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. I plan to modulate the brightness with PWM, but I'd like to have the full 25mA (PIC pin limited) drive current available at all times. Can anyone think of a way to do this? -- Ben Jackson http://www.ben.com/ -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.