Tag Archives: Drivers

How to Connect a Single LED Component into AC Network

I have two blog posts for you focused on how you connect COB LED components into the electrical network. I mean, when you have either a single COB LED or an LED module based on SMD LED components assembled on a PCB board.

Compared to traditional lighting, connecting LEDs to the electrical network is a whole new world. LEDs need direct current (DC) to light them, alternating current (AC) will not work. There are also AC modules available but those are not covered here.

In this post I will concentrate on connecting single COB LEDs. In case you are interested in connecting LED modules, I will write about that in my next post.

LED driver

You will need an LED driver, which is actually an AC/DC converter. It converts the AC voltage/current of the electrical network into the suitable DC voltage/current needed by the LED component. You will find the requirements of the LED from a datasheet provided by the manufacturer. If you need help in choosing a driver, you can read our guide.

Figure 1. Example of an AC/DC converter, LED driver. This one is from ELT with dipswitches, which means that you can choose the driving current.

Connecting COB LED into the AC network

In case of COB, you will have to create a closed electrical circuit so that the electrical current can flow through the LED component. A COB LED is basically a diode in its electrical nature: the current can flow only in a forward mode. This means that you must connect the positive (+) solder pad of the COB LED into the positive terminal of the LED driver. In the same way, you connect the negative (-) solder pad of the COB LED into the negative terminal of the LED driver. See the Figure 2 below.

 

This way, you create the closed electrical circuit that is needed to feed current through the LED so that it gives light. This closed electrical circuit formed by the LED driver and the COB LED is called the secondary side of the LED driver. LED driver feeds the power and current into the closed electrical circuit, and thus through COB LED, on the secondary side.

 

Figure 2. COB-AC Network

 

On the primary side, the LED driver gets electrical power from electrical network, AC network. The terminals of the LED driver on the primary side are called line and neutral. They are connected into the line and neutral connections of the AC network. If you have an LED driver with cables, they are usually blue (neutral) and brown (line). Some drivers also have a ground terminal, which is usually connected to the luminaire body with grounding wire. However, the closed electrical circuit is needed also on the primary side; between the network and the driver.

Usually, you will need to use some kind of terminal block to connect the driver into the electrical network on the primary side.

Picture of a terminal block

Figure 3. The example of terminal block to connect the LED driver into the electrical network.

Two options

Finally, as for physically connecting a COB LED into the LED driver, you have two ways to do it:

  1. solder the wires on the solder pads of the COB
  2. use solderless connectors.

In the first method, you manually solder the wire by using soldering iron with high temperature that melts the soldering material such as tin. After cooling, there is a joint between the wire and the COB solder pad. You need two wires, one for plus and one for minus solder pad.

In the second method, you use a solderless connector.

Figure 4. The solderless connector.

The solderless connector does the same effect as the soldered wire. You need the electrical connection also in this method, but you won’t need to solder the wire by melting tin. You just push the wire into the push-in terminals of the connector. Again, positive to positive and negative to negative terminal. They are marked on the connector. Basically these push-in terminals work with a combination of metal plates and springs that then make the connection to the solder pad of the COB LED.

The difference between these methods is, that unlike with soldered joints, in the solderless connector method the springs may loosen a bit over time and loss of contact may occur. Solderless connectors are generally thought to be more expensive than manual soldering.  

In my next post I will go through the steps for connecting LED modules.

Thank You for Everyone at Elfack 2017

I would like to thank everyone who we met at the Elfack Exhibition in Gothenburg, Sweden.

We had some good conversations with our existing customers as well as new people. This year we tested the color quality of Citizen’s LEDs at our stand. We got many answers through our questionnaire and found out that many visitors were excited about this new way of lighting.

If you took part in the test, you will receive the test results soon. We will also share these results with the public a little later.

We had a chance to show you our new products and the feedback we got from you was very encouraging.  I went through all the products in my last blog post, and if you wish to download more information about them, you are most welcome to do so here.

The products displayed at Elfack include:

  • aLED Engine
  • Citizen Gen 6
  • AC COB
  • Citizen Vivid Series
  • Furukawa Heatpipe
  • Merrytek sensors
  • Letaron & aLED Drivers

Our personnel will contact you as agreed, if they haven’t already. In case you have anything to ask, you can contact us directly.

 

How to Choose Constant Current LED Driver for your Application [Infographic]

The selection of Constant Current driver is not always that simple, Esko wrote a post about it some time ago. You can read that here.

Below you can find an infographic about the same topic. If you like it, feel free to share.

How To Choose Constant Current Driver [Infograpgh]

How To Choose Constant Current Driver [Infographic]

Here is a link to our Lightbuilder.

How to select modules + driver package

In this blog post we concentrate on how to design a LED lighting package as a whole. And what different aspects you will have to take into account when selecting a light source and a driver.
I decided to write this as a case example so that the post is more concrete.

Most of the luminaire projects starts with the need for certain amount of lumen needed out from the luminaire. Then there can also be requirements for the shape and size for the light source. Color temperature, color rendering and lifetime expectancy might also be critical, but those are topics for a blog posts of their own.

LED Modules

LED Module

Case example

So in this case you have specified that the luminaire needs to achieve:

  • Lumen output 2000lm
  • Color Temperature 4000K
  • Ra(min)80
  • Lifetime 50 000 hours (LM70 for the whole luminaire)
  • Efficacy >120lm/W
  • Linear light source. Max length of 120cm

With these specifications, the finding of the suitable solution shouldn’t be a problem.
There are, however few things that have to be taken into account when looking at the data of LED modules:

  1. Lumen output: Some of the lumens from the light source will be lost due to the optics. The amount of lost lumens is around 10%. Therefore, you should look for light sources that can give you at least 10% more lumens than you need.
  2. The shape of the light source. Do you have a minimum size for the light emitting surface? The luminaire in this example can be built with modules around 30cm in length, but that would probably not be perfect fit your luminaire. It would leave a lot of empty space and the light distribution wouldn’t be even.

With those two in mind, you would need a light source that gives you roughly 2200lm and fills the whole 120cm evenly. That could be reached with for example 4 modules with lumen output of 550lm and length of 30cm or with two modules with 1000lm output and length of 60cm.

Selection of LED Drivers

Selection of LED Drivers

The Driver

For the case study presented above, you still have one more step to go: choosing a LED driver. Esko already wrote a good guide on this, so I’m going to be brief.

Before we can start, you have to specify one thing: How many LED modules do you want to drive with one LED driver? Only one module or several modules in series?

In this example you would probably want to drive all the modules with just one driver. This might be the case with all luminaires. In more complex lighting systems you might use several drivers. To find a suitable driver you will need to:

  1. Check the current that you want to drive your light source(or sources) with.
  2. Check the voltage of your light source (or sources) and check that it fits the driver’s voltage range.

You should always leave some room for the voltage as there might be some variations in the diodes. Check that the driver has around 10% lower minimum voltage and 10% higher maximum voltage than your light source.

So there you have it in brief. If you need more help or would like to leave a comment, please leave a comment or contact me!

You can also use our free tool to build your luminaire.

How to Choose a Suitable Constant Voltage LED Driver for Your Application

We discussed earlier about general characteristics of LED drivers and how to choose a suitable constant current LED driver for your application.  Now, I’m going to tell you how to choose a right LED driver for your constant voltage application.  As told in the previous posts, LED drivers are divided into two different categories: constant current and constant voltage drivers. But that is not the only thing you have to take into account when selecting the driver. In this post, we are focusing in constant voltage drivers.

Constant voltage drivers are generally used when you need a stabile voltage fed to your LED. You can check the datasheet of your light source whether it needs constant current or constant voltage. If it says for example 12V or 24 V, then it needs constant voltage. And for example 350 mA or 700mA means that you need a constant current driver. Constant voltage driver (power supply) keeps voltage constant (e.g. as 12 V DC), but feeding current varies according to the load (the higher the load the bigger the current)

Datasheet of Constant Current and Constant Voltage LED Module. The circled value tells you does the module need constant current or constant voltage.

Datasheet of Constant Current and Constant Voltage LED Module. The circled value tells you does the module need constant current or constant voltage.

With these easy step-by-step instructions, you will find a suitable driver for your luminaire or signage application.

Step one: What voltage does your LED application need?

As already mentioned, you should find the voltage that your LED needs, from the datasheet or from the product itself.  For example if your LED needs a voltage of 12 V, you should find a driver with 12 V DC output voltage. If LED demands 24V, you should find a driver with 24 V DC output voltage. So that is pretty straightforward.

Step two: How powerful driver do you need?

The power consumption of the LED application can also be found from the datasheet or from the value label in the product.

Remember that if using multiple LED components, you have to find a driver that can feed all the LED components in your luminaire (in parallel connection).

 

GE Lightech 12W, 12V LED driver

GE Lightech 12W, 12V LED driver

Step three: What current range you need from the driver?

Again take a look at the datasheet and check the current of the LED application. If you have multiple LEDs, you should add the current together. Then you should find a driver with a current range that your LEDs fit into.  On the other hand if you have checked well the power you need then your driver will give enough current to get your LED application burn on the right level.

And in some constant voltage LED applications the current is not mentioned at all, only the voltage and the power. Then you can skip this part.

Step four: Do you need dimming? And what type of dimming?

A need for dimming is mainly dependent of the specification of your LED application. If you don’t need dimming, a normal on/off driver is enough for you. If you need dimming, there are many different types of dimming, but that is a topic for another post.  But e.g. in signage applications dimming is not normally required.

Step five: What are the physical dimensions the driver has to fit into?

You should also consider if there are some limitations for the physical dimensions of the driver. These will obviously have an impact on your driver selection. You will generally find the physical dimensions of the driver from its datasheet.

Step six: is the driver placed inside the LED application or outside (built in or independent version)?

If the driver is placed outside the LED application without any fixing the driver should be classified as an independent version. This means that the input and output cables of LED driver have strain reliefs to secure safe cable connections in case of any pulling force.

Step seven: What kind of environment the LED application is used in?

Where is your LED application designed to be used in? If it is designed for indoor use, then you probably won’t need to think about IP-classification so much. Of course if the luminaire is used in a room with a lot of dust or moisture, this has to be taken into account.

And for outdoor use check that the product is approved for min IP67 area.

GE Lightech 200 W 12V, IP67 driver

GE Lightech 200 W 12V, IP67 driver

IP20 class drivers it means that this driver can be used in indoor lighting applications but hardly stands harsh conditions in outdoor lighting unless the luminaire itself is waterproof thus protecting the driver.

But when designing a luminaire to outdoor use, then you should check that that the driver has good enough IP-class.

Usually IP67 drivers are heavier in weight, driver electronics is molded in many cases with plastic (e.g. potted) and the electrical throughputs of the wires both on primary voltage and the secondary voltage side are sealed with required protection against moisture.

Step eight: Approvals, is the driver suited for European or American standards?

Does the driver have any approvals? And are the approvals for Europe (ENEC), America (UL) or for another area? This can generally be found from the datasheet of the driver. In most cases it is the benefit of both the customer and supplier that drivers are certified for that area where they are used.

ROAL Strato CV 24V with ENEC and UL approvals

ROAL Strato CV 24V with ENEC and UL approvals

So there you have it. With these steps you should be able to find a suitable LED driver for your application. If you don’t, please leave a comment or contact me directly.