Red XR LED current limit

[KrisP]

Hi,

I am making a red LED light on a budget and all the cheaper driver boards make 950-1000mA on max, around 300-350mA on medium and around 100mA on low. The data sheet for these LEDs says they handle "up to 700mA", but the white XR-E data sheet says up to 1,000mA and people drive them up to 1.5A and over with no short term problems. Do you think the red Cree will take 950mA for a few minutes at a time without a problem? It will be heatsinked well in a Maglite host.


Thanks

 

[SemiMan]

Take it? Likely. Worth it? Not likely. RED LEDs decrease in output significantly when they get warm. For this reason, there is often a point at which increasing the current stops becoming beneficial. You will probably notice it is quite bright when it turns on, then relatively quickly reduces in output. Realistically they are not that expensive. I would just try it.

Semiman

 

[TorchBoy]

... all the cheaper driver boards make 950-1000mA on max, around 300-350mA on medium and around 100mA on low.

Depending on the type of board you might be able to disable one third of it, thus giving ~670mA on high.

 

[KrisP]

Great idea... The boards I have are DX and Kai boards which have three 7135's on them. I'd originally planned to use a multimode 1A board and a 700mA reg in series which did work but takes up extra space. I might just disable one of the 7135's on the multimode board to be safe

 

[TorchBoy]

:twothumbs

Would it be easiest to take the thing off completely or just break the connection to either the regulator/control pin or the negative pin?

Edit: Does this board work by pulse width modulation?

 

[KrisP]

I'm not sure how it works... It has 3 regs and an IC. I'll just cut the common pin on one of the regs

 

[SteveDavis]

The specs for an InGaN die (blue, green, white) should never be assumed to apply to AlInGaP (red, amber, yellow)

 

[KrisP]

I'm not assuming one set of specs apply to another...

I was referring to people being able to overdrive white Crees by 50% and wondering if red Crees can also be overdriven by 50% without short term damage. My question was answered by SemiMan