74ACT818 Просмотр технического описания (PDF) - Fairchild Semiconductor

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74ACT818

8-Bit Diagnostic Register

Fairchild Semiconductor 

Pin Descriptions

Pin Names

D0–D7

SDI

DCLK

MODE

PCLK

OEY

SDO

Y0–Y7

Description

Data Inputs

Serial Data Input

Diagnostics Clock

Control Input

Pipeline Register Clock

Output Enable Input

Serial Data Output

Data Outputs

Functional Description

Data transfers into the diagnostic register occur on the

LOW-to-HIGH transition of DCLK. Mode and SDI deter-

mine what data source will be loaded. The pipeline register

is loaded on the LOW-to-HIGH transition of PCLK. Mode

selects whether the data source is the data input or the

diagnostic register output. Because of the independence of

the clock inputs, data can be shifted in the diagnostic regis-

ter via DCLK and loaded into the pipeline register from the

data input via PCLK simultaneously, as long as no setup or

hold times are violated. This simultaneous operation is

legal.

Function Table

Inputs

Outputs

 SDI MODE DCLK PCLK SDO Diagnostic Reg. Pipeline Reg.

X

L

X

S7

SI<SI − 1,

NA

X

L

L

H

X



X

S7

L

SO<SDI

NA

SI<YI

PI<DI

NA

X

H

X

 SDI

NA

PI<SI

H

H

X

H

Hold

NA

H = HIGH Voltage Level

L = LOW Voltage Level

X = Immaterial

= LOW-to-HIGH Clock Transition

Operation

Serial Shift; D7–D0 Disabled

Normal Load Pipeline Register

Load Diagnostic Register from Y;

DI Disabled

Load Pipeline Register from

Diagnostic Register

Hold Diagnostic Register; DI

Enabled

Diagnostic Register

Block Diagram

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