LED lighting systems require more than simply connecting LEDs to an electrical outlet. LEDs need a compatible device that converts incoming electricity into the voltage and current required by the light source. This device is generally called an LED driver, although constant voltage models are also commonly described as LED power supplies or LED transformers.

Two main types of LED drivers are used in lighting systems:

• Constant current LED drivers
• Constant voltage LED drivers

Although their names sound similar, they operate differently and are designed for different LED products. Using the wrong type may cause insufficient brightness, flickering, unstable operation, overheating, premature lumen depreciation, or permanent damage.

The basic rule is simple:

Use a constant voltage driver for LED products marked with a fixed voltage, such as 5V, 12V, 24V, 36V, or 48V. Use a constant current driver for LED products marked with a specific operating current, such as 350mA, 500mA, 700mA, or 1050mA.

Most flexible LED strip lights, LED neon flex, addressable LED strips, and signage modules use constant voltage power. Many high-power LED modules, COB light sources, downlights, spotlights, streetlights, and integrated luminaires use constant current drivers.

However, exceptions exist. Always check the label and datasheet of the LED product before selecting the driver.

For a standard LED strip project, you can also read our detailed guide on how to choose a power supply for your LED strip project.

🔴What Is an LED Driver?

An LED driver is an electrical device that regulates the power delivered to an LED or LED lighting system.

Most buildings supply alternating current, such as 120VAC, 220VAC, 230VAC, or 240VAC. Low-voltage LED products typically operate on direct current. The LED driver converts incoming AC electricity into suitable DC power while controlling either the output voltage or output current.

Depending on its design, an LED driver may also provide:

• AC-to-DC conversion
• Voltage regulation
• Current regulation
• Short-circuit protection
• Overload protection
• Overvoltage protection
• Overtemperature protection
• Surge protection
• Power-factor correction
• Dimming control
• Flicker reduction
• Smart lighting communication

The term LED driver is frequently used for both constant current and constant voltage devices. In LED strip lighting, people may also call a constant voltage driver an LED power supply, adapter, transformer, or switching power supply.

These terms are sometimes used interchangeably, but their output specifications must still match the connected LED product.

Once you have selected the correct driver, follow the appropriate wiring procedure in our guide on how to connect an LED strip to a power supply.

🟠Why Do LEDs Need Drivers?

LEDs are semiconductor components whose brightness is mainly determined by the current flowing through them.

A relatively small change in voltage can produce a significant change in current. Temperature also affects an LED’s forward voltage. As the LED becomes hotter, its forward voltage may decrease, allowing more current to flow. More current generates additional heat, which can further increase electrical stress.

Without proper current control, this cycle can cause:

• Excessive LED temperature
• Reduced luminous efficiency
• Color shift
• Accelerated lumen depreciation
• Premature component failure
• Thermal runaway in poorly designed circuits

An LED system therefore needs one of two current-control arrangements:

1. The external LED driver directly regulates current.
2. The LED product contains resistors, regulator ICs, or other current-limiting components and receives a regulated voltage from the power supply.

The first arrangement normally uses a constant current driver. The second generally uses a constant voltage driver.

🟡What Is a Constant Current LED Driver?

A constant current LED driver maintains a predetermined output current while automatically adjusting its output voltage according to the requirements of the connected LED load.

For example, a constant current driver may have these specifications:

• Rated output current: 700mA
• Output voltage range: 18–42VDC
• Maximum output power: 29.4W

When a compatible LED module is connected, the driver attempts to maintain a current of 700mA. Its output voltage changes within the specified 18–42V operating window according to the forward voltage of the LED string.

The driver does not continuously supply 42V. Instead, it supplies the voltage necessary to push 700mA through the connected load, provided that the required voltage remains within its operating range.

🟢How Does a Constant Current LED Driver Work?

A constant current driver monitors the current flowing through the LED circuit.

When load conditions change, the driver adjusts its output voltage to keep the current close to the rated value.

For example:

• If the LED string requires 28V to operate at 700mA, the driver provides approximately 28V.
• If temperature changes cause the required forward voltage to fall to 26V, the driver reduces its output voltage while continuing to provide approximately 700mA.
• If the required voltage rises above the driver’s maximum output voltage, the driver may not reach the rated current.
• If the required voltage falls below the driver’s minimum operating voltage, the system may flicker, shut down, dim incorrectly, or operate outside its specified range.

This regulation gives the LEDs stable current and helps maintain predictable brightness.

🔵Common Constant Current Ratings

Constant current drivers are commonly available with output ratings such as:

• 150mA
• 250mA
• 300mA
• 350mA
• 500mA
• 600mA
• 700mA
• 900mA
• 1050mA
• 1200mA
• 1400mA
• 1500mA

Some drivers have a fixed output current. Others allow the installer or luminaire manufacturer to adjust the current using:

• DIP switches
• Programming software
• NFC configuration
• External resistors
• Internal potentiometers
• Digital control systems

An adjustable driver must still be configured within the safe current range of the connected LED module.

🟣Which LED Products Use Constant Current Drivers?

Constant current drivers are frequently used for LED products in which the LEDs are connected directly as a series string without individual current-limiting resistors.

High-Power LED Modules

High-power LED boards may be specified for 350mA, 700mA, 1050mA, or another controlled current.

The current rating determines the appropriate driver. The module’s forward-voltage range determines the voltage window the driver must provide.

COB LED Light Sources

Many chip-on-board LED light engines used in spotlights, downlights, track lights, and high-bay lights require a constant current driver.

This should not be confused with flexible COB LED strip lights. Most flexible COB strips contain current-limiting components and operate on constant voltage, such as 12V or 24V.

For more information about flexible COB technology, applications, power requirements, and installation, read our ultimate guide to COB LED strips.

Recessed Downlights

Many complete downlights have an external constant current driver matched to the internal LED board.

A replacement driver must match the original current rating, voltage window, power rating, dimming method, and connector configuration.

Track Lights and Spotlights

Commercial spotlights often use high-output COB modules powered by constant current drivers.

The selected drive current affects:

• Brightness
• Heat generation
• Efficiency
• Color stability
• Expected LED lifespan

Panel Lights

Some LED panel lights have internal series-connected LED strings that require a constant current driver.

Streetlights

Professional streetlights frequently use high-power constant current drivers with:

• Surge protection
• Programmable output current
• Thermal protection
• 0–10V or DALI dimming
• Automatic power reduction
• High power factor

High-Bay and Low-Bay Fixtures

Industrial luminaires commonly use constant current drivers because they contain high-power LED boards designed for a controlled operating current.

Automotive LED Lighting

Headlights, daytime running lights, signal lights, and other automotive LED systems frequently use regulated constant current circuits because the vehicle supply voltage can vary considerably.

🟤Advantages of Constant Current LED Drivers

Constant current drivers provide precise control over the current passing through the LED load. This makes them particularly suitable for high-power LEDs and professional luminaires where brightness, temperature, and reliability must remain predictable.

Stable LED Current

The driver regulates current despite reasonable variations in input voltage, LED forward voltage, and temperature.

Consistent Brightness

Because LED brightness is closely related to forward current, current regulation produces more predictable light output.

Better Protection for Bare LEDs

A properly selected driver prevents excessive current from flowing through LED modules that do not contain their own current regulation.

Efficient Series Connections

Multiple LEDs can be connected in series so that the same current passes through every LED. This can help maintain consistent current across the complete string.

Precise Luminaire Design

The luminaire manufacturer can select a specific drive current to balance:

• Brightness
• Efficiency
• Temperature
• Color stability
• Expected service life

Advanced Dimming Options

Many constant current drivers support:

• 0–10V
• 1–10V
• DALI
• TRIAC
• PWM
• Push dimming
• Bluetooth
• Zigbee
• KNX
• Casambi
• Programmable current control

🔴Disadvantages of Constant Current LED Drivers

Although constant current drivers provide excellent LED current control, they require more careful electrical matching than standard constant voltage power supplies.

The driver cannot be selected only by wattage. The rated current, minimum voltage, maximum voltage, LED forward-voltage range, and total output power must all be considered.

More Complicated Matching

The rated current must match the LED module, and the module’s forward voltage must fall within the driver’s output-voltage window.

Less Flexible Load Changes

Adding or removing LED modules changes the total forward voltage. The redesigned load must remain within the driver’s operating range.

Parallel Connections Can Be Difficult

Connecting bare LED strings in parallel can cause unequal current sharing unless each branch has suitable current regulation or balancing.

Replacement Requires Careful Specification Checking

A replacement driver must match:

• Output current
• Voltage range
• Maximum power
• Input voltage
• Dimming system
• Environmental rating
• Connector type
• Physical dimensions

Not Normally Suitable for Standard LED Strips

A constant current driver should not be connected to an ordinary 12V or 24V LED strip unless the strip manufacturer explicitly specifies constant current operation.

🟠What Is a Constant Voltage LED Driver?

A constant voltage LED driver maintains a fixed output voltage while allowing the connected load to draw the current it requires, up to the maximum output capacity of the driver.

Common constant voltage outputs include:

• 5VDC
• 12VDC
• 24VDC
• 36VDC
• 48VDC

A 24V constant voltage power supply attempts to maintain approximately 24V at its output. The LED strip or module contains resistors, constant-current ICs, pixel-control ICs, or other circuitry that controls the current flowing through individual LEDs.

🟡How Does a Constant Voltage Driver Work?

Suppose a 24V constant voltage driver is rated at 150W.

The output remains close to 24V while the connected LED strips draw current according to their combined power consumption.

At different load levels:

• A 24W load draws approximately 1A.
• A 72W load draws approximately 3A.
• A 120W load draws approximately 5A.
• A 150W load draws approximately 6.25A.

The driver does not force 6.25A through every connected product. The 6.25A value represents the maximum rated current available at 24V.

The connected LED products draw only the current they need, provided that the total demand does not exceed the driver’s rated capacity.

🟢Which LED Products Use Constant Voltage Drivers?

Flexible LED Strip Lights

Most SMD and COB flexible LED strips operate at a fixed voltage, commonly 12V or 24V.

Examples include:

• SMD2835 LED strips
• SMD5050 LED strips
• SMD2216 LED strips
• SMD3528 LED strips
• SMD3014 LED strips
• Flexible COB LED strips

You can view our available single-color LED strip lights for residential, commercial, architectural, cabinet, display, and signage applications.

Addressable LED Strips

SPI pixel strips such as WS2811, WS2812B, WS2815, SK6812, UCS, GS, TM and similar products normally use a regulated constant voltage power supply.

Depending on the model, the required voltage may be:

• 5V
• 12V
• 24V
• 36V
• 48V

Visit our addressable LED strip product collection to compare different SPI and digital pixel strip options.

For help selecting a suitable pixel strip, controller, signal type and operating voltage, read our addressable LED strip selection guide.

RGB, RGBW and RGBCCT LED Strips

Color-changing strips use a constant voltage power supply together with a compatible controller.

The controller switches or modulates the color channels to control brightness, color, color temperature, and lighting effects.

Our RGBX color-changing LED strip range includes:

• RGB LED strips
• RGBW LED strips
• RGBWW LED strips
• RGB+CCT LED strips
• RGBCCT LED strips
• COB RGB strips
• COB RGBW strips
• Addressable RGBX strips
• DMX RGBX strips

LED Neon Flex

Most low-voltage silicone LED neon flex operates from a constant voltage source, commonly 12V or 24V.

Some long-run or addressable neon products may use 36V or 48V to reduce current and voltage drop.

Signage Modules

Injection-molded LED modules used in channel letters, light boxes, and advertising signs commonly operate at 12V or 24V.

Cabinet and Furniture Lighting

LED bars, strips, shelf lights, mirror lights, and display lighting products often operate on 12V or 24V constant voltage power.

Landscape Lighting

Low-voltage outdoor strips, modules, and linear fixtures may use waterproof constant voltage power supplies.

Architectural Linear Lighting

Long runs of cove lighting, wall washing, handrail lighting, and concealed linear lighting usually use 24V or 48V constant voltage systems.

🔵Advantages of Constant Voltage LED Drivers

Constant voltage systems are popular because they are flexible, easy to expand, and compatible with a wide range of LED strips, controllers, dimmers, and accessories.

Once the correct voltage has been selected, multiple LED strips can normally be connected in parallel to the same power supply. Each strip receives the same voltage and draws its required current.

Simple Voltage Matching

The driver output voltage needs to match the rated voltage of the LED product.

For example:

• 5V strip → 5V power supply
• 12V strip → 12V power supply
• 24V strip → 24V power supply
• 48V strip → 48V power supply

Easy Parallel Connections

Several LED strips can be connected in parallel to the same power supply, provided that the total load remains within its rated wattage and current.

For larger installations, follow the recommended methods in our guide on how to connect multiple LED strip lights.

Flexible System Expansion

Additional branches can often be added without changing the voltage, as long as the power supply, controller, wiring, and connectors have sufficient capacity.

Broad Product Compatibility

Constant voltage power supplies are widely used with:

• LED strips
• LED neon flex
• RGB controllers
• CCT controllers
• SPI controllers
• DMX decoders
• Signal amplifiers
• Smart lighting systems

Convenient Color Control

RGB, RGBW, RGBCCT, SPI and DMX systems are commonly designed around constant voltage power distribution.

Multiple Power Supply Formats

Constant voltage power supplies are available as:

• Plug-in adapters
• Desktop adapters
• Plastic enclosed supplies
• Metal enclosed supplies
• Slim power supplies
• DIN-rail power supplies
• Waterproof power supplies
• Dimmable LED drivers
• Battery-powered systems
• Solar-powered systems

🟤Disadvantages of Constant Voltage LED Drivers

Constant voltage systems are simple to use, but they still require careful wattage calculation, wiring design, and voltage-drop control.

The power supply regulates voltage at its output terminals, but it cannot completely compensate for resistance in long wires, connectors, or flexible LED strip PCBs.

Constant voltage systems are simple to use, but they still require careful wattage calculation, wiring design, and voltage-drop control.

Voltage Drop Over Long Distances

Long cables and LED strip conductors have electrical resistance. As current travels through them, part of the voltage is lost.

The LEDs at the far end of a long strip may therefore become dimmer or show inaccurate colors.

Power injection can solve many long-run problems. Read our complete guide on how to inject power into an LED strip.

Higher Current at Lower Voltages

For the same power level, a 12V system draws approximately twice the current of a 24V system.

Higher current can require:

• Thicker wires
• Higher-capacity connectors
• More power-injection points
• Larger controllers
• More careful fuse protection

For a detailed comparison, read 12V vs. 24V LED strip lights.

Current Regulation Depends on the LED Product

The power supply regulates voltage, but the connected strip or module is responsible for controlling LED current.

Low-quality resistors, poor PCB design, inadequate copper thickness, excessive voltage, or poor thermal management can still shorten product life.

Power Capacity Must Be Calculated

The total wattage of all connected strips, controllers, modules, and accessories must remain below the power supply’s safe operating capacity.

🟤Constant Current vs. Constant Voltage LED Drivers: Key Differences

The Main Difference: Where Is the Current Controlled?

The most important difference is not simply the number printed on the driver. It is where the LED current is regulated.

Constant Current System

In a constant current system:

• The LED module usually has little or no independent current regulation.
• The external driver directly controls current.
• The driver adjusts voltage according to the LED string.
• The module is normally marked with a current rating.

Example marking:

700mA, Vf 28–34V

Constant Voltage System

In a constant voltage system:

• The LED product contains resistors or current-control electronics.
• The external power supply maintains a fixed voltage.
• The product draws the current it needs.
• The strip or module is normally marked with a voltage rating.

Example marking:

24VDC, 14.4W/m

How to Identify Which Driver Your LED Needs

Before buying a driver, inspect the LED product label, packaging, PCB printing, connector, product page, or datasheet.

Look for a Voltage Rating

A product marked with one of the following usually needs a constant voltage driver:

• DC5V
• DC12V
• DC24V
• DC36V
• DC48V

Examples include:

• 24V COB LED strip
• 12V RGBW strip
• 5V WS2812B pixel strip
• 24V LED neon flex
• 12V channel-letter module

Look for a Current Rating

A product marked with a specific operating current normally needs a constant current driver:

• 350mA
• 500mA
• 600mA
• 700mA
• 900mA
• 1050mA
• 1400mA

The product may also show a forward-voltage range.

Example:

700mA, 30–36VDC

Examine the Existing Driver

When replacing a driver, read its output specifications rather than choosing one based only on its physical size or total wattage.

A constant current driver may show:

Output: 700mA, 20–42VDC, 29.4W maximum

A constant voltage driver may show:

Output: 24VDC, 6.25A, 150W maximum

Check the Manufacturer’s Datasheet

The datasheet should identify:

• Required driver type
• Rated voltage or current
• Forward-voltage range
• Maximum power
• Wiring method
• Dimming compatibility
• Environmental requirements
• Maximum operating temperature

Do not rely exclusively on the appearance of the LED product. Two similar-looking modules may have completely different electrical requirements.

🔴How to Choose a Constant Current LED Driver

A constant current driver must satisfy several specifications simultaneously.

1. Match the Rated Output Current

The driver current must match the LED module’s required current.

For example:

• LED module: 700mA
• Correct driver: 700mA
• Incorrect driver: 1050mA

Using a higher current can make the LED brighter temporarily, but it may also:

• Increase junction temperature
• Accelerate lumen depreciation
• Shift the LED color
• Damage the phosphor
• Shorten the product’s lifespan

Do not add a 20% margin to the current rating. A 700mA LED module should not automatically be paired with an 840mA or 900mA driver.

Current is an operating specification, not spare capacity.

2. Check the Forward-Voltage Range

Add the forward voltages of all LEDs or modules connected in series.

The total must fall within the driver’s constant-current output-voltage window.

Example

Four LED modules are connected in series.

Each module has:

• Forward voltage: 8–9V
• Rated current: 700mA

Total forward voltage:

• Minimum: 4 × 8V = 32V
• Maximum: 4 × 9V = 36V

A suitable driver may be rated:

• Output current: 700mA
• Output voltage: 27–42V

The 32–36V load remains inside the driver’s 27–42V operating window.

A driver rated at 700mA and 12–24V would not be suitable because its maximum voltage is too low.

3. Check the Driver’s Power Capacity

Calculate approximate output power using:

Power = Voltage × Current

For a 36V LED load operating at 700mA:

36V × 0.7A = 25.2W

The driver must be capable of delivering at least this power at the required current and voltage.

4. Consider the Minimum Output Voltage

Installers sometimes check only the maximum voltage.

However, the LED load must also remain above the driver’s minimum constant-current voltage. A load below this level may produce:

• Unstable regulation
• Flickering
• Limited dimming range
• Repeated shutdown
• Incorrect output current

5. Select the Appropriate Dimming Method

Possible constant current dimming systems include:

• TRIAC or phase-cut
• 0–10V
• 1–10V
• DALI
• Push dimming
• PWM input
• Resistance dimming
• Bluetooth
• Zigbee
• KNX
• Casambi
• Programmable current reduction

The driver, dimmer, and control system must be mutually compatible.

6. Check Environmental Protection

Choose the enclosure according to the installation:

• IP20 for protected indoor locations
• IP44 or IP54 for limited dust or moisture exposure
• IP65 for outdoor or damp environments
• IP67 for stronger water protection
• IP68 for specially designed immersion applications

Use our IP rating guide to understand the differences between IP20, IP44, IP54, IP65, IP67 and IP68.

Do not assume that a waterproof LED module makes the complete installation waterproof. Drivers, connectors, cable joints, controllers, and wire entrances also require suitable protection.

🟠How to Choose a Constant Voltage LED Driver

Selecting a constant current driver requires matching several specifications at the same time. A driver with the correct current but an incorrect voltage range may not operate properly.

1. Match the Output Voltage Exactly

The output voltage of the power supply must match the LED product.

Examples:

• 5V LED strip → 5V power supply
• 12V LED strip → 12V power supply
• 24V LED strip → 24V power supply
• 48V LED strip → 48V power supply

Do not connect a 12V strip to a 24V power supply. The excessive voltage can rapidly overheat and damage:

• LEDs
• Resistors
• PCB conductors
• Pixel-control ICs
• Connectors
• Solder joints

A 24V strip connected to a 12V supply will normally be very dim or may not operate properly.

2. Calculate the Total LED Load

Use the following formula:

LED strip wattage per meter × total length = total strip wattage

Example

A 24V LED strip consumes 14.4W per meter.

The installation uses 10 meters.

14.4W/m × 10m = 144W

The connected LED load is approximately 144W.

Remember to include all connected branches, not only the longest individual strip.

3. Add Power-Supply Headroom

Avoid operating the power supply continuously at its maximum rated output.

For many typical projects, adding approximately 20–25% capacity is a practical approach.

Using a 20% margin:

144W × 1.2 = 172.8W

A practical selection would be a power supply rated at approximately 180W or 200W.

The appropriate margin can vary according to:

• Manufacturer recommendations
• Ambient temperature
• Enclosure ventilation
• Installation position
• Continuous operating time
• Startup characteristics
• Controller losses
• Local electrical requirements

For additional calculation examples, refer to our guide on selecting an LED strip power supply.

4. Calculate the Required Current

Use:

Current = Power ÷ Voltage

For a 144W load operating at 24V:

144W ÷ 24V = 6A

The power supply must provide more than 6A. After adding headroom, an 8A or similarly rated supply may be suitable, depending on the available model.

5. Account for Controllers and Amplifiers

Some RGB, RGBW, RGBCCT, SPI and DMX systems include controllers whose current limits are lower than the power supply capacity.

Check:

• Total controller amperage
• Per-channel amperage
• Per-output amperage
• Maximum pixel quantity
• Data-signal limitations
• Amplifier requirements
• Connector current ratings

A 300W power supply does not mean that a controller rated for 10A can safely carry the full 300W load.

6. Check the Installation Environment

Choose the power supply style according to the application.

Indoor Dry Installation

An IP20 enclosed or open-frame power supply may be acceptable when installed inside a suitable ventilated electrical enclosure.

Damp or Outdoor Installation

Use a properly rated waterproof power supply and waterproof all connections.

For waterproof strip selection, sealing methods, and application recommendations, read our guide to waterproof LED strip lights.

Furniture and Cabinet Installation

Use a compact, certified supply with suitable thermal clearance and protection from combustible materials.

Industrial Installation

Consider:

• Surge protection
• Power factor
• Harmonic performance
• Inrush current
• Ambient temperature
• Electrical enclosure design
• Certification requirements

🟡Constant Current vs. Constant Voltage Wiring

Constant current and constant voltage products normally use different wiring structures.

Constant Current Wiring

LED modules are commonly wired in series.

Driver + → LED 1 → LED 2 → LED 3 → Driver –

The same current flows through every LED module, while their forward voltages are added together.

When three modules each have a forward voltage of 10V, the total load voltage is approximately 30V.

Do not connect multiple bare LED strings in parallel to a single constant current output unless the system is specifically designed for current balancing.

Constant Voltage Wiring

LED strips and modules are normally connected in parallel.

Power Supply + → Strip 1 +

               → Strip 2 +

               → Strip 3 +

Power Supply – → Strip 1 –

               → Strip 2 –

               → Strip 3 –

Each branch receives the same supply voltage and draws its own current.

For long installations, parallel wiring and power injection help reduce voltage drop and maintain consistent brightness.

Before cutting and rewiring a strip, follow the steps in our guide on how to cut and connect LED light strips.

🔵What Happens If You Use the Wrong LED Driver?

Using the wrong driver can damage both the LED product and the power supply.

Connecting a Constant Voltage Supply to a Bare Constant Current LED

A bare high-power LED or COB module may draw excessive current when connected directly to a fixed-voltage source without suitable current regulation.

Possible results include:

• Sudden excessive brightness
• Rapid temperature increase
• Color shift
• LED degradation
• Thermal runaway
• Permanent LED failure

A resistor or onboard regulator may make voltage drive possible in certain engineered circuits, but an unregulated bare LED should not be connected directly to an arbitrary voltage supply.

Connecting a Constant Current Driver to a Constant Voltage LED Strip

A standard constant voltage LED strip is designed to receive a fixed voltage.

A constant current driver may raise or lower its output voltage while attempting to reach its rated current. Depending on the driver current, voltage window, strip length and internal strip circuit, the strip may:

• Remain off
• Flicker
• Operate at incorrect brightness
• Receive excessive voltage
• Overheat
• Be damaged
• Cause the driver to enter protection mode

Do not use this combination unless the complete system has been electrically designed and approved for it.

Connecting the Wrong Constant Voltage

24V Supply on a 12V Strip

This can severely overdrive the strip and cause rapid failure.

12V Supply on a 24V Strip

The strip may be dim, unstable, or unable to illuminate correctly.

5V Supply on a 12V Addressable Strip

The control ICs and LEDs may not start reliably.

Excessive Voltage on Addressable LEDs

Pixel-control ICs can be damaged immediately when their maximum input voltage is exceeded.

Incorrect power selection is one of the most frequent installation problems. Review our article covering 10 common LED strip installation mistakes before completing the project.

🔴Dimming Constant Current and Constant Voltage Drivers

Both driver types can be dimmable, but they may use different methods.

Constant Current Dimming

A constant current driver can reduce light output using several methods.

Amplitude or Current Reduction

The driver decreases the regulated LED current.

This method can provide smooth light output, but extremely low current may affect:

• Color consistency
• Efficiency
• Minimum brightness
• Dimming stability

PWM Dimming

The driver switches the LED current on and off rapidly. The perceived brightness depends on the duty cycle.

A high-quality PWM system should use an appropriate frequency to reduce:

• Visible flicker
• Camera banding
• Stroboscopic effects
• Eye discomfort

Primary-Side Phase-Cut Dimming

A compatible TRIAC or phase-cut driver can work with leading-edge or trailing-edge wall dimmers.

The driver and dimmer must be tested for compatibility.

Control Interfaces

Commercial constant current drivers may support:

• 0–10V
• 1–10V
• DALI
• Push dim
• DMX
• KNX
• Wireless control

Constant Voltage Dimming

Constant voltage systems are commonly dimmed in one of two ways.

Output-Side PWM Controller

A controller is installed between the constant voltage power supply and the LED strip.

This is common for:

• Single-color strips
• CCT strips
• RGB strips
• RGBW strips
• RGBCCT strips

Dimmable Constant Voltage Power Supply

The power supply itself receives a dimming signal and changes or modulates its output.

Available control methods include:

• TRIAC
• 0–10V
• DALI
• Push dim
• PWM
• Wireless control

An incompatible power supply, controller, or dimmer may produce unstable output. See our troubleshooting guide on how to fix a flickering LED strip when a strip flashes, pulses, or flickers after installation.

🟠Constant Current vs. Constant Voltage for LED Strip Lights

Most flexible LED strip lights use constant voltage power.

This includes:

• SMD2835 strips
• SMD3528 strips
• SMD5050 strips
• SMD2216 strips
• SMD2110 strips
• SMD2020 strips
• Standard COB strips
• RGB COB strips
• RGBW COB strips
• RGBCCT strips
• SPI strips
• DMX strips
• LED neon flex

A typical strip specification may read:

DC24V, 12W/m, 5m per roll

This indicates that the strip requires a 24V constant voltage power supply.

The 12W/m value is used to calculate the required power capacity.

Important Exception

Some specialist linear products are designed as constant current systems, and some long-run strips contain onboard constant-current ICs.

However, a strip containing constant-current ICs can still require an external constant voltage supply. The onboard IC regulates LED current while the external power supply provides a fixed 12V, 24V or 48V input.

Always follow the strip’s input specification rather than assuming its driver type from the component layout.

For projects requiring extended continuous runs, review our guide on the longest run length of LED flexible strip lighting.

Constant Current vs. Constant Voltage for COB LEDs

The term COB LED can refer to different products.

COB LED Light Engine

A rigid high-power COB light source used in a spotlight or downlight commonly requires constant current.

Example:

• Rated current: 1050mA
• Forward voltage: 30–36V
• Approximate power: 35W

COB LED Strip

A flexible COB strip usually has many small LED chips mounted continuously along a flexible PCB. It normally includes current-limiting resistors or regulator components.

Example:

• Input: 24VDC
• Power: 10W/m
• Quantity: 480 chips/m

This product requires a 24V constant voltage power supply.

Therefore, the word “COB” alone does not identify the correct driver. Check whether the product is specified by current or voltage.

Explore our COB LED strip product range for single-color, CCT, RGB, RGBW, addressable and waterproof COB lighting options.

🟣Which Driver Is More Energy-Efficient?

Neither constant current nor constant voltage is automatically more efficient in every application.

Efficiency depends on:

• Driver topology
• Input voltage
• Output voltage
• Load level
• Power rating
• Power factor
• Switching frequency
• Dimming level
• Thermal conditions
• Component quality
• Current-limiting method inside the LED product

A well-designed constant current system can efficiently operate a series LED string with precise current regulation.

A well-designed constant voltage system can efficiently power multiple LED strips and controllers. However, resistor-based strips lose some energy as heat in their current-limiting resistors.

When comparing drivers, check the complete efficiency curve rather than relying only on the maximum efficiency printed on the label. A driver may achieve its highest efficiency only within a particular load range.

🟤Which Driver Provides Better LED Lifespan?

The correctly matched driver provides the better lifespan.

For bare LEDs and high-power modules, controlled current helps prevent overdriving and excessive junction temperature.

For LED strips, a stable and correctly sized constant voltage supply helps prevent:

• Overvoltage
• Excessive ripple
• Repeated overload operation
• Unstable brightness
• Controller shutdown
• Power supply overheating

Driver selection should also consider:

• Output ripple
• Ambient temperature
• Surge protection
• Dimming behavior
• Power quality
• Ventilation
• Installation enclosure
• Maximum case temperature
• LED heat dissipation

A correctly selected driver cannot compensate for poor thermal management. High-power LEDs still need suitable heatsinks, and high-power LED strips should normally be installed inside aluminum profiles.

🔴Constant Current, Constant Voltage and CV+CC Drivers

Some power supplies are described as:

• CV+CC
• Constant voltage plus constant current
• Dual-mode power supplies
• Adjustable laboratory power supplies

These products normally operate in constant voltage mode under ordinary conditions. When the load attempts to draw more than the rated current, the power supply enters current-limiting mode.

For example, a 24V, 10A CV+CC supply may:

• Maintain 24V while the load draws less than 10A
• Reduce output voltage when the load attempts to exceed 10A
• Limit output current to approximately 10A

This overload-limiting behavior does not necessarily make the supply a replacement for a dedicated precision constant current LED driver.

The terminology can vary between manufacturers. Read the datasheet carefully to determine:

• Which mode is intended for normal operation
• Current-regulation accuracy
• Output-voltage range
• Dimming compatibility
• Whether the product is approved for direct LED driving
• Whether the current limit is adjustable
• Whether constant current operation is continuous or only protective

🟠Practical LED Driver Selection Examples

Example 1: 10m of 24V Single-Color LED Strip

Specifications:

• Voltage: 24V
• Power: 9.6W/m
• Length: 10m

Load:

9.6W × 10 = 96W

With 20% headroom:

96W × 1.2 = 115.2W

Recommended selection:

• 24V constant voltage power supply
• At least approximately 120W
• Suitable IP rating
• Compatible dimmer when required

Example 2: 5m of 12V RGB LED Strip

Specifications:

• Voltage: 12V
• Power: 14.4W/m
• Length: 5m

Load:

14.4W × 5 = 72W

With 20% headroom:

72W × 1.2 = 86.4W

Recommended selection:

• 12V constant voltage power supply
• Approximately 100W
• RGB controller rated above the strip’s total current
• Suitable wiring and connectors

Example 3: A 700mA COB Module

Specifications:

• Rated current: 700mA
• Forward voltage: 30–34V

Approximate maximum power:

34V × 0.7A = 23.8W

Recommended driver:

• Constant current output
• 700mA rating
• Voltage window covering at least 30–34V
• Output power above 23.8W
• Compatible dimming when required

Example 4: Three Constant Current Modules in Series

Each module:

• Rated current: 500mA
• Forward voltage: 9–11V

Combined voltage:

• Minimum: 27V
• Maximum: 33V

Recommended driver:

• 500mA constant current
• Output-voltage window covering 27–33V
• Output power of at least 16.5W

Example 5: 5V Addressable LED Strip

Specifications:

• Voltage: 5V
• Maximum estimated current: 15A

Recommended selection:

• Regulated 5V constant voltage power supply
• Current rating above the calculated load
• Multiple power-injection points
• Suitable power-wire thickness
• Common ground between the power supply, controller, and strip
• Fuse protection for high-current branches

🟢Common LED Driver Selection Mistakes

Mistake 1: Choosing by Wattage Alone

Two 40W drivers may have completely different outputs.

One may be:

• 24V constant voltage
• 1.67A maximum

Another may be:

• 700mA constant current
• 28–57V

They are not interchangeable.

Mistake 2: Confusing Maximum Current With Forced Current

A 24V constant voltage supply rated for 10A does not force 10A into a small LED strip.

The strip draws the amount of current required by its internal circuit.

Mistake 3: Adding Headroom to Constant Current

Power headroom can be useful, but the rated current must remain compatible with the LED module.

Do not replace a 700mA driver with a 1000mA driver merely to gain additional capacity.

Mistake 4: Ignoring the Constant Current Voltage Window

Matching 700mA is not enough. The LED string’s forward voltage must also remain within the driver’s operating range.

Mistake 5: Mixing 12V and 24V Products

The controller, power supply, amplifier, and LED strip must all support the selected system voltage.

Mistake 6: Ignoring Voltage Drop

A correctly rated power supply cannot prevent voltage drop caused by:

• Excessively long strips
• Thin wires
• Undersized connectors
• Poor solder joints
• Insufficient power injection
• High-current loads

A 24V system normally experiences less voltage drop than a comparable 12V system because it draws less current for the same wattage. Read our 12V and 24V LED strip comparison for more details.

Mistake 7: Running the Driver at Maximum Capacity

Continuous full-load operation can increase temperature and reduce reliability, particularly in enclosed or poorly ventilated locations.

Mistake 8: Ignoring Dimming Compatibility

A dimmable driver may still be incompatible with a particular wall dimmer or control protocol.

Mistake 9: Using an Indoor Driver Outdoors

Waterproof strips do not protect an indoor power supply from:

• Rain
• Condensation
• Dust
• Water jets
• Corrosive environments

Mistake 10: Ignoring Certification and Safety Requirements

Select products that comply with the electrical and safety standards required by the installation country and application.

For additional troubleshooting information, read our LED strip common trouble and solution guide.

🔵Quick LED Driver Decision Guide

Choose a constant current LED driver when:

• The LED is marked with an mA rating.
• The product datasheet specifies a constant operating current.
• You are powering a bare COB module or high-power LED board.
• The LEDs are arranged as a series string.
• The LED load depends on the external driver for current regulation.
• The driver’s voltage window covers the complete LED forward-voltage range.

Choose a constant voltage LED driver when:

• The product is marked 5V, 12V, 24V, 36V, or 48V.
• You are powering an ordinary flexible LED strip.
• You are powering LED neon flex.
• You are using an RGB, RGBW, RGBCCT, SPI, or DMX controller.
• Multiple strip branches need to be connected in parallel.
• The LED product contains resistors or onboard current regulation.
• You have calculated the total wattage and added appropriate capacity.

🟣FAQs About Constant Current and Constant Voltage LED Drivers

🟤Conclusion

Constant current and constant voltage LED drivers perform the same broad task—providing suitable electrical power to LED lighting—but they regulate different output parameters.

A constant current driver maintains a specified current and adjusts its voltage within an operating range. It is commonly used for:

• Bare high-power LEDs
• COB light modules
• Downlights
• Spotlights
• Panel lights
• Streetlights
• Industrial luminaires

A constant voltage driver maintains a fixed voltage while the connected LED product controls its own current. It is the standard choice for:

• Flexible LED strips
• COB LED strips
• LED neon flex
• RGB lighting
• RGBW lighting
• Addressable LED strips
• Signage modules
• Architectural linear lighting

For most LED strip projects, follow these steps:

1. Match the strip’s rated voltage.
2. Calculate wattage per meter multiplied by the total length.
3. Add suitable power-supply headroom.
4. Verify controller and wire capacity.
5. Select the proper IP rating and dimming method.
6. Plan power injection for long runs.
7. Test the complete system before final installation.

For constant current modules:

1. Match the rated operating current.
2. Calculate the complete series-string forward voltage.
3. Confirm that the voltage stays inside the driver’s operating window.
4. Check maximum output power.
5. Verify dimming, thermal, and environmental requirements.

MSHLED supplies a wide selection of constant voltage LED strip lighting products, including:

• Single-color LED strips
• COB LED strips
• RGB, RGBW and RGBWW LED strips
• Addressable LED strips
• LED neon flex
• Waterproof LED strips
• Customized linear lighting solutions

Correctly matching the LED strip, power supply, controller, wiring, and installation environment will produce a safer, more reliable, and longer-lasting lighting system.