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

 

[Mark (UK)]

Hiya!

12v - 5v = 7v drop at 1 amp supply is 7W (roughly), so yes, it will get
rather warm and you'll need a heatsink!

Yours, Mark.

Daniel Kelly (AKA Jack) 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

 

[Stan Shankman]

If I use a voltage regulator then will I lose a significant amount of power?
Do voltage regulators dissipate much power?

Thanks,
Jack

Jack,

To answer your question:
It depends on the type of voltage regulator you are using.
(And also on what you mean by "significant" power loss.)

But basically, you have two choices:
You could use a "switching mode" regulator, or you could use a conventional "dissipative" regulator.
By comparison, the switching type of regulator will be very efficient,
(as it only allows enough energy to pass as is required) while the dissipative type will be mush less efficient
(as it converts unwanted energy into heat).
In fact, for any given output voltage, the "dissipative" type of regulator will become
increasingly more inefficient as greater and greater input voltages are presented to it.

Switching-mode regulators are clearly the way to go.
It is the inefficiency found in conventional voltage regulators that
is the main reason why switching-mode regulators have become popular.

Commercial switching mode regulators to convert between 12 volts (car battery)
and 5 volts (many consumer devices) are readily available and selecting one would be my choice.

Hope this helps,

- Stan Shankman

 

[Randy]

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in message
news:c3snc0$m9a$2@uns-a.ucl.ac.uk...

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


Jack,

The power dissipated by the voltage regulator is equal to the
difference of 12v minus 5v times the current of 1 amp. So in your case the
power your regulator would need to dissipate would be (12 - 5) X 1 = 7
Watts. That's a lot of power to get rid of with cooling.
You could buy a switcher power supply module. This would take in 12
volts and put out five volts with only about 20 percent of the power thrown
away by the analog regulator. .2 X 7 = 1.4 Watts.
Sometimes you can find these regulators surplus at places like all
electronics or new at Newark.com.


Hope this helps a little.


Randy


>

 

[Daniel Kelly (AKA Jack)]

Thanks everyone for your great input!

Jack



"Randy" <rfinch2@qwest.net> wrote in message
news:AQF8c.777$0R.70026@news.uswest.net...

"Daniel Kelly (AKA Jack)" <d.kellyNOSPAM@NOSPAM.ucl.ac.uk> wrote in
message
news:c3snc0$m9a$2@uns-a.ucl.ac.uk...
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


Jack,


The power dissipated by the voltage regulator is equal to the
difference of 12v minus 5v times the current of 1 amp. So in your case
the
power your regulator would need to dissipate would be (12 - 5) X 1 = 7
Watts. That's a lot of power to get rid of with cooling.
You could buy a switcher power supply module. This would take in 12
volts and put out five volts with only about 20 percent of the power
thrown
away by the analog regulator. .2 X 7 = 1.4 Watts.
Sometimes you can find these regulators surplus at places like all
electronics or new at Newark.com.


Hope this helps a little.


Randy