Lightning overvoltage device is divided into clamp type overvoltage device and switch type overvoltage device, lightning protection device switching overvoltage device known as the ceramic gas discharge tube, semiconductor discharge tube and glass tube clamp device; overvoltage transient suppression diodes, varistors, SMD varistors and ESD discharge diode; overcurrent device the PTC element self recovery fuse, the following is the specific role:
1 discharge tube:
The discharge tube is often used in multilevel protection circuit in the first level or two level, since the discharge of lightning transient overcurrent and overvoltage limiting effect, the discharge tube is through the voltage limit at a relatively low level, which play a protective role. Kai electronic
The discharge tube is divided into gas discharge tube and solid discharge tube, gas discharge tube with ceramic gas discharge tube and glass gas discharge tube, the specific application of the discharge tube type and the type selection is required according to the product application engineer
Port protection level and related selection parameters to determine.
2 transient suppression diode: transient suppression diodes to minus 12 seconds speed of 10 magnitude, the high impedance between the poles into the low impedance, absorb up to several kilowatts of power surge, the voltage clamp between two poles at a predetermined value, the effective protection of precision components for electronic circuit the damage from the surge pulse. 3: varistor varistor is a voltage limiting type protection devices, circuit protection is mainly based on the characteristics of nonlinear varistor, when overvoltage appears in the varistor between the poles, the varistor voltage can be clamped to a fixed voltage value, and realizes the protection of circuit the.
4 the role of SMD varistors: SMD varistors are mainly used to protect components and circuits to prevent the power supply, control and signal lines generated by ESD.
5.ESD electrostatic discharge diode function: ESD electrostatic discharge diode is a kind of overvoltage, anti-static protection components, is designed for high-speed data transmission applications I/O port protection devices. ESD protection devices are used to avoid the effects of ESD (electrostatic discharge) on sensitive circuits in electronic devices. It offers very low capacitance, excellent transmission line pulse (TLP) test, and IEC6100-4-2 test capability, especially in the case of multiple sampling up to 1000, thereby improving the protection of sensitive electronic components.
6.PTC resettable role: the normal work of the circuit when the resistance is very small (pressure drop is very small), when the circuit over-current makes it when the temperature rises, the resistance increases several orders of magnitude, the current in the circuit is reduced below the safety value, so that the back of the protected circuit. When the fault is removed, the PPTC component is cooled quickly and will revert to the original low resistance state, which can be re worked as a new PPTC element.
7: the relationship between electromagnetic inductive role believe we all know that the inductive role is when the circuit at the beginning, when everything was uncertain, if the current through the inductor, induction current will generate a current in the opposite direction (Faraday electromagnetic induction law), until a circuit operation after some time, everything is stable, not what the current changes, electromagnetic induction is not current, it is stable, does not appear sudden changes, so as to ensure the safety of the circuit, like water, a start rotating slowly due to resistance, then gradually calm.
Inductance is also a function of the DC, AC resistance, which is not much use, I do not know how to use specific, and so used to share with you
8 bead role: beads have very high resistivity and permeability, he is equivalent to the resistance and inductance in series, but the resistance and inductance values with frequency change. He has high frequency filtering characteristics better than ordinary inductance, showing resistance at high frequency, so it can maintain a high impedance in a wide frequency range, so as to improve the frequency filtering effect, used in Ethernet chip.