SN54/74LS242 • SN54/74LS243
AC CHARACTERISTICS (TA = 25°C, VCC = 5.0 V)
Limits
LS242
LS243
Symbol
Parameter
Min Typ Max Min Typ Max Unit
tPLH
tPHL
Propagation Delay, Data to Output
9.0 14
12 18
12 18
12 18
ns
tPZH
Output Enable Time to HIGH Level
15 23
15 23
ns
tPZL
Output Enable Time to LOW Level
20 30
20 30
ns
tPLZ
Output Disable Time from LOW Level
15 25
15 25
ns
tPHZ
Output Disable Time from HIGH Level
10 18
10 18
ns
Test Conditions
CL = 45 pF,
RL = 667 Ω
CL = 5.0 pF,
RL = 667 Ω
AC WAVEFORMS
VIN
1.3 V
tPLH
VOUT
1.3 V
1.3 V
tPHL
1.3 V
Figure 1
VIN
1.3 V
tPHL
VOUT
1.3 V
1.3 V
tPLH
1.3 V
Figure 2
TO OUTPUT
UNDER TEST
VCC
RL
SW1
5 kΩ
CL*
SW2
VE
VE
VOUT
1.3 V
1.3 V
tPZL
1.3 V
tPLZ
≈ 1.3 V
0.5 V
VOL
Figure 3
VE
VE
VOUT
1.3 V
tPZH
1.3 V
1.3 V
tPHZ
≥VOH
≈ 1.3 V
0.5 V
Figure 4
SWITCH POSITIONS
SYMBOL
tPZH
tPZL
tPLZ
tPHZ
SW1
Open
Closed
Closed
Closed
SW2
Closed
Open
Closed
Closed
Figure 5
FAST AND LS TTL DATA
5-395