SN54221, SN54LS221, SN74221, SN74LS221

DUAL MONOSTABLE MULTIVIBRATORS

WITH SCHMITT TRIGGER INPUTS

SDLS213B − DECEMBER 1983 − REVISED NOVEMBER 2004

11

POST OFFICE BOX 655303

PARAMETER MEASUREMENT INFORMATION

B†

CLR

Q

3 V

3 V

0 V

0 V

VOH

VOL

≥ 50 ns

CONDITION 4: TRIGGERING FROM POSITIVE TRANSITION OF CLR

≥ 50 ns

A‡

CLR

Q

Q

3 V

3 V

0 V

0 V

VOH

VOH

VOL

VOL

tw

≥ 60 ns

tPLH

tPHL

tPHL

tPLH

CONDITION 5: TRIGGER FROM A, THEN CLR

A‡

Q

Q

3 V

0 V

VOH

VOH

VOL

VOL

tw

CONDITION 6: TRIGGER FROM A

tw

† A is low.

‡ B and CLR are high.

NOTES: A. Input pulses are supplied by generators having the following characteristics: PRR

≤ 1 MHz, ZO ≈ 50Ω; for SN54/74221, tr ≤ 7 ns,

tf ≤ 7 ns, for SN54/74LS221, tr ≤ 15 ns, tf ≤ 6 ns.

B. All measurements are made between the 1.5-V points of the indicated transitions for the SN54/74221 or between the 1.3-V points

for the SN54/74LS221.

Figure 1. Switching Characteristics (Continued)