DIR

OE

A1

B1

1

2

18

19

To Seven Other Channels

SN54HC245, SN74HC245

SCLS131E – DECEMBER 1982 – REVISED SEPTEMBER 2015

www.ti.com

8 Detailed Description

8.1 Overview

These octal bus transceivers are designed for asynchronous two-way communication between data buses. The

control-function implementation minimizes external timing requirements. The SNx4HC245 devices allow data

transmission from the A bus to the B bus or from the B bus to the A bus, depending on the logic level at the

direction-control (DIR) input. The output-enable (OE) input can be used to disable the device so that the buses

are effectively isolated. To ensure the high-impedance state during power up or power down, OE should be tied

to VCC through a pullup resistor; the minimum value of the resistor is determined by the current-sinking

capability of the driver.

8.2 Functional Block Diagram

Logic Diagram (Positive Logic)

8.3 Feature Description

The SNx4HC245 devices have a wide operating VCC range from 2 V to 6 V with slower edge rates to minimize

output ringing.

8.4 Device Functional Modes

Table 1 lists the function modes of the SNx4HC245.

Table 1. Function Table

INPUTS

OPERATION

OE

DIR

L

L

B data to A bus

L

H

A data to B bus

H

X

Isolation

8

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