Philips Semiconductors

Product specification

74F646/A/74F648/A

Transceivers/registers

1990 Sep 25

5

FUNCTION TABLE

INPUTS

DATA I/O

OPERATING MODE

OE

DIR

CPAB

CPBA

SAB

SBA

An

Bn

74F646/74F646A

74F648/74F648A

X

X

↑

X

X

X

Input

Unspecified*

Store A, B unspecified*

Store A, B unspecified*

X

X

X

↑

X

X

Unspecified*

Input

Store B, A unspecified*

Store B, A unspecified*

H

X

↑

↑

X

X

Input

Input

Store A and B data

Store A and B data

H

X

H or L

H or L

X

X

Input

Input

Isolation, hold storage

Isolation, hold storage

L

L

X

X

X

L

Output

Input

Real time B data to A bus

Real time B data to A bus

L

L

X

H or L

X

H

Output

Input

Stored B data to A bus

Stored B data to A bus

L

H

X

X

L

X

Input

Output

Real time A data to B bus

Real time A data to B bus

L

H

H or L

X

H

X

Input

Output

Stored A data to B bus

Stored A data to B bus

NOTES:

1. H = High–voltage level

2. L

= Low–voltage level

3. X = Don’t care

4.

↑ = Low–to–high clock transition

5. *

= The data output function may be enabled or disabled by various signals at the OE and DIR inputs. Data input functions are

always enabled, i.e., data at the bus pins will be stored on every low–to–high transition of the clock.

ABSOLUTE MAXIMUM RATINGS

(Operation beyond the limit set forth in this table may impair the useful life of the device. Unless otherwise noted these limits are over the

operating free air temperature range.)

SYMBOL

PARAMETER

RATING

UNIT

Supply voltage

–0.5 to +7.0

V

Input voltage

–0.5 to +7.0

V

Input current

–30 to +5

mA

Voltage applied to output in high output state

V

Current applied to output in low output state

74F646A, 74F648A

72

mA

74F646, 74F648

128

mA

Operating free air temperature range

0 to +70

Storage temperature range

–65 to +150

RECOMMENDED OPERATING CONDITIONS

SYMBOL

PARAMETER

LIMITS

UNIT

MIN

NOM

MAX

Supply voltage

4.5

5.0

5.5

V

High–level input voltage

2.0

V

Low–level input voltage

0.8

V

Input clamp current

–18

mA

High–level output current

–15

mA

Low–level output current

74F646A, 74F648A

48

mA

74F646, 74F648

64

mA

Operating free air temperature range

0

+70