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From: Joerg on 4 Jun 2010 20:56
Gents,

Does anyone know of a little AC/DC switch mode converter module that can
take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k
qty would be nice, availability in the US would be even nicer.

All I see is 24VAC to 12VDC and placing two in a row costs effiency.
Sure, I could roll my own again but this time we want to avoid NRE and
agency hassle (EMC et cetera).

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: krw on 4 Jun 2010 21:02
On Fri, 04 Jun 2010 17:56:04 -0700, Joerg <invalid(a)invalid.invalid> wrote:

>Gents,
>
>Does anyone know of a little AC/DC switch mode converter module that can
>take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k
>qty would be nice, availability in the US would be even nicer.

Check out Intersil's new buck regulators. They'll go up to 42V and up to 10A,
IIRC.

>All I see is 24VAC to 12VDC and placing two in a row costs effiency.

Regulatory problems, too.

>Sure, I could roll my own again but this time we want to avoid NRE and
>agency hassle (EMC et cetera).
From: Joerg on 4 Jun 2010 21:20
krw(a)att.bizzzzzzzzzzzz wrote:
> On Fri, 04 Jun 2010 17:56:04 -0700, Joerg <invalid(a)invalid.invalid> wrote:
>
>> Gents,
>>
>> Does anyone know of a little AC/DC switch mode converter module that can
>> take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k
>> qty would be nice, availability in the US would be even nicer.
>
> Check out Intersil's new buck regulators. They'll go up to 42V and up to 10A,
> IIRC.
>
>> All I see is 24VAC to 12VDC and placing two in a row costs effiency.
>
> Regulatory problems, too.
>
>> Sure, I could roll my own again but this time we want to avoid NRE and
>> agency hassle (EMC et cetera).


Yes, I'd could roll my own buck with some automotive chip. Sorry, forgot
to mention one minor detail: Must be isolated, or should be (we may be
able to live without if it really has to be).

Thing is, with one of those ubiquitous 24VAC -> 12VDC switchers plus
another buck we'd be at 60% overall efficiency or less and we can't
quite afford that.

--
Regards, Joerg

http://www.analogconsultants.com/

"gmail" domain blocked because of excessive spam.
Use another domain or send PM.
From: Michael Kellett on 5 Jun 2010 05:07

"Joerg" <invalid(a)invalid.invalid> wrote in message
news:86tllfFibtU1(a)mid.individual.net...
> Gents,
>
> Does anyone know of a little AC/DC switch mode converter module that can
> take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k qty
> would be nice, availability in the US would be even nicer.
>
> All I see is 24VAC to 12VDC and placing two in a row costs effiency. Sure,
> I could roll my own again but this time we want to avoid NRE and agency
> hassle (EMC et cetera).
>
> --
> Regards, Joerg
>
> http://www.analogconsultants.com/
>
> "gmail" domain blocked because of excessive spam.
> Use another domain or send PM.

Why not use a transformer to take the 24V AC up to 110V and then use any bog
standard switcher to get your 3.3V ?
Michael Kellett


From: Ross Herbert on 5 Jun 2010 06:28
On Fri, 04 Jun 2010 17:56:04 -0700, Joerg <invalid(a)invalid.invalid> wrote:

:Gents,
:
:Does anyone know of a little AC/DC switch mode converter module that can
:take 24VAC and put out well regulated 3.3V at 1.5A or more? $25 in 1k
:qty would be nice, availability in the US would be even nicer.
:
:All I see is 24VAC to 12VDC and placing two in a row costs effiency.
:Sure, I could roll my own again but this time we want to avoid NRE and
:agency hassle (EMC et cetera).


I don't think there are any 24Vac input converters off the shelf - almost zero
demand I would think.

Why not use one of the 6 - 10W, 18-36V input DC-DC converters (eg. V-Infinity)?
Provide a bridge rectifier and bulk filter cap in front of it. A few bucks for
the BR and cap would keep it under $20 per unit in 1K quantity.
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