Design Of A Surge Suppressor With Negative Pressure Protection

With the rapid development of various communication equipment,base stations,portable devices and other products,electronic products have more and more functions and higher integration.The functional modules in these devices may use multiple power chips for power supply,and the power supply used by the power modules is often the same.The switching opportunities of these functional modules form surges on the power line,and the improvement of integration means that the power supply may be subject to more frequent and greater energy surges.In order to solve the problems of single protection type in the current traditional surge suppression and protection methods,a new surge suppressor is designed in this thesis.Based on the analysis of the causes and types of surge,a new surge suppressor with negative pressure protection is designed in this thesis.The surge suppressor suppresses the startup surge by controlling the soft start of the external NMOS.The suppressor protects the load by driving the external power NMOS tube.The user can set the external circuit according to the application environment to realize the judgment of the suppressor and the adjustment of the clamping threshold.When the surge arrives,the load voltage can be clamped through the control of the power tube.During the clamping process,the magnitude of the surge can be detected to conduct the clamping timing to prevent the power tube from being damaged due to heating.After the power tube is turned off and timing is completed,the power tube will judge whether to restart according to the input voltage.The suppressor can detect the load current,provide current clamping protection for overcurrent and short circuit,and effectively prevent excessive surge on the power supply due to load overcurrent.According to the above design requirements,this thesis first analyzes the voltage loop and current loop,and obtains the reasonable allocation of zero and pole of the loop.According to the working principle,the typical application of surge suppressor is given.Then,based on the 0.18μm 100 V BCD process platform,the circuit is designed,focusing on a segmented temperature compensation bandgap reference with high PSRR and a current comparator that can automatically switch the comparison threshold according to the voltage.The working principle of each module is analyzed,and the module and overall simulation verification are carried out.Finally,the electrostatic discharge（ESD）circuit and adjustment circuit of the chip are designed.The layout is given,and the layout design is completed and verified by simulation.According to the simulation results,when the voltage rises at 160 V / ms to simulate the surge,the load will have an overshoot of 0.6V,and the load voltage will be clamped.After the output current transients,the current can be clamped within 20μs.The circuit can effectively clamp the load voltage and load current,automatically reduce the clamping threshold in case of load short circuit,and set the timing time according to the input and output voltage difference.