Cheap (non-) isolated solution for off-line 3...5V?

Did you try WEBENCH (ti.com/webench)? It is as simple as can be.

Regards,
Maciej 

Dear Maciej,

Thank you for the answer. I now tried the Webench tool. It seems to be simple, yes - but it is rather a hassle.

When I type in "AC / 50Hz / 210...240V / 0.05A / 30°C" It just shows the parts UCC28700 ... UCC28703 which are all isolated converters. I really tried for a long time now and I don't get any other results, sometimes it says: "Your solution is not webbebch enabled".

Regards, Tobias

Hi Tobias,

for 5V or 3.3V/30mA requirement in non isolated configuration you can use Capactive drop power supply followed by DC-dc converter like TPS54060.

Please fine the application note link for it. http://www.ti.com/litv/pdf/slva491 and the excel calculator http://www.ti.com/litv/zip/slvc392.

For isolated case you can use UCC28700/UCC28701/UCC28702/UCC28704 PSR controller.PLease find the link http://www.ti.com/product/ucc28700.You can put your values in the web bench and the web bench tool will give the design.

For isolated you can also use a small 50Hz transformer followed by a LDO as your load is very small and the input ac variation is very small.

Regards,

Harmeet