I'd like to multiplex rows of LEDs with a constant current sink driver. Should I just use BJTs to switch current into the rows of anodes, or is it better to use FETs, an array of FETs, or the same packaged into a convenient IC? It's easy to find current sinking ICs but I'm not sure what to search for on the sourcing side.
I would like to build something substantially similar to the Rainbowduino, http://nkcelectronics.com/rainbowduino-led-driver-platform.html . The Rainbowduino lights 24 LEDs at once with 24 current sinks and one current source using a Darlington array as the so-called "Super Source Driver", then it lights the next row of 24 and so on for 8 rows. Very standard. I would like to find a substitute for their unavailable-in-the-USA Darlington array. What do I need search for on digikey/Mouser to find an IC containing an array of current sources?