Design Of Preventing Electromagnetic Interference For Traffic Lights

people’s living standards are improving day and day. And People pay more attention tothe improvement of the quality of life.More and more people begin to consider buyingcars,More functionality and performance of complex traffic lights appear in our life.Becauseof the complexity of its function, the failure rate increased significantly.More failure frominternal components, and electromagnetic interference between the lines. We must improve itsanti-interference ability.In order for it better serve us. This paper first summarizes theelectromagnetic compatibility (emc) of the research background and research status at homeand abroad.Three elements of electromagnetic interference was introduced.Sources ofinterference,Pathways,Sensitive equipment. Suppression method design including the use oflow radiation,power lines and signal lines are Isolated,Shielded equipment,Connection toGround.Inhibition of using different methods for its different interference.Secondly,,we use bus traffic signal system as the research object，Use PADS Logicsoftware to design its major component-can bus adapter schematics,As its key part, powersupply, reset circuit, can bus and RS232interface circuit and so on，we have carried on thedetailed design of electromagnetic compatibility.In the process of design, we use the most ofthe electromagnetic interference suppression method, including grounding, filtering,shielding.At the same time,Traffic measurement nodes on the hardware design ofelectromagnetic compatibility.Traffic inspection system use3.3V voltage.So using theLM1804-33regulator chip for5V voltage is converted to a stable3.3V voltage.Secondly,due to the coil sensor data transmission,it doped with a large amount of interferencesignals.Using LM393and74HC14shaping circuit export stable waveform.Use PADS Layoutmap PCB.Using pads unique interactive approach when drawing pcb.After the completion ofthe overall design, using of pads verify design tool to check the safety spacing rules conflict. Finally,it introduces the IC is to develop high-speed and miniaturization,Various signalintegrity issues in front of us.The HyperLynx software is developed by Mentor Graphics,Itcan be for PCB signal integrity and circuit implementation of optimization,improving thestability of the hardware circuit.The article using its function across hole model simulation，through the oscilloscope found via lead to time delay circuit，to double board exists primarilycrosstalk modeling and simulation.Finally, the entire board electromagnetic compatibilitytesting,To improve the unreasonable places.