@shanevanj Thank you for the response. I thought about going that route, but I was hoping to find out if it was actually necessary with the particle hardware.
In the datasheet, Particle keeps using different terms which makes it very hard to read, but it appears that the “LiPo Battery voltage” should nominally be 3.3 to 4.4V, and the “Battery Input Voltage” should have an absolute maximum of 6.5V. Assuming (isn’t it great to have to assume when reading technical datasheets) that these two terms both refer to the “Li+” pin on the Xenon, then I should be able to connect 3 AA batteries in series to Li+. New batteries should be 4.8-4.9V, which will pass the 4.4V nominal range, but still be well within the 6.5V absolute maximum. By the time the batteries drop to 3.3V (1.1V per cell), they can be considered depleted, so the low end is fine.
But I’m not comfortable with these assumptions, I still don’t know if Li+ will accept 3.3 to 6.5V without frying the device, and I don’t know where this “supply input voltage” with an absolute maximum of 6.2V fits in. I also don’t know if the extra power from the higher voltage will be efficiently converted on the Xenon (as it will with the part you linked) or dissipated as heat in the regulator, so it would be nice if someone more familiar with the boards could help. Particle could take lessons in documentation writing from Pololu.
@ScruffR Before posting here, I read the relevant Xenon documentation, and the only useful thing I could find was the part number of the regulator used. Then I read the datasheet for the regulator and wasn’t able to find any answers to my questions. For example, with the regulator set for 3.3V, what is the minimum input voltage? It mentions problems if the input voltage isn’t enough above the output, but doesn’t say what enough is. I gather it depends on the current.
It also describes the theory of operation at a level that assumes a great deal of knowledge and I wasn’t able to tell from that anything at all about efficiency. I mean buried within the 3 pages on theory of operation it does mention
The DC/DC converter characteristics depend greatly on the externally connected components as well as on the characteristics of this IC, so refer to the specifications and standard circuit examples of each component when carefully considering which components to select
which means Particle should know the characteristics in this particular application better than the part manufacturer. And since there’s nothing about regulator efficiency in the particle docs, asking the question here seemed appropriate.
Between that and googling directly for an answer to my question, I spent a good hour trying to answer the question on my own before posting here. But thanks for those links…if the answer is actually in there could you please be a bit more specific/noob friendly? I did spent a lot of time with those materials and could not find it.
Googling for “power particle xenon from AA batteries” yields no results (along with similar seaching for particle iot products. So it really doesn’t seem like such a simple thing.