I'm currently developing on a pair of TI CC1352P launchpads, transmitting and receiving on the 900Mhz spectrum, to control some pixel LEDs.  Technically I have a P1 board and a P2 board.  Both have high power transmitters, but one has the added power on the 2.4Ghz radio(P2) and one has the added power on the 900Mhz transmitter (P1).  I'm using the P1 to transmit and the P2 to receive.  I'm using the TI-RTOS for programming, which was a huge adjustment after programming MSP430's.  All of the low-level stuff I was used to dealing with was easier in the RTOS, but then again there was a bunch of higher level overhead that I had to deal with that was harder for me to understand, since it was all buried in someone else's code.  After a lot of work, I have gotten the sleeping current down to 1.8mA, though I still intend to get it lower.  That sounds high, but it was at 8mA when I first finished it--the radio stayed on and waited for a signal for forever.  I plan to power this with C or D cell batteries, and the lights only need to last for a couple of weeks, so 1.8mA should be adequate if I can't improve it.  I realized today I left a bunch of GPIO pins set up so I could see what was happening on my logic analyzer, and tied them all low in the setup, so they're burning some power I can get back.

I was moving down the path of powering these using USB backup batteries, as I found some for a price on par with the cost of batteries + holders.  However, I've realized that all of these batteries have an automatic shut-off at low currents, so after the chip has been asleep for a while, I lose power.

So now I'm back to the drawing board.  I can either power these with 3 cells, and add a wire to every battery holder to pull out a 3V source for the chip (I need 4.5V for the LEDs), or use 2 cells and add a boost converter.  This has the added benefit of keeping the voltage steady as the batteries start to die.  This is what I plan to test next, so I'm shopping for boost converters.  Unfortunately the one I want (TI TPS61023) seems to only ship in volumes of 1k or more.  It's a 23 cent chip....maybe I can talk them into sending me a sample.  Granted, I still have to find a place to buy 100 of them if I do use them--I don't need 1000.

I really wish they had self-contained 5v boost and buck converters, they way they have regulators on one chip.  I know inductors are large, but some of these packages are pretty big--seems like they could fit one in there.