Constant Voltage vs. Constant Current

With a variety of LED power supplies available, selecting the right LED driver for your LED lighting installation can be challenging. There are numerous factors to consider to find the best solution that meets your specific needs. If you need assistance in finding the ideal power supply for your installation, please refer to our LED Power Supply Buying Guide. Understanding power requirements is crucial, but knowing the difference between Constant Current and Constant Voltage can help you avoid costly mistakes.

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Constant Voltage

Constant voltage LED drivers are designed to provide a single DC (direct current) output voltage, commonly 12VDC or 24VDC. LED lights typically specify the voltage they are rated for. These drivers function by converting standard line voltage (120VAC) to a significantly lower direct current voltage. The output voltage remains consistent (either 12V or 24V) regardless of the current load, making constant voltage drivers ideal for installations that prioritize longevity and efficiency.

Constant Current

Constant current LED power supplies are designed with a fixed output current and a variable output voltage. These drivers adjust the voltage across an electronic circuit, maintaining a constant current throughout the LED installation. Higher current ratings may produce brighter LEDs, but if not properly regulated, the LEDs may draw more current than intended. This can drastically reduce the LED lifespan and lead to premature burnout due to excessive heat. While constant current is advantageous for high-power LEDs, it often shortens the lifespan of the LED system.

Which is best: Constant Voltage or Constant Current?

Benefits of Constant Voltage

Constant voltage drivers tend to be slightly more expensive but offer greater energy efficiency and use higher-rated electrical components. These drivers excel at heat dissipation and typically require an additional circuit to deliver the appropriate wattage to the LED lighting system, resulting in more efficient and longer-lasting LEDs. Constant voltage power supplies are specifically designed for use with LED tape lights, strip lights, puck lights, and LED linear bars, making them ideal for undercabinet LED installations.

Benefits of Constant Current

On the other hand, constant current LED power supplies are best suited for high-powered or large LED lighting installations, often not found in residential settings. These drivers excel in scenarios where LED lifespan is not a priority. As previously mentioned, they allow for brighter LEDs, but without regulation, they can lead to increased heat and decreased efficiency, resulting in a shorter lifespan.

Understanding LED Drivers

Choosing an LED driver can be overwhelming due to the many available options. In this article, we discuss the essential details of LED drivers, focusing on Constant Current (CC) and Constant Voltage (CV) drivers, including the circumstances in which you might need each type.

What is an LED Driver?

An LED driver regulates the flow of current through your LEDs. There are two main types: constant voltage (CV) and constant current (CC). The required type will depend on the LED fitting and your specific application needs.

Characteristics of LEDs

LEDs are semiconductor diodes created by combining two different materials to form a PN junction. The P-type has an excess positive charge, while the N-type has an excess negative charge. When DC is applied, they emit light.

Like all semiconductors, LEDs allow current to pass forward while blocking reverse flow. Light is emitted when current flows from an anode (+) to a cathode (-).

LED V-I Characteristic

Similar to traditional PN junction diodes, LEDs depend on current and forward voltage. Small changes in forward voltage can lead to significant changes in forward current. Typically, LEDs have a forward voltage of 2-3.5V and a forward current ranging from 10-200mA, showing that a slight voltage change results in a considerable current change.

LED Temperature Coefficient

Many believe that once LED voltage is fixed, current must also be fixed, so constant voltage and constant current should perform equivalently. However, the volt-ampere (V-I) characteristics of LEDs fluctuate with temperature. While voltage may be constant, current is not and changes with temperature, demonstrating the negative temperature coefficient of LEDs.

Understanding Constant Current LED Drivers

A constant current LED driver adjusts the voltage in the circuit to maintain a steady current flow. These drivers are essential for LEDs designed to function with a fixed current. They keep the current steady even as temperature rises and voltage fluctuates, preventing LED burnout and extending the lifespan.

When is a Constant Current LED Driver Necessary?

Constant current drivers are best suited for LED fittings manufactured using the direct drive method, where the LED driver’s current output directly powers the LED circuit. This method is efficient and straightforward. Such drivers are ideal for custom fixtures or high-powered LEDs and can be utilized for both single bulbs and LED chains.

• If your use case is illumination, constant current drivers provide better brightness control and light quality.
• These drivers are commonly applied in backlighting, commercial LED displays, and signage.

Understanding Constant Voltage LED Drivers

Constant voltage LED drivers are power supplies designed for 12VDC or 24VDC output. They cater to LEDs requiring specific voltage levels to function effectively. For LED devices with built-in current limiters, the voltage remains fixed while the current varies, particularly when using parallel wiring.

Choosing the Right Type of LED Driver

To determine the appropriate LED driver, consider the application, LED voltage and current requirements, and efficiency. Constant voltage drivers work for simple applications, but as the number of LED strings increases, constant current drivers offer better control over current flow.

Summary

LEDs generally operate on constant current, but specific situations may require constant voltage drivers. Understanding the differences between constant current and constant voltage ensures optimal performance and longevity for your LED systems.

uPowerTek’s LED Drivers

uPowerTek offers global certified, high-quality constant voltage and constant current LED drivers. They prioritize safety, security, and product quality management. As members of the Digital Illumination Interface Alliance (DiiA), uPowerTek emphasizes quality and reliability, providing various products, including High Efficiency Constant Current LED Strips.