Understanding LED Power Supplies: A Comprehensive Guide
January 25, 2024
Why LED Power Supplies Matter
LED lighting continues to gain popularity due to its energy efficiency and long lifespans, but these lifespans are drastically shortened if the right power supplies aren’t utilized. In this guide, we will cover the basics of LED power supplies, the different types available, and how to choose the right one for your needs to get the most out of LED lighting.
LED power supplies play a crucial role in ensuring that LED lights receive the proper voltage and current to operate efficiently and safely. Without a suitable power supply, LED lights may not perform optimally, or worse, they could be damaged. Damaged lighting results in flickering, frequent replacements, and more energy wasted. Therefore, it is essential to have a solid understanding of LED power supplies to make informed decisions when it comes to choosing your own.
We’ll start by touching on how LED power supplies can shorten the lifespans of fixtures if the wrong ones are chosen. In the second section of our guide, we’ll provide an overview of the different types of LED power supplies, including constant current and constant voltage LED power supplies, as well as switching power supplies and linear power supplies. In the third section, we will provide you with valuable insights on how to choose the right LED power supply for your specific needs. Next, we'll do a deep dive into a common type of power supply chosen for LEDs: Class 2 rated power systems, and what characteristics to look for in a Class 2 rated power system. Whether you are a lighting professional, an electrician, or a DIY enthusiast, this comprehensive guide will equip you with the knowledge and understanding needed to make informed decisions regarding LED power supplies. Join us as we explore the world of LED power supplies and empower you to make the best choices for your lighting needs.
LED power supplies are the essential components that provide the necessary electrical energy to LED lights, and manage the flow of power. Understanding the basics of LED power supplies is crucial to comprehend how they function and why they are vital for the proper operation of LED lighting systems.
What Is An LED Power Supply?
An LED power supply, sometimes known as an LED driver, is a device that converts the incoming electrical power into the appropriate voltage and current required for LEDs to function optimally. It does so with various power supply components, such as rectifiers (AC to DC converters), and inverters (DC to AC converters). LED power supplies act as a bridge between an electrical source and LED lights, ensuring they receive the correct power levels to prevent damage.
Importance of LED Power Supplies
LEDs operate on low-voltage DC (direct current) power, typically between 1.6V to 4V. However, the power supplied by the electrical grid is typically AC (alternating current) at a higher voltage. LED power supplies play a crucial role in converting the high voltage AC power into the low voltage DC power required for LEDs. This conversion process is necessary to protect LEDs from faults, voltage fluctuations, and more, in order to provide a stable power source. The main function of an LED power supply is to regulate the voltage and current supplied to LEDs. Additionally, LED power supplies may incorporate features such as dimming and LED colour changing capabilities, surge protection, and thermal management to enhance the performance and lifespan of LEDs.
Components of an LED Power Supply: An Example
Power supplies for LEDs are built similarly to those for phone and laptop chargers. Here’s a brief breakdown of the inside of a charging block, courtesy of the article “What’s Inside Your Charger” by Cence Power.
What’s going on in this diagram?
High-voltage AC power enters the driver (AKA. power supplies)
An AC to DC converter, or rectifier, converts voltage into high-voltage DC
A chopper converts DC power back to AC with a higher frequency
A transformer lowers the voltage of the AC power, and isolates power for safety
A bridge rectifier converts the low-voltage AC to low-voltage DC
A DC-DC converter/regulator converts the voltage into one suitable for the powered load (Ex. An LED fixture or the voltage required for the charging needs of the phone or laptop)
The main difference between power supplies for LEDs and phones or laptops is that the drivers for LEDs are typically integrated to fixtures or bulbs. This means that any driver inefficiencies cause energy wasted (in the form of heat), and this heat can cause thermal runaway, which eventually damages the driver. Damaged drivers can cause LED’s to flicker, and have shorter lifespans, resulting in more frequent replacements. It’s worthwhile to mention this to emphasize the benefits of remote LED drivers.
Common Terminology Associated with LED Power Supplies
To understand LED power supplies better, it is important to familiarize yourself with some common terminology used in the industry. Here are a few terms you may come across:
Voltage refers to the electrical potential difference between two points and is measured in volts (V). LED power supplies provide a specific voltage output suitable for the LEDs being powered. You can think of voltage like water pressure, but for electricity.
Current refers to the flow of electric charge, typically measured in amperes (A). There are two types of current: alternating current (AC), and direct current (DC). AC power is typically delivered by power grids, and DC power is the type of power required by many modern devices, such as phones, laptops, LEDs, and all digital devices that utilize semiconductors. It can be generated by photovoltaic (PV) generators (solar).
Wattage is a measure of the power consumed or supplied by an electrical device and is calculated by multiplying the voltage by the current. LED power supplies are rated in watts to indicate their power-handling capabilities.
Efficiency refers to the ratio of output power to input power, expressed as a percentage. LED power supplies with higher efficiency convert a greater proportion of the input power into usable power for the LEDs, resulting in less energy waste. This type of efficiency is called power conversion efficiency. This is different than the efficiency of power converted into visible light by an LED. If you’d like to learn about efficient lighting options, check out this article by Omnify Lighting. It explores the efficiency of different types of lighting.
Understanding the basics of LED power supplies lays the foundation for selecting the right power supply, installing it properly, and ensuring the optimal performance and longevity of your LED lighting system. In the next sections, we will explore the different types of LED power supplies, and how to choose the right one.
Types of LED Power Supplies
LED power supplies come in various types, each designed to meet specific requirements and applications. Understanding the different types of LED power supplies will help you choose the most suitable one for your lighting needs. In this section, we will explore four main types of LED power supplies: constant current, constant voltage, switching, and linear.
Constant Current LED Power Supplies
Power supplies are designed to deliver a steady current flow to power loads, such as LED fixtures. The main difference between different types of power supplies is how they do this. Constant current LED power supplies, as the name suggests, provide a consistent current to the LED load. In order for these power supplies to change the level of power they provide, they modify voltage rather than current (since power equals voltage multiplied by current). Constant current LED power supplies are typically a better source of power for LEDs, according to this article, which states:
“When considering the voltage-current characteristics of a diode, current changes dramatically for small changes in voltage. For this reason, voltage levels are easier to control with precision, and can thus be adjusted more accurately. This precision is what makes constant current drivers a better option for LED lighting applications.”
Therefore, these power supplies are more reliable than constant voltage drivers when it comes to ensuring that LEDs operate within their specified current limits.
Here's the formula for power (measured in Watts) for reference:
Key Features and Benefits of Constant Current LED Power Supplies:
Precise Current Regulation:
Constant current power supplies ensure that LEDs receive a consistent current flow, preventing overcurrent or variations in brightness
Efficient Power Delivery:
By maintaining a steady current, constant current power supplies minimize power wastage and maximize energy efficiency
They minimize voltage drop, so these drivers are great to place in remote locations. This is because they maintain a constant current output, so voltage is automatically increased to compensate for any voltage drop on cables.
Protection for LEDs:
Constant current power supplies often incorporate protection mechanisms such as overcurrent protection and short-circuit protection, safeguarding the LEDs from damage
Constant Voltage LED Power Supplies
Constant voltage LED power supplies, on the other hand, deliver a stable voltage to LEDs, meaning when power needs to be adjusted, current it altered (rather than voltage). As mentioned in the last section, current is harder to control with precision, so these power supplies tend to be less efficient and reliable than constant current power supplies for LED applications. Additionally, they require a current limiter on the LED as an added layer of reliability to make up for their lack of precision. Usually this “current limiter” is a simple resistor that’s placed next to the LED, that protects it by wasting any extra power as heat. These power supplies are often used in small scale applications where a specific voltage is required.
Constant current and constant voltage power supplies can be best understood when compared against each other, and the same can be said about Switching vs. Linear power supplies. We will be diving into that next.
Switching Power Supplies
Linear and switching power supplies are devices that convert electrical energy to provide a stable DC output. Both work by converting AC or DC input power into a low-voltage form that DC devices can use. The main differences between the two involve the amount of electrical noise produced, their size, their efficiency, and the cost of each.
Switching power supplies came into general use in the 1990s, and were developed by NASA for space applications. They are controlled by a control circuit, and work by rectifying and smoothing the voltage before regulating it. They use pulse width modulation (PWM) to regulate the output voltage, which involves switching power supplies on and off rapidly in a steady pattern. This is an efficient method of voltage regulation, but causes significant electrical noise.
Benefits of Switching Power Supplies:
Switching power supplies are generally smaller than linear power supplies because they can make use of smaller transformers. Their transformer doesn’t need to be as big because the current after rectification is sent to the transformer as a high frequency pulse (the higher the frequency, the smaller the required transformer).
Switching power supplies have low energy conversion losses because they don’t waste extra electricity by converting it into thermal energy (like their linear counterparts do). Additionally, the development of GaN (Gallium Nitride) power supplies with more efficient resisters enabled even smaller, more powerful switching power supplies.
More cost effective for high power applications:
If the output power is meant to be large (400 W or more), switching power supplies are the cheaper option due to their efficiency.
Disadvantages of Switching Power Supplies:
Produce more electrical noise:
Voltage noise of a switching power supply is 10x greater, and the current noise is 5x greater, meaning electromagnetic interference (EMI) is more likely.
Space technology and aviation
Superior in limited space applications, applications where efficiency is prioritized, and high power (over 400 W applications)
Linear Power Supplies
Linear power supplies are the more traditional method. They are controlled by the response of the regulator circuit, and work by dissipating excess voltage as heat, which makes them less efficient than switching power supplies. They do this using a transformer to reduce the input voltage until it reaches the preferred level, and then they smooth out any extra energy by using a series-pass transistor, which is what dissipates any excess voltage in the form of heat. Voltage regulation within these power supplies is attained by modifying the resistance of particular transistors to maintain a constant voltage at all times.
Linear power supplies are less efficient than switching power supplies, but they do produce far less noise (as mentioned above). Despite their inefficiencies, they are still used in certain LED lighting applications where cost-effectiveness and simplicity are prioritized over efficiency and size.
Benefits of Linear Power Supplies:
Linear power supplies have a straightforward design, making them easy to understand and troubleshoot.
Linear power supplies generate less electrical noise compared to switching power supplies, which can be beneficial for sensitive applications.
Quick Response Times:
Responds more quickly to load fluctuations because of how they are controlled.
Linear power supplies are more affordable than switching power supplies if the output power is small, making them suitable for budget-conscious projects (if efficiency isn’t a priority).
Hopefully this section has clarified the different types of LED power supplies, as understanding them will help you make informed decisions based on your specific lighting requirements. In the next section, we will discuss how to choose the right LED power supply for your application.
How to Choose the Right LED Power Supply
Choosing the right LED power supply is crucial to ensure optimal performance and longevity of your LED lighting system. Selecting the wrong power supply can result in issues such as flickering lights, reduced lifespan of LEDs, or even damage to the entire system. In this section, we will guide you through the process of choosing the right LED power supply for your project’s needs.
Determining Your LED's Voltage and Current Requirements
The first step in selecting the right LED power supply is to determine the voltage and current requirements of your LED lights. This information is typically provided by the LED manufacturer and can be found in the product datasheet or specifications.
Constant voltage LEDs operate at specific voltage levels, typically ranging from 12V to 48V. It is crucial to match the voltage output of the power supply with the voltage requirements of the LEDs. Using a power supply with a higher voltage output can damage the LEDs, while a lower voltage output may result in dim or non-functional lights.
LEDs have specific current requirements, usually measured in milliamperes (mA) or amperes (A). It is essential to select a power supply that can provide the required current to the LEDs. Using a power supply that cannot supply enough current may result in dim or flickering lights, while providing too much current can lead to overheating and reduced lifespan of the LEDs, or even permanent damage.
Understanding Power Supply Specifications
When selecting an LED power supply, it is essential to understand and evaluate power supply specifications to ensure compatibility with your lighting system. Here are some key specifications to consider:
The output voltage of the power supply should match the voltage requirements of your LEDs
The power supply should be capable of delivering the required current to LEDs. Ensure that the power supply's maximum current rating is equal to or higher than the current requirements of your LEDs
The power rating of the power supply, typically measured in watts (W) or volt-amperes (VA), indicates its maximum power-handling capacity. Ensure that the power supply can handle the combined power requirements of all the LEDs connected to it.
The efficiency of the power supply indicates how effectively it converts the input power into usable power for the LEDs. Look for power supplies with high efficiency ratings to minimize energy waste and reduce operating costs.
Dimming and Colour Changing Compatibility:
If you require dimming capabilities, or would like control over the colour temperature of your LED lighting, ensure that the power supply is compatible with these methods. Some power supplies have built-in dimming functionality, while others may require an external dimmer.
Considering the Environment and Application
In addition to voltage, current, and power supply specifications, it is essential to consider the environment and application in which the LED power supply will be used. Here are some factors to consider:
LED power supplies may have temperature limitations for optimal performance. Ensure that the ambient temperature of the installation location is within the acceptable range specified by the power supply manufacturer.
Depending on the application and installation environment, you may need additional protection features in the power supply. Common protection features include overvoltage protection, overcurrent protection, and short-circuit protection.
Waterproof or Weatherproof Requirements:
If the LED lighting system will be exposed to moisture or outdoor elements, consider using a power supply with waterproof or weatherproof capabilities to ensure durability and safety.
Certifications and Standards:
Look for LED power supplies that comply with relevant safety and performance standards such as UL (Underwriters Laboratories) listing or CE (Conformité Européene) certification.
By considering the voltage and current requirements, power supply specifications, and environmental factors, you can choose the right LED power supply that meets the needs of your specific lighting application. In the next section, we will explore an example of a commonly appreciated type of LED power supplies: the low-voltage DC power system rated Class 2 by the National Electrical Code (NEC).
Class 2 Rated LED Power Supplies
In the NEC, Class 2 rated power systems occupy a crucial position between Class 1 and Class 3 rated systems, in terms of safety and functionality. Similarly to Class 1 and 3 rated systems, they are power-limited for safety but, unlike Class 1 and 3 rated systems, they are considered safe from both a fire initiation and electrical shock standpoint. Examples of Class 2 power systems include Power over Ethernet and Cence LV. In LED applications, it’s ideal for Class 2 power supplies to be remote from LED fixtures, and drivers to be centralized for simple installation and maintenance.
Centralized Power Supplies
When power supplies are “centralized” it means that all the power supplies are located together, in a central location, rather than dispersed throughout a space or building. This simplifies maintenance because all drivers can be accessed in that one location. This means that it’s not only easier to access all the power supplies at once, they are also typically located in a generally easier to access location (such as a storage cabinet).
Remote Power Supplies
When power supplies are “remote” it means they are not integrated into the device itself. For example, your laptop power supplies are not integrated into your laptop, they are located in the charging brick on your charger, making them “remote”. An example of power supplies that are “integrated” would be the driver we see connected to LED bulbs (the components are nestled inside the part of the bulb that’s screwed into a lamp, for example). See the image below
Overall, Class 2 power systems, with their standardized safety measures, play a vital role in ensuring secure electrical distribution, and when they are centralized and remote, these power supplies are the ideal option for low-voltage LED lighting.
A Class 2 Rated Example: Cence LV: A Low-Voltage Direct Current Power Supply Hub
Cence LV is an example of an LED power supply that aligns with the optimal method of powering low-voltage LED lighting. It involves a constant voltage driver, includes 8 power modules within a centralized hub, remotely manages the flow of power, and supplies low-voltage DC power directly to LEDs. Cence LV involves one, centralized, and highly efficient conversion (95%), from AC to DC power, then DC power is distributed to power modules, which can be remotely connected to LED fixtures with cables. Cence LV supports daisy chaining, so more than one LED fixture can be connected to each channel. See the diagram below to visualized how it works:
Here’s an image that sums of the advantages of Cence LV as a type of LED power supplies:
If you’d like to learn about the installation and maintenance process for Cence LV, send Cence a message on their website: cencepower.com.
Understanding LED power supplies, and choosing the right type, are key factors in maximizing the performance and lifespan of your LED lighting system. By following the guidelines and best practices outlined in this comprehensive guide, you can confidently select LED power supplies that are perfect for your project, and create an efficient, reliable, and long-lasting lighting solution. Interested in the most efficient way to power LEDs? Check out Cence LV.
Erin is the Creative Director at Cence Power. She has a New Media degree from the University of Toronto and 5 years of experience in the communications field. She has also done digital content creation for dozens of clients through her own business called Story Unlocked. Erin loves technology, especially when it makes the world a better place.
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