While plan led lights at home, we often ponder: should we choose a constant voltage (CV) or constant current (CC) power supply? In this discussion, "constant voltage (CV)" and "constant current (CC)" refer to whether the output remains stable in voltage or current. This article will help you choose the right solution for your needs by comparing their differences, advantages, limitations, and practical applications. Let's dive into understanding which power supply type best suits your home lighting projects.

Constant-Current LED Drivers

How LEDs Work

Before understanding constant current drivers, we need to understand how LEDs work. LEDs (light-emitting diodes) are semiconductor devices that produce light when current flows through them. However, they require precise control of current and voltage to operate efficiently. Without this control, LEDs can become unstable or overheat. Unlike conventional light bulbs, LEDs are sensitive to fluctuations in current flow. Even small changes can affect brightness or shorten lifespan.

Typical Applications

Many 230V LED lamps available on the market integrate constant current circuit. For example, bulbs, spotlights, and integrated downlights typically have built-in constant-current circuit. Larger panel lights, small circular panel lights, and outdoor fixtures, however, often use external led driver. In such cases, users generally do not need to separately select led driver—purchasing the lamp inherently includes its corresponding constant current circut. If a lamp with a built-in driver fails, the entire lamp is replaced. Conversely, if an externally led driver malfunctions due to a faulty driver, only the external power supply needs replacement.

Limitations in DALI Smart Lighting

In DALI lighting systems, when using 230V lamps, the positive terminal of one lamp must be connected to the negative terminal of another in multi-fixture configurations. This approach not only raises wiring costs but also significantly increases the complexity of the installation.

Additionally, since each lamp with a constant-current driver occupies a unique DALI address, the cost of the master control equipment rises proportionally with the number of fixtures. Furthermore, the 230V input voltage must be converted to the LED operating voltage (typically 3V, 6V, 9V, 12V, or 15V), requiring the driver to handle higher energy conversion losses.

Summmary For Constant-Current LED Drivers

Therefore, constant-current solutions are generally recommended for:

1. High-power applications, such as streetlights, high bay lights.
2. Scenarios where external power supplies may fail and require replacement.
3. The existing lighting system uses external constant-current drivers, and plan to upgrade them to DALI-compatible constant-current drivers

Constant-Voltage LED Drivers

How a Constant-Voltage Driver Works

A constant-voltage LED driver delivers a fixed voltage output, 12 V or 24 V,36V. No matter how many led lights connect, output voltage still fixed. These drivers are particularly suitable for applications where multiple LEDs are connected in parallel. The power consumption depends on the number of LEDs connected to the driver.

Each LED unit requires additional components, such as led strip need resistors, to regulate the current. Our LED spot module has has own IC insid to ensure the constant current for COB, which can keep the same brightness. In contrast to led strip, our spot module solution reduces the voltage drop problem caused by line loss. 

Note: Constant-voltage drivers are ideal for LED strips and modules with integrated current regulation. They offer easy installation and high flexibility.

Advantages of constant voltage drivers

Simplified Installation:
Constant voltage operation eliminates complex power calculations. Simply match the power supply’s rated wattage to the total load wattage. For example, a 100W power supply with a 20% safety margin can safely support loads up to 80W. With TILLUME power supplies, no additional margin is required—we pre-allocate a 20% headroom in our designs. For instance, a 100W-rated unit can sustain 120W. If using our 6W or 8W fixtures, a single power supply supports up to 19×6W or 14×8W loads.

Cost Efficiency:
A single constant voltage power supply can drive an entire lighting group. In DALI systems, each power supply occupies only one address (up to 64 addresses per system), even when controlling multiple fixtures. Since most residential KNX-based smart lighting systems require KNX-to-DALI gateways—whose costs scale with the number of addresses—constant voltage solutions reduce address consumption and lower overall system costs compared to constant current drivers.

Selection Criteria for the Right LED Driver

LED Requirements (Current, Voltage, Wattage)

Choosing the right LED driver begins with a thorough analysis of your LEDs' technical requirements. Each LED has specific parameters that must be considered to ensure optimal performance. These include current, voltage, and wattage.

T ip: Always check the technical specifications of your LEDs. Incorrect voltage or an inappropriate current can damage the LEDs or shorten their lifespan.

LEDs also benefit from their high luminous efficacy and reduced energy consumption. They produce more light per watt than conventional lighting sources, thereby reducing electricity costs and CO₂ emissions. Their long service life also minimizes maintenance and replacement costs.

Project requirements (e.g., dimmability, number of LEDs)

In addition to the technical requirements of the LEDs, the specific requirements of your project also play a crucial role. Consider which functions and features are important for your application.

• Dimmability: If you want to adjust the brightness of your LEDs, you need a driver that supports dimming. Like DT6 or DT8 driver, or MDT led controllers, which offer flexible solutions with preset dimming schedules. These enable autonomous operation without the need for complex lighting management systems.
• Number of LEDs: The number of LEDs in your circuit influences the choice of driver. Constant voltage drivers are suitable for parallel arrangements, while constant current drivers are better suited for single LEDs or modules without integrated current regulation.

Note : Plan your project carefully, considering both the technical requirements of the LEDs and the desired features to find the best solution.