74AC646(1998) Просмотр технического описания (PDF) - Fairchild Semiconductor

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74AC646
(Rev.:1998)

Octal Transceiver/Register with 3-STATE Outputs

Fairchild Semiconductor 

Function Table

Inputs

Data I/O (Note 1)

Function

G DIR CPAB CPBA SAB SBA A0–A7 B0–B7

H

X H or L H or X

X

Isolation

L

H

H

 X

X

X

 X

X

X

X

X

Input

Input Clock An Data into A Register

Clock Bn Data into B Register

L

L

H

X

X

 H

X

L

L

X

An to Bn—Real Time (Transparent Mode)

X

Input Output Clock An Data into A Register

L

H H or L X

H

X

L

 H

X

H

X

A Register to Bn (Stored Mode)

Clock An Data into A Register and Output to Bn

L

L

L

L

X

X

X

 X

X

L

Bn to An —Real Time (Transparent Mode)

L Output Input Clock Bn Data into B Register

L

L

X H or L X

H

L

L

 X

X

H

B Register to An (Stored Mode)

Clock Bn Data into B Register and Output to An

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

= LOW-to-HIGH Transition

Note 1: The data output functions may be enabled or disabled by various signals at the G 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 appropriate clock inputs.

Real Time Transfer

A-Bus to B-Bus

Storage from

Bus to Register

FIGURE 1.

Real Time Transfer

B-Bus to A-Bus

FIGURE 2.

FIGURE 3.

Transfer from

Register to Bus

FIGURE 4.

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