Re: Ac to DC without transformer

From: Alan Turner (alan_at_mrblobbybiccard.com)
Date: 02/11/05 

Date: Fri, 11 Feb 2005 14:22:36 GMT

Hi,

On Wed, 09 Feb 2005 17:21:14 -0800, 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.

If you're after a "transformerless" power supply you might consider
looking at an ATT2406. I played with one of these several years ago - I
still have one or two lying about, but I can't seem to find the data***
on the 'net.

My memory of the details of this IC are very hazy, so take what follows
with a grain of salt. The IC detected zero crossings and charged a
capacitor directly from the mains right at the start of a half-cycle. When
the instantaneous mains voltage reached some threshold the capacitor was
disconnected from the mains and used to supply a linear regulator. The IC
came in a plastic DIP8 package

I don't know if this IC would meet your current requirement of 100mA. Also
note that it does not provide isolation (which may or may not be important
for your application).

I'd avoid transformerless power supplies unless I were desperate.

Regards,
Alan 

-- 
Alan R. Turner | Live never to be ashamed of anything you do or say.
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