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From: "Phil Allison"
Subject: Re: Constant current source with low voltage drop
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Date: Sun, 29 Sep 2002 14:00:46 +1000
NNTP-Posting-Date: Sun, 29 Sep 2002 13:49:25 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Phil Allison" wrote in message
> "markp" wrote in message
> > Hi All,
> > I need a constant current circuit adjustable from 0 to 150mA powered
> > 5V supply. This is to drive LEDs of an LCD backlight. The spec says a
> > 4.4V drop @ 150mA (2 LEDs in series?) so I've got to do this with a
> > of 0.6V voltage drop. Any suggestions?
> > Thanks!
> ** A 6 volt, 3 watt bulb will do nicely in series with the LEDs.
Sorry, I missed the "adjustable" bit. The bulb will only provide a
150 mA current source.
I suspect that PWM is the way to go.
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