Ac to DC without transformer

Hi, I was wondering if there were any single chip solutions to convert from 120V AC to DC We are currently using a transformer but its a bit bulky to put on a printed circuit board. The chip will have to provide 5V DC for a couple of IC's.

0.1A is maximum current required.

Thanks in advance.

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Do a web search on off line power, or off line switcher. Lots of info.

Tim Wescott
Wescott Design Services
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Tim Wescott

At these power levels (1/2 Watt), switchers aren't much smaller than linear transformers. If ALL of your circuitry is isolated properly, you can consider using series capacitance instead of a transformer, but you'll need about 3uF, and properly rated capacitor(s) could also be about as large as a 1VA transformer. You might want to put your energies into looking for the smallest possible linear transformer, especially if your product has any exposed metal. Paul Mathews

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Paul Mathews

No single chips that I know of, but check out Power Integrations and their LNK304 series of chips

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This takes at least 10 other components to make it work, but it works well and they are cheap solution.

At .1A you need too big a series cap to do a simple ac coupled bridge converter for it to be cheap, however, if you can lower current to about 20ma it is a good way to go.

Of course I'm thinking you don't need isolation?


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