# LED Dirive LDD-300H

Discussion in 'The Projects Forum' started by RodneyB, Oct 23, 2013.

1. ### RodneyB Thread Starter Well-Known Member

Apr 28, 2012
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16
I am trying to find out exactly how many LED down lights I can run from the driver. The Specifications of the older drivers which failed are for a 9Watt LED down light

Secondary details of the old driver DC13 - 36 Volts 320mA from the LDD-300H I am trying to find out exactly how many of these LED down lights it will drive.

Many thanks

Rodney

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2. ### mcgyvr AAC Fanatic!

Oct 15, 2009
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It can output up to 52VDC (which will require a 55V power supply)

So the number of LED's it can drive in series is (52V divided by the led Vf) then round down to the nearest whole number.

You do know this requires an external DC power supply right? The LDD series drivers simply converts a constant voltage output into a constant current output.

3. ### RodneyB Thread Starter Well-Known Member

Apr 28, 2012
697
16
The original LED driver had a DC secondary voltage of 13 -36 volts so I am driving them from an external 24 Volt DC power supply. The LED's ae already built into a lamp there are 7 x 1 watt LED's in each lamp the rated current of the lamp is 320mA.

I have 5 of these lamps and want to see if I can drive them all from the single driver. On the originally attached data sheet I did not see if it had a maximum power rating.

Thanks

Rodney

4. ### mcgyvr AAC Fanatic!

Oct 15, 2009
5,394
1,194
300mA @52V max.. Thats all you need to know.

You really need to know the specs on the LED/downlight..

One might assume these lamps have LEDs with a 2 to 3 volt forward voltage.. As such the Vf of the downlight is in the range of 14 to 21VDC.. (7 x 2 or 7 x 3)
Hence if using a 55V power supply then you can run 55/21= 2.6 (round down to 2)
So a single LDD can run 2 of these assuming you can run them in series and you need a 48V supply

You "could" run 4 downlights from it.. with 2 parallel strings of 2 in series. But must be aware how to properly parallel LED's and accept only 150mA for each..

To do it right you would need 3 of the LDD's. 2 with 2 in series and 1 for the 5th