led driver ic ?

look at maxim-ic.com

"mark krawczuk" wrote in news:f5ydndEALaF8_hbanZ2dnUVZ snipped-for-privacy@adnap.net.au:

If they're all on at same brightness, try a DC-DC boost converter and a single series resistor. If the total Vf is very slightly less than the DC output of the converter the efficiency will be very good. Whatever you do should include this, as the losses of 1A through a limit resistor with LED's at maybe 4V Vf on a 6V supply will not be efficient. If you want efficiency without voltage boost you'll need to sense the current and use feedback to control a PWM or similar supply, and things get expensive that way. Can't make specific advice because I don't know anything about your LED network. Series? Parallel? Individually switched? Brightness control?

Look at

and similar ones.

Linear Technology (LT) also do a few IIRC.