HD74LS221

Rev.3.00, Jul.15.2005, page 4 of 8

Switching Characteristics

Item

Symbol

Inputs

Outputs

min.

typ.

max.

Unit

Condition

A

Q

—

45

70

B

Q

—

35

55

ns

A

Q

—

50

80

B

Q

—

40

65

ns

Clear

Q

—

35

55

ns

Propagation

delay time

Clear

Q

—

44

65

ns

Ω

70

120

150

Ω

20

47

70

Ω

600

670

750

ns

Ω

Output pulse

width

A or B

Q or

Q

6

6.7

7.5

ms

µF,

Ω

Ω

Caution in use

In order to prevent any malfunctions due to noise, connect a high frequency performance capacitor between Vcc and

GND, and keep the wiring between the External components and Cext, Rext/Cext pins as short as possible.

Testing Method

Test Circuit

Cext

+–

Load circuit 1

Same as Load Circuit 1.

A Input

P.G.

Ω

B Input

P.G.

Ω

CLR Input

P.G.

Ω

Q

Q

Rext

/Cext

Rext

Cext

CLR

B

A

Notes:

1.

2.

All diodes are 1S2074(H).