Power dissipation of voltage regulators?

[Daniel Kelly (AKA Jack)]

Please could you lend me some of your expertise?

I have a 12V 6Ah battery. I'd like to power a 5V 1Amp device for as long as
possible.

If I use a voltage regulator then will I lose a significant amount of power?
Do voltage regulators dissipate much power? I've looked on the spec sheets
but they don't tell me about power dissipation.

Thanks,
Jack

 

[Walter Harley]

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:c3snbr$m98$1@uns-a.ucl.ac.uk...

Please could you lend me some of your expertise?

Hi, Daniel. As you noticed, your questions got answered on
sci.electronics.design.

As a general rule, when posting to multiple newsgroups, it is best to post
to all groups simultaneously ("cross-post") rather than making multiple
independent identical postings. The reason is that each news posting gets a
unique ID; that way, when I read your message in one newsgroup and then
encounter it again in another newsgroup, my newsreader correctly flags the
message as already having been read. Doing it the way you did makes it
appear as if it was a different message, which is mildly distracting. Just
a tip!

 

[Daniel Kelly (AKA Jack)]

Cool, thanks for your tip!

Daniel

"Walter Harley" <walterh@cafewalterNOSPAM.com> wrote in message
news:c3sqvh$q4b$0@216.39.172.65...

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in
message
news:c3snbr$m98$1@uns-a.ucl.ac.uk...
Please could you lend me some of your expertise?

Hi, Daniel. As you noticed, your questions got answered on
sci.electronics.design.

As a general rule, when posting to multiple newsgroups, it is best to post
to all groups simultaneously ("cross-post") rather than making multiple
independent identical postings. The reason is that each news posting gets
a
unique ID; that way, when I read your message in one newsgroup and then
encounter it again in another newsgroup, my newsreader correctly flags the
message as already having been read. Doing it the way you did makes it
appear as if it was a different message, which is mildly distracting.
Just
a tip!

 

[Chaos Master]

A small dwarf called Daniel Kelly (AKA Jack) said:

Please could you lend me some of your expertise?

I have a 12V 6Ah battery. I'd like to power a 5V 1Amp device for as long as
possible.

If I use a voltage regulator then will I lose a significant amount of power?
Do voltage regulators dissipate much power? I've looked on the spec sheets
but they don't tell me about power dissipation.

If you use a 7805, it should be this:

(Input V-Output V)*Current
(12-5)*1 = 7*1 = 7 W so a heatsink will be needed.

And the efficiency would be in the 40~50% range, AFAIK.

[]s
--
_____ ___ Chaos MasterŽ
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[Dan Dunphy]

You don't have to dissapate all the power in the regulator, put a
power resistor on the input side, and drop 3-4 volts on the regulator.
Just make sure you don't violate the headroom spec.
Dan

On Wed, 24 Mar 2004 19:26:26 -0000, "Daniel Kelly \(AKA Jack\)"
<d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote:

Please could you lend me some of your expertise?

I have a 12V 6Ah battery. I'd like to power a 5V 1Amp device for as long as
possible.

If I use a voltage regulator then will I lose a significant amount of power?
Do voltage regulators dissipate much power? I've looked on the spec sheets
but they don't tell me about power dissipation.

Thanks,
Jack

Colorado Springs, CO
My advice may be worth what you paid for it.