Contents
What is unidirectional TVS diode?
Unidirectional TVS Devices For negative voltage from cathode to anode the TVS has high conductivity above a forward diode drop. For positive voltages there is high impedance up to the reverse bias breakdown voltage. Above the reverse bias breakdown voltage the diode has low resistance.
How does a bidirectional TVS diode work?
BidiRecTionAl TVS deViceS During a transient’s positive cycle, the TVS diode D1 is reversed biased while the other diode D2 is forward biased. D1 acts in avalanche mode (similar to a unidirectional diode) as the transient current (I1) flows to ground.
What is Zener effect and avalanche effect?
The Zener effect is distinct from avalanche breakdown. The avalanche breakdown occurs in lightly doped junctions, which produce a wider depletion region. Temperature increase in the junction increases the contribution of the Zener effect to breakdown, and decreases the contribution of the avalanche effect.
Which is better for USB unidirectional or bidirectional TVs?
If the I-V characteristics of “unidirectional” TVS are as the linked article means (avalanche breakthrough limit for positive spike polarity, and regular diode for negative polarity), then their “unidirectional” devices are better for USB than “bidirectional”.
What does a bidirectional TVS diode symbol mean?
Symbol of a Bidirectional TVS diode is shown in below image. TVS Diodes are connected in parallel with the device or circuit to be protected. The TVS device is specifically designed to breakdown at a specific voltage level and conducts large amounts of current without sustaining damage.
Which is better a bi-directional or unidirectional diode?
A bi-directional diode has the same characteristic curve in the positive and the negative direction, so it does not matter which way they are connected into the circuit. A unidirectional diode has a higher turn-on voltage in the positive direction compared to the negative direction.
How does a unidirectional transient voltage suppressor diode work?
A unidirectional Transient Voltage Suppressor Diode works as a rectifier in a circuit in the forward direction like any other avalanche diode, and this unidirectional diode is made to withstand very large peak currents. Symbol of a unidirectional TVS diode is shown in below image, and it is much like a Zener diode.