Automotive daytime running and position light single LED failure shutdown circuit

Abstract

The utility model discloses a kind of single LED fault shutdown circuit of automobile day running lamp and position lamp, including boost constant current drive module, boost constant current drive module is connected with first LED load and second LED load respectively, first LED load and second LED load are connected with LED fault diagnosis circuit, LED fault diagnosis circuit is connected with LED shutdown circuit, LED shutdown circuit is connected with boost constant current drive module.The utility model is through LED fault diagnosis circuit and LED shutdown circuit cooperation, realize when any one LED short circuit or open circuit in first LED load or second LED load, first LED load and second LED load are turned off and extinguished, need not use multiple linear constant current IC cooperation to realize, effectively reduce cost.

Description

Technical Field

[0001] This utility model belongs to the field of vehicle lighting control technology, specifically relating to a fault shutdown circuit for a single LED in a car's daytime running light and position light. Background Technology

[0002] Daytime running lights (DRLs) primarily serve to illuminate and alert pedestrians and other vehicles. They typically consist of multiple LEDs connected in series and parallel to form a single LED load. One or more such LED strings can be used to form the light source for the entire headlight. To ensure uniformity and stability of LED brightness, constant current driving is generally employed.

[0003] Due to factors such as the operating environment and power supply current and voltage, LEDs may be damaged, resulting in short circuits or open circuits. Automotive lighting regulations generally require that when one LED fails, all LEDs should be extinguished. Conventional methods for detecting LED short circuits or open circuits involve using a DC / DC step-down module and multiple linear constant current ICs, which is relatively expensive. Utility Model Content

[0004] The purpose of this invention is to provide a single LED failure shutdown circuit for automotive daytime running lights and position lights, thereby solving the problems mentioned in the background art. The single LED failure shutdown circuit for automotive daytime running lights and position lights provided by this invention is characterized by low cost.

[0005] To achieve the above objectives, this utility model provides the following technical solution: a single LED fault shutdown circuit for automotive daytime running lights and position lights, comprising a boost constant current drive module, the boost constant current drive module being connected to a first LED load and a second LED load respectively, the first LED load and the second LED load being connected to an LED fault diagnosis circuit, the LED fault diagnosis circuit being connected to an LED shutdown circuit, and the LED shutdown circuit being connected to the boost constant current drive module.

[0006] In this invention, the first LED load further comprises a plurality of LED beads connected in series. The positive terminal of the first LED load is connected to one end of resistor R90 and the LED fault diagnosis circuit, respectively. The other end of resistor R90 is connected to the positive output of the boost constant current drive module, and the negative terminal of the first LED load is connected to the GND terminal.

[0007] In this invention, the second LED load further comprises a plurality of LED beads connected in series. The positive terminal of the second LED load is connected to one end of resistor R91 and the LED fault diagnosis circuit, the other end of resistor R91 is connected to the positive output of the boost constant current drive module, and the negative terminal of the second LED load is connected to the GND terminal.

[0008] In this utility model, the LED fault diagnosis circuit includes an optocoupler U5. Pin 1 of the optocoupler U5 is connected to the positive terminal of the first LED load, pin 2 of the optocoupler U5 is connected to the positive terminal of the second LED load, pin 3 of the optocoupler U5 is connected to one end of resistors R65 and R75 respectively, pin 4 of the optocoupler U5 is connected to the VDD terminal, the other end of resistor R75 is connected to the gate of MOSFET M14, the drain of MOSFET M14 is connected to the LED turn-off circuit and one end of resistor R78 respectively, the other end of resistor R78 is connected to the positive terminal of Zener diode D27, the negative terminal of Zener diode D27 is connected to the output positive terminal of the boost constant current drive module, and the source of MOSFET M14 and the other end of resistor R65 are connected to the GND terminal respectively.

[0009] Furthermore, in this invention, a resistor R48 is connected in series between pin 1 of the optocoupler U5 and the positive terminal of the first LED load.

[0010] Furthermore, in this invention, the gate of the MOS transistor M14 is connected to one end of the capacitor C31 and the negative terminal of the Zener diode D12, respectively, and the other end of the capacitor C31 and the positive terminal of the Zener diode D12 are connected to the GND terminal.

[0011] Further, in this invention, the LED turn-off circuit includes a MOSFET M19. The drain of the MOSFET M19 is connected to the boost constant current drive module. The base of the MOSFET M19 is connected to one end of resistors R87 and R88, and the collector of transistor M18. The base of transistor M18 is connected to one end of resistors R83 and R86, and the collector of transistor M17. The base of transistor M17 is connected to one end of resistors R84 and R85, and the other end of resistor R84 is connected to the positive terminal of Zener diode D28. The negative terminal of Zener diode D28 and the collector of transistor M16 are connected to the RC charging circuit. The base of transistor M16 is connected to one end of resistor R79 and the LED fault diagnosis circuit. The other ends of resistors R88 and R83 are connected to the VDD terminal. The other ends of resistors R87, R86, R85 and R79 are connected to the GND terminal. The source of MOSFET M19 is connected to the GND terminal. The emitters of transistors M18, M17 and M16 are connected to the GND terminal.

[0012] In this invention, the RC charging circuit includes a resistor R82, a capacitor C73, and a capacitor C73 connected in parallel. One end of each of the resistor R82, capacitor C73, and capacitor C73 is connected to the collector of the transistor M16, and the other end of each of the resistor R82, capacitor C73, and capacitor C73 is connected to the GND terminal.

[0013] Compared with the prior art, the beneficial effects of this utility model are:

[0014] 1. This utility model uses an LED fault diagnosis circuit to determine the fault of the detected LED voltage and transmits the fault diagnosis signal to the LED shutdown circuit. After receiving the fault signal, the LED shutdown circuit pulls the PWMIN pin of chip U1 low, causing chip U1 to stop working, thereby realizing the power-off control of the first LED load and the second LED load.

[0015] 2. This utility model, through the cooperation of LED fault diagnosis circuit and LED turn-off circuit, enables the first LED load and the second LED load to be turned off and extinguished when any one of the first LED loads or the second LED load is short-circuited or open-circuited. This is achieved without the need for multiple linear constant current ICs, effectively reducing costs. Attached Figure Description

[0016] Figure 1 This is a circuit connection block diagram of the present invention.

[0017] Figure 2 This is the circuit diagram of the LED fault diagnosis circuit of this utility model.

[0018] Figure 3 This is the circuit diagram of the LED turn-off circuit of this utility model.

[0019] Figure 4 This is a circuit diagram of the first LED load and the second LED load of this utility model.

[0020] Figure 5 This is the circuit diagram of the boost constant current drive module of this utility model.

[0021] In the diagram: 1. Boost constant current drive module; 2. First LED load; 3. Second LED load; 4. LED fault diagnosis circuit; 5. LED turn-off circuit. Detailed Implementation

[0022] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the protection scope of the present utility model.

[0023] Example 1

[0024] Please see Figures 1-5This utility model provides the following technical solution: a single LED fault shutdown circuit for automotive daytime running lights and position lights, including a boost constant current drive module 1. The boost constant current drive module 1 is connected to a first LED load 2 and a second LED load 3 respectively. Both the first LED load 2 and the second LED load 3 are connected to an LED fault diagnosis circuit 4. The LED fault diagnosis circuit 4 is connected to an LED shutdown circuit 5. The LED shutdown circuit 5 is connected to the boost constant current drive module 1. The boost constant current drive module 1 includes a chip U1, which is an A6271-1 type chip. The boost constant current drive module 1 also includes an input reverse connection protection diode D1, an input reverse connection protection diode D5, an input reverse connection protection diode D6, an input filter capacitor C9, an input filter capacitor C10, an input differential mode inductor L1, an energy storage capacitor C11, an energy storage capacitor C12, an energy storage capacitor C13, an energy storage capacitor C14, and an energy storage capacitor C5. 15. Energy storage capacitor C21, decoupling capacitor C23, decoupling capacitor C20, compensation capacitor C34, compensation capacitor C33, soft start capacitor C30, frequency dithering setting resistor R26, frequency setting resistor R24, PWM dimming frequency setting resistor R15, fault pin pull-up resistor R7, pull-down resistor R19, voltage divider resistor R14, voltage divider resistor R21, Zener diode D28, Zener diode D9, filter capacitor C29, MOSFET M2, MOSFET M3, MOSFET M4, MOSFET M9, power inductor L2, rectifier diode D2, filter capacitor C27, filter capacitor C2, filter capacitor C5, filter capacitor C4, filter capacitor C19, filter capacitor C40, filter capacitor C61, resistor R6, resistor R10, resistor R4, resistor R5, resistor R2, resistor R3, resistor R9, resistor R25, resistor R18, resistor R22, and resistor R23.

[0025] By adopting the above technical solution, this utility model uses LED fault diagnosis circuit 4 to judge the fault of detected LED voltage and transmits the fault diagnosis signal to LED shutdown circuit 5. After receiving the fault signal, LED shutdown circuit 5 pulls the PWMIN pin level of chip U1 low, so that chip U1 stops working, thereby realizing power-off control of the first LED load 2 and the second LED load 3.

[0026] Specifically, the first LED load 2 includes several LED beads connected in series. The positive terminal of the first LED load 2 is connected to one end of resistor R90 and resistor R48 respectively. The other end of resistor R90 is connected to the positive output of the boost constant current drive module 1. The negative terminal of the first LED load 2 is connected to the GND terminal.

[0027] By adopting the above technical solution, resistor R90 plays the role of current sharing and voltage feedback.

[0028] Specifically, the second LED load 3 includes several LED beads connected in series. The positive terminal of the second LED load 3 is connected to one end of resistor R91 and pin 2 of optocoupler U5, the other end of resistor R91 is connected to the positive output of boost constant current drive module 1, and the negative terminal of the second LED load 3 is connected to GND.

[0029] By adopting the above technical solution, resistor R91 plays the role of current sharing and voltage feedback.

[0030] Specifically, the LED fault diagnosis circuit 4 includes an optocoupler U5. Pin 1 of the optocoupler U5 is connected to the positive terminal of the first LED load 2, pin 2 of the optocoupler U5 is connected to the positive terminal of the second LED load 3, pin 3 of the optocoupler U5 is connected to one end of resistors R65 and R75 respectively, pin 4 of the optocoupler U5 is connected to the VDD terminal, the other end of resistor R75 is connected to the gate of MOSFET M14, the drain of MOSFET M14 is connected to the base of transistor M16 and one end of resistor R78 respectively, the other end of resistor R78 is connected to the positive terminal of Zener diode D27, the negative terminal of Zener diode D27 is connected to the positive output of boost constant current drive module 1, and the source of MOSFET M14 and the other end of resistor R65 are connected to the GND terminal respectively.

[0031] By adopting the above technical solution, when the first LED load 2 and the second LED load 3 are lit normally, the voltage difference between pin 1 and pin 2 of optocoupler U5 is approximately 0, the output of optocoupler U5 will not be triggered, the voltage across resistor R65 is 0, and MOSFET M14 is not turned on; when any one of the first LED load 2 and the second LED load 3 is short-circuited or disconnected, there is a voltage difference across resistor R90 and resistor R91, there is a voltage difference between pin 1 and pin 2 of optocoupler U5, the output of optocoupler U5 is triggered, the voltage across resistor R65 is high, and MOSFET M14 is turned on.

[0032] Specifically, the LED turn-off circuit 5 includes a MOSFET M19. The drain of MOSFET M19 is connected to pin 7 (PWMIN pin) of chip U1 in the boost constant current drive module 1. The base of MOSFET M19 is connected to one end of resistors R87 and R88, and the collector of transistor M18. The base of transistor M18 is connected to one end of resistors R83 and R86, and the collector of transistor M17. The base of transistor M17 is connected to one end of resistors R84 and R85. The other end of resistor R84 is connected to the Zener diode D28. The positive terminal is connected, the negative terminal of Zener diode D28 and the collector of transistor M16 are connected to the RC charging circuit, the base of transistor M16 is connected to one end of resistor R79 and the drain of MOSFET M14, the other ends of resistors R88 and R83 are connected to VDD, the other ends of resistors R87, R86, R85 and R79 are connected to GND, the source of MOSFET M19 is connected to GND, and the emitters of transistors M18, M17 and M16 are connected to GND.

[0033] By adopting the above technical solution, under normal conditions, when the external power supply is applied, resistor R82, capacitor C72, and capacitor C73 form an RC charging circuit. Transistor M17 will not turn on immediately, while transistor M18 will turn on first. The voltage across resistor R87 is 0. Since the gate voltage of MOSFET M19 is 0, MOSFET M19 will not turn on, and the PWMIN pin of chip U1 will not be pulled low, preventing the first LED load 2 and the second LED load 3 from not being lit during normal power-on.

[0034] When the first LED load 2 and the second LED load 3 are lit normally, the voltage at pins 1 and 2 of optocoupler U5 is approximately 0V, so optocoupler U5 will not be triggered, MOSFET M14 will not conduct, the positive voltage of the first LED load 2 and the second LED load 3 is higher than that of Zener diode D27, so transistor M16 conducts, the base voltage of transistor M17 is 0, so transistor M17 will not conduct, transistor M18 will conduct, the voltage across resistor R87 is 0, and since the gate voltage of MOSFET M19 is 0, MOSFET M19 will not conduct. That is, the PWMIN pin of chip U1 will not be pulled low, chip U1 works normally, and the first LED load 2 and the second LED load 3 are lit normally.

[0035] When any one of the first LED load 2 or the second LED load 3 is short-circuited or open-circuited, there is a voltage difference between pins 1 and 2 of optocoupler U5. The output terminal of optocoupler U5 is triggered, the voltage across resistor R65 is high, MOSFET M14 is turned on, transistor M16 is not turned on, transistor M17 is turned on, transistor M18 is not turned on, MOSFET M19 is turned on, the PMWIN pin of chip U1 is pulled low, chip U1 stops working, the first LED load 2 and the second LED load 3 are turned off and extinguished, realizing the function of turning off one and extinguishing all.

[0036] Example 2

[0037] The difference between this embodiment and embodiment 1 is that, specifically, a resistor R48 is connected in series between pin 1 of the optocoupler U5 and the positive terminal of the first LED load 2.

[0038] By adopting the above technical solution, resistor R48 is used to limit the current flowing through the light-emitting diode inside optocoupler U5, thus protecting optocoupler U5.

[0039] Specifically, the gate of MOSFET M14 is connected to one end of capacitor C31 and the negative terminal of Zener diode D12, while the other end of capacitor C31 and the positive terminal of Zener diode D12 are connected to GND.

[0040] By adopting the above technical solution, capacitor C31 is used to filter the gate voltage of MOSFET M14, and Zener diode D12 is used to limit the gate-to-ground voltage of MOSFET M14 to no more than 10V, thus protecting MOSFET M14.

[0041] Example 3

[0042] The difference between this embodiment and embodiment 1 is that, specifically, the RC charging circuit includes a resistor R82, a capacitor C73, and a capacitor C73 connected in parallel. One end of the resistor R82, capacitor C73, and capacitor C73 is connected to the collector of the transistor M16 and one end of the resistor R81, respectively. The other end of the resistor R82, capacitor C73, and capacitor C73 is connected to the GND terminal, and the other end of the resistor R81 is connected to the VDD terminal.

[0043] By employing the above technical solution, the RC charging circuit functions to turn on transistor M17 after a delay of approximately 1 second, first turning on transistor M18 and then turning off MOSFET M19. This prevents transistor M17 from turning on first during normal power supply, causing MOSFET M19 to turn on and the LED to turn off.

[0044] The specific analysis is as follows: After power is supplied, it takes approximately 40 milliseconds for either LED load 2 or LED load 3 to light up and for the LED+ output to be displayed. Transistor M16 will conduct after 40 milliseconds, while transistor M17 will be cut off. Without the 1-second delay from the RC charging circuit, VDD will instantaneously turn on transistor M17 through resistors R81, R82, R84, R85, and Zener diode D28, while transistor M18 will be cut off. VDD will then conduct through the voltage divider between resistors R88 and R87, turning on MOSFET M19. This pulls the PWMIN pin of chip U1 low, causing either LED load 2 or LED load 3 to turn off.

[0045] In summary, this invention uses the LED fault diagnosis circuit 4 to diagnose the detected LED voltage and transmits the fault diagnosis signal to the LED shutdown circuit 5. Upon receiving the fault signal, the LED shutdown circuit 5 pulls the PWMIN pin of chip U1 low, causing chip U1 to stop working, thus achieving power-off control of the first LED load 2 and the second LED load 3. This invention, through the cooperation of the LED fault diagnosis circuit 4 and the LED shutdown circuit 5, enables the first LED load 2 and the second LED load 3 to be turned off and extinguished when any one of them is short-circuited or open-circuited, without requiring multiple linear constant current ICs, effectively reducing costs.

[0046] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A fault-blocking circuit for a single LED in an automotive daytime running light and position light, characterized in that: It includes a boost constant current drive module, which is connected to the first LED load and the second LED load respectively. Both the first LED load and the second LED load are connected to the LED fault diagnosis circuit, which is connected to the LED turn-off circuit, and the LED turn-off circuit is connected to the boost constant current drive module.

2. The single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 1, characterized in that: The first LED load includes several LED beads connected in series. The positive terminal of the first LED load is connected to one end of resistor R90 and the LED fault diagnosis circuit, respectively. The other end of resistor R90 is connected to the positive output of the boost constant current drive module. The negative terminal of the first LED load is connected to the GND terminal.

3. The single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 1, characterized in that: The second LED load includes several LED beads connected in series. The positive terminal of the second LED load is connected to one end of resistor R91 and the LED fault diagnosis circuit, respectively. The other end of resistor R91 is connected to the positive output of the boost constant current drive module. The negative terminal of the second LED load is connected to the GND terminal.

4. The single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 1, characterized in that: The LED fault diagnosis circuit includes an optocoupler U5. Pin 1 of the optocoupler U5 is connected to the positive terminal of the first LED load, pin 2 of the optocoupler U5 is connected to the positive terminal of the second LED load, pin 3 of the optocoupler U5 is connected to one end of resistors R65 and R75 respectively, pin 4 of the optocoupler U5 is connected to the VDD terminal, the other end of resistor R75 is connected to the gate of MOSFET M14, the drain of MOSFET M14 is connected to the LED turn-off circuit and one end of resistor R78 respectively, the other end of resistor R78 is connected to the positive terminal of Zener diode D27, the negative terminal of Zener diode D27 is connected to the positive output of the boost constant current drive module, and the source of MOSFET M14 and the other end of resistor R65 are connected to the GND terminal respectively.

5. A single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 4, characterized in that: A resistor R48 is connected in series between pin 1 of the optocoupler U5 and the positive terminal of the first LED load.

6. A single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 4, characterized in that: The gate of the MOS transistor M14 is also connected to one end of the capacitor C31 and the negative terminal of the Zener diode D12, while the other end of the capacitor C31 and the positive terminal of the Zener diode D12 are connected to the GND terminal.

7. A single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 1, characterized in that: The LED turn-off circuit includes a MOSFET M19. The drain of MOSFET M19 is connected to the boost constant current drive module. The base of MOSFET M19 is connected to one end of resistors R87 and R88, and the collector of transistor M18. The base of transistor M18 is connected to one end of resistors R83 and R86, and the collector of transistor M17. The base of transistor M17 is connected to one end of resistors R84 and R85. The other end of resistor R84 is connected to the positive terminal of Zener diode D28. The negative terminal of transistor M28 and the collector of transistor M16 are connected to the RC charging circuit. The base of transistor M16 is connected to one end of resistor R79 and the LED fault diagnosis circuit. The other ends of resistors R88 and R83 are connected to the VDD terminal. The other ends of resistors R87, R86, R85 and R79 are connected to the GND terminal. The source of MOSFET M19 is connected to the GND terminal. The emitters of transistors M18, M17 and M16 are connected to the GND terminal.

8. A single LED fault shutdown circuit for automotive daytime running lights and position lights according to claim 7, characterized in that: The RC charging circuit includes resistors R81 and R82, and capacitors C73 and C73 connected in parallel. One end of resistors R81 and R82, and capacitors C73 and C73 are respectively connected to the collector of transistor M16, and the other end of resistors R82, C73 and C73 are respectively connected to the GND terminal.

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