I've used the Allegro A6282
(http://www.allegromicro.com/en/Products/Part_Numbers/6282/index.asp). It
has a shift register input with parallel latch, then constant current
sinks for the LEDs. The currents are all set with a single resistor. You
can vary brightness by either PWM on the OE pin or putting a variable
voltage on the bottom of the current set resistor (instead of grounding
it).

Harold


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