What Is a Constant-Current LED Driver?
Voltage is not the only consideration when you power an LED lighting system. In situations where drawing too much current could be an issue, a fixed-current driver provides you with a safe solution that does not compromise the LED's lifespan.
A constant-current LED power supply takes the incoming alternating current (AC) from electric wiring and converts it into direct current (DC) at the level specified by the LED array’s maximum rating.
LEDs are polarized, which means that the diode requires a constant current to run optimally. The AC from power lines would only power an LED when the current flowed in alignment with the component's polarity. DC power offers a consistent direction of flow that will keep the diode running continuously.
These devices take incoming electricity and provide a constant level of output along one or more lines. A constant-current output LED driver helps to ensure that each LED in the system receives the current needed for consistent illumination.
LED protection is another feature provided by these products. An LED driver regulates the output, helping to prevent dips and spikes that can damage the diode. This can also reduce unwanted heat buildup that can shorten the overall lifespan of an LED.
The constant-current LED driver also acts as an interface between operator and system, which can include operations like light dimming or other control applications.
Why Use a Constant-Current LED Driver?
While LED lighting systems that use constant-voltage LED drivers are typically less expensive, these devices don’t provide protection for LED lights that have a designated maximum current.
A constant-voltage driver will regulate the output voltage, but the current can still fluctuate. Constant-voltage drivers often require a current-limiting device for each LED or module, which may increase the thermal load or power loss.
This is when constant-current LED drivers come into play. They provide an identical current to each LED connected in series within the run, which creates a uniform output in lumens (brightness) and an even color.
Constant-current LED drivers are more efficient, as fewer components are necessary. They can make an LED lighting layout simpler to design and install.
How Does a Constant-Current LED Driver Work?
Electricity comes from the mains in a high-voltage AC form. The rating is far too high for an LED to handle.
Input from the mains converts from a pulsating signal with switching polarity into a steady electrical signal with consistent polarity.
The driver also drops the voltage to a level that the LEDs can handle. They have a voltage range that indicates the minimum and maximum outputs. The driver varies the voltage output to maintain a consistent level of current, rated in amps or milliamps.
Many units are adjustable constant-current LED drivers, providing settings that cover a range of DC outputs. Once set, the LED driver adjusts voltage levels to maintain the prescribed current.
The maintained current adjusts to prevent the buildup of heat or thermal runaway. The consistent signal also runs each LED at maximum efficiency for brightness level and color without flickering.
Can You Dim a Constant-Current LED Driver?
One function of an LED driver is to provide control for various applications, including lumens level. A dimmable constant-current LED driver controls brightness through constant-current reduction (CCR) or pulse-width modulation (PWM).
Constant-current reduction controls the amount of current supplied to the LED. You can dim the LED light system by reducing the amount of current or make it brighter by increasing the total current.
A constant-current LED driver that uses pulse-width modulation will switch the current on and off. Dimmer settings have more "off" time, and more illumination requires more "on" time. The switching happens quicker than the eye can see.
You will need LEDs capable of dimming, as some diodes do not function with CCR or PWM drivers.
Wiring a Constant-Current LED Driver
Constant-current LED drivers function when LEDs are in series, not parallel. Wiring LEDs in series allows the driver to provide equal current to each LED.
Before selecting your location, keep in mind the length of wire runs or sources of interference. Verify that your installation, components and wiring meet all general and local codes. Generally, installation is a simple process:
- Make sure the power is turned off at the main breaker before you begin the installation.
- Connect the high-voltage AC wiring to the input terminals indicated in the product instructions.
- Attach the low-voltage DC wiring from the output terminals to the LED lighting run, as instructed in the installation diagram provided.
- Install other devices along the output circuit as instructed by the manufacturers of each device.
- Verify that all connections are secured safely.
- Turn on power once installation is finished.