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I'm trying to put together a project with some bright LEDs but I'm not sure how to control them. Ideally I'd like to drive about 64 of these LEDs that have a forward current of 300mA and voltage drop of between 2.2V and 3.4V. I'm looking for something similar to the MAX7221 I think but one that can support these high currents. Does anyone have any ideas or experience with driving these kind of LEDs. I'd like to use arduino to control the driver.

edit I came across the LT3492, would that work?

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See chiphacker.com/questions/906/… – starblue Jul 13 '10 at 11:52
Do you need to control them independently? If not, string them all together and use a simple switching dc-dc led driver. Zetex makes some that are really easy to use. – Connor Wolf Jul 14 '10 at 7:50
See this: electronics.stackexchange.com/questions/36118/… And this is the final circuit I ended up with: circuitlab.com/circuit/vwvrj3/pwm-led-circuit – Shamtam Aug 10 '12 at 3:24

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I have controlled the high current LEDs with both current sources and current sinks.

I am just finishing up the testing on an LT3755 driver circuit (current source) that is driving 12 3W Cree XLamps. This driver has excellent performance if you are careful with the layout. This device can do almost a 10:1 boost at 50W! Being able to simulate in LTSpice was extremely convenient.

If you want a simpler layout you could look at current sinks. You would need to get a supply capable of producing a voltage slightly greater than the sum of the Vf(max) of your LEDs. Using a FET and op-amp you would create a voltage controlled current sink. You could PWM this by setting the current to zero. I use an analog switch on my current-sink.

Here is a picture of my current sink design -- http://wiblocks.luciani.org/not-quite-ready/ZB1-ISINK-index.html The FETs are rated for 40A, the connectors are rated for 10A. For an LED application with a reasonable size heatsink you can probably go to 2A. The LEDs in the pictures are being driven at 350mA. No heatsinking is required if the dissipation in the FETs is kept below 1W.

The board in the picture is being controlled by my Arduino compatible NB1 board.

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If you want to control the LED's individually, the only current sink driver I have found that can handle that much current is the STP04CM05XTTR. I use it in my high power LED driver boards. For current sink drivers you have to make sure that the LED supply voltage is not much higher than the LED forward voltage, otherwise the driver will get too hot.

I have written an article about controlling high power LED's with my ShiftPWM library here.

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