I'm working on a circuit based on an ATTiny85 and I need accelerometer input. I was looking at using an analog accelerometer (KXTC9-2050 that runs around 240 uA) because I have the extra pin and I'm a noob so I figured it would be better if I avoided the complexity of I2C right now.
Since that's the case, it looks like I need to drive my 8 LEDs (WS2812B) with 5V (the LEDs at full brightness should consume about 50mA) and my ICs with 3.3V. I'll need to find a power cell I suppose (I'm open to suggestions).
Originally I said, "for space, I'd like to use a coin cell lithium battery so my supply voltage will be nominally 3V." This seems infeasible because the maximum discharge rate won't drive my LEDs
On a related note, these LEDs are really bright at 100%. Chances are good, they'll be PWM'd to less than 50%, they won't all be lit at the same time, and they won't all be full white all the time. Their actual power consumption will likely be considerably less than 50mA. But, I figured you plan for the peaks. If that's wrong, please let me know.
Things I've considered:
The ICs have voltage ranges. Maybe I can power the ATTiny and the accelerometer directly off the battery and use a boost converter to get the 5V that I need for the LEDs. (Which I supposed doesn't really answer the question because I don't have 2 regulated power rails).
I could boost the supply to 5V and use an LDO regulator for the 3.3 rail.
I could boost the supply to 5V and use an LED to drop the voltage down for the 3.3 rail.
I could use 2 boost converters.