Can anybody suggest any European dealer for genuine Cree LEDs mounted on PCB? I’m looking for an XHP70 to be mounted inside a spotlight powered from mains using a 12V/5A power source.
just a 12V5A Power supply wont work
you need a driver
with the 12V XHP70 you can use buck drivers like this on a 24V PSU
you need to adjust max. current for the LED
Why? I was going to use the external power source of an external hard disk, isn’t it supposed to be stabilized? Or there is need for something else?
It has to be current regulated, not voltage regulated (like a normal power source).
“Constant current” is what you drive a LED with.
in rare cases where voltage of PS (power supply) meets led requirements, and PS can not supply more current than led can take, simple voltage regulator may work. in his case 5amps is about 2x over max current. (wire 2 , or even 3 leds in parallel, spread the current, and you should be ok).
if PS was up to 2500ma, i would be ok, and could be used instead of driver, without risk of damaging led,
it usually is, but 5A is a lot for 1 led. also the led is rated 12v, but in reality, it may need a bit more than 12v to run at full power. just like 6v mtg2 is barely pulling an amp with 6v, it needs over 6,5v to run at full power.
so i would connect the led to your power supply, and measure current, if it is not above 2,5A you can get away without a extra driver. leds have tendency of changing voltage, and current they pull as they heat up, measure the current as leds heat up, it will change a bit, but if current does not go above what led can take, you are ok. just hook up the dmm, and let the led run for a while, and watch the current.
The diode takes as much current it can get
If you look at the curve the current needs to be regulated
http://www.cree.com/~/media/Files/Cree/LED-Components-and-Modules/XLamp/Data-and-Binning/ds-XHP70.pdf
The curve is not constant, temperature and other influences can change the voltage needed for the drive current
The LED needs about 12.7V for 2400mA
Another option for LEDs, available bare or ready-mounted on MCPCBs: