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How to Choose an AC/DC Power Adapter for LED Lighting | Differences Between Constant Voltage (CV), Constant Current (CC), and CC/CV
A power supply manufacturer explains how to choose an AC/DC Power Adapter for LED lighting (LED power supply/LED driver) in 8 steps. Learn the differences between constant voltage (CV), constant current (CC), and CC/CV, and determine the right output method for your LEDs. Custom and board-mount power supplies are also available for CC/CV output and outputs exceeding 32 W.
Key points of this page: If the LED side has a current-limiting circuit, use a constant-voltage (CV) AC/DC Power Adapter. To illuminate an LED without a current-limiting circuit, use a constant-current (CC) or CC/CV AC/DC Power Adapter. Our standard AC/DC Power Adapter for LED lighting (ULVU series) provide constant-voltage (CV) output. We offer semi-custom solutions for CC/CV output and CC-only output (output controlled solely by constant current). Our semi-custom service modifies certain specifications based on standard products. We can also provide custom CC/CV output for board-mounted power supplies (open-frame power supplies) built into lighting fixtures. We can accommodate output power, standards, and operating environments not covered by our standard products through custom power supply solutions. Please contact our Sales Department with your required specifications.
Why Output Mode Matters for LED Power Supplies (LED Drivers)
An LED power supply (LED driver) supplies the power needed to illuminate LEDs. The required output mode depends on where the current flowing through the LEDs is controlled. This is because even a slight change in voltage can cause a significant change in the current flowing through an LED.
The brightness of an LED is determined primarily by the current flowing through it.
The voltage generated across an LED when current flows through it is called the forward voltage (Vf). Vf varies depending on the amount of current. It also differs from one LED to another and decreases as the LED's temperature rises.
How Thermal Runaway Occurs
Without constant-current control, the current flowing through an LED varies according to the applied voltage. As a result, thermal runaway may occur through the following process. Thermal runaway is a phenomenon in which repeated increases in LED current and heat generation cause the LED to deteriorate or become damaged.
| Step | What Happens to the LED |
|---|---|
| 1 | When the power supply voltage rises slightly, the current flowing through the LED increases significantly. |
| 2 | As the current flowing through the LED increases, the LED generates more heat and its temperature rises. |
| 3 | As the LED temperature rises, its forward voltage (Vf) decreases. |
| 4 | As Vf decreases, even more current flows through the LED at the same voltage. |
| 5 | Steps 2 through 4 repeat, causing the LED to deteriorate or become damaged. |
With constant-current control, the current flowing through the LED remains constant even if the power supply voltage or LED temperature changes. This prevents thermal runaway.
Key Point:When selecting a power supply for LED lighting, first determine whether the LED current will be controlled by the circuit on the LED side or by the power supply. The required power supply output method depends on this determination.
Differences Between Constant Voltage (CV), Constant Current (CC), and CC/CV
There are three output modes for AC/DC Power Adapter used with LED lighting: constant voltage (CV), constant current (CC), and CC/CV. These modes differ in whether the power supply keeps the voltage, current, or both constant. On this page, connecting an LED to a power supply without using a current-limiting circuit is referred to as "direct drive."
What Is Constant Voltage (CV)?
Constant voltage (CV) is an output mode that maintains a constant output voltage. The output current varies depending on the amount required by the connected device. Most common AC/DC Power Adapter are constant-voltage power supplies.
Constant-voltage power supplies are used with LED modules and LED strip lights that have current-limiting circuits. Examples of current-limiting circuits include resistors and constant-current circuits. Constant-voltage power supplies also have overcurrent protection. However, overcurrent protection is designed to protect the power supply. It does not keep the LED current constant.
What Is Constant Current (CC)?
Constant current (CC) is an output method that maintains a constant output current. The output voltage varies according to the total Vf of the connected LEDs.
A constant-current power supply is used to light LEDs that do not have a current-limiting circuit. When all LEDs are connected in series, the power supply keeps the LED current constant. Therefore, the LED current remains almost unchanged even when there are individual differences in forward voltage (Vf) or changes in temperature. As a result, variations in brightness are also minimized. On this page, an output controlled solely by constant current (CC) is referred to as a "CC-only output."
What Is CC/CV (Constant Current/Constant Voltage)?
CC/CV (constant current/constant voltage) is an output method that controls both the output current and output voltage. While the output current is below the set value, the power supply operates in constant-voltage mode. When the output current reaches the set value, the power supply operates in constant-current mode. On this page, the output voltage setting used when a CC/CV power supply operates in constant-voltage mode is referred to as the "voltage limit."
When directly driving LEDs, set the voltage limit higher than the maximum total Vf. If the voltage limit is higher than the maximum total Vf, the power supply operates in the constant-current region. If an LED becomes disconnected and the output becomes open-circuit (no load), the output voltage is maintained at the set limit.
| Item | Constant Voltage (CV) | Constant Current (CC) | CC/CV |
|---|---|---|---|
| Maintained Constant | Output voltage | Output current | Output current in the constant-current region. Output voltage (limit value) in the constant-voltage region |
| Varies According to the Connected LEDs | Output current | Output voltage | Output voltage in the constant-current region. Output current in the constant-voltage region |
| Main Applications | LED modules and LED strip lights with current-limiting circuits | Directly driving LEDs | Directly driving LEDs when an output voltage limit is also required |
| Selection Considerations | Do not connect LEDs that do not have a current-limiting circuit | Ensure that the total Vf is within the power supply's output voltage range | Set the voltage limit higher than the maximum total Vf |
Relationship to CC/CV Used for Charging Lithium-Ion Batteries: The term CC/CV is also used when charging lithium-ion batteries. The operating principle of the power supply is the same. However, the application and the method for determining the current and voltage settings differ. During charging, operation shifts from constant current to constant voltage as the battery voltage rises. For LED lighting, the power supply is used mainly in the constant-current region. The voltage limit is used for protection. Our Products for charging lithium batteries are introduced on the "AC/DC Power Adapter for Charging Lithium Batteries" page. If you intend to use a Products designed for charging lithium batteries with LED lighting, please consult our sales department in advance.
3 Reasons Why CC/CV Power Supplies Are Often Required for LED Lighting
There are three main reasons why CC/CV power supplies are required for LED lighting. First, they allow the power supply to maintain a constant LED current. Second, they can limit the output voltage to a specified maximum when the output is open. Third, they can also be used with LED modules designed for constant-voltage operation. Many of the inquiries we receive regarding LED lighting also request CC/CV output.
Reason 1: The Power Supply Can Maintain a Constant LED Current
Like a constant-current (CC) power supply, a CC/CV power supply maintains the LED current at the set value while operating in the constant-current region. When all LEDs are connected in series, the current flowing through them remains nearly constant even if there are variations in Vf between individual LEDs or changes in temperature. This helps reduce variations in brightness and the risk of thermal runaway.
Reason 2: The Output Voltage Can Be Limited to a Preset Maximum When the Output Is Open
With a power supply controlled only by constant current (CC), the output voltage rises if the LED is disconnected and the output becomes open. In many power supplies, overvoltage protection is activated and shuts down the output. However, the voltage at which the output shuts down is higher than the voltage when the LED is lit.
A CC/CV power supply maintains the output voltage at the preset maximum voltage even when the output is open. The maximum voltage is set according to the LED configuration. This makes it easier to limit the voltage applied to the LED and surrounding components. Be sure to turn off the power supply before connecting or disconnecting the LED.
Reason 3: Can Also Be Used with Constant-Voltage LED Modules
A CC/CV power supply operates in constant-voltage mode while the output current is below the set value. Therefore, by setting the maximum voltage to the rated voltage of the LED module, LED modules with current-limiting circuits can also be connected. In this case, make sure that the total current consumption of the LED modules is lower than the current setting. If both the maximum voltage and current setting are suitable for both configurations, a single power supply specification can support two configurations. One configuration drives LEDs directly. The other uses LED modules.
How to Choose an AC/DC Power Adapter (LED Power Supply) for LED Lighting: 8 Steps
Choose an AC/DC Power Adapter (LED power supply or LED driver) for LED lighting by following these 8 steps. First, check whether the LED side has a current-limiting circuit.
Step 1: Check the LED Configuration and Whether It Has a Current-Limiting Circuit
Whether the LED side has a current-limiting circuit determines the output type required for the power supply. On this page, a group of LEDs connected in series is referred to as a "string."
| LED-Side Configuration | Suitable Output Type |
|---|---|
| LED modules and LED strip lights with resistors or constant-current circuits on the board, designed to operate at voltages such as 12 V or 24 V | Constant voltage (CV) |
| Boards without a current-limiting circuit, with LEDs connected in series as a single string | Constant current (CC) or CC/CV |
| Boards without a current-limiting circuit, with multiple strings connected in parallel | Constant current (CC) or CC/CV. Also check for current variations between strings. |
Choose CC/CV if you want to limit the open-circuit output voltage to a predetermined value.
Step 2: Determine the Output Voltage and Output Current
For constant voltage (CV), set the output voltage to match the rated voltage of the LED module. Select a power supply with a rated output current greater than the total current consumption of the connected LED modules. When connecting multiple LED modules or LED strip lights to a single power supply, add up the current required by all connected units.
For LED modules that limit current using only resistors, variations in the power supply's output voltage affect the LED current. Be sure to check the accuracy of the power supply's output voltage as well.
For constant current (CC) or CC/CV, set the output current according to the LED's operating current. Determine the operating current based on the brightness and heat dissipation design, ensuring that it does not exceed the maximum rating specified in the LED datasheet.
For constant current (CC) or CC/CV operation, also calculate the total forward voltage (Vf) of the LEDs connected in series. For example, if six LEDs with a Vf of 3 V are connected in series, the total Vf is 18 V. Vf may be higher at low temperatures or due to variations between individual LEDs. It decreases as the LED temperature rises. Make sure that the full range from the minimum to the maximum total Vf is within the power supply's output voltage range.
For CC/CV operation, set the upper voltage limit slightly higher than the maximum total Vf. If the upper voltage limit is too low, the power supply will operate in constant voltage mode, and the LED current will be lower than the set value.
When multiple strings are connected in parallel, the power supply maintains a constant total output current. Current may concentrate in the string with the lowest Vf. The temperature of that string will rise, causing its Vf to decrease further. Also, if one string becomes disconnected, the current flowing through the remaining strings will increase. For parallel connections, consider adding a resistor or constant-current circuit to each string.
Step 3: Allow Sufficient Rated Power Margin
Choose an LED power supply with sufficient rated power margin. The method for calculating the required power varies depending on the output type.
When an LED module with a capacitor on its input side is connected to a constant-voltage (CV) power supply, a large current may flow immediately after the power is turned on. Choose a model with sufficient rated power margin to prevent this current from triggering the power supply's overcurrent protection.
For a constant-current (CC) power supply, calculate the required power by multiplying the set current by the maximum total Vf. For a CC/CV power supply, calculate the required power by multiplying the set current by the upper voltage limit. Make sure that the required power does not exceed the rated power of the power supply. For information on how to determine the appropriate rated power margin, see "How to Choose an AC/DC Power Adapter."
Step 4: Choose the Power Supply Type (AC/DC Power Adapter or Board-Mounted Power Supply)
This page introduces two types of power supplies for LED lighting: AC/DC Power Adapter and board-mounted power supplies. An AC/DC Power Adapter is a power supply placed outside the lighting fixture. A board-mounted power supply (open-frame power supply) is installed inside the lighting fixture. We support CC/CV output through semi-custom or custom designs for both AC/DC Power Adapter and board-mounted power supplies. We specialize in developing and manufacturing compact power supplies. A smaller power supply enables a more compact lighting fixture design.
| Power Supply Type | Key Features | Our Products |
|---|---|---|
| AC/DC Power Adapter | Placed outside the lighting fixture, preventing heat from the power supply from building up inside the fixture. | AC/DC Power Adapter for LED Lighting |
| Board-Mounted Power Supply (Open-Frame Power Supply) | Installed inside the lighting fixture, eliminating the need for space outside the fixture to place the power supply. | Open-Frame AC/DC Power Supplies |
When installing a board-mounted power supply inside a lighting fixture, check the temperature inside the fixture and the power supply mounting method. Board-mounted power supplies do not have an enclosure. The lighting fixture must be designed with structures that prevent electric shock and fire.
Step 5: Check Harmonic Current Standards and PFC
Harmonic current limits apply to lighting equipment at lower power levels than to general electronic equipment. Under the 2018 edition of the international standard IEC 61000-3-2, lighting equipment rated at less than 5 W was exempted from the limits. At the same time, the limits for equipment rated at 25 W or less were expanded to cover all lighting equipment, including LED lighting. Stricter limits apply to lighting equipment rated above 25 W. The 5 W and 25 W thresholds are based on the input power of the lighting equipment, not the output power of the AC/DC Power Adapter.
In Japan, JIS C 61000-3-2:2019 corresponds to the 2018 edition of the international standard. Compliance with this JIS is not legally required under the Electrical Appliances and Materials Safety Act (PSE) or other laws and regulations. However, the Ministry of Economy, Trade and Industry requests that the industry comply with this JIS. The Japan Lighting Manufacturers Association (JLMA) also covers lighting equipment rated at 5 W or higher, including LED lighting.
Compliance with the standard should be verified not only for the AC/DC Power Adapter alone, but also for the lighting equipment combining the AC/DC Power Adapter and LEDs. The standard specifies harmonic current limits, not the inclusion of a PFC circuit. Many lighting products use a PFC (power factor correction) circuit to suppress harmonic currents. The standard is explained in "IEC 61000-3-2 Harmonic Current Regulations."
We have experience developing power supplies that comply with the harmonic current limits applicable to lighting equipment rated at 5W or higher. We also design power supplies that comply with the standards of the countries and regions where they will be sold. Details of our solutions are available in "Lightning Surge, Noise, and Harmonic Countermeasures."
Step 6: Check Safety and EMC Standards
Products sold in Japan require the AC/DC Power Adapter to comply with the Electrical Appliances and Materials Safety Act (PSE). Power supplies used for LED lighting may be required to comply with IEC 61347-1, the safety standard for lighting power supplies (lamp controlgear). EMC standards for lighting equipment include CISPR 15 (EN 55015) for emissions and EN 61547 for immunity. The applicable standards vary depending on the sales region and type of equipment. If compliance with lighting standards is required, we can custom-design a power supply that meets the applicable standards. At the customer's request, we can also handle the process of obtaining safety certifications for AC/DC Power Adapter. For more information about safety standards, see "How Do You Address Safety Standards and Related Issues?"
Step 7: Check the Operating Environment and Lighting Duration
Lighting equipment is often operated for extended periods. The service life of a power supply is primarily determined by the life of its internal aluminum electrolytic capacitors. In general, the life of an aluminum electrolytic capacitor is reduced by approximately half for every 10°C increase in ambient temperature. When using a power supply in an area where heat accumulates, such as above a ceiling, check its operating temperature range and service life. For more information on service life, see "What Is the Difference Between MTBF and Expected Service Life?"
When using a power supply outdoors or near water, also check its waterproof and dustproof ratings. We can customize power supplies that require waterproof and dustproof protection. For more information, see "How to Choose a Waterproof AC/DC Power Adapter" If you plan to use a dimming function or want to minimize flicker, please inform our sales department of the dimming method and LED configuration. We will use the information provided to determine the appropriate power supply specifications.
Step 8: Check the DC Plug and Cable
DC plugs are not standardized. Check the three dimensions - outer diameter, inner diameter, and plug length - as well as the polarity. When used in constant voltage (CV) mode, a long cable may cause a voltage drop and dim the LEDs. When used in constant current (CC) or CC/CV mode, the power supply's output voltage increases by the amount of the cable's voltage drop. Set the CC/CV upper voltage limit higher than the maximum total Vf plus the cable's voltage drop. Also check the cable's length and thickness. For more information about DC plug types, see "What Is a DC Plug?"
Our AC/DC Power Adapter for LED Lighting: ULVU Series (Standard Products)
The ULVU Series is our standard line of AC/DC Power Adapter for LED lighting. We have offered a series of AC/DC Power Adapter for LED lighting since 2021. Our standard products are available in five rated output options: 5W, 12W, 18W, 24W, and 32W. If you require an output above 32W or an output voltage or current not available among our standard products, we can provide a semi-custom or fully customized solution. The ULVU Series features a compact, lightweight design. The main features of the ULVU Series are as follows.
| Item | Description |
|---|---|
| Form Factor | Wall-mount type (plugs directly into an outlet) |
| Output Type | Standard products provide constant-voltage (CV) output. We offer semi-custom solutions for CC/CV output and CC-only output. |
| Harmonic Current Control | Equipped with a PFC (power factor correction) circuit. Designed to comply with the harmonic current standard for lighting equipment (IEC 61000-3-2). |
| Safety Standards | Designed in compliance with IEC 61347-1. Certification status for safety standards such as PSE varies by model (AC plug shape and output voltage). For details, please contact our Sales Department. |
| EMC Standards | Complies with CISPR 15 (emissions) and EN 61547 (immunity) for lighting equipment. |
| Input Voltage | AC 100 V-240 V (allowable range: AC 90 V-264 V) |
| Output Voltage Accuracy | +/-10% (5 W, 12 W, and 24 W), +/-7% (18 W and 32 W) |
| Operating Temperature | 0-40°C (natural air cooling) |
| Protection Circuits | Short-circuit protection, overvoltage protection, and overcurrent protection |
The output voltage and output current for each rated output (standard models) are as follows.
| Rated Output | Output Voltage / Output Current (Standard Models) | Products List |
|---|---|---|
| 5W | 12V 0.5A / 24V 0.25A | 5W Series |
| 12W | 12V 1.0A / 15V 0.8A / 19V 0.63A / 24V 0.5A | 12W Series |
| 18W | 12V 1.5A / 15V 1.2A / 19V 0.95A / 24V 0.75A | 18W Series |
| 24W | 12V 2.0A / 15V 1.6A / 19V 1.3A / 24V 1.0A | 24W Series |
| 32W | 12V 2.5A / 15V 2.0A / 19V 1.63A / 24V 1.33A | 32W Series |
Multiple AC plug types are available for each series. Please check the Products list page for the specifications of each model.
View the List of AC/DC Power Adapter for LED Lighting
Custom Power Supplies for LED Lighting
If standard product specifications do not suit your application, we can provide a solution with our custom power supplies. We design not only the output method, but also the output voltage, output current, power supply size and shape, standards, and operating environment to meet customer specifications. We offer both semi-custom solutions and fully custom solutions designed from scratch. Our semi-custom solutions are based on standard products, with selected specifications modified to meet customer requirements. Semi-customization also includes changes to electrical specifications, such as output characteristics and protection circuits. For the ULVU Series, we offer semi-custom options that change the output to CC/CV output or CC-only output. We also offer semi-custom solutions for LED desk lamps and LED fluorescent lamps (fluorescent-style LED lamps).
Since our founding in 1989, we have specialized in the development and manufacture of compact power supplies. We apply the experience gained from miniaturizing AC/DC Power Adapter to the customization of power supplies built into equipment. Smaller power supplies enable lighting fixtures and equipment enclosures to be designed more compactly. This helps reduce the overall cost of the equipment. Our custom power supply experience covers outputs ranging from 3 W to over 1 kW.
The types of custom power supplies are explained in "What Is Power Supply Customization?" The semi-customization process is explained in "Semi-Customization Workflow"
CC/CV Output of Board-Mount Power Supplies (Open-Frame Power Supplies) for LED Lighting
Board-mount power supplies can be integrated into lighting fixtures. We can customize our board-mount power supplies to support CC/CV output. Our standard board-mount power supplies are introduced on the "Open-Frame AC/DC Power Supplies" page.
Lighting fixtures with built-in board-mount power supplies are also subject to harmonic current standards. We have developed AC/DC Power Adapter and switching power supplies that comply with the harmonic current limits applicable to lighting equipment rated at 5W or higher. For more information on harmonic current standards and PFC, please refer to "IEC 61000-3-2 Harmonic Current Regulations."
Many of our standard board-mount power supplies are Products that comply with standards for information and communications technology equipment and similar devices. If compliance with lighting safety standards or harmonic current standards is required, we can custom-design a board-mount power supply to meet the applicable standards. We can also design the size and shape of the PCB to fit the available space inside the lighting fixture. Please provide our sales department with the required standards, sales regions, and dimensions of the installation space.
Our factory is equipped to apply moisture-proof and dust-proof coatings (conformal coatings) to PCBs. We can therefore supply coated board-mount power supplies for environments where humidity, condensation, or dust may be a concern. For more information, please see "How to Choose a Waterproof AC/DC Power Adapter."
Cases Involving Power Supplies for LED Lighting
Here are examples involving power supplies for LED lighting and modifications to output specifications.
| Case Study | Details |
|---|---|
| Replacement of a Non-PSE-Compliant Adapter | The AC/DC Power Adapter included with an LED light intended for sale in Japan did not comply with the Electrical Appliances and Materials Safety Act (PSE). We analyzed the LED light's voltage and current and semi-customized an existing 24 V product. The replacement with a PSE-compliant product was completed in approximately three weeks. |
| Semi-Custom AC/DC Power Adapter with Special Output Specifications | This case involved special output specifications for which no suitable Products was available on the market. We selected a standard model with similar output specifications and adjusted its output through semi-customization. By utilizing the existing PSE certification, we modified the specifications without incurring initial costs. |
View Custom Power Supply Case Studies
Information to Provide When Contacting Us
When consulting us about power supplies for LED lighting, please provide the following information. We can assist with inquiries about both AC/DC Power Adapter and onboard power supplies. Based on the specifications you provide, we will recommend the most suitable option from among standard, semi-custom, and custom products. You may contact us even if not all specifications have been finalized. If you are unsure about the output method, please provide the datasheet for the LED or LED module, or the model number of the power supply you are currently using.
| Item | Examples of Information |
|---|---|
| Application | Type of lighting fixture and equipment to be used |
| LED Configuration | Number of LEDs connected in series, number of strings connected in parallel, and whether a current-limiting circuit is included |
| Output Type | Whether constant voltage (CV), constant current (CC), or CC/CV is required (if you are unsure, please let us know that it is unknown) |
| Output Voltage and Output Current | For CV, the voltage and maximum current. For CC or CC/CV, the current setting and total Vf range |
| Reference Materials | Datasheets for the LEDs or LED modules, and the model number and specifications of the power supply currently in use |
| Power Supply Form Factor and Size | AC/DC Power Adapter or PCB power supply, required power, and dimensions of the available mounting space |
| AC Plug and DC Plug | AC plug shape, DC plug shape, dimensions and polarity, and cable length |
| Sales Region and Standards | Sales region and required safety and EMC standards |
| Operating Environment | Operating temperature, installation location, whether it will be used outdoors, and whether dimming is required |
Consult Us About Power Supplies for LED Lighting
Glossary of AC/DC Power Adapter for LED Lighting
The main terms used on this page are defined below.
| Term | Definition |
|---|---|
| LED Power Supply (LED Driver) | A power supply used to illuminate LEDs. |
| Constant Voltage (CV) | An output method that maintains a constant output voltage. |
| Constant Current (CC) | An output method that maintains a constant output current. |
| CC/CV (Constant Current/Constant Voltage) | An output method that controls both the output current and output voltage. It operates in constant-voltage mode until the current reaches the set value, then switches to constant-current mode. |
| CC-Only Output | An output controlled solely by constant current (CC). |
| Voltage Limit | The output voltage setting used when a CC/CV power supply operates in constant-voltage mode. |
| Forward Voltage (Vf) | The voltage generated across an LED when current flows through it. |
| String | A group of LEDs connected in series. |
| Direct Drive | Connecting an LED directly to a power supply without using a current-limiting circuit. |
| Thermal Runaway | A phenomenon in LEDs without constant-current control where repeated increases in current and heat generation cause the LEDs to deteriorate or fail. |
| PFC (Power Factor Correction) Circuit | A circuit that shapes the input current waveform to improve the power factor and suppress harmonic current. |
| Board-Mount Power Supply (Open-Frame Power Supply) | A power supply without an enclosure that is designed to be installed inside equipment. |
Frequently Asked Questions About AC/DC Power Adapter for LED Lighting
Q. Are LED power supplies and LED drivers the same thing?
A. Yes. LED power supplies and LED drivers both refer to power supplies used to illuminate LEDs. AC/DC Power Adapter for LED lighting are also a type of LED power supply.
Q. Can LEDs be powered using a standard constant-voltage AC/DC Power Adapter?
A. If the LED has a current-limiting circuit, it can be powered using a constant-voltage AC/DC Power Adapter. If the LED does not have a current-limiting circuit, select a constant-current (CC) or CC/CV AC/DC Power Adapter. Connecting an LED without a current-limiting circuit to a constant-voltage AC/DC Power Adapter may cause the LED to deteriorate due to thermal runaway.
Q. Which power supply should I choose for an LED strip light?
A. Most LED strip lights designed for use at 12V or 24V have current-limiting resistors. In this case, select a constant-voltage (CV) AC/DC Power Adapter that matches the strip light's rated voltage. Choose a power supply with a rated output current greater than the total current consumption of the connected strip lights.
Q. Which should I choose, constant current (CC) or CC/CV?
A. Choose CC/CV if you want to limit the output voltage to a specified value when the output is open. Both constant current (CC) and CC/CV maintain a constant LED current on the power supply side. If you are unsure which is appropriate, please provide our sales department with details of your LED configuration.
Q. Do you offer AC/DC Power Adapter for LED lighting with CC/CV output?
A. Yes. We offer semi-custom CC/CV and CC-only output solutions based on our ULVU Series AC/DC Power Adapter for LED lighting. Standard ULVU Series products have constant voltage (CV) outputs. Please specify the current setpoint and the maximum voltage (or the total forward voltage (Vf) range).
Q. Can board-mount power supplies support CC/CV output?
A. Yes. We can customize board-mount power supplies (open-frame power supplies) installed in lighting fixtures to support CC/CV output. Please provide our sales department with the required current setting and maximum voltage.
Q. How is the maximum CC/CV voltage determined?
A. Set the maximum voltage slightly higher than the maximum total forward voltage (Vf) of the LEDs connected in series. Calculate the maximum total Vf by accounting for low-temperature conditions and variations among individual LEDs. If the cable is long, also account for the voltage drop across the cable. In addition, the power calculated by multiplying the current setting by the maximum voltage must not exceed the rated power of the power supply.
Q. How is the wattage (rated power) of an LED power supply determined?
A. For constant-current (CC) operation, calculate the required power by multiplying the current setting by the maximum total forward voltage (Vf). For CC/CV operation, calculate the required power by multiplying the current setting by the maximum voltage. For constant-voltage (CV) operation, select a model whose rated output current is greater than the total current consumption of the LED modules. Regardless of the operating method, select a model with sufficient rated power capacity.
Q. Can multiple LED strings be connected in parallel to a single constant-current power supply?
A. Yes, but the current may vary among the strings. A string is a group of LEDs connected in series. A constant-current power supply maintains a constant total output current. When connecting strings in parallel, consider adding a resistor or constant-current circuit to each string.
Q. Can you provide power supplies for LED lighting with outputs greater than 32 W?
A. Yes, we can. Our standard AC/DC Power Adapter for LED lighting (ULVU series) range from 5 W to 32 W. If an output greater than 32 W is required, we can provide a custom power supply or board-mounted power supply. Our custom power supply solutions cover outputs ranging from 3 W to over 1 kW. We also offer standard products ranging from 45 W to 200 W for digital signage and small- to medium-sized LED displays (LED video walls). We can also provide semi-custom solutions based on these standard products. For details, see "AC/DC Power Adapter for fixtures and digital signage." Please contact our sales department with the required output power, output method, form factor, sales region, and applicable standards. We will propose a power supply that meets your specifications.
Q. Why are PFC circuits used in power supplies for LED lighting?
A. This is because harmonic current limits apply to lighting equipment at lower power levels than to general electronic equipment. IEC 61000-3-2 and JIS C 61000-3-2 apply to lighting equipment rated at 5 W or higher. Stricter limits apply to lighting equipment exceeding 25 W. In Japan, compliance with this JIS standard is not legally required. However, the Ministry of Economy, Trade and Industry has requested that the industry comply with this JIS standard. A PFC circuit shapes the input current waveform to suppress harmonic currents. Our ULVU series is equipped with PFC circuits.
Summary: Depending on where the LED current is controlled, choose a constant-voltage (CV), constant-current (CC), or CC/CV AC/DC Power Adapter for LED lighting. We offer constant-voltage (CV) output AC/DC Power Adapter for LED lighting as standard products ranging from 5 W to 32 W. If you require CC/CV output, CC-only output, or output greater than 32 W, we can provide a semi-custom or custom solution. We can also provide custom CC/CV output for board-mounted power supplies integrated into lighting fixtures. We offer custom power supplies for standards and operating environments not covered by our standard products. Smaller power supplies enable more compact lighting fixture designs and help reduce the overall cost of the equipment. Please inform our sales department of your LED configuration and required specifications. You can also consult us even if your specifications have not yet been finalized.