HD74LS640
Waveforms 2
t
THL
G
90 %
1.3 V
3V
10 %
t
ZL
Waveform-a
S
1
close
S
2
open
t
ZH
Waveform-b
S
1
open
S
2
close
1.3 V
~0V
~
~ 4.5 V
~
1.3 V
V
OL
V
OH
t
HZ
t
LZ
S
1,
S
2
close
0.5 V
V
OL
V
OH
0.5 V ~
~ 1.5 V
S
1,
S
2
close
~ 1.5 V
~
0V
10 %
t
TLH
90 %
1.3 V
0V
3V
Notes:
1. Input pulse: t
TLH
≤
15 ns, t
THL
≤
6 ns, PRR = 1 MHz, duty cycle 50%
2. Waveform a is an output by internal conditions like "L" except for the case where an output is
disabled by output control.
3. Waveform b is an output by internal conditions like "H" except for the case where an output is
disabled by output control.
Rev.2.00, Feb.18.2005, page 5 of 6