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2

Unit Loading/Fan Out

Functional Description

The 74F823 device consists of nine D-type edge-triggered

flip-flops. It has 3-STATE true outputs and is organized in

broadside pinning. The buffered Clock (CP) and buffered

Output Enable (OE) are common to all flip-flops. The

flip-flops will store the state of their individual D inputs that

meet the setup and hold times requirements on the

LOW-to-HIGH CP transition. With the OE LOW the con-

tents of the flip-flops are available at the outputs. When the

OE is HIGH, the outputs go to the high impedance state.

Operation of the OE input does not affect the state of the

flip-flops. In addition to the Clock and Output Enable pins,

the 74F823 has Clear (CLR) and Clock Enable (EN) pins.

When the CLR is LOW and the OE is LOW, the outputs are

LOW. When CLR is HIGH, data can be entered into the

flip-flops. When EN is LOW, data on the inputs is trans-

ferred to the outputs on the LOW-to-HIGH clock transition.

When the EN is HIGH, the outputs do not change state

regardless of the data or clock inputs transitions. This

device is ideal for parity bus interfacing in high perfor-

mance systems.

Function Table

L

= LOW Voltage Level

H

= HIGH Voltage Level

X

= Immaterial

Z

= High Impedance

 = LOW-to-HIGH Transition

NC

= No Change

Logic Diagram

Please note that this diagram is provided only for the understanding of logic operations and should not be used to estimate propagation delays.

Pin Names

Description

U.L.

HIGH/LOW

Data Inputs

1.0/1.0

20

µA/−0.6 mA

OE

Output Enable Input

1.0/1.0

20

µA/−0.6 mA

CLR

Clear

1.0/1.0

20

µA/−0.6 mA

CP

Clock Input

1.0/2.0

20

µA/−1.2 mA

EN

Clock Enable

1.0/1.0

20

µA/−0.6 mA

3-STATE Outputs

150/40 (33.3)

−3 mA/24 mA (20 mA)

Inputs

Internal Output

Function

OE CLR EN CP D

Q

O

HHL

H

X

NC

Z

Hold

HHL

L

X

NC

Z

Hold

H

H

H

X

X

NC

Z

Hold

LH

H

X

X

NC

NC

Hold

H

L

X

X

X

H

Z

Clear

L

L

X

X

X

H

L

Clear

HHL

 H

H

Z

Load

HHL

 H

L

Z

Load

LH

L

 L

H

L

Data Available

LH

L

 H

L

H

Data Available

L

H

L

H

X

NC

NC

No Change in Data

L

H

L

L

X

NC

NC

No Change in Data