Over-temperature protection circuit, LED control circuit and LED lamp

Abstract

The present invention provides an over-temperature protection circuit, an LED control circuit with the over-temperature protection circuit, and an LED lamp using the LED control circuit. The over-temperature protection circuit provided by the present invention includes a power supply; an LED load; an IC chip, the input pin is connected to the power supply, the output pin is connected to the LED load, and a first resistor is connected between the chip select pin and the GND pin; a switch circuit, including a field effect transistor; a voltage-stabilizing winding including a main coil and an auxiliary coil, the main coil is connected between the output pin of the IC chip and the load, and the same-name end of one end of the auxiliary coil and the main coil connected to the output pin of the IC chip is grounded; a thermistor circuit, one end of which is connected to the same-name end of one end of the auxiliary coil of the voltage-stabilizing winding and the main coil connected to the load, and the other end is connected to the chip select pin of the IC chip, and the resistance of the thermistor circuit decreases as the temperature rises. A freewheeling diode, the positive electrode of which is connected to the output pin of the IC chip, and the negative electrode of which is connected to the LED load.

Description

Technical Field

[0001] The present invention relates to the technical field of electronics and electrical appliances, and in particular to an over-temperature protection circuit, an LED control circuit having the over-temperature protection circuit, and an LED lamp using the LED control circuit. Background Art

[0002] Due to their many advantages such as energy saving and environmental protection, long service life, and high electro-optical conversion rate, LED lamps have gradually replaced traditional incandescent lamps and become the most widely used lighting fixtures in recent years.

[0003] Although the electro-optical conversion rate of LED lamps is much higher than that of incandescent lamps, it is inevitable that part of the electrical energy will be dissipated in the form of heat due to the operation of the LED load and the LED driver circuit. When excessive heat accumulates in the LED lamp and causes the LED load temperature to be high, it will not only cause attenuation and damage to the circuit components including the LED load, but also affect the service life of the LED lamp.

[0004] In the prior art, IC chips with over-temperature protection function are usually used to try to solve the above problem. That is, when the temperature is too high, according to the pre-written program, the IC chip will appropriately reduce the output power of the entire LED drive circuit, that is, the output power decreases as the temperature increases, thereby reducing the input power of the LED load and reducing its heating effect, thereby achieving the over-temperature protection function.

[0005] However, an IC chip designed with an over-temperature protection function needs to be configured with corresponding pins. The number of pins of the IC chip affects the cost and function of the IC chip to a certain extent, and is limited by the design of the integrated circuit structure inside the IC chip.

[0006] Therefore, it is urgent to provide a solution that can provide over-temperature protection without setting the IC chip pins with over-temperature protection function, thereby preventing continuous high temperature from damaging the circuit structure. Summary of the invention

[0007] In view of the above problems, the present invention provides an over-temperature protection circuit. By setting a thermistor circuit, the output power of the circuit can be adjusted according to the change of the temperature rise of the LED load, thereby stably and reliably realizing over-temperature protection of the circuit.

[0008] The over-temperature protection circuit provided by the present invention comprises

[0009] power supply;

[0010] LED load, one end is connected to the power supply;

[0011] The IC chip has an input pin connected to a power source, an output pin connected to an LED load, and a first resistor connected between a chip select pin and a GND pin;

[0012] A switching circuit including a field effect transistor;

[0013] A voltage stabilizing winding including a main coil and an auxiliary coil, wherein the main coil is connected between an output pin of an IC chip and a load, and an end of the auxiliary coil connected to one end of the output pin of the IC chip as the main coil is grounded;

[0014] Thermistor circuit, one end of which is connected to the auxiliary coil of the voltage-stabilizing winding and the same-name end of the main coil connected to one end of the load, and the other end is connected to the chip select pin of the IC chip. The resistance of thermistor circuit decreases as the temperature rises;

[0015] The freewheeling diode has its anode connected to the output pin of the IC chip and its cathode connected to the LED load.

[0016] According to the above circuit structure, when the LED load is working, the voltage at the chip select pin of the IC chip is a fixed value, and a fixed first resistor is connected between the chip select pin and the GND pin, so the current flowing from the chip select pin through the first resistor is a constant value.

[0017] Then, by setting a voltage stabilizing winding between the IC chip and the LED load, the main coil of the voltage stabilizing winding provides a constant output voltage for the LED load, and the auxiliary coil provides a constant voltage for the thermistor circuit. At this time, the current value of the auxiliary coil is added to the current value of the main coil to obtain the current value flowing through the first resistor from the chip select pin. Among them, the current value of the auxiliary coil is the current value in the thermistor circuit, and the current value of the main coil is the output current value of the circuit, that is, the current value flowing through the LED load.

[0018] Therefore, when, for example, an abnormal LED load or other reasons occur, such as excessive input power causing the LED load temperature to rise, or the operating temperature of the LED driver circuit is too high or the heat dissipation effect is poor, causing the heat accumulation temperature to rise, the resistance of the thermistor circuit will decrease as the temperature rises, causing the current value flowing through the thermistor circuit to increase, that is, the auxiliary coil current value to increase, and because the sum of the auxiliary coil current value and the main coil current value, that is, the current value flowing through the first resistor is a constant value, as the auxiliary coil current value increases, the main coil current value decreases, that is, the output current value of the circuit decreases. Therefore, the output power of the circuit decreases, and the output power changes with temperature. The decrease in output power reduces the heating effect of the LED driver circuit and the LED load, thereby reducing the temperature of the LED load, thereby achieving over-temperature protection for the LED load and the entire circuit.

[0019] In the technical solution of the present invention, the switch circuit including the field effect tube can detect the current value flowing from the output pin of the IC chip through the main coil of the voltage stabilizing winding. The switch circuit can be built-in and integrated in the IC chip circuit, or it can be connected between the IC chip and the main coil of the voltage stabilizing winding outside the IC chip.

[0020] In addition, in the technical solution of the present invention, the adjustable range of the circuit output power and even the adjustable range of the temperature in the circuit can be changed by changing the variation range of the thermistor circuit resistance to adapt to different circuit output requirements.

[0021] In the preferred technical solution of the present invention, the thermistor circuit is composed of a thermistor, one end of the thermistor is connected to the same end of the auxiliary coil of the voltage stabilizing winding and the main coil connected to the load, and the other end is connected to the chip select pin of the IC chip, and its resistance value can decrease with the increase of temperature, thereby changing the current in the auxiliary coil circuit of the voltage stabilizing winding and the current in the main coil circuit, so as to achieve the output power of the circuit changing with the temperature. The thermistor is used to form the thermistor circuit, the circuit structure is simple, the cost is low, and the resistance change range of the thermistor and the curve of the resistance change with temperature can be conveniently selected to adapt to different circuits.

[0022] Furthermore, in the over-temperature protection circuit provided by the preferred technical solution of the present invention, the thermistor circuit also includes a voltage-dividing resistor connected in series with the thermistor. According to the preferred technical solution of the present invention, under the premise that the voltage of the auxiliary coil connected to the thermistor remains unchanged, a voltage-dividing resistor connected in series with the thermistor is set, which can reduce the current value flowing through the thermistor to a certain extent, and prevent excessive current from destroying the temperature change characteristics of the thermistor. In addition, since the resistance value of the voltage-dividing resistor is constant and known, the voltage and current values ​​of the thermistor can be calculated by detecting and monitoring the current value or voltage value of the voltage-dividing resistor, thereby realizing the detection of the working state of the thermistor.

[0023] Furthermore, in the over-temperature protection circuit provided by the preferred technical solution of the present invention, the thermistor circuit further includes a diode, the positive electrode of which is connected to the thermistor, and the negative electrode of which is connected to the chip select pin of the IC chip. The unidirectional conductivity of the diode can ensure that the IC chip end will not output a reverse voltage to the thermistor circuit, thereby protecting the safety of the thermistor circuit.

[0024] In a preferred technical solution of the present invention, the over-temperature protection circuit also includes an amplifier circuit connected to the thermistor. Because the rated operating current of the thermistor is usually small, the shunt effect of the thermistor is limited, the variation range of the circuit output current is limited, and the adjustment range of the circuit output power is also limited. Therefore, the provision of an amplifier circuit can expand the variation range of the auxiliary coil current value, improve the shunt effect, and further expand the adjustment range of the circuit output power.

[0025] Furthermore, in the over-temperature protection circuit provided by the preferred technical solution of the present invention, the amplifier circuit includes

[0026] A current limiting resistor is connected in parallel with the thermistor circuit;

[0027] The transistor has its base connected to the thermistor circuit, its collector connected to the current limiting resistor, and its emitter connected to the chip select pin of the IC chip.

[0028] The amplifier circuit including the triode can effectively amplify the current value of the thermistor circuit, thereby expanding the adjustment range of the circuit output power. The amplifier circuit composed of the triode has a simple structure and the current amplification factor can be easily adjusted.

[0029] In the preferred technical solution of the present invention, an LED control circuit is also provided, and the LED control circuit includes any one of the above-mentioned over-temperature protection circuits. Because the over-temperature protection circuit of the present invention is adopted, the output power of the LED control circuit can change with the temperature of the LED lamp, avoiding the damage of the circuit structure caused by continuous high temperature, and realizing the function of over-temperature protection of the circuit.

[0030] In a preferred technical solution of the present invention, an LED lamp is also provided, wherein the control circuit includes any one of the short-circuit protection circuits or LED control circuits described above. The output power of the control circuit of the LED lamp can change with temperature, thereby realizing the function of over-temperature protection of the circuit and preventing continuous high temperature from damaging the circuit structure of the LED lamp and affecting the service life of the LED lamp. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 is a schematic diagram of an over-temperature protection circuit provided in Embodiment 1 of the present invention;

[0032] Figure 2 is another schematic diagram of an over-temperature protection circuit provided in Embodiment 1 of the present invention;

[0033] Figure 3 is a schematic diagram of an over-temperature protection circuit provided in Embodiment 2 of the present invention;

[0034] Figure 4 This is a schematic diagram of an over-temperature protection circuit provided in Embodiment 3 of the present invention.

[0035] Explanation of the accompanying drawings: 1-over-temperature protection circuit, 2-power supply, 3-IC chip, 31-field effect tube, 4-LED load, 51-first resistor, 52-second resistor, 53-third resistor, 54-fourth resistor, 55-fifth resistor, 6-voltage-stabilizing winding, 61-main coil, 62-auxiliary coil, 7-thermistor circuit, 71-thermistor, 72-voltage divider resistor, 73-diode, 8-freewheeling diode, 9-amplifier circuit, 91-current-limiting resistor, 92-transistor. DETAILED DESCRIPTION

[0036] The preferred embodiments of the present invention are described below with reference to the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present invention and are not intended to limit the scope of protection of the present invention. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0037] The purpose of the terms used herein is only to describe specific embodiments and is not intended to be a limitation of the present invention. When used herein, the singular forms of "one", "an" and "said / the" are also intended to include plural forms, unless the context clearly indicates another way. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise clearly and specifically limited. It should also be understood that the terms "compose" and / or "comprise" when used in this specification determine the presence of the features, integers, steps, operations, elements and / or parts, but do not exclude the presence or addition of one or more other features, integers, steps, operations, elements, parts and / or groups.

[0038] In order to fully understand the present invention, detailed steps and detailed structures will be presented in the following description to illustrate the technical solution proposed by the present invention. The preferred embodiments of the present invention are described in detail below, but in addition to these detailed descriptions, the present invention may also have other embodiments.

[0039] Embodiment 1

[0040] like Figure 1As shown, in the first embodiment of the present invention, an over-temperature protection circuit 1 is provided, and the over-temperature protection circuit 1 includes a power supply 2; an IC chip 3, an input pin HV of the IC chip 3 is connected to the power supply 2, an output pin D of the IC chip 3 is connected to the LED load 4, a first resistor 51 is connected between the chip select pin CS and the GND pin, a DVP pin is grounded through a second resistor 52, an RTH pin is grounded through a third resistor 53, and a Vadj pin is connected between a fourth resistor 54 and a fifth resistor 55 connected in series; a switch circuit (not shown), integrated in the IC chip 3, includes a field effect transistor 31, a source of the field effect transistor 31 is connected to the chip select pin CS of the IC chip 3, The drain of the field effect tube 31 is connected to the output pin D of the IC chip 3; the LED load 4 is connected to the power supply 2 at one end and to the main coil 61 of the voltage stabilizing winding 6 at the other end; the voltage stabilizing winding 6 includes a main coil 61 and an auxiliary coil 62, the main coil 61 is connected between the output pin D of the IC chip 3 and the LED load 4, and the same-name end of the auxiliary coil 62 connected to the output pin D of the IC chip 3 with the main coil 61 is grounded; the thermistor circuit 7 is connected to the same-name end of the auxiliary coil 62 of the voltage stabilizing winding 6 and the main coil 61 connected to the LED load 4 at one end, and to the chip select pin CS of the IC chip 3 at the other end, and the resistance of the thermistor circuit 7 decreases as the temperature rises. The freewheeling diode 8 is connected to the output pin D of the IC chip 3 at its positive pole and to the LED load 4 at its negative pole.

[0041] In the over-temperature protection circuit 1 provided in the first embodiment of the present invention, under normal working conditions, the voltage V CS is a fixed value, and the resistance value R of the first resistor 51 connected between the chip select pin CS and the GND pin of the IC chip 3 is 1 is also a fixed value, so it can be obtained that the current flowing through the first resistor 51 is a fixed value I R1 =V CS / R 1 .

[0042] And, if Figure 1 As shown, a voltage stabilizing winding 6 is provided in the over-temperature protection circuit 1, and m and n are the same-named terminals. The voltage stabilizing winding 6 can provide a stable voltage. Because the voltage at both ends of the LED load 4 is stable, and m and n are the same-named terminals, the voltage stabilizing winding 6 can provide a stable voltage for the thermistor circuit 7. Also, because a switch circuit (not shown) with a built-in MOS tube is connected in series between the CS terminal and the D terminal inside the IC chip 3 to detect the current flowing through the main coil 61 of the voltage stabilizing winding 6, the current flowing through the main coil 61 of the voltage stabilizing winding 6 flows from the D terminal of the IC chip 3 into the IC chip 3, and flows out from the CS terminal of the IC chip 3. Figure 1The two branches connected to the CS end of the middle chip select pin are respectively a loop that flows through the thermistor circuit 7 and the auxiliary coil 62 in sequence outside the IC chip 3, and a loop that flows through the switch circuit (not shown) connected in series between the CS end and the D end, the main coil 61 and the LED load 4 in sequence inside the IC chip 3. At the same time, the CS end of the IC chip 3 also has a loop connected to the first resistor 51. It can be seen that the current value of the auxiliary coil 62 is added to the current value of the main coil 61, which is the current I flowing through the first resistor 51. R1 The current value of the auxiliary coil 62 is the current I in the thermistor circuit 7. T , and the current value of the main coil 61 is the output current I of the circuit OUT , that is I R1 =I T +I OUT .

[0043] In summary, when, for example, the LED load 4 is abnormal or other reasons occur, such as the input power is too high or the heat dissipation effect is not good, resulting in the temperature of the LED load 4 rising, or the operating temperature of the LED drive circuit is too high or the heat dissipation effect is not good, resulting in the heat accumulation temperature rising, that is, the temperature of the over-temperature protection circuit 1 gradually rises, the resistance value R of the thermistor circuit 7 T As the temperature rises, it decreases. At this time, the voltage value provided by the auxiliary coil 62 of the voltage-stabilizing winding 6 to the thermistor circuit 7 is constant, and the current I T Increased, and because I R1 =I T +I OUT The current I flowing through the first resistor 51 R1 Constant, the output current I OUT The over-temperature protection circuit 1 reduces the output power of the circuit as the temperature rises, thereby reducing the heating effect of the LED drive circuit and the LED load 4. Therefore, the over-temperature protection circuit 1 allows the output power of the circuit to decrease as the temperature rises, reducing the heating effect, thereby preventing the circuit structure or the LED load 4 from being damaged by continuous high temperature, and realizing the function of over-temperature protection of the circuit.

[0044] Moreover, the output power of the circuit can vary with the resistance value R of the thermistor circuit 7. T The range of change can be changed by changing the resistance value R of the thermistor circuit 7 T The adjustable range can adjust the temperature variation range of the entire circuit to ensure that the circuit and its components can adapt to the requirements of different ambient temperatures.

[0045] refer to Figure 2When the IC chip 3 is not provided with a switch circuit for detecting current, the switch circuit can be connected to the outside of the IC chip 3. The source of the field effect transistor 31 of the switch circuit is connected to the chip select pin CS of the IC chip 3, the drain of the field effect transistor 31 is connected to the output pin D of the IC chip 3 and the freewheeling diode 8, and the gate of the field effect transistor 31 is connected to the gate pin GATE (not shown) of the IC chip 3. The other circuit structures and components in this embodiment are the same as those in the embodiment of the present invention. Figure 1 Thus, when there is no switch circuit for detecting current inside the IC chip 3, the switch circuit connected to the outside of the IC chip 3 can also detect the current value flowing from the output pin D of the IC chip 3 through the main coil 61 of the voltage stabilizing winding 6.

[0046] Furthermore, in the above embodiment, the switch circuit, whether built-in or external to the IC chip 3, includes the field effect transistor 31. In actual applications, the switch circuit can also use other components such as transistors to realize the function of opening and closing the circuit, which is not limited here.

[0047] In addition, the thermistor circuit 7 in this embodiment has no special restrictions on its own circuit structure or the selection of resistors. As long as the resistance value or equivalent resistance value of the thermistor circuit 7 can be reduced as the ambient temperature increases, the present invention can be implemented.

[0048] Embodiment 2

[0049] like Figure 3 As shown, as a preferred embodiment of the present invention, other circuit structures in the second embodiment of the present invention are the same as those in the first embodiment, and will not be described in detail here.

[0050] The difference between the second embodiment of the present invention and the first embodiment of the present invention is that the thermistor 7 of the over-temperature protection circuit 1 is composed of a thermistor 71, and the resistance value of the thermistor 71 is R t As the temperature rises, it decreases, and the resistance R of the thermistor circuit 7 T , as the resistance value R of thermistor 71 t The voltage value provided by the auxiliary coil 62 of the voltage-stabilizing winding 6 to the thermistor circuit 7 is constant, and the current I T Increased, and because I R1 =I T +I OUT The current I flowing through the first resistor 51 R1 Constant, the output current I OUT As a result, the output power of the circuit also decreases. Thus, the over-temperature protection circuit 1 enables the output power of the circuit to decrease as the temperature rises, thereby preventing the continuous high temperature from damaging the circuit structure, thereby achieving the function of over-temperature protection of the circuit.

[0051] The resistance variation range of the thermistor 71 and the resistance variation curve with temperature can be adjusted relatively conveniently to adapt to different circuit output requirements. In addition, the thermistor 71 is used to form the thermistor circuit 7, which has a simple circuit structure and low cost, and is convenient for large-scale application in actual production.

[0052] Preferably, in the second embodiment of the present invention, the thermistor circuit 7 of the over-temperature protection circuit 1 further includes a voltage-dividing resistor 72, which is connected in series with the thermistor 71. In the second embodiment of the present invention, under the premise that the voltage of the auxiliary coil 62 of the voltage-stabilizing winding 6 connected to the thermistor 71 remains unchanged, a voltage-dividing resistor 72 connected in series with the thermistor 71 is provided to increase the total resistance in the thermistor circuit 7, which can effectively reduce the current value in the thermistor circuit 7, protect the thermistor 71, and prevent excessive current from damaging the thermistor 71 and destroying its temperature change characteristics. Furthermore, because the sum of the voltage value of the thermistor 71 and the voltage value of the voltage-dividing resistor 72 remains unchanged, and the resistance value of the voltage-dividing resistor 72 is constant and known, the voltage value and current value of the thermistor 71 can be calculated by detecting and monitoring the current value flowing through the voltage-dividing resistor 72 or the voltage value at both ends of the voltage-dividing resistor 72, thereby realizing the detection of the working state of the thermistor 71. By detecting the voltage value and current value of the thermistor 71, the current resistance value of the thermistor 71 can be obtained, and the current temperature of the thermistor 71 can be inferred from the current resistance value of the thermistor 71. Then, the output power of the circuit can be adjusted according to the current temperature to adjust the ambient temperature, so that the circuit works at a suitable ambient temperature.

[0053] Preferably, the thermistor circuit 7 of the over-temperature protection circuit 1 in the second embodiment further includes a diode 73, whose anode is connected to the voltage-dividing resistor 72 and whose cathode is connected to the chip select pin CS of the IC chip 3. The unidirectional conductivity of the diode 73 allows the current to flow only from the thermistor circuit 7 to the IC chip 3, ensuring that the IC chip 3 will not output a reverse voltage to the thermistor circuit 7, thereby protecting the thermistor circuit 7.

[0054] Embodiment 3

[0055] refer to Figure 4 The third embodiment is a further preferred embodiment based on the first and second embodiments of the present invention. The over-temperature protection circuit 1 provided in the third embodiment further includes an amplifier circuit 9 connected to the thermistor circuit 7. The other circuit structures and components in the third embodiment of the present invention are the same as those in the first or second embodiment, and will not be described in detail here.

[0056] Because the rated working current of thermistor 71 in thermistor circuit 7 is usually small, the current value I TThe variation range of is also small, resulting in limited shunting effect of thermistor circuit 7, limited variation range of circuit output current, and thus limited adjustment range of circuit output power. Therefore, the amplifier circuit 9 provided in the over-temperature protection circuit 1 can amplify the current value I in thermistor circuit 7. T The change range of the thermistor circuit 7 is increased, thereby improving the shunting effect of the thermistor circuit 7, and further expanding the adjustment change range of the circuit output current, so as to expand the adjustable range of the circuit output power.

[0057] Preferably, in the third embodiment of the present invention, the amplifier circuit 9 includes a current limiting resistor 91 and a transistor 92. The current limiting resistor 91 is connected in parallel with the thermistor 71 and the voltage divider resistor 72 in the thermistor circuit 7; the base of the transistor 92 is connected to the thermistor 71 in the thermistor circuit 7, the collector is connected to the current limiting resistor 91, and the emitter is connected to the chip select pin CS of the IC chip 3.

[0058] In the above-mentioned over-temperature protection circuit 1, the resistance value R of the thermistor 71 is t As the temperature rises, the resistance of the voltage divider resistor 72 is constant and connected in series with the thermistor 71. The resistance of the thermistor circuit 7 is R T When the current value I in the thermistor circuit 7 decreases, T Because the rated operating current of thermistor 71 in thermistor circuit 7 is usually small, the base current of transistor 92, i.e., the current value I in thermistor circuit 7, T The range of change is also small. Through the transistor 92 with an amplification factor of β, the current value I T Can be enlarged to βI T , thereby significantly improving the variation range of the current value in the thermistor circuit 7 and improving the shunt effect of the thermistor circuit 7.

[0059] And because I R1 =βI T +I OUT The current I flowing through the first resistor 51 R1 Constant, expand the circuit output current I OUT The range of change thus expands the adjustment range of the circuit output power. Among them, the current limiting resistor 91 is connected in series in the circuit, which can also prevent the excessive current from causing damage such as breakdown to the triode 92.

[0060] Because the structure of the triode amplifier circuit is simple and the amplification factor is easy to adjust, the over-temperature protection effect of the present invention can be achieved at a simple and low cost. In addition, the triode 92 will not output a reverse voltage to the thermistor circuit 7, which also ensures the safe operation of the thermistor circuit 7.

[0061] In this embodiment, transistor 92 is used as an example for explanation. However, the structure of amplifying current in amplifier circuit 9 is not limited to one transistor 92. The same amplification effect can also be achieved through a combination of multiple transistors, or other components or circuits such as current amplifier chips.

[0062] Embodiment 4

[0063] refer to Figure 1 , 2 , 3 and 4, the fourth embodiment of the present invention further provides an LED control circuit, including any one of the over-temperature protection circuits 1 in the above-mentioned first, second and third embodiments. The output power of the LED control circuit can change with the temperature, so as to avoid the damage of the circuit structure caused by continuous high temperature, and realize the function of over-temperature protection of the circuit.

[0064] Embodiment 5

[0065] In a fifth embodiment of the present invention, an LED lamp is further provided, wherein the control circuit thereof includes any one of the over-temperature protection circuits 1 in the above-mentioned embodiments 1, 2, and 3, or the control circuit thereof is the LED control circuit in the above-mentioned embodiment 4. The output power of the LED control circuit varies with the temperature, thereby realizing the function of over-temperature protection of the circuit, and preventing the circuit structure of the LED lamp from being damaged by continuous high temperature and shortening the service life of the LED lamp.

[0066] References to "an embodiment" throughout this specification indicate that a particular feature, structure, function, or characteristic described in conjunction with that embodiment is included in at least one embodiment of the present invention. Thus, the phrase "in an embodiment" that appears in multiple places in the specification does not necessarily all refer to the same embodiment of the present invention. Moreover, the particular features, structures, functions, or characteristics may be combined in any suitable manner into one or more embodiments. For example, the first embodiment may be combined with the second embodiment as long as the two embodiments are not mutually exclusive.

[0067] So far, the technical solutions of the present invention have been described in conjunction with the accompanying drawings, but it is easy for those skilled in the art to understand that the protection scope of the present invention is obviously not limited to these specific embodiments. Without departing from the principle of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will fall within the protection scope of the present invention.

Claims

1. An over-temperature protection circuit, It is characterized in that include power supply; An LED load, one end of which is connected to the power supply; An IC chip, whose input pin is connected to the power supply, whose output pin is connected to the LED load, and whose chip select pin and GND pin are connected with a first resistor; A switch circuit, comprising a field effect transistor, wherein a source of the field effect transistor is connected to a chip select pin of the IC chip, a drain of the field effect transistor is connected to an output pin of the IC chip, and a gate is connected to a gate pin of the IC chip; A voltage stabilizing winding, comprising a main coil and an auxiliary coil, wherein the main coil is connected between the output pin of the IC chip and the load, and the auxiliary coil having the same end as the main coil connected to the output pin of the IC chip is grounded; A thermistor circuit, one end of which is connected to the auxiliary coil of the voltage stabilizing winding and the same end of which is connected to one end of the load by the main coil, and the other end of which is connected to the chip select pin of the IC chip, wherein the resistance of the thermistor circuit decreases as the temperature increases; A freewheeling diode, with an anode connected to the output pin of the IC chip and a cathode connected to the LED load.

2. The over-temperature protection circuit as claimed in claim 1, It is characterized in that The switch circuit is arranged inside the IC chip.

3. The over-temperature protection circuit as claimed in claim 1, It is characterized in that The switch circuit is connected to the outside of the IC chip.

4. The over-temperature protection circuit as claimed in claim 1, It is characterized in that The thermistor circuit includes a thermistor, and the resistance of the thermistor decreases as the temperature increases.

5. The over-temperature protection circuit as claimed in claim 4, It is characterized in that The thermistor circuit further includes a voltage dividing resistor connected in series with the thermistor.

6. The over-temperature protection circuit as claimed in claim 5, It is characterized in that The thermistor circuit further comprises a diode, the anode of the diode is connected to the thermistor, and the cathode of the diode is connected to the chip select pin of the IC chip.

7. The over-temperature protection circuit as claimed in claim 5, It is characterized in that The over-temperature protection circuit also includes an amplifier circuit connected to the thermistor circuit.

8. The over-temperature protection circuit as claimed in claim 7, It is characterized in that The amplifier circuit comprises a current limiting resistor connected in parallel with the thermistor circuit; The triode has a base connected to the thermistor circuit, a collector connected to the current limiting resistor, and an emitter connected to the chip select pin of the IC chip.

9. An LED control circuit, It is characterized in that An over-temperature protection circuit comprising any one of claims 1-8.

10. An LED lamp, It is characterized in that The control circuit thereof comprises the LED control circuit as claimed in claim 9.

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