I've been thinking of using the T.I. TPS63020 buck-boost converter as a driver for an XML at 3A from a single 18650 (or maybe 4 NiMh). Have you heard of its use anywhere?
It may not be ideal because the 3A output can only be sustained at 3.6V and up (to 5.5V).
Take a look at the graph from the datasheet (Courtesy Texas Instruments)
The graph reads 63021 (which is fixed 3.3V output) rather than 63020 (which is variable), but the curves are the same.
Yes, but... The device does not support PWM dimming directly. However some clever circuitry can convert the PWM signal to analog, and this can be summed into the feedback pin, and thus you get dimming. Note that it will be analog dimming - where the current level is lowered and raised, not chopped ON and OFF.
Take a look at this circuit snippet from T.I. app note SLVA364:
This method might require reprogramming the actual PWM signals from the driver. (See the "Flashlight with Perfect Modes" post for information on that.)
That looks perfect. Hope it's mass produced soon on a board or light for us lazy people. Maybe we can ask xtar or tank007 to do a special for us.
