Hi all,

Can an SMD reverse polarity protection diode be damaged by ESD? If yes, can this parameter be found on the diode datasheet?

 

Also, apart from peak inverse voltage and maximum forward current, what can cause a faulty diode?

 

It varies from piece to piece. As far as I know LEDs are more vulnerable to ESD than some integrated circuits/microchips.

Look for preferences of InGaN light-emmiting layer (common in LEDs)

Some LEDs incule a Zenner diode as well, in case of ESD "destruction".

hope this helps

 

sorry, I thought you were talking about LEDs. ¯\_(ツ)_/¯

 

It is a routine procedure to reverse breakdown diodes to measure what the breakdown is. As long as the current is controlled there is no damage.

 

back in the oldeer days of cb repair, a lot of radios came in with shorted reverse protect diodes, someone would hook the radio up backwards, blow the 2 amp fuse, and replace it with a 20 amp fuse, this caused the diode to short. never found an open one, only shorted.

 

Hi all,

Can an SMD reverse polarity protection diode be damaged by ESD? If yes, can this parameter be found on the diode datasheet?

Reverse polarity protection to what?!

There are various configurations for input protection diodes - in extreme cases they can fail during the duty of protecting the main circuit.

There are 2 main configurations of supply reversal protection diode - the shunt variety *SHOULD* have a fuse that blows if the battery gets reversed and forward biases the shunt diode.

The other type uses a series diode that only conducts when the battery is right way round, the reverse voltage rating should be easy to track down from the type number. Sometimes the forward volt drop of a regular silicon diode takes too much of the available voltage, so a Shottky barrier diode is used for its lower Vf, you have to be a bit careful with SB diodes - they start from only 20V reverse rating, and aren't common above 60V. With such low breakdown rating, the risk of static damage is something you should take seriously.

 

Thanks for the replies.
Another quick question. Can a microswitch similar to the one in the link below be damaged from ESD?

http://cpc.farnell.com/1/1/9952-microswitch-v4-pcb-plunger-ss5d-omron.html

If no, why is that? If ESD can reach high voltages which exceeds the switch rating, why it would not be damaged?

Thanks in advance.

 

Thanks for the replies.
Another quick question. Can a microswitch similar to the one in the link below be damaged from ESD?

http://cpc.farnell.com/1/1/9952-microswitch-v4-pcb-plunger-ss5d-omron.html

If no, why is that? If ESD can reach high voltages which exceeds the switch rating, why it would not be damaged?

Thanks in advance.

ESD is (hopefully) low energy and can't cause enough heating effect to melt bits off of switch contacts, but its more than enough to punch through the delicate gate layer in MOS devices.

The back emf from inductive loads like relays is another matter, without a clamp circuit you can get a fat spark every time the switch breaks the current.

Capacitive loads are different again, the charging/discharging surge can in extremes weld switch contacts together - which takes us full circle to ESD, if the charged object is big enough to have significant capacitance to ground, it can deliver an impressive spark big enough to damage more than just sensitive semiconductors.