Lighting circuit with over-temperature protection

Abstract

The present disclosure provides a lighting circuit with over-temperature protection, comprising: a lighting unit, a reference voltage generating unit for generating a reference voltage; a bias voltage adjusting unit, comprising a voltage dividing control unit and a voltage stabilizing diode, for dividing the reference voltage to generate a bias voltage, and adjusting the voltage dividing ratio based on the working temperature of the lighting unit to control the bias voltage, the voltage stabilizing diode being connected between the bias voltage and a reference potential; and a power control unit, comprising a plurality of transistors, the transistors being connected between a power control node and the reference potential, the control ends of the transistors receiving the bias voltage, for adjusting the opening degree of the transistors based on the bias voltage, and in turn controlling the working current flowing through the lighting unit. The present disclosure adjusts the voltage dividing ratio based on the working temperature of the lighting unit to control the bias voltage, so that the bias voltage decreases with the temperature rise in the case of over-temperature of the lighting unit, and in turn reduces the power of the lighting unit, achieving over-temperature protection.

Description

Technical Field

[0001] This utility model belongs to the field of vehicle control technology, specifically relating to a lighting circuit with over-temperature protection. Background Technology

[0002] The vehicle's lighting units need to adjust their brightness. For example, the turn signals inside the rearview mirrors require alternating flashes of light from LEDs, and the ADS sign lights have different brightness during the day and night. Meanwhile, the vehicle's body system directly provides PWM power. Therefore, the vehicle's lighting control system uses a PWM-based power supply method to adjust the brightness of these lighting units.

[0003] The PWM power supply means that a DC-DC switching power supply solution with higher conversion efficiency cannot be used to drive the LED. Only a linear drive circuit can be used. However, linear drive circuits are prone to overheating, which affects the normal operation of the lighting unit.

[0004] Therefore, in order to address the aforementioned technical problems, it is necessary to provide a lighting circuit with over-temperature protection. Utility Model Content

[0005] The purpose of this invention is to provide a lighting circuit with over-temperature protection, which can control the bias voltage by adjusting the voltage division ratio based on the operating temperature of the lighting unit, so that the bias voltage decreases as the temperature rises when the lighting unit is overheated, thereby reducing the power of the lighting unit and performing negative feedback regulation on the operating temperature of the lighting unit.

[0006] To achieve the above objectives, the technical solution provided by a specific embodiment of this utility model is as follows:

[0007] A lighting circuit with over-temperature protection, the lighting circuit comprising:

[0008] The lighting unit has its first end directly or indirectly connected to the input voltage, and its second end connected to the power control node.

[0009] The reference voltage generation unit is connected between the input voltage and the reference potential to generate a reference voltage;

[0010] The bias voltage adjustment unit includes a voltage divider control unit and a Zener diode. The voltage divider control unit is connected between the reference voltage and the reference potential and has a voltage divider node for generating a bias voltage at the voltage divider node based on the reference voltage and adjusting the voltage division ratio based on the operating temperature of the lighting unit to adjust the bias voltage. The Zener diode is connected between the voltage divider node and the reference potential.

[0011] The power control unit includes a plurality of transistors connected between the power control node and a reference potential. The control terminal of the transistor receives the bias voltage and is used to adjust the turn-on degree of the transistor based on the bias voltage, thereby controlling the operating current flowing through the lighting unit.

[0012] In one or more embodiments of this utility model, the reference voltage generating unit includes a voltage reference chip, a first voltage divider unit, and a first resistor matching unit;

[0013] The first terminal of the first resistor matching unit is connected to the input voltage, and the second terminal is connected to the cathode of the voltage reference chip to generate a reference voltage;

[0014] The reference terminal of the voltage reference chip is connected to the voltage divider terminal of the first voltage divider unit, the anode is connected to the reference potential, and the cathode generates a reference voltage.

[0015] The first terminal of the first voltage divider unit is connected to the cathode of the voltage reference chip, and the second terminal is connected to the reference potential.

[0016] In one or more embodiments of this utility model, the voltage divider control unit includes a first voltage divider resistor, a second voltage divider resistor, and a thermistor. The first end of the first voltage divider resistor is connected to a reference voltage, and the second end is connected to the first end of the second voltage divider resistor to form a voltage divider node. The second end of the second voltage divider resistor is connected to the first end of the thermistor, and the second end of the thermistor is connected to a reference potential.

[0017] In one or more embodiments of this utility model, the thermistor is a negative temperature coefficient thermistor.

[0018] In one or more embodiments of the present invention, the bias voltage adjustment unit further includes a first capacitor, the first end of which is connected to the voltage divider node and the second end of which is connected to a reference potential.

[0019] In one or more embodiments of the present invention, the power control unit includes a second resistor matching unit and a plurality of protection resistors. The protection resistors are connected between the control terminal of the transistor and the voltage divider node. The first terminal of the second resistor matching unit is connected to the first terminal of the transistor, and the second terminal is connected to a reference potential. The second terminal of the transistor is connected to the power control node.

[0020] In one or more embodiments of this utility model, the lighting unit includes a plurality of light-emitting devices and a plurality of second capacitors, wherein the light-emitting devices are connected in series between the input voltage and power control node, and each second capacitor is connected in parallel with the light-emitting device.

[0021] In one or more embodiments of this utility model, the lighting circuit with over-temperature protection further includes a voltage regulator unit. The voltage regulator unit includes a voltage regulator device, a filter unit, and an anti-reverse current device. The first terminal of the voltage regulator device is connected to the power supply voltage, and the second terminal is connected to the reference potential. The first terminal of the filter unit is connected to the power supply voltage, and the second terminal is connected to the reference potential. The first terminal of the anti-reverse current device is connected to the power supply voltage, and the second terminal generates an input voltage.

[0022] In one or more embodiments of this utility model, the voltage regulator includes a bidirectional TVS diode.

[0023] In one or more embodiments of this utility model, the filtering unit includes a first resistor and a plurality of third capacitors connected in series, wherein the first resistor is connected between the power supply voltage and the reference potential, and the third capacitors are connected between the power supply voltage and the reference potential.

[0024] In one or more embodiments of this utility model, the reference voltage generating unit further includes a fourth capacitor, the first end of which is connected to the reference voltage and the second end of which is connected to the reference potential.

[0025] Compared with the prior art, the lighting circuit with over-temperature protection of this utility model controls the bias voltage by adjusting the voltage division ratio of the voltage divider control unit based on the operating temperature of the lighting unit. This causes the bias voltage to decrease as the temperature rises when the lighting unit is overheated, thereby reducing the power of the lighting unit and thus reducing the operating temperature of the lighting unit, ensuring the continuous and stable operation of the lighting unit. Attached Figure Description

[0026] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a circuit diagram of a lighting circuit with over-temperature protection in one embodiment of the present invention. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solutions in this disclosure, the technical solutions in the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this disclosure, and not all embodiments. Based on the embodiments in this disclosure, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of this disclosure.

[0029] As mentioned in the background section, according to the national standard GB 5920-2024 (Optical Signaling Devices and Systems for Automobiles and Trailers) issued by the Ministry of Industry and Information Technology in 2024, all Level 3 and above automated driving vehicles are equipped with automated driving sign lights—ADS sign lights. To meet the brightness requirements of both daytime and nighttime environments, ADS sign lights implement two brightness levels. For example, the luminous intensity of the ADS sign light within the light distribution angle range is 0.3 cd, and the luminous intensity range on the reference axis is 50~300 cd during the day and 10~125 cd at night (when the distance between the headlight or fog light and the visible surface of the ADS sign light is <100mm, the luminous intensity increases to 25~125 cd).

[0030] Internal turn signals in car rearview mirrors refer to the turn signal function integrated within the rearview mirror itself. These signals are mounted on the back of the exterior rearview mirror housing or lens and use LEDs or other light sources to emit alternating bright and dim flashes to alert other vehicles and pedestrians to changes in the vehicle's direction of travel. Compared to traditional fender turn signals, internal turn signals in rearview mirrors offer better warning effectiveness because their higher position and closer proximity to the side of the vehicle make them more easily noticed by vehicles and pedestrians to the side and rear, helping to reduce the risk of accidents during lane changes and other maneuvers.

[0031] Therefore, the LEDs installed on the vehicle body need to have at least two different brightness levels. Since the vehicle body directly provides PWM power, the vehicle's lighting control system naturally chooses to adjust the brightness of these lighting units based on PWM power supply.

[0032] PWM power supply prevents the use of high-efficiency DC-DC switching power supplies to drive LEDs, forcing the selection of less efficient linear drive circuits. The inherent inefficiency of linear drive circuits leads to the generation of significant heat during operation. Within the limited installation space, this accumulated heat severely impacts the normal operating lifespan and stability of the LED light source, posing a challenge to the reliability of the entire indicator system.

[0033] To address the aforementioned technical problems, this disclosure provides a lighting circuit with over-temperature protection. By changing the bias voltage of the linear circuit at high temperatures, the current driving the lighting unit is reduced, thereby protecting the lighting unit. The lighting circuit with over-temperature protection disclosed herein specifically includes:

[0034] The lighting unit has its first end directly or indirectly connected to the input voltage, and its second end connected to the power control node.

[0035] The reference voltage generation unit is connected between the input voltage and the reference potential to generate a reference voltage;

[0036] The bias voltage adjustment unit includes a voltage divider control unit and a Zener diode. The voltage divider control unit is connected between the reference voltage and the reference potential and has a voltage divider node for generating a bias voltage at the voltage divider node based on the reference voltage and adjusting the voltage division ratio based on the operating temperature of the lighting unit to adjust the bias voltage. The Zener diode is connected between the voltage divider node and the reference potential.

[0037] The power control unit includes a plurality of transistors connected between the power control node and a reference potential. The control terminal of the transistor receives the bias voltage and is used to adjust the turn-on degree of the transistor based on the bias voltage, thereby controlling the operating current flowing through the lighting unit.

[0038] This disclosure controls the bias voltage by adjusting the voltage division ratio of the voltage divider control unit based on the operating temperature of the lighting unit. This causes the bias voltage to decrease as the temperature rises when the lighting unit is overheated, thereby reducing the power of the lighting unit and thus lowering the operating temperature of the lighting unit, ensuring that the lighting unit continues to operate stably.

[0039] The present invention will be further described below with reference to specific embodiments.

[0040] Example 1:

[0041] like Figure 1 As shown, this embodiment provides a lighting circuit with over-temperature protection, including a lighting unit 10, a reference voltage generating unit 20, a bias voltage regulating unit 30, a power control unit 40, and a voltage regulating unit 50.

[0042] The first terminal of the lighting unit 10 is connected to the input voltage ADS_IN, and the second terminal is connected to the power control node Pg.

[0043] Specifically, the lighting unit 10 in this embodiment includes a plurality of light-emitting devices and a plurality of second capacitors. The light-emitting devices are connected in series between the input voltage ADS_IN and the power control node Pg. Each second capacitor is connected in parallel with one of the light-emitting devices; it is understood that the number of light-emitting devices and second capacitors are matched. The second capacitors are used to eliminate jitter or noise, thereby stabilizing the light-emitting devices and preventing them from flickering.

[0044] The light-emitting device can be a light-emitting diode (LED). Exemplarily, the lighting unit 10 in this embodiment includes a first LED (LED1), a second LED (LED2), a first second capacitor C21, and a second second capacitor C22. The anode of the first LED (LED1) is connected to the input voltage ADS_IN and serves as the first terminal of the lighting unit 10. The cathode of the first LED (LED2) is connected to the anode of the second LED (LED2), and the cathode of the second LED (LED2) is connected to the power control node Pg and serves as the second terminal of the lighting unit 10. The first second capacitor C21 is connected in parallel with the first LED (LED1), and the second second capacitor C22 is connected in parallel with the second LED (LED2).

[0045] Furthermore, in this embodiment, the heat dissipation pin of the light-emitting device is connected to a reference potential.

[0046] Furthermore, in this embodiment, the reference potential is ground potential GND.

[0047] The reference voltage generation unit 20 is connected between the input voltage ADS_IN and the reference potential to generate the reference voltage Vref.

[0048] Furthermore, in this embodiment, the reference voltage generation unit 20 includes a voltage reference chip IC1, a first voltage divider unit 21, and a first resistor matching unit 22.

[0049] The first terminal of the first resistor matching unit 22 is connected to the input voltage ADS_IN, and the second terminal is connected to the cathode of the voltage reference chip IC1 to generate a reference voltage Vref. The reference terminal of the voltage reference chip IC1 is connected to the voltage divider terminal of the first voltage divider unit 21, with the anode connected to the reference potential and the cathode generating the reference voltage Vref. The first terminal of the first voltage divider unit 21 is connected to the cathode of the voltage reference chip IC1, and the second terminal is connected to the reference potential.

[0050] In this embodiment, the first resistor matching unit 22 includes a first matching resistor R4 and a second matching resistor R5 connected in parallel. The first end of the first matching resistor R4 and the first end of the second matching resistor R5 are connected together and serve as the first end of the first resistor matching unit 22. The second end of the first matching resistor R4 and the second end of the second matching resistor R5 are connected together and serve as the second end of the first resistor matching unit 22.

[0051] In this embodiment, the first voltage divider unit 21 includes a first voltage divider resistor R21 and a second voltage divider resistor R22. The first end of the first voltage divider resistor R21 is connected to the second end of the first resistor matching unit 22 and serves as the first end of the first voltage divider unit 21. The second end of the first voltage divider resistor R21 and the first end of the second voltage divider resistor R22 are connected and serve as the voltage divider end of the first voltage divider unit 21. The second end of the first voltage divider resistor R21 is connected to the reference potential and serves as the second end of the first voltage divider unit 21.

[0052] In this embodiment, the voltage reference chip IC1 is AN431. It is understood that in other alternative embodiments, those skilled in the art can use other models of voltage reference chip IC1 and select the total resistance value of the first matching resistor unit and the voltage division ratio of the first voltage divider unit 21 based on circuit requirements.

[0053] It is understood that the voltage reference chip IC1 is well known in the prior art and therefore will not be described in detail here. Any known or unknown voltage reference chip IC1 and high current parallel regulator can be used without restriction.

[0054] Furthermore, the reference voltage generating unit 20 in this embodiment also includes a fourth capacitor C4, the first end of the fourth capacitor C4 is connected to the first end of the first voltage divider unit 21, and the second end of the fourth capacitor C4 is connected to the reference potential.

[0055] The reference voltage generation unit 20 in this embodiment can generate a precise 5V reference voltage Vref, and significantly reduces circuit overhead compared to conventional LDO circuits.

[0056] The bias voltage adjustment unit 30 includes a voltage divider control unit 31 and a Zener diode Z1. The voltage divider control unit 31 is connected between the reference voltage Vref and the reference potential, and has a voltage divider node P1. It is used to generate a bias voltage Vbias on the voltage divider node P1 based on the reference voltage Vref, and adjust the voltage division ratio based on the operating temperature of the lighting unit 10 to adjust the bias voltage Vbias. The Zener diode Z1 is connected between the voltage divider node P1 and the reference potential.

[0057] It is understood that Zener diode Z1 is well known in the prior art and therefore will not be described in detail here. Any known or unknown Zener diode or Zener diode Z1 may be used without restriction.

[0058] The voltage divider control unit 31 in this embodiment includes a first voltage divider resistor R2, a second voltage divider resistor R3, and a thermistor NTC. The first terminal of the first voltage divider resistor R2 is connected to the reference voltage Vref, and the second terminal is connected to the first terminal of the second voltage divider resistor R3 to generate a bias voltage Vbias. The second terminal of the second voltage divider resistor R3 is connected to the first terminal of the thermistor NTC, and the second terminal of the thermistor NTC is connected to the reference potential.

[0059] Furthermore, in this embodiment, the thermistor NTC is a negative temperature coefficient thermistor, meaning that the resistance of the thermistor NTC decreases as the temperature increases.

[0060] Furthermore, the bias voltage adjustment unit 30 in this embodiment also includes a first capacitor C1. The first terminal of the first capacitor C1 is connected to the bias voltage Vbias, and the second terminal is connected to the reference potential. The first capacitor C1 provides a low-impedance path to ground potential GND for the high-frequency noise generated by the Zener diode Z1.

[0061] The power control unit 40 includes several transistors connected between the power control node Pg and the reference potential. The control terminal of the transistor receives a bias voltage Vbias and is used to adjust the turn-on degree of the transistor based on the bias voltage Vbias, thereby controlling the operating current I1 flowing through the lighting unit 10.

[0062] Furthermore, the power control unit 40 includes a second resistor matching unit 41 and several protective resistors. The protective resistors are connected between the control terminal of the transistor and the bias voltage Vbias. The first terminal of the second resistor matching unit 41 is connected to the first terminal of the transistor, and the second terminal is connected to a reference potential. The second terminal of the transistor is connected to the power control node Pg. It can be understood that the number of protective resistors matches the number of transistors, and the second resistor matching unit includes several third matching resistors connected in parallel.

[0063] Several transistors are connected in parallel, and the sum of the currents flowing through all the transistors is the operating current I1 of the lighting unit 10. The second resistor matching unit 41 is connected in series between the first terminal of the transistor and the ground potential GND. The operating current I1 can be adjusted by adjusting the total resistance of the second resistor matching unit.

[0064] For example, the power control unit 40 includes a first transistor Q1, a second transistor Q2, a third transistor Q3, a fourth transistor Q4, a first protection resistor r1, a second protection resistor r2, a third protection resistor r3, and a fourth protection resistor r4. The second resistor matching unit 41 includes four third matching resistors connected in parallel (including...). Figure 1 The first and third matching resistors R41, the second and third matching resistors R42, the third and third matching resistors R43 and R44 are shown.

[0065] The first protective resistor r1 has its first terminal connected to the bias voltage Vbias, and its second terminal connected to the control terminal of the first transistor Q1. The first terminal of the first transistor Q1 is connected to the first terminal of the second resistor matching unit 41, and its second terminal is connected to the power control node Pg. The second protective resistor r2 has its first terminal connected to the bias voltage Vbias, and its second terminal connected to the control terminal of the second transistor Q2. The first terminal of the second transistor Q2 is connected to the first terminal of the second resistor matching unit 41, and its second terminal is connected to the power control node Pg. The third protective resistor r3 has its first terminal connected to the bias voltage Vbias, and its second terminal connected to the control terminal of the third transistor Q3. The first terminal of the third transistor Q3 is connected to the first terminal of the second resistor matching unit 41, and its second terminal is connected to the power control node Pg. The fourth protective resistor r4 has its first terminal connected to the bias voltage Vbias, and its second terminal connected to the control terminal of the fourth transistor Q4. The first terminal of the fourth transistor Q4 is connected to the first terminal of the second resistor matching unit 41, and its second terminal is connected to the power control node Pg.

[0066] It is understood that this embodiment sets up several parallel transistors to share the total operating current I1, reduce the pressure on individual transistor devices, achieve power distribution, and effectively protect the stable operation of the circuit.

[0067] It should be noted that the transistors in this embodiment are all bipolar transistors, with the first terminal being the emitter, the control terminal being the base, and the second terminal being the collector.

[0068] Furthermore, the transistors in this embodiment are all NPN type transistors.

[0069] The voltage regulator unit 50 includes a voltage regulator Z2, a filter unit 51, and an anti-reverse current device D1. The first terminal of the voltage regulator Z2 is connected to the power supply voltage ADS+, and the second terminal is connected to the reference potential. The first terminal of the filter unit 51 is connected to the power supply voltage ADS+, and the second terminal is connected to the reference potential. The first terminal of the anti-reverse current device D1 is connected to the power supply voltage ADS+, and the second terminal generates the input voltage ADS_IN.

[0070] It is understandable that the power supply voltage ADS+ is the PWM power supply provided by the vehicle body, and the input voltage ADS_IN is the operating voltage of the lighting unit 10.

[0071] In this embodiment, the anti-reverse current device D1 includes a diode.

[0072] The voltage regulator Z2 includes a bidirectional TVS diode. The bidirectional TVS diode can absorb extremely high voltage pulses instantaneously, preventing overvoltage damage to subsequent circuits.

[0073] The filter unit 51 includes a first resistor R1 and several third capacitors connected in series. The first resistor R1 is connected in series between the power supply voltage ADS+ and the reference potential, and the third capacitors are connected between the power supply voltage ADS+ and the reference potential. In this embodiment, the third capacitors include a first third capacitor C31 and a second third capacitor C32 connected in series.

[0074] The working principle of this utility model includes:

[0075] Under normal operating conditions, the operating temperature of the lighting unit 10 is maintained at a normal level, and the resistance of the thermistor does not change much. That is, the voltage division ratio of the voltage divider control unit 31 is sufficient to maintain the stable operation of the Zener diode Z1. That is, the bias voltage Vbias is equal to the stable voltage Vz (i.e., the breakdown voltage) of the Zener diode Z1. Since the bias voltage Vbias is fixed, the opening degree of the first transistor to the fourth transistor is fixed. The second resistor matching unit determines the operating current I1 flowing through the LED of the lighting unit 10.

[0076] When the operating temperature of the lighting unit 10 increases (e.g., after prolonged operation or high-power operation), the resistance of the thermistor continuously decreases due to the increase in external temperature. This causes the bias voltage Vbias to continuously decrease along with the voltage division ratio of the voltage divider control unit 31. When the bias voltage Vbias is lower than the stable voltage of the Zener diode Z1, the Zener diode Z1 no longer has the voltage regulation function. The bias voltage Vbias continues to decrease, causing the turn-on degree of the first to fourth transistors to decrease. That is, the operating current I1 flowing through the lighting unit 10 decreases synchronously with the bias voltage Vbias, thereby reducing the power of the lighting unit 10, lowering the LED temperature, and ensuring that the lighting unit 10 continues to operate stably.

[0077] This invention is applicable to lighting circuits powered by PWM power supply, especially vehicle lighting devices such as turn signals and ADS lights.

[0078] As can be seen from the above technical solutions, this utility model has the following beneficial effects:

[0079] This invention uses the voltage division ratio of the voltage divider control unit based on the operating temperature of the lighting unit to control the bias voltage, so that the bias voltage decreases as the temperature rises when the lighting unit is overheated, thereby reducing the turn-on degree of the transistor and reducing the operating current of the lighting unit.

[0080] This invention achieves over-temperature protection with lower circuit costs, reduces the power and operating temperature of the lighting unit, and ensures continuous and stable operation of the lighting unit.

[0081] It will be apparent to those skilled in the art that this disclosure is not limited to the details of the exemplary embodiments described above, and that this disclosure can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of this disclosure is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this disclosure. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0082] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A lighting circuit with over-temperature protection, characterized in that, The lighting circuit includes: The lighting unit has its first end directly or indirectly connected to the input voltage, and its second end connected to the power control node. The reference voltage generation unit is connected between the input voltage and the reference potential to generate a reference voltage; The bias voltage adjustment unit includes a voltage divider control unit and a Zener diode. The voltage divider control unit is connected between a reference voltage and a reference potential and has a voltage divider node for generating a bias voltage at the voltage divider node based on the reference voltage and adjusting the voltage divider ratio based on the operating temperature of the lighting unit to adjust the bias voltage. The Zener diode is connected between the voltage divider node and the reference potential. The power control unit includes a plurality of transistors connected between the power control node and a reference potential. The control terminal of the transistor is directly or indirectly connected to the voltage divider node to receive a bias voltage, which is used to adjust the turn-on degree of the transistor based on the bias voltage, thereby controlling the operating current flowing through the lighting unit.

2. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The reference voltage generation unit includes a voltage reference chip, a first voltage divider unit, and a first resistor matching unit; The first terminal of the first resistor matching unit is connected to the input voltage, and the second terminal is connected to the cathode of the voltage reference chip to generate a reference voltage; The reference terminal of the voltage reference chip is connected to the voltage divider terminal of the first voltage divider unit, the anode is connected to the reference potential, and the cathode generates a reference voltage. The first terminal of the first voltage divider unit is connected to the cathode of the voltage reference chip, and the second terminal is connected to the reference potential.

3. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The voltage divider control unit includes a first voltage divider resistor, a second voltage divider resistor, and a thermistor. The first end of the first voltage divider resistor is connected to a reference voltage, and the second end is connected to the first end of the second voltage divider resistor to form the voltage divider node. The second end of the second voltage divider resistor is connected to the first end of the thermistor, and the second end of the thermistor is connected to a reference potential.

4. The lighting circuit with over-temperature protection according to claim 3, characterized in that, The thermistor is a negative temperature coefficient thermistor.

5. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The bias voltage adjustment unit further includes a first capacitor, with a first terminal connected to the voltage divider node and a second terminal connected to the reference potential.

6. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The power control unit includes a second resistor matching unit and several protection resistors. The protection resistors are connected between the control terminal of the transistor and the voltage divider node. The first terminal of the second resistor matching unit is connected to the first terminal of the transistor, and the second terminal is connected to the reference potential. The second terminal of the transistor is connected to the power control node.

7. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The lighting unit includes several light-emitting devices and several second capacitors. The light-emitting devices are connected in series between the input voltage and power control node, and each second capacitor is connected in parallel with the light-emitting device.

8. The lighting circuit with over-temperature protection according to claim 1, characterized in that, The lighting circuit also includes a voltage regulator unit, which includes a voltage regulator, a filter unit, and an anti-reverse current device. The first terminal of the voltage regulator is connected to the power supply voltage, and the second terminal is connected to the reference potential. The first terminal of the filter unit is connected to the power supply voltage, and the second terminal is connected to the reference potential. The first terminal of the anti-reverse current device is connected to the power supply voltage, and the second terminal generates the input voltage.

9. The lighting circuit with over-temperature protection according to claim 8, characterized in that, The voltage regulator includes a bidirectional TVS diode; and / or, The filtering unit includes a first resistor and several third capacitors connected in series. The first resistor is connected between the power supply voltage and the reference potential, and the third capacitors are connected between the power supply voltage and the reference potential.

10. The lighting circuit with over-temperature protection according to claim 8, characterized in that, The reference voltage generating unit also includes a fourth capacitor, the first end of which is connected to the reference voltage and the second end of which is connected to the reference potential.

Images