MeanWell LDD Information

Simonv92 · May 10, 2020

Hi all! I'm building my own Reef-Pi based aquarium controller, I have a question regarding the LDD led driver, does anyone know if the + input terminal is connected directly with the + output? Because my light has only 3 wires, 1= positive, 2=white negative, 3=blue negative.
Thank you!

peterj66 · May 10, 2020

No, sorry, but you can not use the LDD that way. The LDD keeps the current steady by adjusting the output voltage. It measures the current on the negative side. Because of that it is not suitable for common anode or cathode scenarios

oreo54 · May 20, 2020

Simonv92 said:
Hi all! I'm building my own Reef-Pi based aquarium controller, I have a question regarding the LDD led driver, does anyone know if the + input terminal is connected directly with the + output? Because my light has only 3 wires, 1= positive, 2=white negative, 3=blue negative.
Thank you!

Yea lDD's don't work.
From the description it sounds like your light is run at constant voltage not current.
There are ways to dim it w/ a pi but it's simple and complicated at the same time.

Bare bones description would be to use a PNP digital power MOSFET w/ a circuit to reverse the polarity of the pi's pwm voltage (from point of sale to negative to run the gate of the MOSFET)

There may be other ways.

Your positive ground light is designed that way because you can use cheaper and more efficient NPN power MOSFETS to dim it,
At least as I understand it.

Simonv92 · May 20, 2020

Hi, thank you for your reply. My lights are constant current, now I'm using some pretty big and non so easy to hand on a pcb led driver. These are bare bones pcb so I can see the traces onto it and I've found that the positive lead go straight from In to OUT. The current driving is done on the negative lead.
This way I can run only 1 positive lead to the hood and the 2 negative with dimming function for the 2 led channels.
Now I'm designing a new led drive board and I want something more "pcb friendly" and the LDD were perfect...
If any of you has one of these driver, can tou please check with a multimeter in continuity mode if there's a straight connection from positive IN to positive OUT? thank you!