Hello,

It seems to be a chapter from this book:
https://www.amazon.com/Digital-Elec...KDYGJDNJ730&psc=1&refRID=DNFHPY6SPKDYGJDNJ730
https://www.amazon.com/exec/obidos/ASIN/0073222755/acmorg-20

Bertus

 

thnaj you

 

Most LEDs don't require 10-50mA to emit light. When used as indicators, high brightness LEDs can sometimes be operated at 1mA or less; even standard LEDs will light with 1mA. They won't be very bright, but they will turn on.

LED characteristics don't change when used with different logic families. You're limited by the current sink/source capabilities of the logic family, but the LEDs still function the same.

Last week I was driving some Kingbright Superbright red LED's from 5V CD4060 outputs via 4K7 resistors and they were too bright to look at!

 

The CD 4049 and CD 4050 can sink about 16 mA when using 5 volts, which can be very bright. They do not source much, but sinking works very well.