At 10:12 PM 2/7/2004 -0800, you wrote:
>I want to drive a PIC (and a 5v-only analog device) from a combination
>voltage doubler/low dropout regulator (MAX660+667, modified version of
>their appnote circuit).  The output is a small subset (5-7) of about
>30 Green/Yellow LEDs.  I was thinking of driving the LEDs directly from
>Vbatt (lower power consumption, and none of the DC/DC or regulator loss)
>but over the useful battery life of 3.2 .. 2.6v (Lithium cell or 2 AA)
>the voltage drop across the current limiting resistor varies from
>(3.2-1.9) = 1.3V to (2.6-1.9) = 0.7V.  A factor of 2.

Where are you going to get green/yellow LEDs with only 1.9V Vf at 25mA?

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

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