LED Drivers: Constant Current or Constant Voltage Requirements
In order for typical LEDs to work, they require a DC voltage source. Depending upon how many LEDs are being powered and how they are wired, they will best employ either a constant voltage or constant current supply.
LED arrays with a built-in driver module will only need a constant voltage supply, which delivers a fixed output voltage at any current load up to its maximum rating. Other than application-specific packaging, such as moisture resistance or water proofing, these are ordinary switching power supplies.
LED arrays consisting of multiple strings may require a constant current driver which talks directly to the LED strings. In these, the output current is fixed, instead of the voltage. As the current drawn by the LEDs change, the output voltage will vary, within a preselected min-max voltage range.