Continue to Site

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 Full bridge SMPS control ic's do not have output overload protection?

Status
Not open for further replies.
T

treez

Guest
The following are the most common current mode full-bridge SMPS control chips in the world for 90-265VAC input SMPS’s….

UCC3808, LM5030, LM5037 , UC3846, LTC3721-1

None of these chips has output overload protection. By “output overload protection”, I mean that if the error amplifer internal to them is railed high for more than 1 second, then these chips do *not* latch off.

Most offline flyback smps chips have this facility, so why do none of the full-bridge smps chips have this?

LM5030
http://www.ti.com/lit/ds/symlink/lm5030.pdf

LM5037
**broken link removed**

LTC3721
http://cds.linear.com/docs/en/datasheet/37211fs.pdf

UCC3808
http://www.ti.com/lit/ds/symlink/ucc3808-2.pdf

UC3846
http://www.ti.com/lit/ds/symlink/uc3846.pdf
 

Correct, sometimes you want full power....!
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
..Those chips can give full power. What we wonder is why no offline full-bridge controller has output overload protection, or output short circuit protection?
 

The features of the chip itself can be exploited in many unusual ways by a clever designer.

They all have some kind of current limit function, and the soft start pin can also be used as a duty cycle limiting feature quite independent of the normal current limit pin.

Its usual to provide a current limit for the switching devices, but there is no reason why an output current limit cannot also be fitted in addition to that,
 
  • Like
Reactions: treez

    T

    Points: 2
    Helpful Answer Positive Rating
Thanks, here is our fault protection circuit, for use with these "unprotective" chips...
 

Attachments

  • fault protection schematic.jpg
    fault protection schematic.jpg
    133.9 KB · Views: 139

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top