Things to consider before selecting an LED driver

What type of LEDs are being used and how many?
- Find out forward voltage, recommended driving current, etc.
Do I need a constant current LED driver or a constant voltage LED driver?
- We go over constant current vs. constant voltage here.
What type of power will be used? (DC, AC, batteries, etc.)
- Running from AC? See how an AC driver will benefit you!
What are the space limitations?
- Working in a tight area? Not a lot of voltage to work with?
What are the main goals of the application?
- Size, cost, efficiency, performance, etc.
Any special features needed?
- Dimming, pulsing, microprocessor control, etc.

First Off, You Should Know

There are two main types of drivers, those that use low voltage DC input power (generally 5-36VDC) and those that use high voltage AC input power (generally 90-277VAC). LED drivers that use high-voltage AC power are called Off-Line drivers, or AC LED drivers. In most applications using a low voltage DC input LED driver is recommended. Even if your input is high voltage AC, using an additional switching power supply will make it possible to use a DC input driver. Low voltage DC drivers are recommended as they are extremely efficient and reliable. For smaller applications there are more dimming and output options available compared to high voltage AC drivers so you have more to work with in your application. If you have a large general lighting project for residential or commercial lighting, however, you should see how AC drivers might be better for this type of job.

Second Thing You Should Know

Secondly, you need to know the drive current that you want to put to the LED. Higher drive currents will result in more light from the LED, and will also require more wattage to run the light. It is important to know your LED’s specs so you know the recommended drive currents and heat sink requirements so you don’t burn the LED out with too much current or excess heat. Lastly, it is good to know what you are looking for from your lighting application. For example, if you want dimming then you need to choose a driver with dimming capabilities.

A Little Bit About Dimming
Dimming LEDs varies with what kind of power you are using; so I will go over both DC and AC dimming options so we can better understand how to dim all applications, whether DC or AC.

How many LEDs can you run with a driver?
The maximum number of LEDs you can run from a single driver is determined by dividing the maximum output voltage of the driver by the forward voltage of your LED(s). When using LuxDrive drivers, you determine the maximum output voltage by subtracting 2 volts from your input voltage. This is needed because the drivers need a 2 volt overhead to power the internal circuitry. For example, using the Wired 1000mA BuckPuck driver with a 24 volt input, you would have a maximum output voltage of 22 volts.

What do I need for Power?
This leads us to finding what input voltage we need for our LEDs. Input voltage, after all, equals our maximum output voltage for our driver after we take into account the driver circuit overhead voltage. Make sure you know the minimum and maximum input voltages for your LED drivers. For an example we will stick with the Wired 1000mA BuckPuck, which can take input voltages from 7-32VDC. In finding what your input voltage should be for an application you can use this simple formula.

Vo + (Vf x LEDn) = Vin
Where:

Vo = Voltage overhead for drivers – 2 if you are using a DC LuxDrive driver or 4 if you are using an AC LuxDrive driver

Vf = Forward voltage of LEDs you wish to power

LEDn = The number of LEDs you want to power

Vin = Input voltage to the driver