For project updates, visit http://protofusion.org/picobuck
For purchasing, visit SparkFun Electronics
The PicoBuck is a small and inexpensive 3-channel LED driver. It employs constant-current buck driving which approaches an efficiency of 95%.
You can set drive currents up to around 0.7A (untested!) / channel drive strength by changing the current limiting resistor. The resistor is in a fairly easy-to-solder 0805 package.
More documentation is on the way! If you have any questions, please email firstname.lastname@example.org
The controller IC provides two control modes which may be used individually or in conjunction.
If you don't need to control your LEDs and simply want them to be on all the time, leave the inputs to the PicoBuck disconnected. Internal pullups will drive the LED at full brightness without any connection!
To use digital drive mode, apply a standard 3.3v or 5v PWM signal to any of the 3 inputs. This method gives good brightness resolution over the entire range of brightness when using 8 to 10 bit PWM.
To use analog mode, apply an analog voltage between 0v and 2.5v to any of the 3 inputs. This analog voltage controls how much current the LED is driven at, up to the current set by the current-limiting resistor. Note that the analog method is not effective for the last 20% of current—at this point, the current drops to zero.
Alternatively, you may employ a compound approach using analog dimming for high brightness and PWM dimming for low brightness. This method achives optimal brightness resolution with minimal flicker, but is more challenging to implement in software.
The PicoBuck is currently available for purchase from SparkFun Electronics. Buy one now!