FishPill... New CC LED Driver... anyone want to try?

thefish

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As some of you may remember I have been developing and LED driver off and on since well forever it seems... anyway after about 4 revisions on the computer and then 2 revisions in hardware I now have one that I can happy with...

Specs:
  • Nominal Dia = 0.69"
  • 350ma CC Voltage Boost
  • Vin = 3V-3.6V (not tested outside this range)
  • Absolute Max Vin = 6V (above this will destroy the IC)
  • Vlockout = 1.4-1.8V (to protect cells)
  • Auto dimming on low battery detect (1.85-2.2V)
  • Analogue Current Control 20-100% (swap R1 for a Pot)
  • Efficiency ~88% @ 3V
I have 1 of these powering a Cree running off of 3 x NiMH AAA batteries (thus 3.6V) with no problems...


Runtime Data
  • 3x AAA Sanyo 1000ma NiMH
  • 141 min (high power)
  • 3 min (transition time)
  • 75 min (low power) <-- Note test stopped early
I have 2 revision 2 circuits I am willing to part with (I could build more if there is interest)... anyone want to test it out and give me feedback of possible improvements? $10 shipped in USA (add $1.50 international) just to cover costs on these prototypes/engineering samples.


LED-Driver2.jpg


My paypal address:
CC (Pls Add 1%) [email protected]
Cash payments [email protected]
 
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Martin

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Re: My LED driver... anyone want to try?

I want to do an upgrade to a Dorcy LED lantern based on the LTC3490.
Do you happen to have any extras of these components that you are willing to part with ? I'd love to have 5 sets of parts (IC, L, Cs).
Would you sell me one board to try this on 1.5 V input and 60mA load where I expect to achieve a fairly high efficiency ?
 

thefish

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Re: My LED driver... anyone want to try?

Martin said:
I want to do an upgrade to a Dorcy LED lantern.
Do you happen to have any extras of these components that you are willing to part with ? I'd love to have 5 sets of parts (IC, L, Cs).
Would you sell me one board to try this on 1.5 V input and 60mA load where I expect to achieve a fairly high efficiency ?

Well revision 1 would to 1.5V input or 3V input based on the position of the dip switch, but I dont think I have any more of these... revision 2 is really limited to 3V input because the IC is set to "2 cell mode" as controlled by pin 1. At this moment I dont have any spare sets of components I want to part with but I may get some more in the future.
 
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hord

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Re: My LED driver... anyone want to try?

I am unfortunetly not in the USA or I would stick my hand up for a try! One question I did have though -> would it still work with 2 x D cells (alkalines should, but I am assuming NiMH wouldn't)?

Also is there scope in your design to have the CC at higher levels than 350ma? Or have you run out of circuit real estate?

Good luck with the project... it looks really good!

Cheers Harvey
 

thefish

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Re: My LED driver... anyone want to try?

hord said:
I am unfortunetly not in the USA or I would stick my hand up for a try! One question I did have though -> would it still work with 2 x D cells (alkalines should, but I am assuming NiMH wouldn't)?

Also is there scope in your design to have the CC at higher levels than 350ma? Or have you run out of circuit real estate?

Good luck with the project... it looks really good!

Cheers Harvey

2 x D cells is actually a very good match, I did have plans to try this in a 2 D Cell M@g... where are you located I could check how much shipping costs I may still be able to get you one. As for above 350ma CC it may be possible although it is not officially supported by the chip I know it can be done (with a drop in efficiency).


As for a host I am not totally sure... I have been using http://www.dealextreme.com/details.dx/sku.79 it is not a perfect match (this light actually needs a bit larger circuit like revision 1, but it does fit well enough to make it work. I think most 2 x AAA lights would probably be able to host it.
 

Walt175

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Re: My LED driver... anyone want to try?

Would the cutoff be good enough for this to work with unprotected 18650's?
I'm not sure, but I think I'd need 2v or 2.2v for the LV cutoff. Can it be adjusted? I'm working on a mod for my Metal Gear, and I think this might work.
 

thefish

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Re: My LED driver... anyone want to try?

Walt175 said:
Would the cutoff be good enough for this to work with unprotected 18650's?
I'm not sure, but I think I'd need 2v or 2.2v for the LV cutoff. Can it be adjusted? I'm working on a mod for my Metal Gear, and I think this might work.

With the current Rev2 board it is not really possible to change the LC cutoff; the 1.4-1.8 range is to low for Li-ion cells. However as it has the auto dimming on low voltage detect you could use that to warn you its time to stop the battery. Low battery detect turns on in the 1.85-2.24 V range.


Note to self for Rev 3: (look into possibilities)
  • Adjustable input range for 1.5V or 3V (1 or 2 cell)
  • Adjustable LV cutoff
 
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OddOne

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Re: My LED driver... anyone want to try?

I'm interested and can give you some field info on how well it works with an XR-E. I can also give it a whirl with 5-6VDC off my mini-switcher power supply if you think it'd survive. :D

oO
 

hord

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Re: My LED driver... anyone want to try?

Thanks for the Offer... I am based in Tasmania Australia - but I think its better for others based closer to you to have a play with this driver & report back on their findings! Especially as there has been quite a bit of interest since I posted yesterday!

I look forward to hearing what others find out!

Cheers Harvey
 

thefish

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Re: My LED driver... anyone want to try?

OddOne said:
I'm interested and can give you some field info on how well it works with an XR-E. I can also give it a whirl with 5-6VDC off my mini-switcher power supply if you think it'd survive. :D

oO

That would be interesting to see... actually I did try 5V just to see what would happen when the whole thing was on my prototype board, nothing bad happened but I think it went DD. The main IC has an absolute max of 6V in so it may take it. If you want one PM me to let me know.



P.S.
My paypal address:
CC [email protected]
Cash payments [email protected]
 
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bombelman

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Re: My LED driver... anyone want to try?

I sent you a pm 24hrs ago, did you get it ?
 

thefish

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Re: My LED driver... anyone want to try?

bombelman said:
I sent you a pm 24hrs ago, did you get it ?

Yes I got it and I sent you an e-mail as requested... I will copy the e-mail to a PM for you.
 

UncleFester

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Re: My LED driver... anyone want to try?

hey guys, even though the chip may have an input voltage up to 6V, don't forget that the circuit is a boost converter and that the input voltage needs to be lower than the output voltage (the Vf of the LED)
 

thefish

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Re: My LED driver... anyone want to try?

UncleFester said:
hey guys, even though the chip may have an input voltage up to 6V, don't forget that the circuit is a boost converter and that the input voltage needs to be lower than the output voltage (the Vf of the LED)

Yes this is true anything above the Vf of the LED will go into direct drive and may cause damage if too high...
 

thefish

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Re: My LED driver... anyone want to try?

I have discovered something new and interesting that may make this much more versital than I had thought when designing it.

From the datasheet "If the battery voltage is greater than the required LED compliance, it will cycle off periodically to maintain the correct average current."

My own testing w/ Cree XR-E star:

3xAAA Sanyo 1000mah NiMH Cells fresh off charger:
4.12V @ no load
3.12V @ LED

AW ICR 123A LI-ION
4.00V @ no load
3.22V @ LED

It looks like this boost converter can in fact run as buck/boost to some extent!
 
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