# wide range voltage input

Discussion in 'Electronic Basics' started by ltj, May 19, 2004.

1. ### ltjGuest

If you had a small 3.3V, 50mA circuit how could you make it to accept a
5-24VDC input range? Cost is an issue.

2. ### John PopelishGuest

Are you talking about responding to logic signals or measuring analog
signals?

3. ### ltjGuest

oops...for powering the circuit. A regulator will get too hot if I drop too
much voltage across it, so what is a good way to have a wide power input
range?

4. ### John PopelishGuest

A switching regulator converts one voltage to another with minimal
power loss. Here is a tutorial on the subject to get you started.
http://www.national.com/appinfo/power/files/f5.pdf

regulator for you, to your specifications:
http://www.national.com/appinfo/power/

That said, 50 ma drawn from a 24 volt source represents only 1.2
watts, total. So a linear regulator would have to waste no more than
(24-3.3)*.05=1.03 watts. That is about what a square inch of heat
sink could dump.