Problem 2
(6 points)
Read the data given in the table below:
Comparison of Logic Families
Logic Family Parameter Basic Gate Fan out Power dissipation (mW) Noise Immunity Propagation delay (ns) Clock Rate for FFs (MHz)
TTL 74L 74LS NAND 20 20 1 2 Very Very Good Good 33 9.5 3 45
74
74H
745
74AS 74ALS
10 10 Very Good 10 35
10 22 Very Good
10 19 Very Good 3 125
40 10 Very Good 1.5 175
20 1 Very Good 4 50
Logic Family Parameter Basic Gate Fan out Power dissipation (mW) Noise Immunity Propagation delay (ns) Clock Rate for FFs (MHz)
CMOS 74HCT
74C
74HC NOR OR NAND
74AC
74ACT
50 20 1.01 0.6025 Very Good Very Good 70 18 10 60
20 0.6025 Very Good 18 60
50 0.755 Very Good 5.25 100
50 0.755 Very Good 4.75 100
a) Choose which TTL family has the maximum fan-out?
b) Choose which logic family, TTL or CMOS, has more fan-out in general?
c) Choose which TTL family has the maximum power dissipation?
d) Choose which logic family, TTL or CMOS, dissipates less power in general?
e) Choose which TTL family is the fastest?
f) Choose which CMOS families are the fastest?