Powering a PIC

[dhouston]

where can i read up on these UL requirements? (www.ul.com) but do you have a pdf document with these norms.. i could not find it. So basically you are telling I need a switching supply ? no transformer ?

Sorry, it's been a few years since I investigated this. The biggest issue is UL wants to have ongoing access to your operation to verify assembly operations. It's just not practical for a small business - you're better off using approved external modules like the $5 wall transformer I referenced. While I'm not familiar with the internals of the Spark Fun PS, most of these have internal transformers (at a high frequency) and provide isolation from the power line.

You could design a switch mode supply into your device and choose an offshore assembler that can meet UL requirements but, again, this really isn't practical (or cost effective) for a small business.

California already has power supply efficiency standards that can only be met by use of a switch mode supply. Other jurisdictions are sure to follow.

Why does your design have an isolation transformer? Are you doing power line communication?

[mister_e]

If you feel lucky, and if there's room... wind some extra turn on the secondary side of the isolation transformer...

[lerameur]

I need 200 watt at 120VAC. I already have a big transformer that I am using. So I want to use a bit of the power out of that to supply my PIC. I would also like this to be safe and regulated because I would like to eventually commercialize this.

K

[dhouston]

Many chipmakers offer SMPS chips.

• http://www.fairchildsemi.com/applica...er_supply.html
  http://www.st.com/internet/analog/class/1454.jsp
  http://www.microchip.com/stellent/id...redirects=SMPS

But, if you commercialize your product, it would be prudent to get UL approval. Otherwise, one fire plus one attorney could bankrupt you.

[Ioannis]

Keeping in mind all the safety matters, look also here:

http://www.picbasic.co.uk/forum/show...former+elektor

Ioannis