Looking for Constant Voltage Boost Converter

MatajumotorS · Feb 22, 2007

I am looking for boost converter - to boost one li-on to about 4,5 - 5V constant at 1A to feed FluPic.
Could anyone sudgest me something, sell me something :grin2:

, maby someone has experience with boost converter building, i had tried to bulid some but ... :rant:

i need help, recently i tried MAX1771 with IRLU2905 and nothing :ohgeez:

(i am angry because of spending $11 vor MAX1771 and nothing :rant:

)it is oscilating i see pulses on gate and drain (short) and it tries to work at some mystic 2.3V or about that, but no current handling...

MatajumotorS · Feb 22, 2007

Anyone?

RCatR · Feb 22, 2007

For just boosting a BB1000

For buck/boost a GD1000

I beleive either of these will do the trick, I'd email the shoppe to be 100% sure

65535 · Feb 22, 2007

You realize how much efficiency your getting?? about <75%

MatajumotorS · Feb 22, 2007

All of theese converters ar constant current sources, - they do not like open load. I saw only one - Shark, but voltage there is too high - 11V and board too big...

MatajumotorS · Feb 22, 2007

65535 said:
You realize how much efficiency your getting?? about <75%

I thought about it, but it would be a compromis, i would get 100% brightnes for an 1hour vs 10min 100% .... then 1h 65%... etc

Other simplier way i am considering is using Led with smaler Vf, but as i have no acsess to large quantities it is a bit dificult to me, i need something like 1Amp @ 3,5V offcourse less is better :naughty: .

65535 · Feb 22, 2007

I assume you are using the flupic and want the multi levels? if you don't care just get the proper board. What exactly are you doing?

Genes · Feb 22, 2007

Try the National LM2621 or LM2623. I have used many for boost circuits, and I believe that these are among the very best on the market today. These both work great for driving Leds in constant voltage mode.

Gene

MatajumotorS · Feb 22, 2007

65535 said:
I assume you are using the flupic and want the multi levels? if you don't care just get the proper board. What exactly are you doing?

i am driving seul led via flupic from single 18650, and i am short in current :scowl: i am getting arround 650ma @ 3,7v on a batt and because of that, there is no difference between 10th level an burst. With This led i need something like 4V-4.1V to get FluPic into regulation at a burst mode witch is about 1,3A in my case.

And Yes, i like the way FluPic work (levels, modes , etc).

enLIGHTenment · Feb 22, 2007

You'd get better runtime by using two 16340 (R123A) rather than an 18650 with a boost converter. The battery capacity you'd loose will be more than offset by the greater efficiency of using only one converter in step-down mode.

MatajumotorS · Feb 22, 2007

For now i think i will try to obtain another Seul Led with lower Vf

..

doc_felixander · Feb 25, 2007

I'll jump in here. Basically I have the same question. I'm running a Cree from a 18650 with a FluPIC. As goldserve's new Piglets will operate in the lower current range, they're no option.
So, my basic question is: would it be possible to hook up the FluPIC to any driver board (via SYNC or STDN pin which many driver ICs have) directly via the PIC's output pin, omitting the LDOs?
If using 2 R123 cells and a buck converter, the voltage to the FluPIC could be limited by a linear regulator (e.g. 7805) now that it has only PWM controlling functions.

hmmm....right?

goldserve · Feb 25, 2007

With a little bit of hacking, you can devise your own power supply and just make sure to drop the voltage to the flupic board to around 3-4V using LDO regulators and hook up pin 2 to some kind of FET as the PWM output is on that pin.

MatajumotorS · Feb 25, 2007

doc_felixander said:
I'll jump in here. Basically I have the same question. I'm running a Cree from a 18650 with a FluPIC. As goldserve's new Piglets will operate in the lower current range, they're no option.
So, my basic question is: would it be possible to hook up the FluPIC to any driver board (via SYNC or STDN pin which many driver ICs have) directly via the PIC's output pin, omitting the LDOs?
If using 2 R123 cells and a buck converter, the voltage to the FluPIC could be limited by a linear regulator (e.g. 7805) now that it has only PWM controlling functions.

hmmm....right?

I think Goldserve mean to control the boost converter by flupic. You wil need anly to find boost converter whith control input.

But what is for me - i wil try to get seul led with lower drop voltage @ 1A i need something like 3,5 - max3,6V @ 1A because of flupic drops around 200mV

goldserve · Feb 25, 2007

What about those low VF seoul leds fred is selling now? Seems like a good candidate...

MatajumotorS · Feb 25, 2007

yes, i am hoping exact on them :grin2:

, but i dont know theit parameters, before PhotonFanafic will get them and play with them.

MatajumotorS · Feb 25, 2007

but for comparsion:
the kenbar light from DealExtreme wit seul Led @ 700mA is Brighter than
my DIY light with fraen narrow long optic with cree p3 @ 1,1A

doc_felixander · Feb 25, 2007

this might be due to the reflector.....remember, it's smooth and pretty large in diameter (almost double) and gives both throw and enough spillbeam. ~20mm vs ~40mm is an unfair battle.

@goldserve: i guess this is the original FluPIG solution. however, if i find a way to control the converter directly via a sync input, I'll be able to hook up converters that are not open-load protected. and wouldn't have any losses at the mosfet (although minimal).

or am i missing something? didn't want to dig up the whole old FluPIG thread...

CM · Feb 25, 2007

A badboy (not nextgen, but the one that uses the LT1618) has open circuit protection. It is designed to kick it into constant voltage regulation if the load opens up. If you have some electronics knowledge, you can determine what resistor divider network to use to get you the desired constant voltage output. As someone pointed out above, your efficiency is going to suck rocks. The total efficiency is the product of the individual converter efficiencies. So let's say the BB is 80% efficient and the FlupIC is 75% efficient. The total efficiency is going to be 60%.

doc_felixander · Feb 25, 2007

The only point why efficiency would suffer any further in this setup (either by controlling the converter chip via PWM signal or by using a MOSFET) is the PWM at full current (I was thinking about 1000mA) itself due to the LED's lower efficiency in those ranges.
What you mean is the efficiency drop at the FluPIC's LDOs at higher voltages, which won't be needed any more.

Looking for Constant Voltage Boost Converter

Enlightened

Enlightened

Enlightened

Flashlight Enthusiast

Enlightened

Enlightened

Flashlight Enthusiast

Newly Enlightened

Enlightened

Enlightened

Enlightened

Newly Enlightened

Flashlight Enthusiast

Enlightened

Flashlight Enthusiast

Enlightened

Enlightened

Newly Enlightened

Flashlight Enthusiast

Newly Enlightened

Similar threads