LED Power Supply Guide – How To Choose The Best Power Supply?

Whether you’re making your own LED fixture, repairing and retrofitting existing fixtures, or buying new LED lights, you’ll need to find the right power source for your LEDs.

To get your LEDs to work properly, you’ll need either a constant current LED driver or a constant voltage power supply, or a combination of the two.

When selecting a power supply for LED lighting, there are numerous factors to consider. This LED power supply guide will go over all of those factors and assist you in choosing the best power supply for your LEDs!

Ascertain that you have control over the current flowing to your LEDs

Ascertain that you have control over the current flowing to your LEDs

To prevent LEDs from being overdriven, most LEDs require a current-limiting device, such as a driver or a resistor. This constant current driver, also known as a current limiting resistor, regulates current to the LEDs, keeping them safe and maximizing their lifetime.

As LEDs heat up, their electrical characteristics change; if the current is not regulated, LEDs will draw too much current over time. This current overdraw causes LED brightness to fluctuate, resulting in excessive internal heat and, eventually, LED light failure.

You will need a constant current device in your system if you are building your own LED fixture or working with any of the component star LEDs. Most finished LED products or LED strip lights (that you’d buy in a store) already have drivers or resistors built in to regulate the current.

If you’re not sure whether you need a constant current source, read this helpful post to find out. If you don’t have a current limiting device, the first step is to find a driver; however, if your LED product already has current under control, you can use this post to find a constant voltage power supply.

Read more: Lux Lumens Conversion – What to pay attention to?

Power Supplies with Constant Voltage

LED lights equipped with resistors or constant current drivers can be powered by a constant voltage power supply. These kinds of products will almost always require a constant DC voltage.

Consider yourself fortunate if you are powered by a battery or have a constant DC voltage that is sufficient for your lights. Almost always, this will not be the case, and you will require a power supply to convert your power to a safe DC voltage for your lights.

LED flex strips, for example, have on-board current limiting resistors, as seen built into the flex board base. There would be no need for a power supply if you wanted to install this in your car.

Car batteries produce 12VDC, give or take. The battery’s 12V supply would be more than enough for your lights. However, in order to use these strips in homes, an AC to DC converter is required, which will take the standard household voltage of 120VAC and convert it to 12VDC.

How Do I Select the Best Power Supply?

So, you’ll need a constant voltage power supply that can convert your household’s alternating current voltage to a safe direct current voltage.

There are numerous factors to consider when selecting the best power supply for your needs. First, we must restrict the amount of power we require from our power source.

How Do I Select the Best Power Supply_

#1. Wattage

To begin, determine how many watts your light will require. Add the wattages together to get the total watts used if you want to power multiple lights with a single power supply.

Give yourself a 20% buffer over the total wattage you calculate from your LEDs to ensure you have a large enough power supply. This is simple to accomplish by multiplying your total wattage by 1.2 and then looking for a power supply rated for that wattage.

Assume we have four runs of LED strips that each consume about 12 watts. Simply multiplying these results in a system wattage of approximately 48 Watts. With 48 x 1.2 = 57.6 Watts, we can now add the 20% recommended cushion. This project will require a 60-Watt (or higher) power supply.

Example: Power supply calculation for LED strips

Four 12V LED strips with 12 watts each shall be operated:

12 watts x 4 (quantity) = 48 watts

Add 20% power reserve:

1.2 x 48 watts = 57.6 watts

→ A 60 watts (or higher) power supply would be a perfect choice here.

#2. Voltage/Current

When constructing an LED fixture or replacing a failed power supply, it is critical to ensure that the output voltage is compatible with the voltage of the LEDs. LED products with built-in current regulators are usually quite good at specifying what input voltage to use.

For example, because our LED flex strips require 12V power, we would use a 12V power supply with them. Another common application is the use of high-power LEDs with constant-current drivers that require a direct current voltage input.

Assume we have six Cree LEDs powered by a Mean Well LDD-H driver. Each LED operates at approximately 3.1 volts. Our total voltage in this series circuit would be 18.6VDC if we used six of these.

Low voltage drivers, such as the Mean Well LDD-H, typically perform better when there is a small margin of safety above the voltage they require.

Mean Well LDD-H driver
Mean Well LDD-H driver

I would use a power supply that outputs at least 24VDC for this setup. It is important to remember that the low voltage driver in use (Mean Well LDD-H in this case) should always be rated for the voltage you intend to input. Because the Mean Well LDD-H can accept 9-56VDC, we’re all set in this situation.

More information on calculating voltage in various circuits can be found here.

Also, make certain that the power supply you choose can handle the input power you have. Line voltage varies depending on where you are in the world. Check to see if you have low-line AC power (90-120VAC) or high-line AC power (200-240VAC).

Many power supplies, such as Mean Well products, are rated for the full range, but it is always a good idea to know your AC input and ensure that the power supply you use is compatible with it.

#3. Calculator for LED power supply

The power calculation of an LED transformer has previously been described in detail. It’s even easier now that there’s an online calculator.

In this section, you can specify the power consumption of all LED lamps that will be powered by the power supply, as well as the desired power reserve. Alternatively, the transformer can be calculated by inputting the LED operating voltage and total current of all lamps.

LED power supply calculator ở đây

Read more: Power Consumption Calculator Of Any Electrical Equipment

#4. Weather and Temperature

When selecting a power supply, it is critical to consider the area and environment in which it will be used. When power supplies are used within their temperature parameters, they operate most efficiently. A safe operating temperature range should be specified in the power supply specifications.

It is best to stay within this range and avoid placing your power supply somewhere where heat can build up and exceed the maximum operating temperature. It’s never a good idea to put a power supply in a small enclosure with no ventilation.

This allows even the smallest amount of heat produced by the source to accumulate over time and eventually cook the power source. As a result, make sure the area isn’t too hot or cold, and that heat doesn’t build up to dangerous levels.

Each LED power supply will also be rated for ingress protection (IP). IP ratings are a two-digit code that indicates the size of solids and liquid pressures that a power supply can withstand.

The first number denotes the size of solids that the unit can withstand, while the second denotes the amount of liquid that the unit can withstand. The level of protection increases as the number increases.

As the first number increases, the product is shielded by smaller and smaller objects, all the way down to dust particles), making it less vulnerable to anything entering and harming it. As the second number increases, the product is no longer only protected in light rain but also in full immersion.

#5. LED Power Supplies with Dimmability

PWM Dimming & TRIAC Dimming
PWM Dimming & TRIAC Dimming

If your LEDs are dimmable and you want to adjust their brightness, make sure you use a power supply that supports dimming. Power supply specifications should state whether or not a power source is dimmable and what type of dimmer control it employs. I’ll go over the two types of controls briefly:

PWM dimming, also known as pulse-width modulation dimming, is a type of dimming that can be used on any power supply. Even power supplies on our site that do not explicitly state ‘dimmable’ can be dimmed using wall-mounted or remote PWM dimmers.

This is due to the fact that PWM dimmers are installed in line with the strip lights, dimming on the 12VDC side of the circuit. PWM dimmers pulse the lights at high frequencies to alter the perception of light to the naked eye. The brighter they are, the higher the frequency.

TRIAC Dimming: With this type of dimming, LEDs can be dimmed using standard dimmers. Check the specifications to ensure that a power supply qualifies for alternating current (TRIAC) dimming. Magnitude Dimmable Power Supplies are our current products that provide dimming controls like this.

These power supplies operate by varying the power on the alternating current side of the circuit using a TRIAC dimmer. The dimmer’s change in power on the AC input side will vary the voltage on the DC output and control the brightness of the LEDs. TRIAC dimmers are widely available in hardware stores. The most well-known and recognizable brands are Lutron and Leviton.

#6. Size

When choosing a power supply for your LED project, consider where it will fit or be installed. If you want to put it inside the product you’re making, it must be small enough to fit in the available space.

If it is outside the scope of the application, it should be possible to mount it nearby. There are a variety of power supplies available in various sizes and shapes to meet your requirements.

#7. Efficiency

The efficiency of a power supply indicates how much power is actually used to light the LED. The higher the percentage of efficiency of the power supply, the more power you save. It is best to choose a power source with an efficiency of 80% or higher for LED applications. Mean Well and Phihong power supplies are the most efficient options, with efficiency ratings well into the 90th percentile.

Phihong PSAC30U-050L6 Bench PSU
Phihong PSAC30U-050L6 Bench PSU

Read More: How to Convert Lumen to Watts – Lumen Watt Conversion Calculator

Is it better to be in Class II or Class 2?

These two ratings are easily confused, so let’s make sure we understand them now that we’re nearing the end of our journey through LED power supplies. A Class 2 power supply complies with the National Electric Code (NEC) limited power levels and meets the requirements of Standard UL 1310.

Class 2 power supplies have a maximum voltage of 60 volts and a maximum power output of 100 watts. Class 2 power supplies, due to their limited power, cannot power as many LEDs as those outside the rating.

This is the point at which you must decide whether you want to run a longer length from a single power supply or stick with the safety of a Class 2 power supply, which is protected against fire and electric shock.

A Class II rating simply means that the input and output wires are double insulated. Because they do not require a ground connection, Class II drivers are popular.

Read more: Lumen Calculator How do calculate the lumens of LED lights?


#1. Is it okay to use any power supply for LED lights?

Unfortunately, LED strips are not as simple to install and set up as traditional incandescent light bulbs. Because they operate on low voltage DC, they necessitate the use of a power supply device that converts 120V/240V AC, depending on your location, into the voltage signal that LED strips can use.

#2. Do LED lights require alternating current (AC) or direct current (DC)?

LEDs are typically powered by a direct current (DC) power supply. LEDs use direct current to produce light; with alternating current, the LED will only light when the current flow is in the correct direction. When AC is applied to an LED, it will blink on and off, and at high frequencies, the LED will appear to be lit continuously.

LEDs are typically powered by a direct current (DC) power supply
LEDs are typically powered by a direct current (DC) power supply

#3. Can LED lights be powered by 12V AC?

To power an LED-based fixture from a mains supply (e.g., 120 V AC), electronics must be installed between the supply and the devices to provide a DC voltage (e.g., 12 V DC) capable of driving multiple LEDs. A novel approach is to create AC-LEDs, which can operate directly from an alternating current power supply.


This LED power supply guide should have been useful in assisting you in finding the right power supply for your LED lights. There are numerous options to choose from, so take your time and choose the one that best fits your situation and meets the safety requirements of the surrounding area in order for it to last a long time.

If you’re looking for a place to start, I’d recommend Mean Well Power Supplies; they’re a reputable brand with a large selection of LED drivers and supplies that come with fantastic warranties.

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