1.2, Transient Voltage suppressors TVS (Transient Voltage Suppressor) : TVS is a solid-state diode, specifically designed to prevent ESD Transient Voltage sensitive semiconductor devices.Compared with the traditional zener diodes, TVS diode P/N junction area is larger, the structure improvements make TVS have more pressure to bear ability, but also reduces the voltage cut-off rate, thus to protect the safety of hand-held

The transient power and current performance of TVS diode are proportional to the area of junction. The diode junction has a large cross-sectional area and can handle high transient currents caused by lightning and ESD. TVS also has junction capacitance, usually 0.3 pF to dozens of pF. TVS has unipolar and bipolar TVS, pay attention when you use them

1.3, the structure of the multilayer metal oxide device (MLV) : generally called varistor.MLV instantaneous high pressure shock can also effectively suppressed, such devices with nonlinear (behave) impedance, voltage - current cut-off voltage can be up to the initial voltage of 2 ~ 3 times.This feature for the voltage is not too sensitive circuits and components of electrostatic or surge protection, such as the power supply circuit, but there is no good TVS, protection and varistor have aging life.
2, the series impedance
Can generally by series resistance or magnetic beads to limit the ESD discharge current, achieve the goal of ESD.
3, increase the filter network
Mentioned the electrostatic energy spectrum, if use filter to filter out the main energy can also achieve the goal of electrostatic protection.
For low frequency signal, such as GPIO inputs, ADC, audio input can use 1 k + 1000 pf capacitor for electrostatic protection, as poor as pressure sensitive resistance performance, if use 1 k + 50 pf the piezoresistive composite protective measures (below), the effect is better, experience has shown that protective effect is sometimes more than TVS.
For microwave antenna of the radio frequency signal, if use TVS tube, pressure sensitive capacitive devices for electrostatic protection, such as rf signal attenuation, will be so demanding TVS capacitance is very low, so that increase the cost of ESD measures.For microwave signals can be over the ground a few nH inductance in parallel to provide a discharge passage for electrostatic, will have little impact on microwave signal, for 900 MHZ and 1800 MHZ phones often use 22 nH inductance.This will put the main energy spectrum of electrostatic absorb a lot of energy.
4, composite protection
There is a device called EMI filter, he has a good effect of ESD protection
In practical application can use a resistor + a varistor way.There are both low-pass filter function, and function of varistor, and resistor in series with the current limiting function.Is the best protection way, the price for the high impedance signal can use 1 k + 50 pf pressure sensitive resistance;For TP series resistance signal cannot too big otherwise affect the linear of TP, can use 10 euro resistance.Although the small resistance, low pass filter effect was gone, but the current limiting function is very important.

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