Can you use Adafruit 16channel pwm with meanwell LDD-1000H

[patrikk]

Hi I was wondering if its possible to use the Adafruit 16 channel 12 bit pwm ( product id 815) with meanwell LDD-1000H (http://www.meanwell.com/search/LDD-H/LDD-H-spec.pdf) and the PSU meanwell SP320-36 ( http://www.meanwell.com/search/sp-320/default.htm)

how would I go about connecting them and would I need anything else? I want to control 48-72 high power(about 3-5W each) LEDs from Cree. or do you have any other suggestions?

[adafruit_support_mike]

Meanwell is a well-respected PSU vendor, so I don't think you'd have any trouble connecting the PWM breakout to one of their supplies.

The breakout can't drive high-power LEDs though. There are current-limiting resistors between the chip and all the output pins. They protect the chip as well as the devices being controlled. The PCA9685 is a good chip, but it isn't made to swing several amps around.

You can use the breakout's signals to control mosfets which in turn control the high-power LEDs.

[patrikk]

Cant you just use the Product id 815 for the PWM ( as a pwm expansion) for the Mega and only connect the PWM to the Meanwell LDD-1000H and then connect the PSU to the meanwell drivers from from the drivers to the LEDs? and therefore not sending any high power voltage through the adafruit 16 channel pwm?

[adafruit_support_mike]

Using the PCA9685 as a PWM controller for the LDD-1000H would work. Using the LDD-1000H with a Meanwell PSU is an interesting question though.

The LDD-1000H is a step-down converter, and it looks like the minimum input voltage is 9v. Using that with a Meanwell PSU would mean you have a high-quality power supply generating excess voltage just so the LDD-1000H can step it down to the level the LEDs want. The LDD-1000H has 80-95% conversion efficiency, so with a 300W PSU you'd only get 240-285W of usable power to the LEDs. That's toward the middle of your power requirements.. not a show-stopper, but it will probably put some limits on what you can do.

What's the nominal forward voltage for the LEDs you want to run?

[patrikk]

well the typical Vf is 2.85 and max of 3.5 but I'm guessing that I would end up with a Vf at about 3. that would mean that I would be able to have about 10 LED in a string and 7-8 strings with led to comply with the driver and the PSU ( the psu has an output of 36V and 8.8 A). so dividing the amp on 8 strings gives each string 1.1A and about 32 V( the LDD consumes some as well I guess).and as the vf of the led will be about 3V at 1A that would be 10 led on each string.

here is one the LEDs types that I will be using:
http://www.rapidled.com/cree-xt-e-royal-blue-led-1/


or do I have it all wrong?

I might also mix some LDD-1000H with LDD-700H.

[adafruit_support_mike]

That should work. I wasn't sure whether you wanted to run the LEDs in chains or individually.

For that arrangement, each LED will be running at 3W, which leaves you enough headroom for an LDD-1000H on each chain.