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Topic: Any interest in high-power LED driver shields? (Read 2 times) previous topic - next topic

allanw

Oct 25, 2010, 09:44 am Last Edit: Oct 25, 2010, 10:00 am by allanw Reason: 1
I'm working on a buck converter constant current source capable of 350mA/700mA with a wide range of input voltages and output voltages for flexibility in driving any sort of LED load. I'm developing it in shield form, with three independent drivers capable of PWM dimming. There will be an on-board attiny which will generate the PWM signal, controllable easily by I2C so that the host Arduino barely has to do any work. Stacking these shields allows you to independently dim as many RGB LED's as wanted.

Sparkfun sells a similar 700mA triple driver, but it's very pricey at $50 and doesn't let you dim as easily as mine.

Is there any interest in this shield? So I know if I should make a bunch of boards.

A preview:

mowcius

I suppose I would say I might be interested in one (as an alternative to my master for Blinkm which the regulator blew up on) but it depends on the price. Any ideas on how much it might be?

Is it 700mA per channel then? (or 350 or what?)

I might suggest you double the spacing on the LED connection pins to allow 0.2" spacing screw terminals (common size).

Not convinced by the spacing of the bucks in relation to the LED connections... closer is normally better  ;)

Mowcius

allanw

I'm planning on selling both a 350mA and 700mA version, since those are the two common max currents I've seen. Going from 350mA to 700mA is just a matter of soldering on another current sense resistor in parallel. Easy to customize the output current yourself too, since I've left room to put three current sense resistors in parallel.

I believe that if the LED's are going to be connected through some wires then a few inches of PCB trace won't matter too much. I might move them closer but I still need to layout the on-board MCU.

Might have to get a little creative to fit in six 0.2" spacing terminal blocks. Also I'm looking for a way to be able to stack these boards while being able to screw/unscrew the terminal blocks.

Pricing: probably around $25 + $5 shipping for a fully fitted board.

mowcius

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Might have to get a little creative to fit in six 0.2" spacing terminal blocks.

Six?

Six connections... 3 terminal blocks...

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Also I'm looking for a way to be able to stack these boards while being able to screw/unscrew the terminal blocks.

Hmm well you shouldn't really be screwing/unscrewing LEDs when it's powered up so I don't see why you need to be able to do this.

Shields are pretty much only used for prototyping anyway so it's not likely that it'll be so restrictive in a case that you can't take the shields apart...

Mowcius

allanw

Just a matter of convenience :)

The driver handles hot swapping of loads anyway. It's a nice feature to have.

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