~1.8-3.x Vin, 1A out LED driver design / feeler / suggestion thread

[Stereodude]

First let me start out by saying Mods, if this is in the wrong forum please move it. I wasn't sure where to put it. This seemed like the right place to get the best input from the right people.

Myself and two other CPF members (Flipside & SafetyBob) are considering to develop and produce a new LED driver design to replace the venerable, but discontinued, and no longer available Taskled.com VIP driver. Beyond that, we think we can make some performance improvements to the original VIP driver.


Here's what we are targeting: (as of now)
- Single mode (on/off) constant current regulation boost driver, Vin < Vf
- Ruler flat 1A output over the entire Vin operating range.
- 2 x NiMH / 3.0V Lithium rechargeable / 3.0V Lithium primary battery support
- User adjustment of the output current to below 1A.
- High Efficiency (>80%)


Notes:
- it will not support standard 2.7-4.2V Lithium-Ion rechargeable batteries as it's not a buck-boost driver.
- 2x Alkaline batteries, while supported, are generally not recommended due to the current load presented by the driver.


So, the questions and feedback that we're looking for are:
1) Would "you" (the reader) be interested in a driver like this?
2) What size / form factor would "you" like this driver in?
3) What would "you" change / add from what I've listed.


Thanks! We look forward to your feedback.

PS: Please note, this thread is not a promise to develop or produce the above described driver. This is just a design / feeler / suggestion thread to investigate a possible design.

 

[TorchBoy]

It would be nice if the output current could be switched between high and low values, perhaps by externally switching in or out various set resistors.

 

[Stereodude]

It would be nice if the output current could be switched between high and low values, perhaps by externally switching in or out various set resistors.

That should be possible.

 

[kavvika]

I am interested in a driver like that. Or rather, was, until I salvaged the driver from a Lowes TF 2C. But, while a great >1amp driver, it isn't really regulated. Now if you can keep regulation above 90% for the first 3/4 of battery life, achieve your target of 80% efficiency (competing with buck driver), and have adjustable output, I'm game for at least one if the price could be kept under $20 shipped, and more if the price is less. By adjustable output, do you mean that current would be set by a pot, or it is multi-mode where when the user clicks on-and-off in a preset time, it will switch from one brightness level to the next? The price might not be an issue for most, but as a college student, I can't really justify a BB Nexgen at $23 plus shipping. I'm a fan of the 2C Maglite form factor, and there does seem to be a lack of drivers for 2x NiMH cells. Is it possible to make a multi-LED driver, or is this only for driving one LED? Form factor and size is not of a concern for me, but might be for others than want to use this an AA-battery light.

 

[LukeA]

If it's 17mm dia, and 8mm or less in total height, then I'm in, as long as it can be adapted to put out ~500mA.

 

[Stereodude]

Now if you can keep regulation above 90% for the first 3/4 of battery life, achieve your target of 80% efficiency (competing with buck driver), and have adjustable output

Did you read the first post?

- Ruler flat 1A output over the entire Vin operating range.

That would be 100% regulation over the entire battery life.

By adjustable output, do you mean that current would be set by a pot, or it is multi-mode where when the user clicks on-and-off in a preset time, it will switch from one brightness level to the next?

It will be set by a pot or resistor. It is not a multi-mode driver. It is a single mode driver (on/off).

I'm a fan of the 2C Maglite form factor, and there does seem to be a lack of drivers for 2x NiMH cells. Is it possible to make a multi-LED driver, or is this only for driving one LED?

This is not a multi-LED driver. It is meant to drive a single LED. It's not really possible to drive multiple LEDs at 1A from 2x NIMH cells (at least with any of the currently available drivers).

 

[kavvika]

Yeah, I did read the first post. I guess I'm not that hard to please, as the regulation I mentioned would suit me just fine. If you can do better, then it's gravy! Thanks for answering my other questions. You can put me down for one if this does come into fruition.

 

[Upplyst]

I am most interested, especially if it fits a standard fenix-compatible tube @16 mm. What would especially suit me would be rulerflat, 3 hour runtime @ 500 mA output.

 

[BigBoy]

I would be interested in this driver. 17 mm diameter or less, less than 8 mm height ( 6mm would be better). Depending on price and timeframe I would purchase 10 for starters. Is far as I know there is nothing out there at 1 amp for 2 nimh. It feels like nimh is generally overlooked these days ...

BTW: you might get a little more activity in this thread if it were posted to "Flashlight electronics - batteries included".

 

[TorchBoy]

BTW: you might get a little more activity in this thread if it were posted to "Flashlight electronics - batteries included".

Don't know about how much activity it might generate, but that probably is where it should go.

 

[DM51]

Well, it is electronics, so at the request of the OP I'm going to move it to the 'Flashlight Electronics - Batteries Included' section.

If there is a bellow of protest from SilverFox when he finds it in his forum, and he sends it on somewhere else, you'll know I got it badly wrong!

 

[Stereodude]

Thanks DM51!

So far, it looks like everyone wants a 1 Amp output 2 x AA NiMH driver. oo:

 

[TorchBoy]

So far, it looks like everyone wants a 1 Amp output 2 x AA NiMH driver.

Yes, but it depends on the price. Got any sort of idea what you might be able to make them/get them made for?

 

[Stereodude]

Yes, but it depends on the price. Got any sort of idea what you might be able to make them/get them made for?

No idea at the moment. Sorry.

 

[Doh!Nut]

I would be interested also, most likely usage would be in a 2D mag.

To add a suggestion, if altering current with sense resistors it would be great if someone other than a brain surgeon could do it .

I have a vauge idea where you have a large solder pad or through holes either side of the sense resistor so that it can be bridged. You could put in a jumper wire, a switch to create a bi level light.

Just a thought
Nick

 

[MorePower]

I would be interested also, most likely usage would be in a 2D mag.

To add a suggestion, if altering current with sense resistors it would be great if someone other than a brain surgeon could do it .

I'd buy a bunch, for 2C and 2D mags, especially if the sense resistor was easy to hand-solder (no SMD, please).

As I'd be putting these in lights to give to friends / family, 1 amp drive is a bit much. As long as they'd work okay with alkaline cells at lower (350-500mA) drive levels, and were competitively priced to say, Micropucks, I'd be in for quite a few if this discussion comes to fruition.

 

[Mr_Light]

I would be interested in maybe a dozen (depending on the price). Size doesn't matter to me since these would be 2C and 2D lights. It would be nice if there was some kind of low battery warning. What I don't want is flat bright output ending in darkness without a warning. Moon mode or declining output at the end would be fine.

 

[Stereodude]

Moon mode or declining output at the end would be fine.

Moon mode is under consideration as is the potential of 1.2A output.

 

[Stereodude]

especially if the sense resistor was easy to hand-solder (no SMD, please).

We want to make this easy to change, but it may still be SMD. However if it ends up SMD, we won't make it a 0402 resistor. It would be sometime more along the lines of a 1206 so it can be easily hand soldered.

 

[TexLite]

Since there are already a couple of high-quality 2 cell 1000ma drivers on the market,with drive levels configurable for less output if needed,I would like to make a few suggestions.
1.Higher Efficiency.At least 90%,preferably better,shouldnt be too hard with the right components.
2.Lower cost
3.Low battery warning,this is what made the VIP 1000/750 so appealing,to me anyway.Especially well suited for the older or the young.

With those features and with the goal that has been stated so far,I would need quite a few of these.

Michael

Also:I agree with what has been said so far in regards to regulation,much better to be totally flat UNTIL close to the end of the battery life,then a gradual decline that wont leave you in the dark.That feature along with/or a low battery indicator is essential.