Monthly Archives: January 2015

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.