Okk i will make my requirement clear.i am designing this smps to provide power for a powerline communication board. I will need two secondary output one of 3.3v 1A and other of 16v 0.2a. The efficiency is very important since its going to be industrial product. Now as a trial i used some transformer for viper series other than viper22a but i remember both where having switching freq 60khz.so i expected it to work really well. But the max efficiency i am getting is only 57%.this transformer is for 5v/12w so i designed it for 5v and when load is applied to get 1.5 A the voltage drops to 4.8v. I believe the transformer is the culprit.
The advantages of a switch-mode power supply (SMPS) are just too great to ignore. Efficiency is the primary benefit, with efficiencies over 90% for many designs. Such as online design software.
I am not so experienced with designing transformers and smps. I tried the link of that software its broken.please give some other link to access it.
Thanks to all. Thanks buddy thankyou very much.This is a really tool of ST right. We can Trust this know? Expecting your cooperation regards let me try this out ---------- Post added at 05:54 ---------- Previous post was at 04:49 ---------- hai, in this software tool i saw primary side regulation and secondary side regulation.i have a good idea about secondary regulation where we take feed back from secondary output and use it to control the pwm of viper. Can anyone explain to me whats primary side regulation and how it works in viper 22a. I saw they use a zener at feed back pin.but couldnt quiet get it working.isnt viper22a a using current feed back. Keep in mind your overall efficiency is going to be limited by the 3.3V output.
It's rectifier diode will eat up about 13% of the power on that output, so there's really no way to get above 87% without switching topologies or doing something like a synchronous rectifier on the output. Gujarati tera font suraj. Transformer losses should be in the range of 2-5% of your transmitted power for a good design (probably closer to 5% for low power flybacks). So you're almost certainly looking at overall efficiency of less than 80%, probably more like 75%. Yes, the conduction losses of the diode will be the main issue. Synchronous rectification means that instead of just using a diode as the secondary rectifier, you use a FET which is turned on during the flyback period. The conduction losses of the FET can be much lower than that of the diode it replaces.
However for offline isolated converters you need an isolated gate driver, or a gate drive transformer. Also synchronous rectification means that the secondary will always be in continuous conduction mode (unless special control methods are used), which can decrease light load efficiency. Synchrounous rectification isn't something that's feasible if you want to use a simple controller chip like the topswitch stuff.