Adjustable voltage SMPS for intelligent car battery charger

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Three years ago I designed and build a few tens of intelligent car battery chargers (controlled by microcontrollers) for a company that sells car batteries. The design was using a TOP249 and a 140W flyback transformer (in fact by reading the datasheet of that transformer I found about your company :) ). I wasn't very experienced and that's why the design has a pretty low safety margin but even so, most of those chargers still work until today.

Now I want to improve the original design and produce is a greater number and for a longer time period. Since I have first-hand proof that your SMPS drivers are really good and help in getting a robust and cost-effective product I want to include them in this future design.

Before restarting my research and design I want to ask your opinion on which SMPS topology and Power Integration drivers it would be wise to go on considering these target requirements:
- variable output voltage between 5V to 16V (I want to be able to charge 6V and 12V batteries);
- maximal continuous output current: 10A;
- AC input voltage: 195-265;
- I plan to include a temperature triggered fan to avoid overheating of the transformer and of the driver;
- I want a cost-effective design but I also want at least 5% safety margin (so if the required output power in worst case is 16Vx10A=160W, I want the design to be able to deliver at least 160W x 1.05 ~ 170W).

So kindly please advise me which SMPS topology and Power Integration drivers variant you think suits better my requirement.

P.S. I am aware of your PI Expert suite. I used it in the last design. Unfortunately, not all your products are included in that suite so I can't check by myself what is the best topology/driver for my problem.

Dear All
I am using LNK625PG in design.but out put voltage is not coming 5V .Out voltage is coming 12v. please tell me solution

Syemtics.pdf112.78 KB

Hi om3333333,

Thanks for reaching us! As for your query, the initial thing that you can do is to check your feedback components both Rupper and Rlower it should follow the recommendations of the PIexpert online suite, secondly do also check the bias winding of your transformer if it is correct.

If the problem still persist, please provide me the following:

1) PIexpert online suite design sheet.
2) Transformer construction

Thank you!



I bought last week LNK625PG from and according to your instruction I use it, and its working very well, it works properly, plz keep sharing these helpful ideas.

I hope you found it.