Which Of the components fails most often in low power offline SMPS?

Status
Not open for further replies.
T

treez

Guest
Hello,
Which of the components in a low power (<20W) offline SMPS (flyback) would be likely to be most vulnerable to failure?...

1..Switching FET
2..Mains rectifier diodes
3...MOV at mains input
4..Electrolytic capacitors in primary
5...Electrolytic capacitors in secondary
5...Primary side PCB fuse blows (eg due to mains surge etc)
6...Output diode
7...X caps
8...Y caps
 

OK, thanks, i should have said that I am talking about a "failure" that totally stops the light from working...as opposed to say, a 25% drop in capacitance which may be called a "failure" in certain industrial circles.
 

5 then 4 then 1
2 if there has been a surge on the ac input

if a capacitor of the secondary has a drop in capacity, or a high in esr, then the smps stops functionning
and sometimes this high esr destroys the main switching mosfet.
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Thanks, of course, as you know, all of these "demons" exist in mains LED lightbulbs, so I am not sure why they always quote the LED lifetime of 50000 hours when quoting bulb life?
 

make yourself a regular non smps power supply
led dont need much current, so your power supply will really last more than an smps one,
or replace the capacitors in smps with known good brand names low esr caps ( Panasonic, Rubycon, Chemicon, Nichicon )
 
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Or, better still, increase the switching frequency by several magnitudes and use dry capacitors. Oh, and develop faster diodes to do the rectifying. I'm busy right now but I'll have it all worked out by tomorrow :-D

Brian.
 


This can be fully answered on PDF document referred on topic bellow, which brings parametric way to predict its lifetime :

https://www.edaboard.com/threads/205648/#post867215





+++
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…