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EEVblog => News/Suggestions/Help => Topic started by: Fabiosapplou on April 25, 2017, 10:19:35 pm

Title: How to design mains AC to DC adaptores, for small loads...
Post by: Fabiosapplou on April 25, 2017, 10:19:35 pm

I'd really enjoy a take on how David would design a steep down mains adaptor to power small loads shuch as a esp8266... Not using the obvious route of a small transformer 50/60hz transformer with regulation...

Title: Re: How to design mains AC to DC adaptores, for small loads...
Post by: David Hess on April 26, 2017, 01:47:15 pm

If you do not have other constraints, then there is another way to use a line frequency transformer; include the transformer for line isolation and follow it with a switching power supply.  A power factor correction stage could even be used to provide a unity power factor on the input.  There are also some EMI advantages since RF filtering can be done at a low voltage.

Title: Re: How to design mains AC to DC adaptores, for small loads...
Post by: thm_w on April 26, 2017, 08:09:51 pm

Use an off the shelf module or an existing supply (like a USB supply) and integrate it into your design.

http://www.hlktech.net/product_detail.php?ProId=54 (http://www.hlktech.net/product_detail.php?ProId=54)
https://skippy.org.uk/quick-look-at-the-hlk-pm01/ (https://skippy.org.uk/quick-look-at-the-hlk-pm01/)

I assume you care about low cost here, otherwise you can get good modules from digikey.