The first step to avoid interference in the layout design of the automobile license plate light circuit is to perform reasonable circuit isolation. Different electronic systems have different current characteristics and signal frequencies when working. Physically isolating the license plate light circuit from other electronic system circuits can reduce the possibility of interference from the source. For example, when wiring, separate the power line of the license plate light from the car's audio, navigation and other electronic system lines that are more sensitive to electromagnetic interference, maintain a certain safe distance, and prevent current fluctuations from affecting each other. At the same time, the use of an independent power supply circuit is also a common isolation method, allowing the license plate light to have an exclusive power supply line, avoid sharing the same power supply with other high-power electronic equipment, reduce interference caused by power supply voltage fluctuations, and ensure stable operation of the license plate light circuit.
Optimizing the grounding design is a key measure to reduce circuit interference. Good grounding can provide a low-impedance discharge path for interference current, allowing stray current to quickly enter the earth, thereby reducing the impact on other electronic systems. In the automobile license plate light circuit, the use of a single-point grounding method can effectively avoid the generation of ground loops and prevent the potential difference between different grounding points from causing interference current. Specifically, the grounding wire of the license plate light is centrally connected to the same grounding point of the car body, and the grounding point is ensured to be in close contact with the metal part of the car body to reduce the grounding resistance. In addition, a dedicated grounding wire can be used, whose material and wire diameter are specially designed to enhance the conductivity, improve the grounding effect, further reduce circuit interference, and ensure the normal operation of the license plate light and other electronic systems.
Shielding technology plays an important protective role in the layout of the automobile license plate light circuit. Since the license plate light will generate a certain amount of electromagnetic radiation when working, these radiations may interfere with the surrounding electronic systems; at the same time, external electromagnetic interference may also affect the normal operation of the license plate light circuit. By shielding the power line, signal line, etc. of the license plate light, the propagation of electromagnetic radiation can be effectively blocked. A common shielding method is to use a shielded wire, which is wrapped with a layer of metal braided mesh or metal foil on the outside, which can limit the electromagnetic radiation generated by the internal wire to the shielding layer and prevent external electromagnetic interference from entering the wire. In addition, metal materials can be used on the shell of the license plate light and it can be well grounded to form a Faraday cage to shield electromagnetic interference, create a relatively stable electromagnetic environment for the license plate light circuit, and reduce mutual interference with other electronic systems.
Reasonable design of the filter circuit is also an important means to avoid interference. There are clutter signals of various frequencies in the automotive circuit. These clutter may enter the license plate light circuit through the power line, signal line, etc., or be transmitted from the license plate light circuit to other electronic systems, causing interference problems. Installing a suitable filter circuit in the license plate light circuit can effectively suppress these clutter signals. For example, an electromagnetic interference (EMI) filter is connected to the power input end. It is composed of components such as inductors and capacitors. It can filter out high-frequency clutter on the power line and make the power input to the license plate light purer. At the same time, a signal filter is set on the signal transmission line to attenuate interference signals of specific frequencies to ensure accurate transmission of the control signal of the license plate light, avoid problems such as light flickering and abnormal lighting caused by signal interference, and ensure the stable operation of the license plate light and other electronic systems.
Reasonable planning of the wiring direction of the circuit is crucial to reduce interference. In the case of limited space inside the car, the wiring of the license plate light circuit needs to follow certain rules to avoid cross interference with other electronic system lines. When wiring, the line should be as short and straight as possible, the length and bending degree of the wire should be reduced, and the inductance and capacitance of the wire should be reduced, thereby reducing electromagnetic radiation and signal attenuation. At the same time, different types of lines should be arranged in categories, such as separating the power line from the signal line, and separating the analog signal line from the digital signal line to avoid mutual interference. For example, the power line of the license plate light is arranged in a line area away from sensitive electronic equipment such as on-board computers and sensors to prevent the electromagnetic interference generated by the power line from affecting the normal operation of these devices; the control signal line of the license plate light is arranged parallel to other control signal lines and kept at a certain distance to reduce crosstalk between signals and ensure the rationality and stability of the circuit layout.
Reasonable selection and layout of electronic components in the circuit can also effectively avoid interference problems. When selecting electronic components for the license plate light circuit, components with good anti-interference performance and high stability are preferred. For example, low-noise power chips, amplifiers with high common mode rejection ratio, etc. are selected to reduce interference from the component level. In terms of component layout, separate interference source components (such as switching power modules) from sensitive components (such as control chips) to avoid mutual influence. At the same time, arrange the order and direction of components reasonably to make the signal transmission path shortest and without crossover, reducing the chance of signal reflection and interference. Through the careful selection and layout of electronic components, the performance of the license plate light circuit is optimized and the risk of interference with other electronic systems is reduced.
After completing the layout design of the automotive license plate light circuit, strict testing and verification are required to ensure that it will not interfere with other electronic systems. By simulating various actual working conditions, such as car starting, acceleration, braking, etc., the electromagnetic compatibility (EMC) of the license plate light circuit under different working conditions is detected. Use professional electromagnetic interference test equipment to measure the electromagnetic radiation intensity generated by the license plate light circuit and the degree of interference to the surrounding electronic systems, and at the same time detect the ability of the license plate light circuit to resist external electromagnetic interference. According to the test results, adjust and optimize the circuit layout, such as adding shielding measures, improving the filter circuit, etc., until the electromagnetic compatibility requirements of the automotive electronic system are met, ensuring that the license plate light circuit can coexist harmoniously with other electronic systems and operate stably and reliably.
