Interfacing of ULN2803A with Arduino PWM Pins for driving 'Dimming Pins' of a constant current LED Driver.

[krish_ece]

Hello All!
In my project, I am interfacing these components in the order as follows:

Arduino Uno ---> ULN2803A ---> LED Driver ---> LED

Here, my goal is to send a PWM signal from Uno, to drive the LED Driver and to control the LED suitably.

SPECS OF DRIVER:
The LED Driver that I choose is a constant current LED Driver with dimming support.
Vout = 36V, Iout = 0.5A
It also has DIM+ and DIM- pins that support (1-10V)PWM Dimming.

With no inputs connected to DIM+ and DIM-, both LED and Driver are working as expected.
But, I am struck with Interfacing the DIM+ and DIM- of LED Driver to Arduino PWM Pins.

I read that we can use ULN2803A. How to use it exactly as per the above-mentioned order?
Also, suggest a good resource to learn about ULN and Darlington concepts!

thanks in advance!!!

 

[KlausST]

Hi,

Urgently needed:
* datasheet of LED driver. Look at the manufacturer's internet site for additional informations.
* a (hand drawn) sketch of your idea.

Klaus

 

[krish_ece]

1. LED Driver Datasheet: https://www.meanwell-web.com/content/files/pdfs/productPdfs/MW/LPF-16D/LPF-16D-spec.pdf
(I am working on Model no. LPF-16D-36, Please see Page no.2)

2. My idea

Also, I want to know the use of ULN here! Is is actually needed or not? What is the major advantage this IC offers?

Basically, I am interested in knowing about this ULN series of IC from scratch. Please help on that also...
Thanks in Advance!

 

[betwixt]

ULN series IC are many years old, maybe 40 or more! They are nothing more than an array of transistors packaged in one device for convenience, they have no special function or 'intelligence'.

I would be very careful how you wire up your Arduino to the LED driver module, do not assume any output connection is 'ground' or can be safely connected to 'GND' on your board.

I think I would experiment first by wiring the output side of an opto-coupler across DIM+ and DIM- and wiring its input side to the PWM output of the Arduino through a suitable current limiting resistor. That would be safe and from my understanding of the data sheet should work.

Brian.