Ac to DC without transformer

[Foaad]

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.

 

[Tim Wescott]

Foaad wrote:

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.

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

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com

 

[Paul Mathews]

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

 

[Rock]

No single chips that I know of, but check out Power Integrations and
their LNK304 series of chips (www.powerint.com). 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?

Rocky