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User avatar
By leon_heller
#40404
What are the drive requirements?

Leon
By azog
#40406
The LED says 350mA peak; the AVR I have in mind can source 40mA directly off a port pin.
User avatar
By leon_heller
#40410
That's a lot of current, you can't just connect it to an output pin. You need some sort of driver.

Leon
By NleahciM
#40422
azog wrote:The LED says 350mA peak; the AVR I have in mind can source 40mA directly off a port pin.
Didn't you just answer your own question?
By azog
#40444
NleahciM wrote:
azog wrote:The LED says 350mA peak; the AVR I have in mind can source 40mA directly off a port pin.
Didn't you just answer your own question?
Yea, but I was hoping to get a different answer than the one I gave myself.
By daemondust
#40448
Image
User avatar
By phalanx
#40463
daemondust wrote:http://i18.tinypic.com/6prgm5s.png
I would not recommend driving a Luxeon with a ballast resistor. At 350mA and a 5V source you will be dissipating about half a watt in the resistor which is very inefficient. If you are using a 7805 as a power source, you will also dissipate a lot of power there too since it is a linear component.

If your MCU has a built in comparator, you can very easily make a simple current controlled buck converter to drive it with around 90% efficiency. If not, there are a number of ICs available that will do it for you with minimum support hardware. For instance, the Zetex ZXLD1350 only requires a coil, sense resistor, and schottky diode: http://www.zetex.com/3.0/product_portfo ... o=zxld1350

-Bill
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