Protection circuit and vehicle lamp device

Abstract

The utility model provides a protection circuit and a vehicle lamp device, and the low-voltage protection module carries out the voltage division of an input voltage through a first resistor and a second resistor, and then provides the divided input voltage to the inverted input end of a comparator, and also provides the input voltage to the in-phase input end of the comparator through a voltage stabilizing diode. When the input voltage provided by the driving power supply is normal, the Zener diode is conducted, the in-phase input end voltage of the comparator is higher than the inverted input end voltage after voltage division, the lamp panel can be normally grounded, and when the voltage of the driving power supply is lower than the conduction voltage of the Zener diode, the output signal of the comparator is overturned, and the switching transistor is switched off. A conductive loop of the lamp panel can be automatically turned off, and lamp turn-off power-off protection is achieved. The protection circuit and the vehicle lamp device provided by the utility model are simple and effective in structure, can effectively reduce the low-voltage protection cost of the vehicle lamp power supply, and reduces the overall implementation cost of the vehicle lamp.

Description

Technical Field

[0001] The utility model relates to the technical field of power protection, and particularly relates to a protection circuit and a vehicle lamp device. Background Art

[0002] In the era of rapid development of current automotive lighting technology, LED (light emitting diode) lighting gradually occupies a dominant position in vehicle lighting due to its characteristics of energy conservation, environmental protection, long service life, and rapid response.

[0003] There is a risk that the traditional manual control switch may forget to turn off the vehicle lamp, resulting in over-discharge of the battery, which poses a threat to the starting performance of the vehicle and even the service life of the battery. Although the power consumption of the LED is lower than that of the traditional vehicle lamp, forgetting to turn off the vehicle lamp still has the risk of causing over-discharge of the battery.

[0004] Therefore, in the prior art, an integrated chip is generally used to intelligently monitor the battery voltage to ensure that the LED lighting power supply is automatically cut off before the electric energy drops to a safe threshold, thereby effectively preventing deep discharge of the battery. However, the integrated chip is often very expensive and the circuit is relatively complex, which increases the overall cost of the vehicle lamp in actual production and reduces the market competitiveness. Summary of the Utility Model

[0005] Based on this, the purpose of the utility model is to provide a protection circuit and a vehicle lamp device to solve the problem that the implementation cost of low-voltage protection of the battery in the prior art is relatively high, which increases the overall cost of the vehicle lamp and reduces the market competitiveness.

[0006] On the one hand, the utility model provides a protection circuit for low-voltage protection of a vehicle lamp power supply. The protection circuit includes a power input module and a low-voltage protection module connected to a lamp board. Among them,

[0007] The input end of the power input module is connected to a driving power supply, and the output end of the power input module is connected to the positive end of the lamp board;

[0008] The low-voltage protection module includes a comparator, a zener diode, a switching transistor, a first resistor, and a second resistor. The switching transistor is connected in series between the negative end of the lamp board and the ground. The output end of the comparator is connected to the control end of the switching transistor. The zener diode is connected between the output end of the power input module and the non-inverting input end of the comparator. The first resistor and the second resistor are connected in series between the output end of the power input module and the ground in sequence, and the middle node of the first resistor and the second resistor is connected to the inverting input end of the comparator.

[0009] Optionally, the low-voltage protection module further includes a third resistor, which is connected in series between the output end of the power input module and the output end of the comparator.

[0010] Optionally, the power input module includes a first diode connected in series between the input end and the output end of the power input module.

[0011] Optionally, the power input module further includes a transient diode connected between the input end of the power input module and the ground.

[0012] Optionally, the power input module further includes a first capacitor connected between the input end of the power input module and the ground.

[0013] Optionally, the switching transistor includes an NMOS transistor or an insulated gate bipolar transistor.

[0014] The present utility model also provides a vehicle lamp device, which includes a lamp board and the above-mentioned protection circuit.

[0015] Optionally, the lamp board includes a third resistor and a lamp string connected in sequence between the positive end and the negative end of the lamp board, and the lamp string includes light-emitting diodes.

[0016] Optionally, the lamp board further includes a second capacitor connected in parallel with the lamp string.

[0017] The protection circuit provided by the present utility model is used for low-voltage protection of a vehicle lamp power supply. It includes a power input module and a low-voltage protection module connected to the lamp board. Among them, on the one hand, the low-voltage protection module divides and samples the output voltage provided by the power input module through a first resistor and a second resistor, and provides the sampling signal to the inverting input end of the comparator. On the other hand, it connects the output end of the power input module to the non-inverting input end of the comparator through a voltage-regulator diode. When the power supply voltage drops to the conduction voltage of the voltage-regulator diode, the voltage at the non-inverting input end of the comparator becomes zero, the voltage at the inverting input end decreases, and a logic low level is output to control the switching transistor to turn off. It can automatically turn off the lamp board when the power supply voltage is lower than the set voltage, avoiding the situation that the user forgets to turn off the power supply, resulting in the lamp board continuously consuming the power supply and causing power feed. When the power supply voltage reaches the conduction voltage of the voltage-regulator diode, the voltage at the non-inverting input end of the comparator is greater than the voltage at the inverting input end after voltage division, and the conduction of the switching transistor can be maintained to ensure the normal operation of the lamp board. The protection circuit provided by the present utility model has a simple and effective structure, can effectively reduce the cost of low-voltage protection of the vehicle lamp power supply, and reduce the overall implementation cost of the vehicle lamp.

[0018] The vehicle lamp device provided by the present utility model includes the above-mentioned protection circuit, and the overall structure is simple and effective, which can effectively reduce the cost of low-voltage protection of the vehicle lamp power supply and reduce the overall implementation cost of the vehicle lamp. Description of the Drawings

[0019] Figure 1 This is a schematic diagram of the circuit structure of the protection circuit in the present utility model.

[0020] The following specific embodiments will further illustrate the present utility model in conjunction with the above-mentioned drawings. Specific Embodiments

[0021] To facilitate the understanding of the present utility model, the present utility model will be described more comprehensively below with reference to the relevant drawings. Several embodiments of the present utility model are given in the drawings. However, the present utility model can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present utility model more thorough and comprehensive.

[0022] It should be noted that when an element is referred to as being "fixedly provided on" another element, it can be directly on the other element or there may also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present utility model belongs. The terms used in the description of the present utility model herein are only for the purpose of describing specific embodiments and are not intended to limit the present utility model. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0024] To solve the problem that the implementation cost of battery low-voltage protection in the prior art is relatively high, which increases the overall cost of the vehicle lamp and reduces the market competitiveness. The utility model provides a protection circuit for low-voltage protection of the vehicle lamp power supply, including a power input module and a low-voltage protection module connected to the lamp board. Among them, on the one hand, the low-voltage protection module divides the output voltage provided by the power input module through a first resistor and a second resistor for sampling, and provides the sampling signal to the inverting input terminal of the comparator. On the other hand, it connects the output terminal of the power input module to the non-inverting input terminal of the comparator through a voltage-regulator diode. When the power supply voltage drops to the conduction voltage of the voltage-regulator diode, the voltage at the non-inverting input terminal of the comparator becomes zero, the voltage at the inverting input terminal decreases, and a logic low level is output to control the switch transistor to turn off, which can automatically turn off the lamp board when the power supply voltage is lower than the set voltage, avoiding the lamp board continuously consuming the power of the power supply due to the user forgetting to turn off the power, resulting in power feed. When the power supply voltage reaches the conduction voltage of the voltage-regulator diode, the voltage at the non-inverting input terminal of the comparator is greater than the voltage at the inverting input terminal after voltage division, which can maintain the conduction of the switch transistor and ensure the normal operation of the lamp board. The overall structure is simple and effective, which can effectively reduce the low-voltage protection cost of the vehicle lamp power supply and the overall implementation cost of the vehicle lamp.

[0025] Specifically, as Figure 1 shown, it is a schematic circuit diagram of the protection circuit in the utility model. The protection circuit in this embodiment mainly includes a power input module 10 and a low-voltage protection module 20 connected to the lamp board 01. The input terminal of the power input module 10 is connected to the driving power supply VCC, and the output terminal of the power input module 10 is connected to the positive terminal of the lamp board 01, which is used to provide a stable DC voltage supply for the lamp board 01. The low-voltage protection module 20 is connected to the output terminal of the power input module 10, and is used to turn off the conductive circuit of the lamp board 01 when the DC voltage provided by the power input module is lower than the set threshold, avoiding it from continuing to consume the power of the driving power supply VCC and causing power feed of the driving power supply.

[0026] The low-voltage protection module 20 includes a comparator U1, a voltage-regulator diode D3, a switch transistor Q1, a first resistor R1 and a second resistor R2. The switch transistor Q1 is connected in series between the negative terminal of the lamp board 01 and the ground. The output terminal of the comparator U1 is connected to the control terminal of the switch transistor Q1. The voltage-regulator diode D3 is connected between the output terminal of the power input module 10 and the non-inverting input terminal of the comparator U1. The first resistor R1 and the second resistor R2 are connected in series between the output terminal of the power input module 10 and the ground in sequence, and the middle node of the first resistor R1 and the second resistor R2 is connected to the inverting input terminal of the comparator U1.

[0027] When the power of the driving power supply VCC is sufficient, the driving voltage is greater than the conduction voltage of the zener diode D3. After subtracting the voltage drop of the zener diode D3 from the driving voltage, it acts on the non-inverting input terminal of the comparator U1. On the zero path, the driving voltage is divided by the first resistor R1 and the second resistor R2 and then acts on the inverting input terminal of the comparator U1, and the divided voltage is less than the voltage after the voltage drop of the zener diode D3. Thus, when the power of the driving power supply VCC is sufficient, the voltage applied to the non-inverting input terminal of the comparator U1 is greater than the voltage applied to the inverting input terminal. The comparator U1 outputs a logic high level, which satisfies the conduction condition of the switching transistor Q1, and can control the switching transistor Q1 to conduct, and the ground circuit of the lamp board 01 is connected. When the driving power supply VCC supplies power to the lamp board 01, the lamp board 01 can be normally lit. Among them, to ensure the lighting control under normal conditions, the voltage division ratio of the first resistor R1 and the second resistor R2 needs to be specifically set according to the voltage of the driving power supply VCC and the voltage drop of the zener diode D3.

[0028] In implementation, for example, the driving power supply is a 12V standard power supply, the output voltage under load is 13V, the conduction voltage of the zener diode is of 12V standard, and the conduction voltage drop is 0.7V. Then, during normal operation, the zener diode can conduct normally. The voltage applied to the non-inverting input terminal of the comparator is 12.3V. When the power of the driving power supply decreases and the output voltage drops below 12.7V, the zener diode turns off, and low-voltage protection can be triggered. In practical applications, the specific specifications of the zener diode can be selected according to the specific specifications of the driving power supply and the protection voltage. Without special limitation on its specific parameter selection as long as it can meet the low-voltage protection logic of this application.

[0029] When the power of the driving power supply VCC is lower than the set value, the supplied voltage no longer satisfies the conduction condition of the zener diode D3, and the zener diode D3 turns off. The non-inverting input terminal of the comparator U1 loses power, while the inverting input terminal still has a certain voltage. The voltage applied to the non-inverting input terminal is less than the voltage applied to the inverting input terminal. The comparator U1 outputs a logic low level, and the switching transistor Q1 turns off, thus realizing automatic turning off of the light when the driving voltage VCC is low.

[0030] Among them, the high bias voltage (the voltage of the logic high level) and the low bias voltage (the voltage of the logic low level) of the comparator U1 can be specifically selected according to the conduction condition of the actually selected switching transistor, and this application does not make special limitations on this. For example, the high bias voltage can be selected as the supply voltage of the driving power supply, and the low bias voltage can be selected as the ground. A boost voltage regulator circuit or a buck voltage regulator circuit can also be set to boost or buck the supply voltage of the driving power supply and then provide the high bias voltage, which can improve the stability of the high bias voltage and ensure the reliability of control.

[0031] In a specific example, the high-level bias voltage is directly provided by the driving power supply, and there is no voltage stabilizing circuit to regulate the high-level bias voltage. It can change with the change of the supply voltage of the driving power supply. When the supply voltage of the driving power supply drops to a certain value, even if the zener diode D3 remains conducting, the logic high level output by the comparator U1 is not sufficient to control the switching transistor Q1 to conduct, and the low-voltage automatic shutdown of the lamp board can be achieved. In this way, when the zener diode D3 has a short-circuit fault, a certain low-voltage protection ability can be maintained, avoiding the continuous discharge of the driving power supply resulting in power shortage and affecting the vehicle starting ability.

[0032] To improve the reliability of low-voltage protection, in this embodiment, the low-voltage protection module 20 further includes a third resistor R3. The third resistor R3 is connected in series between the output terminal of the power input module 10 and the output terminal of the comparator U1, which can suppress the output oscillation of the comparator and reduce the risk of abnormal inversion of the output state of the comparator U1 caused by power supply fluctuations, thereby improving the accuracy and reliability of low-voltage protection and reducing the risk of power supply fluctuations interfering with the normal operation of the lamp board 01.

[0033] To ensure the stability of the supply voltage, in this embodiment, the power input module 10 includes a first diode D1 connected in series between the input terminal and the output terminal of the power input module 10, which can ensure the DC characteristics of the voltage output to the rear end and reduce the risk of damage to the LED caused by reverse power supply interference.

[0034] To further enhance the protection ability, in this embodiment, the power input module 10 further includes a transient diode D2 connected between the input terminal of the power input module 10 and the ground. When the driving power supply is interfered and an overvoltage anomaly occurs, the transient diode D2 conducts, which can avoid damage to the rear-end lamp board 01 caused by the overvoltage anomaly.

[0035] To improve the working stability, in this embodiment, the power input module 10 further includes a first capacitor C1 connected between the input terminal of the power input module 10 and the ground, which can reduce the risk of AC interference in the driving power supply being transmitted to the rear end, improve the stability of the voltage supplied by the power input module 10 to the rear end, and ensure the working reliability of the low-voltage protection module 20 and the lamp board 01.

[0036] The switching transistor Q1, which conducts corresponding to the logic high level, can be an NMOS transistor or an insulated gate bipolar transistor. When the system loses power, it can remain in the off state, avoiding the safety of the lamp board 01 being affected by interference factors such as static electricity when the system loses power.

[0037] The present utility model further provides a vehicle lamp device, which includes a lamp board 01 and the above protection circuit. When the driving power supply voltage is too low, the protection circuit can automatically cut off the grounding loop of the lamp board 01, achieving automatic power-off when the driving power supply is under-voltage, and avoiding the problem that the user forgets to turn off the lamp, resulting in continuous consumption of the driving power supply by the lamp board 01, leading to power feed of the driving power supply and affecting vehicle starting.

[0038] To improve the working reliability of the lamp board 01, in this embodiment, the lamp board 01 includes a third resistor R3 and a lamp string connected in sequence between the positive end and the negative end of the lamp board 01. The lamp string includes light-emitting diodes LED. The third resistor R3 can limit the magnitude of the driving current and avoid burning out the light-emitting diodes in the lamp string due to overcurrent.

[0039] To reduce AC interference, the lamp board 01 further includes a second capacitor C2 connected in parallel with the lamp string. The second capacitor C2 can bypass the lamp string with the AC interference signal, avoiding damage to the light-emitting diodes in the lamp string caused by the reverse current in the AC interference.

[0040] The protection circuit and the vehicle lamp device provided by this application achieve low-voltage power-off protection based on the characteristics of the zener diode. The circuit structure is simple and effective, which can effectively reduce the low-voltage protection cost of the vehicle lamp power supply and the overall implementation cost of the vehicle lamp.

[0041] In the description of this specification, the description with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present utility model. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0042] The above-described embodiments only represent several specific implementation manners of the present utility model. The description is relatively specific and detailed, but it should not be construed as a limitation on the scope of the patent of the present utility model. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present utility model, several modifications and improvements can still be made, and these all belong to the protection scope of the present utility model. Therefore, the protection scope of the patent of the present utility model should be subject to the appended claims.

Claims

1. A protection circuit for low-voltage protection of a vehicle lamp power supply, characterized in that, The protection circuit includes a power input module and a low-voltage protection module connected to the lamp board. Among them, the input end of the power input module is connected to the driving power supply, and the output end of the power input module is connected to the positive end of the lamp board; the low-voltage protection module includes a comparator, a zener diode, a switching transistor, a first resistor and a second resistor. The switching transistor is connected in series between the negative end of the lamp board and the ground. The output end of the comparator is connected to the control end of the switching transistor. The zener diode is connected between the output end of the power input module and the non-inverting input end of the comparator. The first resistor and the second resistor are connected in series between the output end of the power input module and the ground in sequence. The middle node of the first resistor and the second resistor is connected to the inverting input end of the comparator.

2. The protection circuit according to claim 1, wherein The low-voltage protection module further includes a third resistor, and the third resistor is connected in series between the output end of the power input module and the output end of the comparator.

3. The protection circuit according to claim 1, wherein The power input module includes a first diode connected in series between the input end and the output end of the power input module.

4. The protection circuit according to claim 3, wherein The power input module further includes a transient diode connected between the input end of the power input module and the ground.

5. The protection circuit according to claim 3 or 4, characterized in that, The power input module further includes a first capacitor connected between the input end of the power input module and the ground.

6. The protection circuit according to claim 1, characterized in that, The switching transistor includes an NMOS transistor or an insulated gate bipolar transistor.

7. A vehicle lamp device, characterized in that, It includes a lamp board and the protection circuit according to any one of claims 1 to 6.

8. The headlight device according to claim 7, characterized in that, The lamp board includes a third resistor and a lamp string connected in sequence between the positive end and the negative end of the lamp board. The lamp string includes light-emitting diodes.

9. The headlamp device according to claim 8, characterized in that, The lamp board further includes a second capacitor connected in parallel with the lamp string.

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