Driving Luxeon LEDS

[archangel2]

HI, i was wondering if anyone here has anyexperience in driving Luxeon LED's. Im using a LXHL-PRD5 LED with driving current of 700mA and forward voltage of 6.8V My main concern is finding the smallest possible constant current driver. I'll be using a single LED, emitter configuration. :lol: I hope you guys can help me out, thankx in advance!

 

[Roff]

What is the voltage of your power source? How much current can it supply? Is efficiency important, i.e., can you waste power, which means lower battery(?) life and more heat?

 

[archangel2]

What is the voltage of your power source? How much current can it supply? Is efficiency important, i.e., can you waste power, which means lower battery(?) life and more heat?

im currently starting with the design of the driver, then decide on the power circuitry, which means i can use A/C adaptor so i can have "unlimited" current.

so basically i desire less heat, no clause for power consumption, small circuitry, and more importantly, constant current, even at high temp.

with regards to power supply, i can adjust from 5-12V

i'll be using pic microcontroller to control some stuff --> i dont know if it is of any importance

im sorry if it sounds stupid since i am very new with hardware design, am a software/firmware designer but was task to do this so any help would be gretly appreciatedÜ

thankxÜ

 

[Axe_Murderer]

http://www.speleogroup.org/lt1512a.html

or... http://www.google.com/search?q=luxeon+constant+current&hl=en&lr=&ie=UTF-8&oe=UTF-8
:wink:

 

[Roff]

Here's another idea, which I took from this app note. It should provide 700ma drive, but you would need to test it carefully before driving an expensive LED. I would buy a 6.8v, 10 watt zener to test it on, such as NTE5181A.
Read the app note carefully. It explains the purpose of the 10 volt zener and how the resistors, transistor, Schottky diode, and inductor were chosen. I may have made mistakes. I haven't tested it or simulated it.
Here are datasheets to the other parts:
**broken link removed**
Schottky diode
MOSFET
**broken link removed**

 

[olly_k]

Have you tried the led yet??? I just want to know do these things live up to the hype. Also where did you go and how much did you pay?
Sorry about the q's I just can't wait to get my hands on one of these things!

 

[Roff]

Olly, from what I could gather from their web site, this particular LED is characterized for curing dental "epoxy". They have others with different characteristics.

 

[Axe_Murderer]

Have you tried the led yet??? I just want to know do these things live up to the hype. Also where did you go and how much did you pay?
Sorry about the q's I just can't wait to get my hands on one of these things!

I have used the 1Watt versions. They are amazingly bright for the package. The overall brightness compares to a mini maglight, but thge quality of light is way better. And of course, being an LED, the battery drain is quite a bit less. The 5 watt versions are sure to be painfully bright.

 

[olly_k]

Olly, from what I could gather from their web site, this particular LED is characterized for curing dental "epoxy". They have others with different characteristics.

lol I certainly aren't planning on doing any dental work! Although what with the extortionate prices dentists charge around here and the fact I haven't been for ten years I might as well start somewhere!
I was specifically asking about the white versions currently available I guess I will have to save up and see this for myself.

 

[Axe_Murderer]

Oh yeah... expect to pay around $15 for the 1W and around $35 for the 5W versions. You will also want the optics for them if your's doesn't come with. Here's a source: https://www.king-cart.com/cgi-bin/cart.cgi?store=elektrolumens

 

[archangel2]

Have you tried the led yet??? I just want to know do these things live up to the hype. Also where did you go and how much did you pay?
Sorry about the q's I just can't wait to get my hands on one of these things!

Tried it with a resistor and a voltage source, and how bright it was? i thought it exploded....
i got it from a singapore distributor, i live somewhere in southeast asia, and it cost $45, huhuhuhuhuhuhuÜ but the company is paying for it, so implanning in buying more and play with it!

 

[archangel2]

To Ron H and Axe_merderer: thanks a lot guys! will try this out and post here on the development! This board rocks! :lol:

 

[archangel2]

Here's another idea, which I took from this app note. It should provide 700ma drive, but you would need to test it carefully before driving an expensive LED. I would buy a 6.8v, 10 watt zener to test it on, such as NTE5181A.
Read the app note carefully. It explains the purpose of the 10 volt zener and how the resistors, transistor, Schottky diode, and inductor were chosen. I may have made mistakes. I haven't tested it or simulated it.
Here are datasheets to the other parts:
**broken link removed**
Schottky diode
MOSFET
**broken link removed**

Just would like clarify that the vcc to use is 5V? the forward voltage of the prd5 is 6.8V, will this be able to drive the LED? thankx again.

 

[Roff]

Here's another idea, which I took from this app note. It should provide 700ma drive, but you would need to test it carefully before driving an expensive LED. I would buy a 6.8v, 10 watt zener to test it on, such as NTE5181A.
Read the app note carefully. It explains the purpose of the 10 volt zener and how the resistors, transistor, Schottky diode, and inductor were chosen. I may have made mistakes. I haven't tested it or simulated it.
Here are datasheets to the other parts:
**broken link removed**
Schottky diode
MOSFET
**broken link removed**

Just would like clarify that the vcc to use is 5V? the forward voltage of the prd5 is 6.8V, will this be able to drive the LED? thankx again.

Yes. In fact, VCC must be less than the output voltage, or I believe you'll get smoke from the diode and/or the inductor.