The Function of an LED Driver
The function of an LED driver is to deliver a regulated supply of power to an LED light fitting or a light-emitting diode (LED).
An LED driver is an electronic device that is a switch-mode power supply. LED drivers are also sometimes referred to as LED power supplies or LED transformers.
The term transformer is not used correctly in this context. A transformer has a solid core with a copper winding. Power supplies that used to be supplied with electronic equipment were much heavier than they are today. This is because they were transformers, which have now been replaced by switch-mode power supplies.
Types of LED Driver Available
There are many different types of LED drivers available, most of which you can buy online from Power Supplies Australia.
The type of LED driver you need very much depends on the following factors:
If you are powering an LED or multiple LEDs (light emitting diode) directly.
If you are powering an LED light fitting (also called luminaire).
If you need to dim the LEDs.
The type of dimming controller you will be using.
Where the LED driver will be located (indoors, or outdoors).
The power output required to drive (power) the LEDs.
Constant Current LED Drivers
Constant current LED drivers are primarily used to power LEDs (light emitting diodes) directly. They are also used to power some luminaires or LED strips, which don’t have built in current regulation.
As the name suggests, a constant current LED driver regulates the current (amps) being supplied to the LED so that the current remains constant. The driver will allow the voltage to “float” to maintain the current at the required level.
When selecting a constant current LED driver, you need to know two things. The current required to power the LEDs (or luminaire). This is usually stipulated in milliamps, so you may see something like 350mA in the specification sheet.
Secondly, you need to know the voltage range at which this needs to be delivered. This is usually referred to as the forward voltage range.
So, the full specification would be something like 350mA (24~48VDC).
The LED driver you select must be able to supply the current within the entire range stipulated. For example, you could use a 350mA (6~54VDC) LED driver to power LEDs with the above specifications. But you couldn’t use one rated 350mA (40~58VDC) because the lower end of the required forward voltage range is not covered.
We have grouped our entire range of constant current LED drivers into one category, to make it easier for you to browse. Use the following link to navigate to our range of constant current LED drivers.
Constant Current LED Drivers in Stock
Important: Do not use an LED driver with a higher current output than specified by the LED manufacturer. You could shorten the lifetime of the LEDs or cause them to fail.
Constant Voltage LED Drivers
Constant voltage LED drivers are mainly used to power LED strips and luminaires that have built-in current regulation.
Constant voltage LED drivers regulate the voltage being delivered to the LED strip or luminaires, allowing the current to “float”.
You will need to know two things before you can select a constant voltage LED driver:
The required output voltage (Volts).
The required power output (Watts).
The two most common voltages used are 12V and 24V DC. Power Supplies Australia has an extensive range, and to make it easier to browse, we have split the range into two categories. These can be browsed by clicking on either of the link below:
We will further discuss weatherproof LED drivers in more detail in this article.
We also stock other voltages.
You need to ensure that the LED driver's power output is high enough to cope with the power the LEDs will draw. We recommend leaving yourself a headroom of around 20% to avoid accidental overloading.
Therefore, if you need a 24V 120-watt LED driver, you may be better off going for a 24V 150-watt model. This model has the additional capacity to deal with unexpected spikes.
Dimmable LED Drivers
If you want to dim your LEDs, then you will need to select an LED driver that is dimmable.
To do this, you need to know the type of dimmer or controller that you intend to use. There are several different types available:
Trailing edge, or leading-edge dimmers
0-10V, or 1-10V dimmers
PWM dimmers
Resistance dimming
DALI controllers
KNX controllers
Once you have established the type of dimmer or controller you are using, you then need to make sure that the LED driver is compatible with the type of dimmer in question.
Be mindful that some manufacturers of centralised lighting control systems or home automation systems may offer more than one type of dimming control option under the same brand name.
Trailing edge and leading-edge dimmers are installed across the AC input wiring to the LED driver. These are the most common types of dimmers in most Australian homes. To work with these types of dimmers, you need an LED driver with phase cut dimming.
As this is a very common type of dimmable LED driver, we have listed them all together under one category on this website. You can navigate to the correct page by clicking on the link below:
For all the other types of dimmers, the LED driver has dedicated dimming terminals or wires that the dimmer must be connected to. You cannot dim these LED drivers by placing a dimmer across the AC input wiring, and the dimmer would be damaged if you did so.
Just a word of caution about the term PWM dimmers.
At the moment, we are talking about types of dimmers. Some home automation and lighting control systems give out a low-voltage control signal with a Pulse Width Modulation (PWM) duty cycle. This control signal is fed to the dedicated dimming wires or terminals on the LED driver. As the duty cycle increases or decreases, the light level changes.
You will also encounter another term when discussing dimmable LED drivers: “LED drivers with a PWM output.” This is completely different and has nothing to do with the type of dimmer you are using.
LED Drivers with PWM Output
LED drivers with a PWM output are constant voltage LED drivers, which have a PWM duty cycle built into the output.
Power Supplies Australia stocks Phase Cut Dimmable, 0-10V dimmable, PWM dimmable, resistance dimmable, and DALI dimmable LED drivers with a PWM output.
Many dimmable LED drivers effect the dimming by varying the amplitude of the output current. On constant voltage LED drivers this can cause a phenomenon known as dead travel. If you only place a 50% load on this type of LED driver, nothing will happen until you have turned the dimmer down past the 50% mark, after which point, the light output will immediately drop to a minimum.
To overcome dead travel, you must ensure the loading on the LED driver is at least 90% of its maximum output rating.
LED drivers with a PWM output are not affected by dead travel. The duty cycle of the PWM output overcomes this problem.
Environmental Considerations for LED Drivers
As we have already mentioned, you need to know where the LED driver is going to be used before you make your final selection.
If the LED driver is going to be used outdoors, it needs to be weatherproof. By weatherproof, we mean it must have an IP (ingress protection) rating that indicates it can withstand penetration caused by rain. We recommend you use an LED driver with an IP65, IP66, or IP67 rating for outdoor use.
Do not mount an LED driver in direct sunlight, even if it is weatherproof. This will cause the temperature inside the LED driver to rise above its maximum working temperature range, which has the potential to cause a failure. The manufacturer's warranty does not cover such failures.
Heat is still a consideration, even if you are using the LED driver indoors.
All switch mode power supplies lose efficiency at higher temperatures. You will find a derating curve in the LED driver data sheet, which indicates the maximum load you can place on the LED driver at higher temperatures. This is shown as a percentage of the maximum rating. See the below derating curve taken from the PDV-100-24 datasheet:
In this example you can see that at temperatures higher than 50°C you cannot place the maximum rated load on the LED driver. At 60°C, the load should be no more than 60% of the LED driver’s maximum rating.
Therefore, you need to be aware of how hot it will get in the area where the LED will be mounted.
Some locations can be very dusty, especially in industrial applications. LED drivers with an IP rating of IP65, IP66, or IP67 are also resistant to dust ingress. Do not use an LED driver without one of these ratings in a dusty environment.
Assistance in Selecting an LED Driver
This article covers quite a bit of ground. If it is a bit too much to digest all at once, don’t worry. Our expert team is on hand to answer any questions you may have and will gladly suggest which of our LED drivers you should consider for your application.
You may call us at 1800 632 693, or if you prefer, you can email the Power Supplies Australia team via our inquiry form on our contact page here.