Constant current vs. Constant voltage
If you have been buying LED lights, you may have found the terms constant current and constant voltage. You may also have no idea what those terms mean. This publication should clarify the confusion of the constant current against the constant voltage.
Constant current conductors
LEDs usually have a power limiting device (controller or resistors) to prevent LEDs from overloading. A constant current controller is used to regulate the amount of current supplied to an LED or LED matrix to maximize LED life.
If the current is not regulated, the brightness of the LED may fluctuate and the service life may be reduced. The constant current controller is used for LEDs or lighting artifacts that require a stable output current and operate within a voltage range.
Most finished LED products already have a constant current controller or resistors to regulate current. If you are building an LED accessory or replacing a constant current controller, it is important to verify that the output current and voltage of the controller are compatible with the current and voltage of the LEDs.
If your LED product already has a constant current controller or uses resistors in the LED array, you may need a constant voltage power supply.
Constant voltage power supplies
Constant voltage power supplies can be used to power LED products that have resistors or constant current controllers. Products with these current regulation devices may require a constant voltage power supply if they need a different operating voltage than that supplied by the power source (home, vehicle, etc.).
For example, LED light strips are equipped with current regulator yal resistances. If the light strip operates within a direct current (DC) range of 9-14.8 volts, it can be installed inside a vehicle with a 12-volt DC system without using a constant voltage power supply.
For that strip of light to be installed in a home with a 120 volt AC wiring system, the voltage should be reduced and converted from AC to DC with a power supply. In some cases, constant current drivers that match the voltage and current requirements of the product and power supply (home, vehicle, etc.) are available, and a constant voltage power supply would not be required.