What is a transient voltage suppressor diode ( TVS )?
What is a transient voltage suppressor diode ( TVS )?
Transient voltage suppressor diode is a new type of overvoltage safety protection device. The utility model has the advantages of small size,large peak power,strong anti-surge voltage,good breakdown voltage curve,good bidirectional voltage symmetry,and low zener impedance,the reverse leakage current is small,and the response speed of the pulse is fast.When used in the protected circuit,when the high energy transient surge voltage is encountered,it can reverse breakdown rapidly and change from high resistance to low resistance,the voltage clamp is located at the specified value,which can be quickly broken down when the voltage is increased again,so that the fuse protects the instrument and equipment from damage.The internal structure and symbols of the transient voltage suppressor diode are shown in Figure.It is mainly composed of three parts of the chip lead electrode tube body.The chip is the core of the device,which is formed by the diffusion of semiconductor silicon material,and has two kinds of structures:unipolar and bipolar.The unipolar type has only one PN junction,which is widely used in the over-voltage protection circuit of various instruments,household appliances,automatic control systems and lightning protection devices.The symbol and characteristic curves are shown in Figure.The bipolar type has two PN junctions,and the symbol and characteristic curves are shown in Figure.The transient voltage suppressor diode works by utilizing the zener breakdown characteristics of the PN junction,and each PN junction has its own reverse breakdown voltage VB,within the rated voltage,the current does not turn on;when the applied voltage is higher than the rated voltage,the PN junction enters the breakdown state rapidly,with a large current flowing through the PN junction,and the voltage is limited to the rated voltage.The structure of the bipolar chip is not simply connected in series by two back-to-back monopole chips,but is produced on both sides of the same silicon chip a back-to-back PN junction,which can be used for bi-directional overvoltage protection.