Re: LEDs in flashlights?

From: Gareth (me_at_privacy.net)
Date: 07/17/04 

Date: Sat, 17 Jul 2004 20:20:42 +0100

DaveC wrote:
> Such as this one:
>
> http://www.brightguy.com/detail.html?cart=1090077700192795&sku=OPA3W
>
> how are the LEDs configured? Are they paralleled? Each with a series
> resistor? Regulator?
>
> In this application, the source is 2.4-3.0 volts, depending on type of cell.
> Any idea?

There are switched mode power supply ICs designed to drive white LEDs.
It could well use one of these. Certainly that would give the constant
light output they claim:

"The light output of the NewBeam LED module maintains a perfectly
constant level for almost all of the batteries' useful life"

For an example of such an IC have a look at:

http://pdfserv.maxim-ic.com/en/ds/MAX1553-MAX1554.pdf

Gareth. 

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