9 Application and Implementation

Note

Information in the following applications sections is not part of the TI component specification, and TI

does not warrant its accuracy or completeness. TI’s customers are responsible for determining

suitability of components for their purposes. Customers should validate and test their design

implementation to confirm system functionality.

9.1 Reference

The SN74HCS165 is a parallel-input shift register, which can be used to reduce the number of required inputs on

a system controller very significantly in some applications. Parallel data is loaded into the shift register, then the

stored data can be loaded into a serial input of the system controller by clocking the shift register.

Multiple shift registers can be cascaded to provide more data inputs while still only using a single serial input to

the system controller. This process is primarily limited by the required data input rate and timing characteristics

of the selected shift register, as defined in the Timing Charactestics and Switching Charactestics tables.

An example block diagram is shown for using a single shift register in the Typical application block diagram

below.

9.2 Typical Application

System

Controller

SER

CLK INH

SH/LD

8-Bit Shift Register

A B C D E F G H

Data Loading Gates

CLK

Control

Logic

Peripheral

DATA[7:0]

Figure 9-1. Typical application block diagram

9.2.1 Design Requirements

9.2.1.1 Power Considerations

Ensure the desired supply voltage is within the range specified in the Recommended Operating Conditions. The

supply voltage sets the device's electrical characteristics as described in the Electrical Characteristics.

The positive voltage supply must be capable of sourcing current equal to the total current to be sourced by all

any transient current required for switching. The logic device can only source as much current as is provided by

Maximum Ratings.

The ground must be capable of sinking current equal to the total current to be sunk by all outputs of the

current required for switching. The logic device can only sink as much current as can be sunk into its ground

connection. Be sure not to exceed the maximum total current through GND listed in the Absolute Maximum

Ratings.

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SN74HCS165

SCLS828 – AUGUST 2020

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