On Tue, Jul 17, 2001 at 08:57:40AM -0400, Robert E. Griffith wrote:
> I have a design that uses a 12v wall wart power supply because an LCD needs
> the 12v.  The main circuit runs on 5v and 3v.  In the prototype I have a 5v
> regulator (LM340TS) dropping the 12v to 5v and a 3v regulator (TPS7230QP)
> that drops 5v down to 3v. This device will be on all the time.
>
> I have a heat sink on the 5v reg and it gets hot. I want to put the finished
> circuit in a project box with vents but no fan.
>
> My question is: is there an easy, low cost, solution to implementing a
> switcher to drop the 12v to 5v? Is this done? The 3v reg does not provide
> much power so it is not a problem.

Easy? yes. Low cost? Depends on your price range. Take a look at the National
semiconductor Simple switcher series. Requires little more than a coil, diode,
and a cap. But the total cost will be in the $10 range.

BAJ

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