LEDs with high brightness (high power LEDs) offer a lumens / watt ratio very higher than traditional incandescent or fuorescent lamps:
This type of LED has to be driven by a constant current source: 3W LEDs have a nominal current value of 350mA. I designed a module to drive a single 3W LED and to change its brightness using a PWM signal.
R2 resistor and L1 inductor form – in conjuction with U1 device – a self-oscillating buck converter.
R1 resistor and T1 transistor allow a PWM digital signal (generated, for example, by a microcontroller) to drive the ADJ PIN of the ZXLD1350 IC and therefore the brightness of the connected LED.
The PCB has all the components in SMD package, except the supply, PWM and output connectors:
All the project was designed using the free version of Eagle CAD and the files (.sch, .brd and the partlist) are available on Github.
Here’s a photo about the first prototype:
And a short video about its working:
Thanks to my friend Mauro Alfieri for his review about my driver!