On Feb 14, 1:34 am, "ElderUberGeek" <aribl...@gmail.com> wrote:
> I have a board that has components requiring both 5v and 3.3v supply.
> The unit is supposed to be powered from a 12v or 24v battery.
> Can anyone suggest such a dual output DC/DC converter? Needs to be PCB
> mounted and of course inexpensive... (and should preferable handle
> polarity changes in source).
> Apart from the above, if BOM cost is to be minimized, would it be
> better to build it from discretes or not worth the hassle?
>
> Thanks!

What currents and how many do you want?

We have some 3A switching modules.
They can be set at 1.8V, 2.5V, 3.3V or 5V.

http://linnix.com/smps

On 14 Feb, in article
     <1171445675.757949.177150@q2g2000cwa.googlegroups.com>
     aribloch@gmail.com "ElderUberGeek" wrote:

>I have a board that has components requiring both 5v and 3.3v supply.
>The unit is supposed to be powered from a 12v or 24v battery.
>Can anyone suggest such a dual output DC/DC converter? Needs to be PCB

Everything depends on the power requirements of EACH rail, it is often
cheaper and simpler to get a DC/DC that can cope with the total power at
5V output and put a seperate LDO regulator to give  3V3 rail.

>mounted and of course inexpensive... (and should preferable handle
>polarity changes in source).

If the item has NO other connection to anything else connected to 12V/24V
battery then you could put a diode brdige in front.

IF any connection (including gnd) is tied back to the original supply
then the best you can do is a blocking diode to stop current if reverse
connected.

>Apart from the above, if BOM cost is to be minimized, would it be
>better to build it from discretes or not worth the hassle?

That all depends on

        Power requirements
        Space - area and height available.
        Heat dissipation
        and many other factors you have not specified
                such as what is 'inexpensive' to you

>Thanks!
>
>

-- 
Paul Carpenter          | paul@pcserviceselectronics.co.uk
<http://www.pcserviceselectronics.co.uk/>    PC Services
<http://www.gnuh8.org.uk/>              GNU H8 & mailing list info
<http://www.badweb.org.uk/>             For those web sites you hate

I have a board that has components requiring both 5v and 3.3v supply.
The unit is supposed to be powered from a 12v or 24v battery.
Can anyone suggest such a dual output DC/DC converter? Needs to be PCB
mounted and of course inexpensive... (and should preferable handle
polarity changes in source).
Apart from the above, if BOM cost is to be minimized, would it be
better to build it from discretes or not worth the hassle?

Thanks!