Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Offline LED drive SMPS >50W must have open feedback loop protection via aux coil?

Status
Not open for further replies.
T

treez

Guest
Hello,
We are doing a 100W led lamp, it is powered by a 100w offline smps.
If the led load goes open, we have an opto which crosses the isolation barrier and shuts down the pwm controller on the primary side.
..but is this enough?...do we also need to have a auxiliary coil in the isolation transformer which gets used for overvoltage protection by relaying an "image" of the output voltage back to a shut down cct on the primary side.?

Or is a simple opto, on its own, enough?
 

Dan Mills

Advanced Member level 2
Joined
Nov 10, 2013
Messages
510
Helped
239
Reputation
478
Reaction score
229
Trophy points
43
Activity points
4,558
Re: Offline LED drive SMPS >50W must have open feedback loop protection via aux coil?

Depends, how high does the output go in the event of a fault, and how much energy is potentially available?

Maybe you can use the turns ratio on the magnetics to limit the worst case output voltage to something SELV?
Maybe you can just have the magnetics saturate before the voltage becomes dangerous and take out a fuse?

I am assuming that at the 100W level the topology is something a bit smarter then a flyback?

Regards, Dan.
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating

SunnySkyguy

Advanced Member level 5
Joined
Sep 26, 2007
Messages
6,980
Helped
1,709
Reputation
3,416
Reaction score
1,697
Trophy points
1,413
Location
Richmond Hill, ON, Canada
Activity points
51,518
Re: Offline LED drive SMPS >50W must have open feedback loop protection via aux coil?

Smart Drivers have OVP and UVP with latching hysteresis
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
T

treez

Guest
Re: Offline LED drive SMPS >50W must have open feedback loop protection via aux coil?

Thanks, this is a qr flyback running off 400v pfc output.
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Top