On Wed, Mar 6, 2019 at 4:53 PM Dwayne Reid wrote: > I have considered using 4- 74HC595 shift-register chips as a > high-side driver by shifting the ground pin by 3.5 Vdc or so, then > using simple level-shift circuits for the data, clock, strobe > pins. But the maximum package current for the HC595 is 70mA and I > want to drive the segments at 20mA each (140mA total per package). The output of a 74HC595 won't go below it's ground pin. Are you sure this would turn off the LEDs sufficiently? I suggest: bias all the LEDs "on" with resistors to the desired current. Then use the open-drain xPIC6C595 (where x varies per manufacturer) to short out the unwanted segments. --=20 Regards, Mark markrages@gmail --=20 http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist .