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Why does luxeon led neea a driver circuit??

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antoniodilen

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Hi everybody,
need little help understanding how these POWER LED's work...
all i know is that they are much brighter than the average leds...
so if any body has time please teach me about these led's...
and why they need driver circuits..
many thnks in advance:)

(sorry...i have made a spelling mistake on the thread heading)
 
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They're just like any other LED. You just need to limit the current going to them. I think they're more sensitive to forward voltage drop variations so constant current circuits are often used instead of resistors.
 
Do they generate a lot of heat too?
is there a simple way to drive them ???
is it possible to drive many with a 12v supply as we drive a few normal led's in series?
 
Yes, they generate heat, for their full rated power I think they often need to be heat sinked. The cooler you keep them the longer they live. You can drive them with resistors just like any other LED, but you're dealing with more power so the resistors will be generating heat too, resistors change value when heated. Basically you just have to be more careful than with a low power LED.
 
Yes, they generate heat, for their full rated power I think they often need to be heat sinked. The cooler you keep them the longer they live. You can drive them with resistors just like any other LED, but you're dealing with more power so the resistors will be generating heat too, resistors change value when heated. Basically you just have to be more careful than with a low power LED.

Thanks again:)
 
I think the forward voltage of the high power LED drops as it heats which causes thermal runaway. Heat makes more current which makes more heat which makes more current then KABOOM! You can't see the LED when it is smoking.

Use a constant current driver instead of a simple resistor.
 
Or value the resistor conservatively.. which will limit your initial brightness.
That's pretty much why they need drivers =)
 
Yes, you can drive them in series. If you have a 12 volt supply, check out these ready made high power LED drivers.

**broken link removed**

Easier then making your own from scratch.
 
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They're just like any other LED. You just need to limit the current going to them. I think they're more sensitive to forward voltage drop variations so constant current circuits are often used instead of resistors.
I think it's more an efficiency thing: there's no point in paying a lot for an expensive efficient LED and wasting over half the power in a resistor which also requires a large heat sink.

It you don't need current regulation then a good way of driving a power LED is to just use an oscillator (e.g. a 555 timer), MOSFET, Schottky diode and inductor - it's cheap, efficient and achieves similar current regulation to a resistor.

How much current does the LED require? Don't give the absolute maximum rating, give the recommended operating current.

What's the typical forward voltage?

What's the voltage range of your power supply?
 
I think it's more an efficiency thing: there's no point in paying a lot for an expensive efficient LED and wasting over half the power in a resistor which also requires a large heat sink.
Actually 100Lm/W with a series resistor can still be more efficient than junk LEDs.

I would still use a good driver.
 
I think the forward voltage of the high power LED drops as it heats which causes thermal runaway. Heat makes more current which makes more heat which makes more current then KABOOM! You can't see the LED when it is smoking.

Use a constant current driver instead of a simple resistor.

...thank you for your time
 
I think it's more an efficiency thing: there's no point in paying a lot for an expensive efficient LED and wasting over half the power in a resistor which also requires a large heat sink.

It you don't need current regulation then a good way of driving a power LED is to just use an oscillator (e.g. a 555 timer), MOSFET, Schottky diode and inductor - it's cheap, efficient and achieves similar current regulation to a resistor.

How much current does the LED require? Don't give the absolute maximum rating, give the recommended operating current.

What's the typical forward voltage?

What's the voltage range of your power supply?

i'm planning on driving them with a 12V supply...
thanks i got some driver's from older threads posted in this site
 
Expensive drive, but a lot of features, well suited for expensive leds =)
 
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