Automobile LED turn signal driving circuit

Abstract

The utility model discloses a car LED steering lamp drive circuit, including light modulation circuit, constant current drive circuit, detection circuit, light modulation circuit includes first resistance R1, third resistance R3, fifth resistance R5, first triode Q1, second triode Q2, when PWM light modulation end output high level, first triode Q1 and second triode Q2 are turned on, and the current is allowed to flow to LED lamp group, constant current drive circuit includes sixth resistance R6, seventh resistance R7, eighth resistance R8, third triode Q3, fourth triode Q4, and the base and collector of fourth triode Q4 are connected and are connected to the power supply VCC through eighth resistance R8 after, and with third triode Q3, sixth resistance R6, seventh resistance R7 constitute static operating point stabilizing circuit, and detection circuit includes ninth resistance R9, tenth resistance R10 and constitutes voltage division circuit, and the voltage negative pole voltage signal of LED lamp group of steering lamp is transferred to the LED voltage acquisition end of MCU. The utility model has solved the problem of higher cost of current detection circuit and LED tail lamp drive of existing.

Description

Technical Field

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

[0002] Automotive turn signals are crucial signaling devices used by motor vehicles to indicate to other vehicles when turning or overtaking. Their operation directly impacts traffic safety. Controlling turn signals requires both controlling the flashing of the turn signal and displaying a fault indication when the main headlight has stopped working. Currently, most turn signal headlights and side lights on the market use incandescent bulbs, while taillights often use LEDs, driven by intelligent power driver chips with current feedback detection. However, due to the lower power of LED taillights, if an LED taillight stops working, the current change in the circuit is relatively small, resulting in minimal change in the current feedback from the intelligent power driver chip. Furthermore, the instability of automotive voltage levels makes it even more difficult to accurately determine the current feedback from the driver chip, making it challenging to precisely identify when a turn signal LED taillight has stopped working, thus hindering fault indication. To solve these problems, separate drivers and current detection are needed for the turn signal LED taillights to identify when they stop working, requiring two sets of intelligent power driver chips, significantly increasing production costs. Utility Model Content

[0003] The purpose of this invention is to add a protection circuit to the charging protocol chip of automobiles, thereby solving the problem of high cost of existing LED taillight drivers and current detection circuits.

[0004] The technical solution adopted by this utility model to solve its technical problem is: A driving circuit for automotive LED turn signals includes a dimming circuit, a constant current driving circuit, and a detection circuit. The dimming circuit includes a first resistor R1, a third resistor R3, a fifth resistor R5, a first transistor Q1, and a second transistor Q2. The first end of the first resistor R1 is connected to a PWM dimming terminal, the second end of the first resistor R5 is connected to the base of the first transistor Q1, the emitter of the first transistor Q1 is grounded, the collector of the first transistor Q1 is connected to the second end of the third resistor R3, the first end of the third resistor R3 is connected to the base of the second transistor Q2, the emitter of the second transistor Q2 is connected to a power supply, the collector of the second transistor Q2 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is connected to the positive terminal of the LED lamp assembly. The constant current drive circuit includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a third transistor Q3, and a fourth transistor Q4. The collector of the third transistor Q3 is connected to the negative terminal of the LED lamp group. The emitter of the third transistor Q3 is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the second end of the seventh resistor R7 and is grounded together. The first end of the seventh resistor R7 is connected to the emitter of the fourth transistor Q4. The base of the fourth transistor Q4 is connected to the base of the third transistor Q3 and the collector of the fourth transistor Q4. The collector of the fourth transistor Q4 is connected to the second end of the eighth resistor R8. The first end of the eighth resistor R8 is connected to the power supply. The detection circuit includes a ninth resistor R9 and a tenth resistor R10. The first end of the ninth resistor R9 is connected to the negative terminal of the LED lamp group and the collector of the third transistor Q3, respectively. The second end of the ninth resistor R9 is connected to the first end of the tenth resistor R10 and the LED voltage acquisition terminal, respectively. The second end of the tenth resistor R10 is grounded.

[0005] Preferably, in conjunction with the above scheme, the dimming circuit further includes a second resistor R2, the first end of the second resistor R2 is connected to the second end of the first resistor R1 and the base of the first transistor Q1, and the second end of the second resistor R2 is connected to the emitter of the first transistor Q1 and grounded.

[0006] Preferably, in conjunction with the above scheme, the dimming circuit further includes a fourth resistor R4, the first end of which is connected to the emitter of the second transistor Q2 and connected to the power supply VBAT.

[0007] Preferably, in conjunction with the above scheme, the dimming circuit further includes a first capacitor C1, the first end of which is connected to the second end of the fifth resistor R5 and the first end of the LED lamp group.

[0008] The beneficial effects of this invention are as follows: This circuit controls the operating state of the LED turn signal assembly load by controlling the on / off state of the first transistor Q1 and the second transistor Q2 via the MCU when the turn signal is activated; the MCU identifies whether the LED turn signal load is faulty by detecting the voltage level on the detection circuit. The entire circuit eliminates the need for an additional intelligent power driver chip to drive the taillights and detect circuit problems, reducing production costs.

[0009] The present invention will be described in more detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0010] Figure 1 This is a circuit diagram of a car LED turn signal drive circuit according to the present invention. Detailed Implementation

[0011] like Figure 1 The diagram shows a driving circuit for an automotive LED turn signal, including a dimming circuit, a constant current driving circuit, and a detection circuit. The dimming circuit includes a first resistor R1 (current limiting resistor), a third resistor R3 (current limiting resistor), a fifth resistor R5 (current limiting resistor), a first transistor Q1 (NPN type), and a second transistor Q2 (PNP type). The first terminal of the first resistor R1 is connected to the PWM dimming port PWM_LED of the MCU. The second terminal of the first resistor R5 is connected to the base of the first transistor Q1. The emitter of the first transistor Q1 is grounded. The collector of the first transistor Q1 is connected to the second terminal of the third resistor R3. The first terminal of the third resistor R3 is connected to the base of the second transistor Q2. The emitter of the second transistor Q2 is connected to the power supply VBAT. The collector of the second transistor Q2 is connected to the first terminal of the fifth resistor R5. The second terminal of the fifth resistor R5 is connected to the positive terminal of the LED lamp group. The constant current drive circuit includes a sixth resistor R6 (current limiting resistor), a seventh resistor R7 (current limiting resistor), an eighth resistor R8 (current limiting resistor), a third transistor Q3 (NPN type), and a fourth transistor Q4 (NPN type). The collector of the third transistor Q3 is connected to the negative terminal of the LED lamp group. The emitter of the third transistor Q3 is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the second end of the seventh resistor R7 and is grounded together. The first end of the seventh resistor R7 is connected to the emitter of the fourth transistor Q4. The base of the fourth transistor Q4 is connected to the base of the third transistor Q3 and the collector of the fourth transistor Q4. The collector of the fourth transistor Q4 is connected to the second end of the eighth resistor R8. The first end of the eighth resistor R8 is connected to the power supply VCC. The detection circuit includes a ninth resistor R9 (voltage divider resistor) and a tenth resistor R10 (voltage divider resistor). The first end of the ninth resistor R9 is connected to the negative terminal of the LED lamp group and the collector of the third transistor Q3, respectively. The second end of the ninth resistor R9 is connected to the first end of the tenth resistor R10 and the LED voltage acquisition terminal MCU_AD_LED of the MCU, respectively. The second end of the tenth resistor R10 is grounded.

[0012] The dimming circuit also includes a second resistor R2 as a pull-down resistor. The first end of the second resistor R2 is connected to the second end of the first resistor R1 and the base of the first transistor Q1. The second end of the second resistor R2 is connected to the emitter of the first transistor Q1 and grounded.

[0013] The dimming circuit also includes a fourth resistor R4, which also serves as a pull-up resistor. The first end of the fourth resistor R4 is connected to the emitter of the second transistor Q2 and to the power supply VBAT.

[0014] In order to achieve a filtering effect and make the signal more stable, the dimming circuit also includes a first capacitor C1, the first end of the first capacitor C1 being connected to the second end of the fifth resistor R5 and the first end of the LED light group.

[0015] The principle of this invention: See Figure 1 In the dimming circuit, when the turn signal is turned on, the MCU controls the PWM dimming terminal (PWM_LED) to output a high level, thereby turning on the first transistor Q1, providing a conduction path for the second transistor Q2, so that the second transistor Q2 also turns on, allowing current to flow to the LED light group of the turn signal.

[0016] In the constant current drive circuit, the base and collector of the fourth transistor Q4 are connected to the power supply VCC through the eighth resistor R8, and it is always in the amplification state. Together with the third transistor Q3, the sixth resistor R6, and the seventh resistor R7, it forms a static operating point stabilization circuit to ensure that the third transistor Q3 works in the amplification region and the collector current remains unchanged.

[0017] In the detection circuit, the ninth resistor R9 and the tenth resistor R10 form a voltage divider circuit, which transmits the voltage signal from the negative terminal of the LED light group of the turn signal to the LED voltage acquisition terminal of the MCU (MCU_AD_LED). When the LED light group is out of order, the voltage at the LED voltage acquisition terminal of the MCU is almost zero. When the LED light group is short-circuited, the voltage divided by the ninth resistor R9 and the tenth resistor R10 is higher. When the LED light group is fault-free, the voltage divided by the ninth resistor R9 and the tenth resistor R10 is lower. By acquiring different voltages, the MCU can determine the various faults of the LED light group.

[0018] 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 turn signals, characterized in that, The device includes a dimming circuit, a constant current drive circuit, and a detection circuit. The dimming circuit includes a first resistor R1, a third resistor R3, a fifth resistor R5, a first transistor Q1, and a second transistor Q2. The first end of the first resistor R1 is connected to the PWM dimming terminal, the second end of the first resistor R1 is connected to the base of the first transistor Q1, the emitter of the first transistor Q1 is grounded, the collector of the first transistor Q1 is connected to the second end of the third resistor R3, the first end of the third resistor R3 is connected to the base of the second transistor Q2, the emitter of the second transistor Q2 is connected to the power supply, the collector of the second transistor Q2 is connected to the first end of the fifth resistor R5, and the second end of the fifth resistor R5 is connected to the positive terminal of the LED lamp group. The constant current drive circuit includes a sixth resistor R6, a seventh resistor R7, an eighth resistor R8, a third transistor Q3, and a fourth transistor Q4. The collector of the third transistor Q3 is connected to the negative terminal of the LED lamp group. The emitter of the third transistor Q3 is connected to the first end of the sixth resistor R6. The second end of the sixth resistor R6 is connected to the second end of the seventh resistor R7 and is grounded together. The first end of the seventh resistor R7 is connected to the emitter of the fourth transistor Q4. The base of the fourth transistor Q4 is connected to the base of the third transistor Q3 and the collector of the fourth transistor Q4. The collector of the fourth transistor Q4 is connected to the second end of the eighth resistor R8. The first end of the eighth resistor R8 is connected to the power supply. The detection circuit includes a ninth resistor R9 and a tenth resistor R10. The first end of the ninth resistor R9 is connected to the negative terminal of the LED lamp group and the collector of the third transistor Q3, respectively. The second end of the ninth resistor R9 is connected to the first end of the tenth resistor R10 and the LED voltage acquisition terminal, respectively. The second end of the tenth resistor R10 is grounded.

2. The automotive LED turn signal drive circuit according to claim 1, characterized in that, The dimming circuit further includes a second resistor R2. The first end of the second resistor R2 is connected to the second end of the first resistor R1 and the base of the first transistor Q1. The second end of the second resistor R2 is connected to the emitter of the first transistor Q1 and grounded.

3. The automotive LED turn signal drive circuit according to claim 1, characterized in that, The dimming circuit also includes a fourth resistor R4, the first end of which is connected to the emitter of the second transistor Q2 and to the power supply VBAT.

4. The automotive LED turn signal drive circuit according to claim 1, characterized in that, The dimming circuit also includes a first capacitor C1, the first end of which is connected to the second end of the fifth resistor R5 and the first end of the LED lamp group.

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