Surge Protection Design Of Gigabit Ethernet Switch

As the age of big data is coming,people's demand for data communication is growing up every day,while switch is an important part of data communication,realizing the function of storage and forwarding to supply real-time communication for people.However,in recent years,the instances of lighting striking and damaging to switches have occurred from time to time,bringing great losses for people.The design of surge protection of switch is in urgent need.In this background,this paper studied the design of surge protection of switch.This paper firstly analyze lightning waveform to determine two important parameters——the wavefront time and half the peak time.And in accordance with GB17626.5-2008 "electromagnetic compatibility test and measurement technology surge(impact)immunity test",identify two common waveforms in lightning surge test——1.2/50 ?S combination wave and 10/700 ?S combination wave and the generator circuits,and determine the simulation software,test programs and criteria.On the foundation of determining the POE switch hardware architecture,this paper selects three common surge protection devices——Gas Discharge Tube,Mental Oxide Varistor and Transient Voltage Suppressor,analyzes its surge protection theory,volt-ampere characteristics and important parameters,determines the advantages and disadvantages of the three surge protection devices.Based on these above,confirms the protection level and completes the design the four schematics of surge protection design,in power source port,in signal port of POE switch in different circumantances and POE slave card,desperately.On the basis of the design of the circuit,firstly simulated the 1.2/50 ?S combination wave and the 10/700 combination wave in Saber,and then used the existing compoments in library to take the place of complex surge protection devices,establishes a preliminary protection circuit simulation models,preliminarily verify the validity of the surge protection circuit.Secondly,determine the test model and set up the test environment,according to GB17626.5-2008 "electromagnetic compatibility test and measurement technology surge(impact)immunity test" standard,complete the signal port and slave card surge test in different voltage levels in EMC lab.And the test waveforms and the following function test have proved the effectiveness of the surge protection circuits.