i am intersting for CONSTANT-CURRENT shift register for example TLC5916 http://focus.ti.com/lit/ds/symlink/tlc5916.pdf
all i want to do is to connect 8 RED LED (1.63 - 2.03v) with the outputs of a shift register without resistors (between of them).
as i saw datasheet it needs a resistor (Rext) to control current
i'll supply IC with 5V i want 20ma current for led led needs 1.63 - 2.03v.
what resistor do i need o add to ic? and how i caclulate it?