MPQ8633B would be the Buck IC with similar specs, I have info on that one too. No high power Boost-Buck that I am aware of yet, but the MP28164 is a 4.2A Boost-Buck chip.
Not affiliated with MPS in any way, i just found their catalog and thought they make some nice chips for flashlight drivers.
Both of those are interesting options. The MPQ8633B looks real good but it is hard to tell from the cover sheet, is the output voltage limited to 5.5v? Or is that just the reference voltage?
The MP28164 looks like it would make a great general use driver for small lights as you don’t need more then 4A anyways in most cases. I also like how few external components it needs.
The output voltage is limited to 5.5V, good catch, I didn’t see that. In that case, the MPQ8632-20 Is probably the better candidate, up to 13V output and similar in other specs. Little bit larger footprint though. The MPQ8632-12 has the same size footprint as MPQ8633B but a 12A limit (still probably enough).
Hmm, 13V is not quite enough for a 12V LED at reasonable currents but at least it would handle 6V LED’s.
Who knows maybe they have some wiggle room in the voltage tolerance and could handle ~14-14.5v, kinda like how we push everything else past the datasheets as well lol.
There are certainly plenty of high powered Boost-Buck controllers out there, but many require 4 external MOSFETs which makes space a problem. Using some super small surface mount FETs it might be possible to build something in the 30mm range. LTC3780 comes to mind here.
I’m willing to bet the MP8632 would output beyond 13V by a bit, similar to how the TPS61088 will actually max out around 13.7V instead of 12.5 like the datasheet says. We do tend to operate a lot of things outside of specs here. Haha.
Yeah, those FET’s really eat up the space which would already be tight without them. Thats what makes these chips so attractive. Plus the lack of FET’s reduces the complexity which is always good for small designs.
Forgot that, the inductor is 1.5uH.
But I haven’t tested the circuit myself, so I just can hope it works. I will check the pinout one more time. I can recommend some Opamps, but I need the input voltage range for that. To get 1.4A, your resistor R3 should be as close to 5932.2 Ω as possible. Less resistance for less current, more resistance for more current.