Comparison of LED constant current driver and constant voltage driver
As far as LED lamp beads, strips or modules are concerned, one way to ensure the consistency of their brightness is to use a professional LED driver. There are two types of drives:
Constant voltage driver-This type of driver has a fixed voltage output, which depends on the rated voltage of the LED. Its output voltage is fixed. The current output of the drive will have the maximum rating. If the actual current demand of the circuit does not exceed its current rating range, it can work normally.
Constant current driver-This type of driver has a fixed current output, which depends on the current required by the LED. The voltage output is variable. The voltage will vary with the number of LEDs used. Make sure that the actual voltage is within the rated voltage range.
The LED driver can be board mounted or external/internal (external). In some cases, AC/DC power can also be used, depending on the LED used. To understand the required voltage and current specifications, please check the relevant LED specifications.
The following is a supplementary description of the typical uses of constant current and constant voltage applications.
Constant current drivers can generally extend the life expectancy of LEDs and improve continuity of light, especially when dimming is required. LED is a non-linear material, so it is difficult to maintain consistency. A small increase in voltage will cause the current to increase exponentially, and if it is not adjusted properly, it can sometimes damage the LED. In addition, thermal runaway is not easy to occur in the constant current circuit, which improves the reliability of the LED for long-term operation. Thermal runaway refers to the fact that the heat generated inside or outside the component itself causes the bias, which causes the forward resistance to drop (reduces the voltage difference) and increases the current through the device. Although the constant voltage driver is adjusted with voltage as a parameter, the voltage drop of the LED itself may fluctuate as the LED is turned on or the temperature rises. Constant current drivers are more common in pure series circuits, but they can also be used in some series-parallel combination circuits. Please note that in a combined constant current circuit, when one or more LEDs are burned, damaged or removed from the light strip, the remaining LEDs may be damaged, because the fixed current may be too high for the remaining LEDs.
Constant voltage drivers are more common in multi-color displays, as well as series-parallel combination LED strips with built-in resistors or other current limiting devices. Addressable LEDs usually also need to use constant voltage drivers, because such products usually configure a constant current driver chip in each LED. In comparison, the constant voltage driver is more convenient to operate, because as long as the current of the driver is equal to or higher than the total current when the LED is in use, you can add or remove LEDs in the circuit at will.
Although it is recommended to use LED drivers for LED lighting, the industry generally uses such industrial power supplies to "drive" LED lighting. Although these power supplies have very tight voltage output tolerances, they may not be able to provide specific LED lighting specifications such as THD (Total Harmonic Distortion) and ripple specifications. For more specialized LED drivers, the output of industrial power products may have some THD (total harmonic distortion) and ripple, but it is generally not clearly stated in the specification, so it is impossible to know.
For further information, please refer to ☞Comparison between constant voltage LED driver and AC/DC power supply.
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