3A+ Buck Boost Driver Size?

Flashlight Modding and DIY Parts
4

since it is easy to add size, but impossible to make them (much) smaller…then as small as possible seems logical.

I put 17, since I’m guessing any smaller would be very difficult?

but I’m sure I’d be in for 20mm, and even 26mm if it is more efficient than the 3-18V 5A that is available

5

Kent,

I am very intrigued by this. Do you have a plan for the voltage range? If we're talking about a driver that can run an XML off 2 nimh cells @ 3A this could be a very big deal. A multi mode driver like that in a 17mm size would rock the flashlight world.

I would not only be in for a bag of those, but a larger size if it meant the option of getting the current up to like 4A.

6

I would prefer one li-ion, but if it were 2NIMH, it wouldn’t need buck capability, and you would have maybe 15 mins of battery life

7

VOB,

The driver IC I’m currently looking at is similar to the DIY 1A Buck Boost thread, which is a 2.7-5.5V driver, so 1 li-ion, or 3 x alkaline, nimh cells. With 2 nimh cells, you woud be looking at a straight boost circuit which is 1.8V capable.

8

17mm good. If you can’t go that small, then smaller is better.

9

Are there any tests for it with 1 LiIon cell?

17mm would be awesome but as small as possible is fine. Height might be an issue, but I would prefer a 17mm*10mm board over a 22mm*5mm board.

10

I tested a little. see the torchlite thread. the driver gets hot. I’ll test more when I get 3 mode replacements for the 5 mode drivers i received (so that I can pot them).

11

This post? 50% efficiency with one cell sucks..

12

that’s putting it mildly.

i suspect it will improve marginally w/ some heatsinking of the driver.

13

I was thinking buck/boost to provide versatility. Say one user wants to use 2 nimh cells and another wants a single li-ion. Basically it would appeal to a wider range of customers :)

14

Well if you ever decide to do a straight boost for 3 amp I'd be in for some of those too.

I am still interested in this driver also provided it can boost the VF higher than whats needed to drive an XML. If it can jump the voltage up to like 4.5V to get the 3A, this way LEDs that cannot be driven directly by 1x Li-ion cell to 3A will be included.

Thanks for putting in the time and effort on these projects Kent.

15

I was thinking buck/boost would be good for single cell lights w/ xml2 or xre that is driven hard.

I’ve been testing some green xre-r2 and the Vf is so high that you can’t push them very hard in a single cell light - even direct drive from CGR18650CH I’m only getting ~1.5A to the emitter, and you don’t get long at that current because as the voltage sags, the current goes down.

16

I’d vote 20mm, although bigger than that isn’t an issue for me as I don’t do much work with flashlights. Still, for the widest audience, it would probably have to be 17mm and tall, even though I have no idea as to the average depth of a P60 (or other) pill.

Are there any other buck-boost drivers that have a larger Vin range, say 8.4 or 11.1V? I know that complicates things, I’m just curious :slight_smile:

17

The P60 pill that I’ve got from FastTech is around 6.5mm deep (slightly over 16/64” by my pocket rule). The Inductor alone is a hair taller than the inner support ledge.

I’m sure they have chips that could handle your voltage situation :slight_smile: .

18

I’m looking …. and getting confused :slight_smile:

19

Single board, 17mm, thick as a Nanjg 105C, highly effective, good modes or programmable ==> priceless.

Did you manage to find a buck boost that handles so much Amps? Or will you use 3 times 1A buck boost?

Double sided board is fine, though the coil does add quite a height. But I doubt it’s doable on one side only. You would really have to have a chip that does buck/boost at 3A.

20

Wire the LEDs in parallel and use a buck driver. 8.4-11.1V is a 3 lion cell, you can drive 2 LEDs in series no problem, easy to make such simple circuit, just limit the max current.

21

Single board, double sided, might be possible if no battery spring pad, but I think that would defeat the purpose?

Now that I know the depth of the ledge of the P60 pill, I see that there are other inductor candidates that would work with less height. A Nanjg 105C is 4.8mm in height excluding the spring, with a two board solution, maybe 8mm at best.

My 1A buck boost boards are coming in the mail, so lots to do on that for the time being.

22

If I wanted to use a buck driver, I’d just use a buck driver :slight_smile: This is more to drive a 2S (or 3S) LED light with an equal no. of series li-ion cells, but without the large power losses you get in a linear driver or the dimming you get with a buck driver in this set up as Vin drops below Vf+overhead. Not a common requirement, but it’s what I’m interested in.

23

I dont use Li-Ion cells so would love a driver that could slightly boost 3 x C or D NiMH cells just enough to allow a longer “regulated” output at 3A using emitters with high Vf, especially now that the XM-L2 is starting to become available.

…or a buck driver to allow 4 NiMH cells to be used to increase the regulated run time without just burning most of the fourth cell off as heat, like linear drivers do. There are heaps of 4 cell lights (eg JetBeam PA40, Fenix TK70, NiteCore EA4) so it must be possible!