I would like to multiplex 8, 7-segment LED displays with two, 8-bit shift-registers.
The required current for one segment is
20mA. I have no desire to overdrive the leds with 8 times the specified current, that will shorten their precious lifetime.
Since the displays are common cathode, the
TPIC-6B-595 is suitable for sinking current, but I did not find any current-sourcing shift registers, so I need to use an octal buffer/line-driver. I prefer octal-buffers over Transistor/FET arrays.
74**244 datasheets are not clear about the current-sourcing parameters, to me it looks like they are only sinking and cannot handle 7+1 (dot) * ~30 mA =
This is the circuit diagram:
Does anybody knows any solution to my problem?