Automobile LED lamp driving circuit

Abstract

The utility model provides a kind of automobile LED car light driving circuit, the negative pole of LED lamp is connected to the drain of MOS tube Q1, the source of MOS tube Q1 is respectively connected to the first end of first resistance R1, the reverse end of operational amplifier U1A, the second end of first resistance R1 is grounded, the same direction end of operational amplifier U1A is respectively connected to the second end of third resistance R3, the first end of fourth resistance R4, the first end of third resistance R3 is connected+5V low voltage power supply, the second end of fourth resistance R4 is grounded;The output end of operational amplifier U1A is respectively connected to the gate of MOS tube Q1, the collector of triode Q2, the emitter of triode Q2 is grounded, the base of triode Q2 is connected to the second end of sixth resistance R6, the first end of sixth resistance R6 is respectively connected to the second end of fifth resistance R5, PWM signal input end, the first end of fifth resistance R5 is connected to low voltage power supply.The utility model solves the problem of insufficient stability of existing LED driving circuit.

Description

Technical Field

[0001] This utility model relates to the field of automotive circuit design, and in particular to an automotive LED headlight driving circuit. Background Technology

[0002] With the rapid development of LED technology, the requirements for the driver circuits of automotive LED lights are becoming increasingly stringent. LEDs are driven in two modes: constant voltage and constant current. Differences in the performance of LED driver circuits indirectly affect the lifespan of the LEDs. Constant voltage driving is susceptible to external ambient temperature, which affects the LED's current and lifespan. Meanwhile, in constant current mode, the current output of some LED driver circuits cannot adapt to the lighting needs of different scenarios. In other words, traditional LED driver circuits have several significant problems: 1. They are easily affected by power supply voltage fluctuations and load changes; 2. The constant current output cannot maintain high-precision stability, resulting in poor adaptability. Therefore, a new automotive LED light driver circuit needs to be designed to solve these problems. Utility Model Content

[0003] The purpose of this invention is to add a protection circuit to the charging protocol chip of automobiles and solve the problem of insufficient stability of existing LED driver circuits.

[0004] The technical solution adopted by this utility model to solve its technical problem is: An automotive LED headlight driving circuit includes an LED lamp, the negative terminal of which is connected to the drain of a MOSFET Q1, the source of which is connected to the first terminal of a first resistor R1 and the inverting terminal of an operational amplifier U1A, the second terminal of the first resistor R1 is grounded, the non-inverting terminal of the operational amplifier U1A is connected to the second terminal of a third resistor R3 and the first terminal of a fourth resistor R4, the first terminal of the third resistor R3 is connected to a power supply, and the second terminal of the fourth resistor R4 is grounded. The output terminal of the operational amplifier U1A is connected to the gate of MOSFET Q1 and the collector of transistor Q2, respectively. The emitter of transistor Q2 is grounded, and the base of transistor Q2 is connected to the second terminal of the sixth resistor R6. The first terminal of the sixth resistor R6 is connected to the second terminal of the fifth resistor R5 and the PWM signal input terminal, respectively. The first terminal of the fifth resistor R5 is connected to the power supply.

[0005] Preferably, in conjunction with the above scheme, the circuit further includes a second resistor R2, the first end of which is connected to the output terminal of the operational amplifier U1A, and the second end of which is connected to the gate of the MOS transistor Q1 and the collector of the transistor Q2.

[0006] Preferably, in conjunction with the above scheme, the positive terminal of the LED lamp is connected to the load power supply.

[0007] Preferably, in conjunction with the above scheme, the positive power supply terminal of the operational amplifier U1A is connected to a power supply, and the negative power supply terminal of the operational amplifier U1A is grounded.

[0008] Preferably, in conjunction with the above scheme, the driving circuit further includes a sensor signal input circuit, which includes a seventh resistor R7. The first end of the seventh resistor R7 is connected to the sensor signal input terminal, the second end of the seventh resistor R7 is connected to the first end of an eighth resistor R8, and the second end of the eighth resistor R8 is connected to the sensor signal output terminal.

[0009] Preferably, in conjunction with the above scheme, the sensor signal input circuit further includes a voltage clamping protection circuit, which includes a Schottky diode D1. The second terminal of the Schottky diode D1 is connected to a low-voltage power supply, the first terminal of the Schottky diode D1 is grounded, and the third terminal of the Schottky diode D1 is connected between the second terminal of the seventh resistor R7 and the first terminal of the eighth resistor R8.

[0010] Preferably, in conjunction with the above scheme, the sensor signal input circuit further includes a first capacitor C1, the first end of the first capacitor C1 is connected to the sensor signal input terminal, and the second end of the first capacitor C1 is grounded.

[0011] Preferably, in conjunction with the above scheme, the sensor signal input circuit further includes a second capacitor C2, the first end of the second capacitor C2 is connected to the sensor signal output terminal, and the second end of the second capacitor C2 is grounded.

[0012] The beneficial effects of this invention are as follows: This circuit is suitable for different scenarios. Under different ambient light intensities, the light sensor will input different voltage signals to the MCU through the sensor signal input circuit. Then, the MCU will output a PWM signal with a corresponding duty cycle to the automotive LED headlight driver circuit, thereby adjusting the brightness of the LED. A special feedback loop design is adopted, so the output current is not affected by power supply and load changes. The MCU can adjust the current by adjusting the PWM duty cycle to adapt to different scenario requirements. Even with a duty cycle as low as 1%, the circuit can still maintain accurate current output. It is energy-efficient and highly effective, greatly extending the lifespan of the LED.

[0013] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0014] Figure 1 This utility model provides a circuit diagram for driving LED automotive lights.

[0015] Figure 2This is a circuit diagram of the sensor signal input circuit in this utility model. Detailed Implementation

[0016] like Figure 1 The circuit shown is a car LED headlight driver circuit that can be applied to car LED dome lights. The circuit includes an LED light, the negative terminal of which is connected to the drain of a MOSFET Q1. The source of the MOSFET Q1 is connected to the first terminal of a first resistor R1 (sampling resistor) and the inverting terminal of an operational amplifier U1A. The second terminal of the first resistor R1 is grounded. The non-inverting terminal of the operational amplifier U1A is connected to the second terminal of a third resistor R3 (voltage divider resistor) and the first terminal of a fourth resistor R4 (voltage divider resistor). The first terminal of the third resistor R3 is connected to a +5V power supply, and the second terminal of the fourth resistor R4 is grounded.

[0017] The +5V reference voltage after being divided by the third resistor R3 and the fourth resistor R4 is used as the reference voltage of the non-inverting input of the operational amplifier U1A. The operational amplifier U1A compares the difference between the constant voltage at the non-inverting input and the voltage at the inverting input, and inputs the difference voltage through the output terminal. The output terminal of the operational amplifier U1A is connected to the gate of MOSFET Q1 and the collector of transistor Q2, respectively. The emitter of transistor Q2 is grounded, and the base of transistor Q2 is connected to the second terminal of the sixth resistor R6 (current limiting resistor). The first terminal of the sixth resistor R6 is connected to the second terminal of the fifth resistor R5 (pull-up resistor) and the PWM signal input terminal, respectively. The first terminal of the fifth resistor R5 is connected to the +5V power supply.

[0018] In order to limit the current at the output terminal of the operational amplifier U1A, the circuit also includes a second resistor R2 (current limiting resistor). The first end of the second resistor R2 is connected to the output terminal of the operational amplifier U1A, and the second end of the second resistor R2 is connected to the gate of MOSFET Q1 and the collector of transistor Q2, respectively.

[0019] In order to provide power to the LED and to provide sampling current to the first resistor R1, the positive terminal of the LED is connected to a +12V load power supply.

[0020] To provide power to operational amplifier U1A, the positive power supply terminal of operational amplifier U1A is connected to a +5V power supply, and the negative power supply terminal of operational amplifier U1A is grounded.

[0021] To input analog signals from external sensors to the MCU (using AutoChips' AC78406YGLA), the automotive LED headlight driver circuit in this embodiment can be used in conjunction with a sensor signal input circuit. This driver circuit includes a seventh resistor R7 (a voltage divider resistor). The first terminal of R7 is connected to the sensor signal input terminal CON_5 (connected to the light sensor), and the second terminal is connected to the first terminal of an eighth resistor R8 (a voltage divider resistor). The second terminal of R8 is connected to the sensor signal output terminal MCU_AD1. The sensor signal input circuit processes the voltage signal from the external light sensor and inputs it to the MCU.

[0022] To protect the sensor signal output terminal MCU_AD1, the input voltage is clamped to approximately 5.3V. The sensor signal input circuit also includes a voltage clamping protection circuit, which includes a Schottky diode D1 (model BAT54S). The second terminal of the Schottky diode D1 is connected to the low-voltage power supply +5V, the first terminal of the Schottky diode D1 is grounded, and the third terminal of the Schottky diode D1 is connected between the second terminal of the seventh resistor R7 and the first terminal of the eighth resistor R8.

[0023] To achieve the filtering effect and ensure the stability of the input signal, the sensor signal input circuit also includes a first capacitor C1. The first end of the first capacitor C1 is connected to the sensor signal input terminal CON_5, and the second end of the first capacitor C1 is grounded.

[0024] Preferably, in conjunction with the above scheme, the sensor signal input circuit further includes a second capacitor C2, the first end of the second capacitor C2 is connected to the sensor signal output terminal MCU_AD1, and the second end of the second capacitor C2 is grounded.

[0025] The principle of this utility model: See Figure 1 In this embodiment, the PWM signal input terminal can be connected to the MCU controller. When the light sensor on the vehicle body detects a change in light intensity, the MCU controller outputs a corresponding voltage PWM duty cycle signal (the stronger the light, the weaker the PWM signal, and the weaker the light, the stronger the PWM signal). This signal passes through the sixth resistor R6 and the fifth resistor R5 to control the conduction and cutoff of the collector and emitter of transistor Q2, and outputs a corresponding duty cycle voltage signal. When the duty cycle signal voltage is large, the collector and emitter of transistor Q2 are turned on, and the output signal of operational amplifier U1A goes directly to ground and does not reach the gate of MOSFET Q1, thus maximizing the brightness of the LED light. When the duty cycle signal voltage is small, the collector and emitter of transistor Q2 are open, and the output voltage signal of operational amplifier U1A reaches the gate of MOSFET Q1, controlling the drain and source of MOSFET Q1 to conduct, thus reducing the brightness of the LED. When the drain and source of MOSFET Q1 are conducted, the sampled voltage is compared with the reference voltage at the non-inverting input of operational amplifier U1A, and the difference voltage is output to the gate of MOSFET Q1, thereby controlling the conduction level of the drain and source of MOSFET Q1.

[0026] In summary, in this embodiment, the operational amplifier U1A adjusts the gate voltage of the MOSFET Q1, thereby adjusting the conduction level of the MOSFET Q1 and maintaining a constant output current. When the PWM duty cycle signal changes, the operational amplifier U1A automatically adjusts the voltage at its output terminal, thereby changing the current through the MOSFET Q1 and maintaining a constant output current.

[0027] The present invention has been described above with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any improvements made using the inventive concept and technical solution of the present invention, or any direct application to other situations without modification, fall within the protection scope of the present invention.

Claims

1. A driving circuit for automotive LED lights, comprising an LED light, characterized in that, The negative terminal of the LED is connected to the drain of the MOSFET Q1. The source of the MOSFET Q1 is connected to the first terminal of the first resistor R1 and the inverting terminal of the operational amplifier U1A. The second terminal of the first resistor R1 is grounded. The non-inverting terminal of the operational amplifier U1A is connected to the second terminal of the third resistor R3 and the first terminal of the fourth resistor R4. The first terminal of the third resistor R3 is connected to the power supply, and the second terminal of the fourth resistor R4 is grounded. The output terminal of the operational amplifier U1A is connected to the gate of MOSFET Q1 and the collector of transistor Q2, respectively. The emitter of transistor Q2 is grounded, and the base of transistor Q2 is connected to the second terminal of the sixth resistor R6. The first terminal of the sixth resistor R6 is connected to the second terminal of the fifth resistor R5 and the PWM signal input terminal, respectively. The first terminal of the fifth resistor R5 is connected to the power supply.

2. The automotive LED headlight driving circuit according to claim 1, characterized in that, The circuit also includes a second resistor R2, the first end of which is connected to the output of the operational amplifier U1A, and the second end of which is connected to the gate of the MOSFET Q1 and the collector of the transistor Q2.

3. The automotive LED headlight driving circuit according to claim 1, characterized in that, The positive terminal of the LED is connected to the load power supply.

4. The automotive LED headlight driving circuit according to claim 1, characterized in that, The positive power supply terminal of the operational amplifier U1A is connected to a power source, and the negative power supply terminal of the operational amplifier U1A is grounded.

5. The automotive LED headlight driving circuit according to claim 1, characterized in that, The driving circuit also includes a sensor signal input circuit, which includes a seventh resistor R7. The first end of the seventh resistor R7 is connected to the sensor signal input terminal, the second end of the seventh resistor R7 is connected to the first end of an eighth resistor R8, and the second end of the eighth resistor R8 is connected to the sensor signal output terminal.

6. The automotive LED headlight driving circuit according to claim 5, characterized in that, The sensor signal input circuit also includes a voltage clamping protection circuit, which includes a Schottky diode D1. The second terminal of the Schottky diode D1 is connected to a low-voltage power supply +5V, the first terminal of the Schottky diode D1 is grounded, and the third terminal of the Schottky diode D1 is connected between the second terminal of the seventh resistor R7 and the first terminal of the eighth resistor R8.

7. The automotive LED headlight driving circuit according to claim 5, characterized in that, The sensor signal input circuit further includes a first capacitor C1, with its first end connected to the sensor signal input terminal and its second end grounded.

8. The automotive LED headlight driving circuit according to claim 5, characterized in that, The sensor signal input circuit further includes a second capacitor C2, the first end of which is connected to the sensor signal output terminal, and the second end of which is grounded.

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