Hello everybody, my first post for my new hobby 
I've got a cheap flashlight 3 x aaa 9 white leds that I'm going to change to red leds, 5mm ultrabrights.
The Vf of red leds is 2V ish, but I don't want to use resistors or linear regulators to drop the volts as its inefficient.
I've found the TPS61042 http://focus.ti.com/lit/ds/symlink/tps61042.pdf which should be able to drive 20mA through 9 red leds in series. Plus its got a ctrl pin so I could make it a blinky by adding a pic. Looks a bit fiddly to solder though.
Has anyone got any other suggestions for a suitable circuit?
I've got a cheap flashlight 3 x aaa 9 white leds that I'm going to change to red leds, 5mm ultrabrights.
The Vf of red leds is 2V ish, but I don't want to use resistors or linear regulators to drop the volts as its inefficient.
I've found the TPS61042 http://focus.ti.com/lit/ds/symlink/tps61042.pdf which should be able to drive 20mA through 9 red leds in series. Plus its got a ctrl pin so I could make it a blinky by adding a pic. Looks a bit fiddly to solder though.
Has anyone got any other suggestions for a suitable circuit?
