Transistor Constant Current Led Driver. The t2 transistor can be bc547 if you use only usual leds the 20ma versions but it is recommended to use bd135 bd137 or bd139 because they have a higher power dissipation. Product overview type number package name version ncr420pas dfn2020d 6 sot1118d ncr421pas.
Led drivers monolithically integrate transistors diodes and resistors to function as a constant current regulator ccr for linear led driving in a variety of automotive industrial and consumer applications. If the led has a higher power requirement then it is best to use an npn transistor as a driver. The t2 transistor can be bc547 if you use only usual leds the 20ma versions but it is recommended to use bd135 bd137 or bd139 because they have a higher power dissipation.
This circuit allows you to use any voltage between 2v and 24v to drive almost any type of led with power consumption up to 5w.
Transistor mosfet constant current driver like the single transistor current regulators this type of led driver is also a linear supply. This circuit allows you to use any voltage between 2v and 24v to drive almost any type of led with power consumption up to 5w. Led drivers monolithically integrate transistors diodes and resistors to function as a constant current regulator ccr for linear led driving in a variety of automotive industrial and consumer applications. Some additional advantages have to do mainly with the circuit s efficiency which many times is not a balancing factor at all.
