Dear Team,
For protection purpose we have placed TVS diodes in the power circuitry.

During assembly, The assembly house made Issue like TVS diode(unidirectional) was reversed in polarity & mounted,because of that my board was not powering on.

Query:
1) what will be the behaviour of TVS diode during reverse bias.
2) can anybody explain about the TVS diode concepts.

 

If the diode is installed the wrong way, that is with the Anode to the +ve, it will be a "short" on the supply, with around a 0.7V drop.
The TVS diode needs to be connected with the Cathode to +ve.
You will need to remove it and install it the other way around if it is wrong.

 

1) what will be the behaviour of TVS diode during reverse bias.

A TVS diode acts like a zener diode.

2) can anybody explain about the TVS diode concepts.

 

The confusion comes from the fact that TVS are used in reverse bias (like a zener)... so when you ask what the behavior is reverse bias I believe you mean what's their behavior forward biased with the anode positive. In forward bias (which is reversed in your case) a TVS (or transil) behave just like a diode, it would not last long without current limiting. It would drop approximately 0.7 volts and send the rest to ground and possibly pop.

standard wiring for TVS is reverse biased:



Because a TVS is a diode, we still use the terms "forward" and "reverse" bias just like we would any other diode:



Hopefully that clarifies what happened and why your board is not powering up. If you have tried to power them up like this, the chances are you've blown them and should be checked before re-using them.