Circuit ESD protection electrostatic discharge (ESD) is the knowledge that engineers engaged in the design and manufacture of hardware must possess. Many developers often encounter such a situation: the development of products in the laboratory, the test is passed, but the customer after a period of time, there will be abnormal, failure rate is not very high. In general, most of these problems are due to surge, ESD impact and other reasons. In the process of assembly and manufacture of electronic products, more than 25% of the damage to the semiconductor chip is attributed to ESD. With the wide application of micro electronics technology and more and more complex electromagnetic environment, people pay more and more attention to the electromagnetic field effect of electrostatic discharge, such as electromagnetic interference (EMI) and electromagnetic compatibility (EMC). The circuit design engineers through a certain number of transient voltage suppressor (TVS) devices to increase protection. Such as solid devices (diodes), metal oxide varistor (MOV), silicon controlled rectifier and other variable voltage materials (new device), the spark gap gas tube and simple. With the emergence of a new generation of high-speed circuits, the operating frequency of the device has been increased from a few kHz to GHz, and the requirements for the high capacity passive devices used for ESD protection are becoming higher and higher. For example, TVS must respond quickly to the arrival of the surge voltage, when the surge voltage reaches 8KV at 0.7ns (or higher) peak, TVS devices trigger or adjust the voltage (in parallel with the input line) must be low enough to serve as an effective voltage divider.
Now, ESD is increasingly used in circuit design engineers in high frequency circuit design. Despite the low cost silicon diode (or rheostat) trigger / clamp voltage is very low, but its high capacity and leakage current can not meet the growing demands of applications. Polymer ESD suppressor at frequencies up to 6GHz when the attenuation is less than 0.2dB, the circuit effect is almost negligible.
Electromagnetic compatibility and circuit protection are unavoidable problems for the design of all electronic products. The circuit design engineers familiar with the relevant standards of electromagnetic compatibility, the need to consider the performance of the device itself, the parasitic parameters, product performance, cost and system design of each functional module design, layout optimization, by adding decoupling capacitance, magnetic ring, magnetic beads, shielding, PCB resonant suppression measures to ensure that the EMI in the control range. In the design of circuit protection design, the most important thing is to master the technical scheme and design method, and then choose the correct ESD protection device.