What's LED driver?
LED driver is converter which converts the input power voltage to a specific current or voltage to driver LED unit. Typically, the input power voltage of LED driver include high frequency AC voltage, lower voltage direct current, high voltage direct current, low voltage high frequency(like output of electric transformer) ect.
While the output power voltage of LED driver is constant current source which can change voltage according to the positive voltage drop value of LED unit. Main component of LED driver include a switch controller, inductor, switch component(Mosfet), feedback resistor, input filter component, output filter component and so on.
According to the requirements of various using application, circuits with overvoltage protection or input undervoltage protection, or LED open protection or overcurrent protection are also needed.
Classified by driving way
(1) Constant current type
The output current of constant current driver is constant, while the output DC voltage varies in a certain range according to the different value of load resistance. The output voltage will be lower when the load resistance value is smaller; and it will be higher when load resistance value is higher.
Constant current driver is not afraid of short circuit; but prohibit complete open circuit.
Constant current driver is a more ideal solution for LED product, but price is also higher.
Please take care of the maximum current and voltage of the driver, which set a limitation of No. of LED Beads.
(2) Constant voltage type
The output voltage of constant voltage driver is a specific value when all technical data in the circuit is confirmed, while the output current is changeable according the load resistance.
Constant voltage driver is not afraid of open circuit; but prohibit complete short circuit.
To obtain the average brightness with constant voltage driver, we need to add suitable resistor in every group of LEDs. And the brightness will be effected by the change of rectified voltage.