resistor R11, the anode of diode D5, and one end of resistor R17 are all connected to the gate of power switch Q2. The drain of power switch Q2 is connected to the transformer circuit. The source of power switch Q2 is connected to the other end of resistor R17, one end of resistor R18, one end of resistor RS1, and one end of resistor RS2. The other ends of resistors RS1 and RS2 are both connected to the power supply ground. The other end of resistor R18 and one end of capacitor C6 are both connected to the CS pin of chip U1. The other end of capacitor C6 is connected to the power supply ground. The VCC pin of chip U1 is connected to the auxiliary power supply circuit.

3. The LED driver power supply according to claim 2, characterized in that, The feedback circuit includes an optocoupler, chip U3, resistors RJ1, R19, R20, R21, R23, R28, RN1, Zener diode DN1, capacitors C3, C7, C9, and C10. The first end of the optocoupler is connected to the positive terminal of the Zener diode DN1 through resistor R19. The negative terminal of the Zener diode DN1 and one end of resistor RN1 are connected to the output terminal of the transformer circuit. The other end of resistor RN1 is connected to one end of resistor R20. The other end of resistor R20 is connected to one end of capacitor C7, one end of capacitor C10, one end of capacitor C9, one end of resistor R28, and the reference terminal of chip U3. The other end of resistor R28, the other end of capacitor C9, and the positive terminal of chip U3 are all connected to signal ground. The other end of capacitor C7 is connected to the second end of the optocoupler through resistor R23. The other end of capacitor C10 and the negative terminal of chip U3 are both connected to the second end of the optocoupler. Resistor R21 is connected in parallel between the first and second ends of the optocoupler. The third end of the optocoupler is connected to power ground. The fourth end of the optocoupler is connected to the FB pin of chip U1 through resistor RJ1. One end of capacitor C3 is connected to the FB pin of chip U1, and the other end is connected to power ground.

4. The LED driver power supply according to claim 3, characterized in that, The temperature control circuit includes a first temperature control branch and / or a second temperature control branch; The first temperature control branch is connected between the FB pin of chip U1 and the power ground. The first end of the second temperature control branch is connected to the output terminal of the transformer circuit. The second end of the second temperature control branch is connected to the signal ground. The third end of the second temperature control branch is connected to the reference ground of chip U3.

5. The LED driver power supply according to claim 4, characterized in that, The first temperature control branch includes a negative temperature coefficient resistor R7, a resistor R8, and a resistor R16. One end of the negative temperature coefficient resistor R7 is connected to the FB pin of the chip U1, and the other end of the negative temperature coefficient resistor R7 is connected to one end of the resistor R8 and one end of the resistor R16. The other ends of the resistor R8 and the other ends of the resistor R16 are both connected to the power supply ground.

6. The LED driver power supply according to claim 4, characterized in that, The second temperature control branch includes a negative temperature coefficient resistor R30, a resistor R31, a resistor R32, and a diode D8; One end of the negative temperature coefficient resistor R30 is connected to the output terminal of the transformer circuit, the other end of the negative temperature coefficient resistor R30 is connected to one end of resistor R31, the other end of resistor R31 is connected to the positive terminal of diode D8 and one end of resistor R32, the negative terminal of diode D8 is connected to the reference ground of chip U3, and the other end of resistor R32 is connected to signal ground.

7. The LED driver power supply according to claim 2, characterized in that, The transformer circuit includes a transformer, resistors R1, R2, R3, R4, R5, and R6, capacitors C1, C2, and C1A, and diodes D1, D2, D3, D4, and D7; the transformer includes a first primary coil, a second primary coil, and a secondary coil. The first end of the first primary coil is connected to the input rectifier filter circuit, and the second end of the first primary coil is connected to the drain of the power switch Q2. Resistors R2, R3, R4, R5, capacitor C1, and capacitor C1A are all connected in parallel between the first end of the first primary coil and the cathode of diode D3. The cathodes of diodes D4 and D7 are both connected to the cathode of diode D3. The anodes of diodes D3, D4, and D7 are all connected to the second end of the first primary coil. The first end of the secondary coil is connected to one end of resistor R1, one end of resistor R6, the anode of diode D1, and the anode of diode D2. The other end of resistor R1 is connected to the other end of resistor R6 and one end of capacitor C2. The other end of capacitor C2 is connected to the cathodes of diodes D1 and D2, and the connection node is the output terminal of the transformer circuit. The second end of the secondary coil is connected to signal ground. The first end of the second primary coil is connected to the auxiliary power supply circuit, and the second end of the second primary coil is connected to power ground.

8. The LED driver power supply according to claim 7, characterized in that, The auxiliary power supply circuit includes resistors R24, R25, R29, and R22, capacitors C8 and CE7, and diode D6. Resistors R24, R25, and R29 are connected in series, with one end connected to the input rectifier filter circuit and the other end connected to the VCC pin of chip U1. One end of capacitor C8, one end of capacitor CE7, and one end of resistor R22 are all connected to the VCC pin of chip U1. The other ends of capacitor C8 and capacitor CE7 are connected to the power supply ground. The other end of resistor R22 is connected to the negative terminal of diode D6, and the positive terminal of diode D6 is connected to the first end of the second primary coil.

9. The LED driver power supply according to claim 7, characterized in that, The LED driver power supply also includes an output filter circuit, which includes capacitors CE2, CE3, CE4, and CE5. Capacitors CE2, CE3, CE4, and CE5 are all connected in parallel between the output terminal of the transformer circuit and the second terminal of the secondary coil.

10. The LED driver power supply according to claim 1, characterized in that, It also includes an input protection circuit and an EMI filter circuit. The input AC power is transmitted to the input rectifier filter circuit in sequence through the input protection circuit and the EMI filter circuit. The input rectifier and filter circuit includes a rectifier bridge DB1, a capacitor CE1, and a capacitor CE6. The first and second input terminals of the rectifier bridge DB1 are connected to the EMI filter circuit, the first output terminal of the rectifier bridge DB1 is connected to the transformer circuit and the auxiliary power supply circuit, the second output terminal of the rectifier bridge DB1 is connected to the power supply ground, and both capacitors CE1 and CE6 are connected in parallel between the first and second output terminals of the rectifier bridge DB1.

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