At the very least the XHP35 is the brightest “single die” LED we have that doesn’t have issue with donut holes and can net some pretty good throw figures too boot.
I’d be happy if it had a 6v setup… I’m not sure why they couldn’t do the same as the others; maybe the XP footprint didn’t have room for separate pads?
If we get a smooth reflector for the L6, I just might have to buy 4 26350’s like Dale and do it anyways
Dale, did you get yours from Banggood? The generic purple ones? If so, how are they?
Yeah PD, they’re kind of a light lavender, marked as 2000mAh.
I haven’t tried a direct FET driver on one yet to see what it delivers in comparison to other cells but need to do that. I got 10 of em, figured I’d find uses for em all pretty quick and wish I’d gotten more. lol
I CAN say that the L6 with an L2 single cell tube and 2 of these is a sweet combo!
I have a TangsFire TS2010 with SBT-70 and an FET driver. The 4000mAh gold King Kong does 6.71A (rested, probably not a full charge) One of these little 26350’s will do 6.98A! Top dog cells allow considerably more of course, but they’re not too shabby.
Edit: The King Kong cell is at 4.12V while the 26350 is at 4.19V. Still…
Edit II: 4.40A to an XP-L in a F-13 with Bistro X6 driver, same cell.
That is quite impressive for the size. Glad I grabbed a couple. I tried the L6+single cell tube the other day and agree it is an interesting size light and amazing performance for the size.
Hmm now I need to figure out what little 26650 light I want to put an MTG in…. An L2 with MTG would be sweet…. but I already have one and I never buy two of the same light.
TA they fit in your L2 tube lengthwise? I know Dale already bored his out
The L6 works with em, the L2 does not. It’s the L2 tail cap that I added depth to for the longer 26700 cell to work in. The L6 tail cap is a wee bit longer, it looks almost exactly the same but it’s very minutely different. Threads on ok though.
Cutter was the only place I found the high CRI XHP-70, I put one in my Olight SR90 Intimidator that they said was 96 CRI. I lost some lumens, but it’s a great tint and I like it a lot. I’ve got the battery tube reworked to house a pair of 32650’s so it’s got tremendous run time over the factory set-up.
Edit: If memory serves… I was getting like 6400 lumens on the top tier binned XHP-70 I first went with, the High CRI is making ~5600.
Yes to first approximation( a 7135 -- edit, I meant to say PWM, was confused -- might be useful for moonlight if the Buck becomes innefficient that low but that seems like possibly a version 2 feature if it ever even works). Anyway the input to iadj says it comes from 7135. I think its just a stale label. It seems to match up sensibly with an out from the mcu.
By the way I would consider 4s battery to 2s led. Problem is it will require twice the current handling but it should regulate longer at high power as batteries get low.
I know what you mean about it being to easy, the light is well made and it’s simple to make tweaks for ultimate performance.
The Nitecore TM03 on the other hand, is not that kind of light! I feel like I’ve accomplished a lot just de-soldering the massive 14ga leads from the thick copper heat sink/proprietary mcpcb so I can slice the XHP-70. Complex light, this one! (the kind that kinda scares me, lol)
Yeah, that is just an old label from the TA drivers. It is simply a PWM output from the MCU, I can/will swap that around later if we determine the best pin to use.
The buck IC should have a dimming range down to lower then that of a 7135, so i doubt we will need to go with a 7135.
If we get this working it could run any combo of leds from any voltage source we use with a swapping of the passive components. The first one will most likely be for xhp35’s and/or xhp50’s for the upcoming Q8.
If it works with those it should work fine for any other combo.
I was confusing myself and you but I did have point under the confusion. Of course 7135 is useless. What mght be useful for moonlight is true LED PWM. The buck will certainly go very low, but at some very low level it might be more efficient to buck down to say .1A or whatever and PWM down from there. It's not obvious to me though which is better. It adds complication. The FET wouldn't have to be so big and expensive though to handle the lower currents.
And, yes I'm with you on the running any combination of things. Amperage is the only issue really, both in handling the amps and setting the correct maximum amps. Aiming for a high current scenario from the start sounds good.
It is possible to use a second pin from the MCU to PWM the buck IC as well if that was desired. It could be difficult to make it work though. I have a feeling this will need a 4 layer PCB but I will see. I suppose I could start laying it out and make minor changes as we select the parts list.
But I'll cliffs notes. (I don't like how casually it treats many of the linear approximations and averages, but ok)
It derives a detailed form of the duty factor including voltages losses in switches and diodes, but then I like the Ti approach of just calling it
V0/(eff*Vin).
The ripple current vs frequency and inductance is useful (and maybe helpful for choosing the inductor size and switching frequency) but also it's included in equation 10 here, a better document anyway:
Useful to go through all that, but equation 11 summarizes it. But better to look at 7 and 8 instead. 7 is the mosfet loss and 8 is the freewheel diode loss except they use a mosfet there too. For the diode I guess you have to look at the loss as Vf*I instead of I^2R, simple enough change. So that's losses for both of those components.
Oh and equation 4 gives the inductor loss, which is almost stupidly just I_out^2*R_L. So that's easy to figure too.
However you get to equation 12 and they say blah "+ other losses"
Oops, some nastiness there to figure out, especially switching losses, that looks fun:
Oh, why was Ti using a Mosfet instead of a diode?:
So there's that too, but I don't think it's compatible with your IC.
Then there is discontinuous current mode to worry about at very low power probably.
But that's all just introductory for basic bucks. This 3409 looks pretty fancy (aside from using a diode I guess), with variable frequency, off time control etc. I'm just starting to look at its actual docs. I prefer their math actually. They don't make the approximations so casually, but then they don't start with -LdI/dt either, so that's too bad, unless you only want answers.
Anyway, the obvious things are obvious, keep Rdson low for the switch, diode Vf low, inductance high, frequency high (but not too high, see that link about switching losses, last figure), capacitor ESR matters significantly less, and here already are a few simple guidelines to put numbers on some of it. I think it's really not so bad.