Secret chip in ARC-LS ckt public, yet?

I've got an injured ARC-LS grey kit. When they were first released, Peter slipped and said the name of the chip on the board. I believe Wayne reminded him that it was not time to drop the curtain, so Peter edited the post, but mentioned that at some time all would be revealed.

Well, is it time? Or, did I miss it? I'd like to see this clever design in all its glory. /ubbthreads/images/graemlins/smile.gif

That, and I'd like to try to debug/fix my wounded board....

I don't think it's time yet.....is it?
Wayne?

I have independently designed (that is, prior to seeing the ARC-LS; I was planning the design prior to the availability of the Luxeon LEDs) an LED drive circuit which appears to use the exact same chip (same size, same connections where the circuits match, same markings--but the markings do not include a part number), I feel that I've honestly come by sufficient information to claim to 'know' what the chip is. Honestly in the sense that I didn't steal any information or design from Peter, as well as honestly in that I feel that my evaluation is correct.

At this point, is there any reason that the information shouldn't be considered public? Any serious competitor will know about this chip.

-Jon

I'm, personally, aware of what part ## the chip was. Maybe I wasn't clear about that in my post, but thanks for all of the personal messages with all that trade secret information. /ubbthreads/images/graemlins/smile.gif

I was thinking along the lines as Jonathan was. It should be quite easy for any interested 'hostile' party to come by this informaiton with little effort. So, is there still value in keeping it from us fine law abiding CPFers? Hey, I'm law abiding. I stop at stop signs. Heck, I even stop at crosswalks when there are people there. Those two things, alone, have to put me in the 95+th percentile of drivers in NJ. /ubbthreads/images/graemlins/frown.gif

We are honoring Dat2zip's request. It is up to him since this circuit is his design.

Peter

Dat2zip. *poke* *poke* *poke* Gonna' tell? huh? huh? huh? *poke* *poke* *poke* huh? huh? huh? Don't make me cut and paste more of those in....

Sure, What part of the part number do you wish.. /ubbthreads/images/graemlins/smile.gif

The IC is a Linear Technology IC and the part number is....

LT1618.

So, Willmore, why the curiousity? huh? *poke* *poke* *poke* *poke* *poke* *poke* *poke*

Whatcha going to do with the info...??

You've got me curious now.

Wayne

Yeah, no one should put this in a commercial product without Wayne's permission. He put the circuit together, he should get the credit.

Thanks again Wayne!

Peter

Willmore,

Wayne isn't keeping all his secrets tight. Everyone who has a grey kit knows that it's a LT1618 chip by simply searching for the LTNH. The circuit is hours of hard work by these CPF people, buy ARC, Madmax or Badboy to support them!

Vince.

Data sheet:

http://www.linear.com/prod/datasheet.html?datasheet=736

Geez, everyone's acting like I'm trying to crank out ARC-LS clones! Admittedly, I'd like a nice large volume end fed lathe to put in the garage and the ability to do HA at home, but I'm not seriously looking into that. /ubbthreads/images/graemlins/smile.gif I'm thinking, maybe a 14x6" lathe with some milling ability so that I can make my own lights--like CNCDan.

So, as I said *in the first post in this series*, I have an injured grey kit that I want to heal. I had been told, behind closed doors, the part ## for the chip, but this reminded me that it had been mentioned that it would, at some time, become public knowledge. See what a little *pokeing* can do? (triumvarate films (sp?) Pokey-pokey for anyone who's interested)

Thanks, Wayne and Peter.

For Wayne, I looked at the design and think it's a great combination of small and efficient, so please, take a bow. /ubbthreads/images/graemlins/smile.gif I, personally, would never have used it as I'm more willing to sacrifice space and weight for efficiency and flexability. But, I'm not trying to fit a ckt into an already designed light where space is at a premium. I'm gonna' put a big, fat torrid right in there and a synchronous buck regulator with some d2pak sized FETs with the lowest R(on) I can find....

The power source will be 2 or 3 roughly 1.5Ah Li-ion cells (depending on if it's the 1W or 5W version).

Construction will be simple thick walled tube stock + threads. I'll work out those details whenever my fiance gets me a lathe (and I'm all out of birthdays for a while). So, noone hold their breath.

It will be open source, though. All plans mechanical, electrical, or firmware will be freely available. I'm not interested in becoming a flashlight company.

So now that this circuit is "open" so to speak, lets talk about modding it...

I've heard it whispered that one might be able to mod the LS circuit to make it into a buck/boost (ala SureFire KLX). This would make the UBH w/Arc LS head combo even more versatile.

Comments? Call it rediculous or call it possible...please.

Mark

Without additional inductors, the LT1618 _must_ boost its output relative to the negative supply. (With additional inductors, you can build a SEPIC design, and probably others.) So you can't get a classic 'buck-boost' out of the LT1618, in the sense of voltage measured relative to ground.

The trick is to remember that the LED is an isolated load; there is no requirement that one terminal of the LED be connected to ground, simply that one terminal of the LED be positive relative to the other terminal. By placing the LED in different parts of the circuit, you can get either a 'buck-boost' effect (topologically an 'inverting' converter, but who cares, the load is isolated /ubbthreads/images/graemlins/smile.gif ) or a buck converter.

One caveat with the 'buck-boost' is that _all_ of the energy to run the LED must be stored in the inductor each switching cycle, whereas in the conventional boost design you only need to store the energy to boost the battery voltage up to what the LED needs. I don't know if the LT1618 has the current handling capacity to run a Luxeon in the buck-boost circuit.

-Jon