You could definitely go switcher but depends on how you define low-cost.
If $10 seems reasonable, then it's definitely low-cost 3#-)

Otherwise, I find the LM7805T works quite well for a linear regulator
and ultimately, requires only a clip-on TO220 heatsink clip provided
that you're drawing no more than about 500mA from it.

Adios,
LarZ

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-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Robert E. Griffith
Sent: Tuesday, 17 July 2001 10:58
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]:Voltage Reg vs Switcher

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.

Thanks,

--BobG

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