In my application I need to drive LED displays with segment currents as low as 0.5mA and up to 20mA. Doing this with the TLC5926 in standard configuration does not seem to be possible. Is it possible to switch the "R-EXT" between two values so that I could have a lower range and a higher range ? I guess the current through R-EXT is used in a current mirror so whatever resistance variation I might do there has an immediate effect on the current through the on-segments. The datasheet does not describe the implementation (but has lots of confusing formulas, e.g. a polynomial where CC0 relates to 2^5 and CC5 relates to 2^0).