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74ACT323CW

8-Bit Universal Shift/Storage Register with Synchronous Reset and Common I/O Pins

Fairchild Semiconductor 

Functional Description

The ACT323 contains eight edge-triggered D-type flip-flops

and the interstage logic necessary to perform synchronous

reset, shift left, shift right, parallel load and hold operations.

The type of operation is determined by S0 and S1 as shown

in the Mode Select Table. All flip-flop outputs are brought

out through 3-STATE buffers to separate I/O pins that also

serve as data inputs in the parallel load mode. Q0 and Q7

are also brought out on other pins for expansion in serial

shifting of longer words.

A LOW signal on SR overrides the Select inputs and allows

the flip-flops to be reset by the next rising edge of CP. All

Mode Select Table

other state changes are also initiated by the LOW-to-HIGH

CP transition. Inputs can change when the clock is in either

state provided only that the recommended setup and hold

times, relative to the rising edge of CP, are observed.

A HIGH signal on either OE1 or OE2 disables the 3-STATE

buffers and puts the I/O pins in the high impedance state.

In this condition the shift, load, hold and reset operations

can still occur. The 3-STATE buffers are also disabled by

HIGH signals on both S0 and S1 in preparation for a paral-

lel load operation.

SR

L

H

H

H

H

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

= LOW-to-HIGH Clock Transition

Inputs

S1

S0

X

X

H

H

L

H

H

L

L

L

Response

CP







Synchronous Reset; Q0–Q7 = LOW

Parallel Load; I/On→Qn

Shift Right; DS0→Q0, Q0→Q1, etc.

Shift Left; DS7→Q7, Q7→Q6, etc.

X Hold

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