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  • Wuxi Kinglux Glass Lens Co.Ltd
  • ADD:No.286,Changjiang North Rd,New Dist,Wuxi,JS prov,China
  • Tel: 86-510-66759801
  • Fax: 86-510-84602998
  • Mobile phone: 86-18168862789
  • E-mail: ledglasslens@163.com
  • Contact person: Huimin Zhang
  • Selecting a Matching Driver
    Mar 26, 2018

    Selecting a Matching Driver

    Now that we’ve gone over the pertinent info for the COBs themselves, choosing a driver is simple. Be warned, when dealing with multiple large COBs, the LED drivers required to drive them are very powerful, and produce enough voltage and current to seriously harm you (or worse). BE CAREFUL.

    Popular Models

    Right now, the most popular LED driver for this application is the Meanwell HLG-C series. There are a number of different versions of the HLG-C series, but all that differs between them is their power output rating, with the lowest being the HLG-60H-C at 70 watts and the highest being the HLG-320H-C at 320 watts. There are a few other LED driver series from Mean Well that will do the job too, like the LPC or NPF-D series, which are made of plastic rather than metal and are for applications where less power is required.

    For the true DIY enthusiast, you can also put together a driver using a power supply and DC-DC boost converter, but we’ll be sticking to the basics here.

    Important Specifications

    Constant Voltage or Constant Current?

    The type of driver you’ll be looking for to use in conjunction with your series circuit is a constant current driver. Constant current drivers will list a range of voltage that your total system voltage drop must be within, in order for the driver to output the desired current. See my post on constant current vs. constant voltage drivers for a more in-depth look at the differences.

    Choosing the Right Size of Driver for your COBs

    If you want to do this the easy way, use our handy-dandy HLG-C selection tool! Enter your COB model, quantity, and drive current, and the spreadsheet will calculate your total forward voltage and highlight all of the Mean Well HLG-C drivers that are compatible with the parameters you entered. If the total forward voltage (Vf Total) of your system falls within the rated constant current range of a driver (between V_min and V_max), that driver will turn green, indicating it is a match. If the Vf total is out of range by 2 volts or less, borderline drivers will be highlighted in orange, indicating that they will probably work, but may depend on temperature and dimming. Now, if you want to learn how to properly size a driver yourself, continue reading below.

    Let’s say you were able to get a good deal on 6 CXB3590 COBs and decide you want to drive them at 1400mA, which is a little under half of their rated maximum current, in order to improve efficiency and reduce heat. Which of the HLG-C series would you have to buy to be able to power them?

    The first step is to figure out what your total required voltage will be. According to the data sheet, the forward voltage of each CXB3590 is 36v (measured at 2400mA of current) so 6 of them would equal 216V , however, we are going to run them at 1400mA, so we must consult Cree’s graph once again to determine the Vf for our current. According to the graph, at 1400mA, the Vf of each COB would actually be closer to 34V, resulting in a total of ~204V.

    To get an idea of how much power your driver needs to be able to put out in watts, multiply the voltage you calculated by the current you’ve chosen. In this case, you’re looking at 204V x 1.4A = 286W

    Now, you need to pull up the data sheets for your potential driver. We know that we’ll need a driver capable of outputting at least 286W, so this narrows the search to only 1 driver in our case (HLG-320H-C), but let’s look at 2 data sheets as examples – one for the HLG-240H-C and one for the HLG-320H-C. Look to the column that shows the 1400mA model and find the “Constant Current Region” row. This specifies what voltage range is required in order to produce the constant current for each rated current in the series.

    On the 240H-C, the constant current region requires a voltage range of 89-179V in order to output 1400mA. Our total voltage is 204V, so this will not work. On the 320H-C, the voltage range required for 1400mA of current is 114-229V. We are within this range, so this driver would do the trick. As you can see in the data sheet, if you decided to lower your current to 1050mA, the smaller 240H-C would run these COBs, but if you want to stick with 1400, you’ll need the big boy.

    240.png

    320.png

    Dimmers

    Many drivers allow you to adjust the current output and effectively dim the lights. Some come with a built in potentiometer (a variable dial that changes the output when turned), some come with leads that you can solder a potentiometer onto, and others require more advanced methods such as pulse-width modulation, or feeding a DC signal of a specific voltage. The easiest of the above options would be to opt for the model with the built-in potentiometer. If this isn’t available, grab the “B” version and get your own 100K ohm potentiometer to solder on.

     

    With any luck, this has shed some light on how to go about selecting and matching different LEDs and drivers – at least at a basic level. Researching new parts and configurations is one of my favourite parts of the build process and I hope you can share in that enjoyment now too.