1W LEDs

Discussion
1

I have a project in mind that uses 1W LEDs.

I’d like to drive maybe 5 or 6 from a portable battery source - probably AAs for convenience - and control with some sort of mini Arduino through PWM. All on or off at the same time - not individually controlled.

I know I need to drive them at 350mA each, 3.2 to 3.6v. I’ve never used LEDs this bright before, and I don’t think a current limiting resistor is going to cut it…

What’s the best way to do this?

I’d really like an off the shelf solution that I can buy for a few quid off AliExpress - no hurry to get this done.

2

Out of interest, why wouldn’t a resistor be suitable??

3

My (limited) understanding is that because of the highish currents involved you are wasting a lot of power as heat. Also (and I understand this even less) the forward voltage of the LED varies with temperature, and as they warm up the resistor you’ve carefully calculated is no longer the right value.

So I’m looking for a simple current controlled solution.

1 Like
4

You need a constant current driver, better if is suited for LEDs .

You can use an LM317 with some resistor but you will waste a lot of energy.

or buy one of this :

2 Likes
5

That’s for mains, no?

6

Wuops , you are right :slight_smile: , well , you need on of that but for battery

7

Like this?

How would I wire the LEDs? In series?

8

If you are using aa batterys you may need a step up converter

9

So when it says ‘up to 10 LEDs’ that would be with a 35v input?

10

Yes

11

Can’t find a module Google

Boost Current Regulators for LED

It will get you to some datasheets

13

Would it be a daft idea to use one of these


to produce 35v from 3 AAs and then fees that into one of these?

14

Might be missing something - but why not just use 4 AA batts (will be more than 5V with regular alkaline batts, would be slightly less with nimh) and feed that into the 350mA CC driver and avoid the inefficiency of skipping it up to 35V?

15

This video might be interesting, the guy uses something similar to these modules:

16

My understanding is that the input voltage to that driver board needs to be at least (number of LEDs) x 3.2v so around 16v

17

I used limiting resistors with 5 strings of 6x 3w LEDs. Works fine. I glued them all to a big heatsink using thermal epoxy to keep the heat down.

18

Unless you get a boost converter.

19

It should not be difficult to frig the feadack loop of the boost converter to make it run content current

20

Have looked at the datasheet for that xl6009 , all you need do is remove two components from the board and add a current sense resistor to pin 5 and bingo you have your regular

21

Don’t offer the flux capacitor doc!