Over-temperature and overvoltage protection circuit

Abstract

The utility model relates to an over-temperature and over-voltage protection circuit which comprises a power supply circuit, a lighting circuit, an operational amplifier power supply circuit, a voltage detection circuit, a temperature detection circuit and an LED power supply circuit. The voltage detection circuit is composed of a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, an eighth resistor, a ninth resistor, a first operational amplifier, a first MOS tube, a second triode and a second voltage stabilizing diode. The temperature detection circuit is composed of a tenth resistor, an eleventh resistor, a twelfth resistor, a second operational amplifier and a thermistor. Whether the input voltage exceeds the normal working voltage or not is judged through the voltage detection circuit, whether the current temperature exceeds the rated temperature of a device or not is judged through the temperature detection circuit, whether the lamp needs to be turned on or turned off or not is judged through the two operational amplifiers, and then a signal is output to control the light-emitting diode to be turned on or turned off.

Description

Technical Field

[0001] The utility model belongs to the field of lighting circuits, and in particular relates to an over-temperature and over-voltage protection circuit. Background Art

[0002] In numerous lighting applications, lamps must adapt to a variety of complex and harsh operating environments and withstand abnormal energy shocks beyond their rated design specifications. Therefore, the quality and reliability of lamps have always been a key research and improvement topic for lighting manufacturers. Internal surges within the utility grid can be caused by the startup and shutdown of high-power equipment, line faults, and the operation of variable-frequency equipment. The sudden disconnection of a high-power appliance generates a large transient voltage, which can damage lamps. Furthermore, when the voltage is too high due to a circuit fault, components such as resistors convert electrical energy into heat, heating up and burning the circuit. Utility Model Content

[0003] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide an over-temperature and over-voltage protection circuit.

[0004] The technical solution adopted by the utility model to solve its technical problems is:

[0005] An over-temperature and over-voltage protection circuit includes a power supply circuit, a lighting circuit, an op amp power supply circuit, a voltage detection circuit, a temperature detection circuit, and an LED power supply circuit. The circuit is characterized in that: the power supply circuit is composed of a rectifier bridge, a fuse, and a varistor, wherein one end of the fuse is connected to the live wire, the other end of the fuse and one end of the varistor are connected to pin 1 of the rectifier bridge, the other end of the varistor and the neutral wire are connected to pin 3 of the rectifier bridge, and pin 4 of the rectifier bridge is grounded; the op amp power supply circuit is composed of a diode, a capacitor, an electrolytic capacitor, a voltage regulator diode, and a fuse resistor, wherein the positive electrode of the diode is connected to the rectifier bridge Pin 2, the negative electrode of the diode is connected to one end of the fuse resistor, the other end of the fuse resistor, the positive electrode of the electrolytic capacitor, the first end of the capacitor, and the negative electrode of the voltage regulator diode output a working voltage of 5.1V. The negative electrode of the electrolytic capacitor, the other end of the capacitor, and the positive electrode of the voltage regulator diode are grounded respectively; the voltage detection circuit is composed of resistor 1, resistor 2, resistor 3, resistor 4, resistor 5, resistor 6, resistor 7, resistor 8, resistor 9, operational amplifier 1, MOS tube 1, transistor 2, and voltage regulator diode 2. Among them, the first end of resistor 8, the drain of MOS tube 1, the first end of resistor 1, and the negative electrode of voltage regulator diode 2 are connected to the whole Connect the 2nd foot of the flow bridge, the other end of resistor 8 and one end of resistor 9 to pin 1 of op amp, one end of resistor 6 and one end of resistor 7 to pin 3 of op amp, the other end of resistor 6 and pin 8 of op amp are connected to the working voltage of 5.1V, pin 4 of op amp is connected to network label OUT1, the positive electrode of Zener diode 2, the other end of resistor 1 and the gate of MOS tube are connected to one end of resistor 2, the other end of resistor 2 is connected to one end of resistor 3, the other end of resistor 3 is connected to the collector of transistor 2, one end of resistor 5 and one end of resistor 4 are connected to the base of transistor, the other end of resistor 4 is connected to network label OUT2, the other end of resistor 9, The other end of resistor 7, pin 2 of op amp 1, the other end of resistor 5, and the emitter of transistor 2 are grounded. The lighting circuit consists of a light-emitting diode, electrolytic capacitor 2, and load resistor 1. The positive electrode of electrolytic capacitor 2, the first end of load resistor 1, and the source of MOS transistor 1 are connected to the positive electrode of the light-emitting diode. The negative electrode of electrolytic capacitor 2, the other end of load resistor 1, and the negative electrode of the light-emitting diode are connected to the network labeled LED-. The temperature detection circuit consists of resistor 10, resistor 11, resistor 12, op amp 2, and the thermistor. The first end of resistor 11, the first end of the thermistor, and pin 8 of op amp 2 are connected to the operating voltage 5.1V, the other end of resistor 11 and one end of resistor 12 are connected to pin 1 of op amp 2, the other end of the thermistor and the end of resistor 11 are connected to pin 3 of op amp 2, pin 4 of op amp 2 is connected to network label OUT2, the other end of resistor 12, the end of resistor 11 and pin 2 of op amp 2 are grounded respectively; the LED power supply circuit consists of control chip 1, control chip 2, control chip 3, control chip 4, control chip 5, control chip 6, equivalent resistor 1, equivalent resistor 2, equivalent resistor 3, equivalent resistor 4, equivalent resistor 5 and equivalent resistor 6 , equivalent resistor seven, equivalent resistor eight, equivalent resistor nine, equivalent resistor ten, equivalent resistor eleven, equivalent resistor twelve, resistor thirteen, resistor fourteen, and MOS tube three, among which equivalent resistor one end and equivalent resistor two end are connected to pin one of the control chip, equivalent resistor three end and equivalent resistor four end are connected to pin two of the control chip, equivalent resistor five end and equivalent resistor six end are connected to pin three of the control chip, equivalent resistor seven end and equivalent resistor eight end are connected to pin four of the control chip, equivalent resistor nine end and equivalent resistor eight end are connected to pin one of the control chip, The first end of the equivalent resistor and the eleventh end of the equivalent resistor are connected to pin 1 of control chip five. The first end of the equivalent resistor and the first end of the equivalent resistor are connected to pin 1 of control chip six. Pin 3 of control chip one, pin 3 of control chip two, pin 3 of control chip three, pin 3 of control chip four, pin 3 of control chip five, and pin 3 of control chip six are connected to the network labeled LED-. The other end of the equivalent resistor one, the other end of the equivalent resistor two, the other end of the equivalent resistor three, the other end of the equivalent resistor four, the other end of the equivalent resistor five, and the other end of the equivalent resistor six are connected to the drain of the MOS tube. The first end of resistor thirteen and the first end of resistor fourteen are connected to the gate of the MOS tube. The other end of resistor thirteen is connected to the network labeled OUT2. Pin 2 of control chip one, pin 2 of control chip two, pin 2 of control chip three, pin 2 of control chip four, pin 2 of control chip five, and pin 2 of control chip six are connected to the other end of equivalent resistor seven, the other end of equivalent resistor eight, the other end of equivalent resistor nine, the other end of equivalent resistor ten, the other end of equivalent resistor eleven, the other end of equivalent resistor twelve, the other end of resistor fourteen, and the three sources of the MOS tubes are grounded respectively.

[0006] Preferably, the operational amplifier 1 and the operational amplifier 2 are both LM321.

[0007] Preferably, the control chip one, control chip two, control chip three, control chip four, control chip five, and control chip six are all ZX9101HT.

[0008] Preferably, the model of the voltage stabilizing chip is HT7125.

[0009] Compared with the prior art, the present invention has the following advantages and effects:

[0010] 1) It can realize input voltage overvoltage protection and make the voltage recover automatically;

[0011] 2) When the environment is overheated or the circuit is damaged and causes overheating, the circuit can protect itself by reducing power and allowing the temperature to recover on its own. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a circuit diagram of the power supply circuit, operational amplifier power supply circuit, voltage detection circuit, and lighting circuit in the embodiment of the utility model.

[0013] Figure 2 Schematic diagram of the temperature detection circuit in the embodiment.

[0014] Figure 3 Schematic diagram of the LED power supply circuit in the embodiment.

[0015] The drawings described herein are used to provide further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute improper limitations on the present application. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0017] Example

[0018] like Figure 1-3 As shown, this embodiment includes a power supply circuit, a lighting circuit, an op amp power supply circuit, a voltage detection circuit, a temperature detection circuit, and an LED power supply circuit. The power supply circuit is capable of converting AC power into DC power and outputting it to the protection circuit. The power supply circuit consists of a rectifier bridge BD1, a fuse F1, and a varistor RV1. One end of the fuse F1 is connected to the live wire, the other end of the fuse F1 and one end of the varistor RV1 are connected to pin 1 of the rectifier bridge BD1, the other end of the varistor RV1 and the neutral wire are connected to pin 3 of the rectifier bridge BD1, and pin 4 of the rectifier bridge BD1 is grounded.

[0019] like Figure 1 As shown, the op amp power supply circuit consists of a diode D1, a capacitor C2, an electrolytic capacitor EC1, a Zener diode ZD1, and a fuse resistor RF1. The anode of diode D1 is connected to pin 2 of the rectifier bridge BD1, and the cathode of diode D1 is connected to one end of the fuse resistor RF1. The other end of the fuse resistor RF1, the anode of electrolytic capacitor EC1, one end of capacitor C2, and the cathode of Zener diode ZD1 output a 5.1V operating voltage. The cathode of electrolytic capacitor EC1, the other end of capacitor C2, and the anode of Zener diode ZD1 are all grounded. In this embodiment, the op amp power supply circuit is composed of a non-isolated step-down circuit, capable of providing a constant voltage of 5.1V to power both op amps.

[0020] like Figure 1As shown, the voltage detection circuit consists of resistor 1 R1, resistor 2 R2, resistor 3 R3, resistor 4 R4, resistor 5 R5, resistor 6 R6, resistor 7 R7, resistor 8 R8, resistor 9 R9, operational amplifier 1 UA1, MOS tube 1 Q1, transistor 2 Q2, and Zener diode 2 ZD2. One end of resistor 8 R8, the drain of MOS tube 1 Q1, one end of resistor 1 R1, and the negative electrode of Zener diode 2 ZD2 are connected to pin 2 of rectifier bridge BD1, the other end of resistor 8 R8 and one end of resistor 9 R9 are connected to pin 1 of operational amplifier 1 UA1, one end of resistor 6 R6 and one end of resistor 7 R7 are connected to pin 3 of operational amplifier 1 UA1, the other end of resistor 6 R6 and pin 8 of operational amplifier 1 UA1 are connected to the operating voltage 5.1V, and the operational amplifier 1 UA1 is connected to the operating voltage 5.1V. Pin 4 is connected to the network labeled OUT1. The anode of Zener diode 2 ZD2, the other end of resistor 1 R1, and the gate of MOS transistor 1 Q1 are connected to one end of resistor 2 R2. The other end of resistor 2 R2 is connected to one end of resistor 3 R3. The other end of resistor 3 R3 is connected to the collector of transistor 2 Q2. One end of resistor 5 R5 and one end of resistor 4 R4 are connected to the base of the transistor. The other end of resistor 4 R4 is connected to the network labeled OUT2. The other end of resistor 9 R9, the other end of resistor 7 R7, pin 2 of op amp 1 UA1, the other end of resistor 5 R5, and the emitter of transistor 2 Q2 are all grounded. In this embodiment, op amp 1 UA1 is an LM321. Op amp UA1 functions as a comparator. Pin 3 of Op amp UA1 is the inverting input, which is the fixed 2.55V potential of resistors R6 and R7. Pin 1 of Op amp UA1 is the non-inverting input, which is the voltage divided by resistors R8 and R9 after the positive terminal of rectifier bridge BD1. When the voltage at pin 1 of Op amp UA1 is higher than the voltage at pin 3 of Op amp UA1 (2.55V), pin 4 of Op amp UA1 outputs a high level. If the voltage at pin 1 of Op amp UA1 is lower than the voltage at pin 3 of Op amp UA1 (2.55V), pin 4 of Op amp UA1 outputs a low level. Simply put, after the voltage detection module detects the input voltage, it feeds it back to pin 1 of Op amp UA1. Op amp UA1 then compares the voltages at pins 1 and 3 of Op amp UA1 to determine the output level of network OUT1, thus implementing the overvoltage protection function.

[0021] like Figure 1 As shown, the lighting circuit consists of a light-emitting diode (LED), an electrolytic capacitor (EC2), and a load resistor (RL1). The positive electrode of the electrolytic capacitor (EC2), one end of the load resistor (RL1), and the source of the MOS transistor (Q1) are connected to the positive electrode of the LED. The negative electrode of the electrolytic capacitor (EC2), the other end of the load resistor (RL1), and the negative electrode of the LED are connected to the network labeled LED-. The load resistor (RL1) is used to reduce the voltage across the LED during standby mode, eliminating the dim light during standby mode.

[0022] like Figure 3As shown, the LED power supply circuit consists of control chip 1 U1, control chip 2 U2, control chip 3 U3, control chip 4 U4, control chip 5 U5, control chip 6 U6, equivalent resistor 1 RS1, equivalent resistor 2 RS2, equivalent resistor 3 RS3, equivalent resistor 4 RS4, equivalent resistor 5 RS5, equivalent resistor 6 RS6, equivalent resistor 7 RS7, equivalent resistor 8 RS8, equivalent resistor 9 RS9, equivalent resistor 10 RS10, equivalent resistor 11 RS11, equivalent resistor 12 RS12, resistor 13 R13, resistor 14 R14, and MOS tube 3 Q3. Among them, one end of equivalent resistor 1 RS1 and one end of equivalent resistor 2 RS2 are connected to pin 11 of control chip 1, one end of equivalent resistor 3 RS3 and one end of equivalent resistor 4 RS4 are connected to pin 1 of control chip 2 U2, and one end of equivalent resistor 5 RS5 and one end of equivalent resistor 6 RS6 are connected to control chip 3 U3 Pin 1, one end of equivalent resistor seven RS7 and one end of equivalent resistor eight RS8 are connected to pin 1 of control chip four U4, one end of equivalent resistor nine RS9 and one end of equivalent resistor eleven RS11 are connected to pin 1 of control chip five U5, one end of equivalent resistor eleven RS11 and one end of equivalent resistor twelve RS12 are connected to pin 1 of control chip six U6, pin 1 of control chip one U13, pin 3 of control chip two U2, pin 3 of control chip three U3, pin 3 of control chip four U4, pin 3 of control chip five U5, pin 3 of control chip six U6 are connected to network label LED-, the other end of equivalent resistor one RS1, the other end of equivalent resistor two RS2, the other end of equivalent resistor three RS3, the other end of equivalent resistor four RS4, the other end of equivalent resistor five RS5, and the other end of equivalent resistor six RS6 are connected to the drain of the MOS tube, one end of resistor thirteen R13 and one end of resistor fourteen R14 are connected to the gate of the MOS tube, the other end of resistor thirteen R13 is connected to network label OUT2, control chip one U1 Pin 2, pin 2 of control chip two U2, pin 2 of control chip three U3, pin 2 of control chip four U4, pin 2 of control chip five U5, pin 2 of control chip six U6, the other end of equivalent resistor seven RS7, the other end of equivalent resistor eight RS8, the other end of equivalent resistor nine RS9, the other end of equivalent resistor ten RS10, the other end of equivalent resistor eleven RS11, the other end of equivalent resistor twelve RS12, the other end of resistor fourteen R14, and the source of MOS tube three Q3 are grounded respectively.

[0023] like Figure 2As shown, the temperature detection circuit consists of resistor R10, resistor R11, resistor R12, op amp UA2, and thermistor NTC. One end of resistor R11, end of thermistor NTC R1, and pin UA28 of op amp 2 are connected to the operating voltage 5.1V, the other end of resistor R11 and one end of resistor R12 are connected to pin UA21 of op amp 2, the other end of the thermistor NTC and end of resistor R11 are connected to pin UA23 of op amp 2, pin UA24 of op amp 2 is connected to network label OUT2, and the other end of resistor R12, end of resistor R11, and pin UA22 of op amp 2 are grounded respectively.

[0024] In this embodiment, op amp UA2 is an LM321. Op amp UA2 functions as a comparator. Pin UA21 of op amp 2 is the non-inverting input, which is the fixed potential of resistors R11 and R12 at 4.51V. Pin UA23 of op amp 2 is the inverting input, which is the voltage divided by the thermistor NTC and resistor R10. Specifically, when the non-inverting input of pin UA23 of op amp 2 is higher than the potential of pin UA21 of op amp 2 (4.51V), pin UA24 of op amp 2 outputs a low level to network labeled OUT2. If the non-inverting input of pin UA23 of op amp 2 is lower than the potential of pin UA21 of op amp 2 (4.51V), pin UA24 of op amp 2 outputs a high level to network labeled OUT2. Simply put, after the temperature detection circuit detects the temperature, it compares the potentials of pins UA21 and UA23 of op amp 2 to determine the output level of network labeled OUT2. In the LED power supply module, driver chip 1, driver chip 2, and driver chip 3 are controlled by MOS tube 3 Q3, while driver chip 4, driver chip 5, and driver chip 6 are not controlled. When the output level of network label OUT2 is low, driver chip 1, driver chip 2, and driver chip 3 do not work, while driver chip 4, driver chip 5, and driver chip 6 work normally, thereby realizing the function of over-temperature power reduction.

[0025] In the temperature detection circuit, operational amplifier UA2 determines the output level of network label OUT2 by comparing the voltage divider of thermistor NTC with the reference potential. The output level of network label OUT2 is connected to MOS tube Q3 as a switch tube to control driver chip 1, driver chip 2, and driver chip 3 to achieve the function of over-temperature power reduction.

[0026] In this embodiment, both the operational amplifier UA1 and the operational amplifier UA2 are LM321; the voltage regulator chip is HT7125.

[0027] The above contents described in this specification are merely examples of the present invention. Those skilled in the art of the present invention may make various modifications, additions, or substitute similar methods to the specific embodiments described, as long as they do not deviate from the contents of this specification or exceed the scope defined by the claims, and shall fall within the scope of protection of the present invention.

Claims

1. An over-temperature and over-voltage protection circuit, comprising a power supply circuit, a lighting circuit, an operational amplifier power supply circuit, a voltage detection circuit, a temperature detection circuit, and an LED power supply circuit, characterized in that: The power supply circuit consists of a rectifier bridge, a fuse, and a varistor. One end of the fuse is connected to the live wire, the other end of the fuse and one end of the varistor are connected to pin 1 of the rectifier bridge, the other end of the varistor and the neutral wire are connected to pin 3 of the rectifier bridge, and pin 4 of the rectifier bridge is grounded. The op amp power supply circuit consists of diode 1, capacitor 2, electrolytic capacitor 1, voltage regulator diode 1, and a fuse resistor. The positive electrode of diode 1 is connected to pin 2 of the rectifier bridge, the negative electrode of diode 1 is connected to one end of the fuse resistor, the other end of the fuse resistor, the positive electrode of electrolytic capacitor 1, one end of capacitor 2, and the negative electrode of voltage regulator diode 1 output a working voltage of 5.1V. The negative electrode of electrolytic capacitor 1, the other end of capacitor 2, and the positive electrode of voltage regulator diode 1 are grounded respectively. The voltage detection circuit consists of resistor 1, resistor 2, resistor 3, resistor 4, resistor 5, resistor 6, resistor 7, resistor 8, resistor 9, op amp 1, MOS tube 1, transistor 2, and Zener diode 2. One end of resistor 8, the drain of MOS tube 1, one end of resistor 1, and the negative electrode of Zener diode 2 are connected to pin 2 of the rectifier bridge, the other end of resistor 8 and one end of resistor 9 are connected to pin 1 of op amp 1, one end of resistor 6 and one end of resistor 7 are connected to pin 3 of op amp 1, the other end of resistor 6 and pin 8 of op amp 1 are connected to the operating voltage of 5.1V, pin 4 of op amp 1 is connected to network label OUT1, the positive electrode of Zener diode 2, the other end of resistor 1, and the gate of MOS tube 1 are connected to one end of resistor 2, the other end of resistor 2 is connected to one end of resistor 3, the other end of resistor 3 is connected to the collector of transistor 2, one end of resistor 5 and one end of resistor 4 are connected to the base of transistor, the other end of resistor 4 is connected to network label OUT2, the other end of resistor 9, the other end of resistor 7, pin 2 of op amp 1, the other end of resistor 5, and the emitter of transistor 2 are grounded respectively. The lighting circuit consists of a light-emitting diode, two electrolytic capacitors, and a load resistor. The positive electrode of the second electrolytic capacitor, one end of the load resistor, and the source of the MOS tube are connected to the positive electrode of the light-emitting diode. The negative electrode of the second electrolytic capacitor, the other end of the load resistor, and the negative electrode of the light-emitting diode are connected to the network labeled LED-. The temperature detection circuit is composed of resistor 10, resistor 11, resistor 12, op amp 2, and a thermistor. One end of resistor 11, one end of the thermistor, and pin 8 of op amp 2 are connected to the working voltage of 5.1V. The other end of resistor 11 and one end of resistor 12 are connected to pin 1 of op amp 2. The other end of the thermistor and the end of resistor 11 are connected to pin 3 of op amp 2. Pin 4 of op amp 2 is connected to the network label OUT2. The other end of resistor 12, the end of resistor 11, and pin 2 of op amp 2 are grounded respectively. The LED power supply circuit consists of control chip 1, control chip 2, control chip 3, control chip 4, control chip 5, control chip 6, equivalent resistor 1, equivalent resistor 2, equivalent resistor 3, equivalent resistor 4, equivalent resistor 5, equivalent resistor 6, equivalent resistor 7, equivalent resistor 8, equivalent resistor 9, equivalent resistor 10, equivalent resistor 11, equivalent resistor 12, resistor 13, resistor 14, and MOS tube 3. Among them, the first end of equivalent resistor 1 and the first end of equivalent resistor 2 are connected to pin 1 of control chip 1, the first end of equivalent resistor 3 and the first end of equivalent resistor 4 are connected to pin 1 of control chip 2, the first end of equivalent resistor 5 and the first end of equivalent resistor 6 are connected to pin 1 of control chip 3, the first end of equivalent resistor 7 and the first end of equivalent resistor 8 are connected to pin 1 of control chip 4, the first end of equivalent resistor 9 and the first end of equivalent resistor 11 are connected to pin 1 of control chip 5, and the first end of equivalent resistor 11 and the first end of equivalent resistor 12 are connected to control chip 6 Pin 1, pin 3 of control chip 1, pin 3 of control chip 2, pin 3 of control chip 3, pin 3 of control chip 4, pin 3 of control chip 5, and pin 3 of control chip 6 are connected to the network label LED-, the other end of equivalent resistor 1, the other end of equivalent resistor 2, the other end of equivalent resistor 3, the other end of equivalent resistor 4, the other end of equivalent resistor 5, and the other end of equivalent resistor 6 are connected to the drain of the MOS tube, one end of resistor 13 and one end of resistor 14 are connected to the gate of the MOS tube, the other end of resistor 13 is connected to the network label OUT2, pin 2 of control chip 1, pin 2 of control chip 2, pin 2 of control chip 3, pin 2 of control chip 4, pin 2 of control chip 5, pin 2 of control chip 6, the other end of equivalent resistor 7, the other end of equivalent resistor 8, the other end of equivalent resistor 9, the other end of equivalent resistor 10, the other end of equivalent resistor 11, the other end of equivalent resistor 12, the other end of resistor 14, and the three sources of the MOS tube are grounded respectively.

2. The over-temperature and over-voltage protection circuit according to claim 1, wherein: The operational amplifier 1 and the operational amplifier 2 are both LM321.

3. The over-temperature and over-voltage protection circuit according to claim 1, wherein: The control chip 1, control chip 2, control chip 3, control chip 4, control chip 5 and control chip 6 are all ZX9101HT.

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