Of course I know how to light a blue LED. The question was click bait.

I'm working on a new design -- a PIC based instrument powered by 2 'AA' batteries. Let's call the low battery condition 1.8V.

The PIC will be powered by a 3.0V high efficiency switcher. I need to drive a single 3.3 Vf (10 - 20mA If) blue LED from the MCU.

I have my own way of doing this. I'm looking for new and different ideas. Guidelines, in order of importance:

1. cheap
2. efficient
3. number of parts

All parts must be small (relatively speaking) and surface mount.

Edit: assume a full compliment of PIC hardware/peripherals are at your disposal.

Floor's open. Anyone?

When I wanted a quantity of blue LEDs - I bought a string of them in a discount store. They ran from 2x AA, I don't know the explanation - there was no additional circuitry.

There were also white LED bicycle headlamps in the Poundland store that run on 2x AA - I never got around to pulling one apart yet.

For the simplest possible booster; there is the PR4401 chip, its in the same case as an SMD transistor and you just add a small inductor (and maybe a diode).

 

@joeyd999 So, have you decided what you will do???

 

@joeyd999 So, have you decided what you will do???

Yes. I decided to use red and green.

 

Yes. I decided to use red and green.

Cheater.