Transient voltage suppressor (TVS) having a fast response time, large transient power, low leakage current, breakdown voltage deviation is small easier to control the clamp voltage, no damage limit, advantages of small size. Has been widely used in computer systems, communications equipment, AC / DC power supply, automobiles, household appliances, instruments and the like. Following on from Li Xin Electronics will combine deep TVS tube characteristics of application and precautions to discuss in detail how to apply the correct application performance TVS TVS tube and the tube was the best.
In actual application, the best way to deal with transient pulse device damage, is to divert from the instantaneous current sensitive device. For this purpose, the TVS circuit board in parallel with the protected circuit. Thus, when the transient voltage exceeds the normal operating voltage of the circuit, the TNS avalanche breakdown occurs, thereby providing transient current path to an ultra-low impedance, as a result the instantaneous current through the TVS is to open, thus avoiding the protection device, and the protected circuit before the voltage returns to normal remained cut-off voltage.
After that, when the pulse after the end of the transient, TVS tube and then automatically return to the high impedance state, the voltage across the circuit enters a normal state.
1, TVS tube application of three elements:
(1) A TVS is added to the signal and power line, a microprocessor or microcontroller can prevent malfunction due to momentary pulse, electrostatic discharge effects, the AC switching power supply noise and surges caused.
(2) electrostatic discharge effect release over 10000V, the above pulse 60A, and can continue to 10ms; and general TTL devices, encountered than 30ms pulse of 10V, will lead to damage. Using TVS tube, which can effectively absorb pulses damage the device, and can eliminate interference (Crosstalk) caused by the switching between the bus.
(3) the TVS is placed between the signal line and the ground, to avoid unnecessary data and control bus of noise.
2, TVS Matter in use should be noted:
Of the absorbed power voltage transient relationship between the width (peak) and the transient voltage pulse. A manual power only at a particular absorption pulse (peak value), the pulse width of the actual line is unpredictable, there must be estimated in advance. For wide-pulse should be derated.
To protect small current loads, may be consciously increase in line current limiting resistor, the resistance as long as a suitable current limiting resistor, does not affect the normal operation of the line, but the current limiting resistor to the generated interference will be greatly reduced but . This makes it possible to use a smaller peak power TVS tube to small current load circuit protection.
Transient voltage suppression recurring, of particular note is the average steady-state power TVS tube is within a safe range.
How to make use of the circuit performance TVS best? Selecting wiring and the circuit element printed circuit board is very important, ground selection process, and the parasitic inductance of the loop region, scientific and rational PCB wiring and pipes by sensible choice TVS TVS placement of the most performance TVS Jiahua