The major advantage of using parallel strings is that a number of LED modules can be powered by a single power supply. In parallel circuits, the output voltage remains the same among all LED modules. Thus a constant voltage power supply can operate a large number of LED modules or light fixtures as long as the total output power remains within the limit of the maximum current that can be supplied.
This feature gives designers great flexibility with respect to the number of modules or fixtures to be connected to the power supply. The use of a CV driver as a remote-mounted power supply substantially reduces power supply cost and eliminates the need for additional spaces or housings to accommodate the bulky power supplies.
As a result, architectural lighting systems can be made with a very slim form factor and seamlessly integrated into various structures. This type of lighting systems includes cove lights, linear lighting profiles, and undercabinet lights which generally use LED tape lights as the light sources. All constant voltage LED power supplies meet the safety extra low voltage SELV and the Underwriters Laboratories UL Class 2 requirements which define that no touchable conducting parts of an electrical system have a voltage relative to ground, or across any two points above 60 V DC, or This feature makes CV drivers the mainstream power supply solution for the low voltage landscape lighting market.
The current limiting device of a constant voltage LED module typically regulates current by dissipates excess power, making constant voltage LED drivers less efficient than constant current LED drivers. In addition to line-voltage dimming using phase control dimmers, constant voltage drivers can only be PWM pulse-width modulation dimmed, while constant current drivers support both PWM and CCR constant-current reduction dimming.
Constant voltage LED drivers more often than not have less efficient ripple filtering, which means light fixtures operated by this type of driver can have a large percentage of flicker, hence they are not suited to ambient and task lighting applications.
Subscribe to Updates and Newsletters. Constant Voltage vs. Constant Current Don't be confused by those "constant voltage vs. These drivers are required when the driver is used to power the LED load directly.
With constant current drivers, the output current is fixed by the driver, while the output voltage varies depending on the LED load. The more LEDs the driver is powering, the greater the output voltage will be, up to a maximum as allowed by the driver specifications.
The Class P program allows luminaire manufacturers the flexibility to source alternate LED drivers without the need to retest for UL certification. Download Class P Sell Sheet. These drivers are required when another LED current controlling device, such as a built in resistor or regulating driver is already connected directly to the LED load.
With constant voltage drivers, the output voltage remains fixed typically at 12Vdc or 24Vdc at any current level, up to a maximum allowable current, as dictated by the maximum output power of the driver. In order to correctly select a constant voltage driver, you need to know the following:. We may need to change this agreement from time to time, and you agree to be bound by future versions. Ownership: All images are protected by U. We reserve all rights not granted in this agreement.
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That way you wont need an external circuit to do the dimming. Add a comment. Active Oldest Votes. Just be aware that it won't work over the very lowest dimming range. On the data sheet, it specifies that it works with a "minimum conductance angle" of 30 degrees. If this is the case, I should understand that for a "Constant Current" LED power supply that is advertised as In: VAC OutV - 29V, ma this means, as I dim from the wall mains power to zero, the voltage will approach 17V, and the current will approach 0, and as I dim up from the wall, the voltage will approach no more than 29V, and the current will approach no more than ma.
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