Constant current sources
Constant current sources serve as current converters and power supply for Highpower-LEDs. LEDs or light emitting diodes are non-linear resistors and run with low-level direct current, that flows in one direction only. Thus, they cannot stand high current, alternating power or power fluctuations. For example, the German electricity grid provides 230V AC/alternating current, a car battery 12V. Therefore, a ballast is necessary to compensate the power out of socket or car battery and to limit the output power (in Ampere), that runs the Hi-power-LEDs. If those LEDs were directly connected to 230V-grid electricity, they might flicker, be damaged and blow. The LED-transformer, a so-called constant current source, regulates the power supply of high-performance LEDs.
How does a constant current source work?
A constant current power supply functions as current controller, that means it regulates the input power and continuously delivers power in equal amount to one or more Highpower-LEDs. A constant current transformer as ballast unit allows series connection of several such LEDs. In order to limit the power running the high-performance LED and to keep it constant, the constant current source automatically changes its internal resistance and voltage. A constant current power supply unit as transformer for HighPower-LEDs provides a constant power while voltage ist variing. It makes the conventional series resistor for operating LEDs redundant.
Constant current and constant voltage source – what is the difference?
Besides constant current sources there is a further type of switching power supply: a constant voltage source. As the name suggests, these transformers provide a constant voltage (Volt). In contrast to constant current sources amperage variies while voltage is consistent. Furthermore, a series resistor is needed to limit power. Of course, it depends on the particular application, to determine which transformer is the appropriate one. Constant current sources are a useful and uncomplicated means for current matching. Without great effort they ensure to run high-performance LEDs with current sources that deliver alternating input voltage like in cars.