VCC

GND

0.1 µF

5.0 V

RI+

RI-

RO

DO+

DO-

DI

DS8921, DS8921A, DS8921AT

SNLS374D – MAY 1998 – REVISED JANUARY 2015

www.ti.com

8 Detailed Description

8.1 Overview

The DS8921x devices are each a differential line driver and receiver pair in a single package. The devices are

designed specifically for ST506, ST412, and ESDI disk drive standards, as well as RS-422 interface applications.

The DS8921 and DS8921A are rated at a commercial temperature range of 0°C to 70°C, whereas the

DS8921AT is rated at an extended temperature range of -40°C to +85°C.

8.2 Functional Block Diagram

8.3 Feature Description

The DS8921x devices each contain a differential driver and receiver.

The driver converts a TTL or CMOS input to complementary outputs that provide differential drive to a twisted-

pair or parallel wire transmission line. The receiver converts the differential signals at its input pins to a TTL

output. The receiver offers an input sensitivity of ±200 mV and supports a common-mode input voltage of ±7 V.

8.4 Device Functional Modes

Table 1. Function Table

RECEIVER

DRIVER

INPUT

OUTPUT

INPUT

OUTPUT

RI+, RI-

RO

DI

DO+

DO-

1

1

1

0

0

0

0

1

Open

1

(1)

8

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