Re: Digital Current Control for LED array

On Fri, 23 Dec 2005 14:34:32 GMT, John_H <johnhandwork@xxxxxxxx> wrote:

>theJackal wrote:
><snipped>

>
>I am suggesting 7 regulators for 7 LEDs. Of *course* connecting 7 LEDs
>in parallel directly with one series regulator will not provide a
>solution. Of *course* connecting 7 LEDs in series with one shunt
>regulator will not work. If one "LED stage" is defines as an LED and a
>regulator, 7 "LED stages" can be connected in parallel if the "LED stage
>is built with a series regulator and 7 "LED stages" can be connected in
>series if the "LED stage is built with a shunt regulator.
>
>I don't contradict a thing. EACH LED is fed with a controllable
>current. Separately. Not "all LEDs are fed with A controllable current."


If I get you right ... you are connecting a series resistor/regulator in each parallel
branch of the LED array.
Suppose you want to brighten a LED you'd decrease the resistance in that branch , but
that would increase the current flowing through it , which would then cause a decrease in
the currents flowing to the other LEDs ... so those would become dimmer . You'd then have
to work on the resistors in the other LED branches. Besides you'd have to take into
account the limiting current and the non linear voltage current characteristic of the LED.



theJackal






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