Choose A Constant Current Or Constant Voltage LED Driver?

This article discusses two driving methods for LED lighting: constant current driver and constant voltage driver. Choosing which driver depends on the application requirements. Constant current driver is suitable for large-scale applications, while constant voltage driver is suitable for cost-sensitive scenarios that require flexible adjustment of the number of LEDs.

Constant Current or Constant Voltage LED Driver: Which is Better?

If you have decided to install LED lighting, you may have noticed that there are a variety of ways to power it. One of the biggest decisions is choosing which Constant current driver still Constant voltage driver . In some cases, both can work, but each has advantages and disadvantages.

Constant voltage driver

In LED lighting systems, constant current dimming is a common dimming method. Typical LEDs require a certain current when working, and constant current dimming keeps the output current unchanged, ensuring that the LED works normally at its rated operating current. When the brightness needs to be changed, the power supply adjusts the output current, and the LED's operating current also changes accordingly, thereby achieving brightness adjustment.

The basic principle of constant voltage dimming:

● Power supply: Constant voltage dimming LED light strips usually receive direct current (DC) voltage from a power supply.

● LED series connection: LED lights are usually connected in series in a circuit to form an LED light strip.

● Voltage regulation: The power supply provides a constant voltage to the LED. When dimming is required, the power supply will adjust the output voltage to change the operating voltage of the LED.

● LED brightness adjustment: The brightness of the LED is proportional to its operating voltage. By adjusting the voltage output by the power supply, the operating voltage of the LED can be changed, thereby achieving LED brightness adjustment.

● Dimming controller: In order to achieve accurate dimming of constant voltage dimming LED strips, a dimming controller is usually used. The dimming controller can receive external signals (such as remote controls, switches, smart home systems, etc.) and change the brightness of the LED by adjusting the output voltage.

● PWM dimming: A commonly used dimming method is pulse width modulation (PWM). That is, the brightness of the LED is adjusted through a fast switching circuit. The PWM dimming controller will periodically change the power-on time of the LED to make the LED work at different brightness.

A constant voltage driver works by providing a fixed voltage to the LEDs. It maintains the overall power level by adjusting the current output. If your LEDs or LED strips are clearly marked for a specific voltage, then a constant voltage driver may be your best choice. Constant voltage drivers are usually available in 12V or 24V. Constant voltage drivers are less expensive than constant current drivers because they require fewer components. Constant voltage drivers are also easier to replace LEDs. You can add or remove LEDs as needed, and as long as the voltage requirements remain the same, the driver should be able to increase or decrease the current to accommodate the new setup (provided that the current requirements of all LEDs are within the range of the driver). When using them, your LEDs need to have built-in over-current protection (OCP). Usually, this is achieved with a resistor, as marked in the red circle below:

When using a constant voltage driver, if the voltage requirements change slightly (such as when temperature changes), the current may change significantly in order to maintain the same power level. This can easily exceed the current limit of the LED, causing fluctuations in light output, shortened life, or even direct damage to the LED . Therefore, it is very important to have OCP on the LED. If your LED is designed with this in mind, it's safe to use a constant voltage driver.

Constant current driver

A constant current driver works by providing a fixed current to the LED. It does this by adjusting the voltage output to maintain the overall power level. Although it is easier to precisely control the current output than the voltage output, it requires more components and is therefore usually more expensive. However, the LEDs will generally have a more stable light output, higher reliability, and better efficiency when using a constant current driver. The downside is that constant current drivers are more cumbersome when making lighting changes. Changing the number of LEDs will naturally change the current requirements of the system, which may cause the driver to increase the voltage to a level that is unsafe for the LEDs, so the driver will need to be adjusted or replaced based on the new current requirements.

The basic principle of constant current dimming:

● Power supply: Constant current dimming LEDs usually receive direct current (DC) current from a power supply.

● LED series connection: LED lights are usually connected in series in a circuit to form LED light strips or LED modules.

● Current regulation: The key to constant current dimming is to keep the LED's operating current constant. The power supply provides a stable current to the LED to ensure that the LED works normally at the rated current.

● LED brightness adjustment: The brightness of the LED is proportional to its operating current. By adjusting the current output by the power supply, the operating current of the LED can be changed, thereby achieving LED brightness adjustment.

● Dimming controller: In order to achieve accurate dimming of constant current dimming LED strips, a dimming controller is usually used. The dimming controller can receive external signals (such as remote controls, switches, smart home systems, etc.) and change the brightness of the LED by adjusting the output current.

● Linear dimming: Constant current dimming usually adopts linear dimming. By adjusting the output current, the LED brightness can be linearly changed. This helps to keep the color temperature of the LED relatively stable at different brightness levels.

Constant current drivers are a good choice for most large scale applications, especially in terms of power usage and maintenance costs. If your LEDs do not have built in overcurrent protection, you will need to use a constant current driver, as shown below. Note that there is no resistor between the LED strips, so a constant current driver must be used.

LEDs that require constant current should list the current requirements as well as the voltage range they can accept to avoid damage. Make sure the driver you choose meets the current requirements and that the voltage output is within the specified range for the LED to prevent overdriving the LED.

In short: constant current drivers are more efficient and less likely to damage your LED investment, but are more cumbersome to adjust. Constant voltage drivers are cheaper and easier to adjust for the number of LEDs, but are more likely to damage the LEDs, use more energy, and require the LEDs to have built-in overcurrent protection. Which you choose depends on your application needs.

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