SN54 / 74LS221
AC WAVEFORMS
B INPUT
tW(in)
≥60 ns
1.3 V
CLEAR
Q OUTPUT
tPLH
tPHL
Q OUTPUT
tPHL
tPLH
A INPUT IS LOW.
TRIGGER FROM B, THEN CLEAR — CONDITION 1
B INPUT
CLEAR
≥ 60 ns
1.3 V
Q OUTPUT
A INPUT IS LOW.
TRIGGER FROM B, THEN CLEAR — CONDITION 2
B INPUT
CLEAR
≥ 50 ns
≥0
ts
TRIGGERED
Q OUTPUT
NOT TRIGGERED
tW(out)
A INPUT IS LOW.
CLEAR OVERRIDING B, THEN TRIGGER FROM B
B INPUT
CLEAR
≥ 50 ns
≥ 50 ns
1.3 V
Q OUTPUT
A INPUT IS LOW.
TRIGGERING FROM POSITIVE TRANSITION OF CLEAR
3V
0V
3V
0V
VOH
VOL
VOH
VOL
3V
0V
3V
0V
VOH
VOL
3V
0V
3V
0V
VOH
VOL
3V
0V
3V
0V
VOH
VOL
Figure 1
FAST AND LS TTL DATA
5-384