SN75LBC971A

SCSI DIFFERENTIAL CONVERTER-DATA

SLLS186B – OCTOBER 1994 – REVISED JULY 1997

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POST OFFICE BOX 655303

Single-Ended Controller When Used With

the SN75LBC970A Control Transceiver

Ten Million Data Transfers per Second

Standard RS-485 and ISO-8482 Standards

With 25-Mil Terminal Pitch

23 mA Typ

description

The SN75LBC971A SCSI differential converter-data is

an adaptation of the industry’s first 9-channel RS-485

transceiver, the SN75LBC976. When used in conjunc-

tion with its companion control transceiver, the

SN75LBC970A, the resulting chip set provides the

superior electrical performance of differential SCSI

from a single-ended SCSI bus or controller. A 16-bit

SCSI bus can be implemented with just three devices

(two data and one control) in the space efficient, 56-pin,

shrink small-outline package (SSOP) and a few

external components. An 8-bit SCSI bus requires only

one data and one control transceiver.

In a typical differential SCSI node, the SCSI controller

provides an enable for each external RS-485

transceiver channel. This could require as many as 27

extra terminals for a 16-bit differential bus controller or

relegate a 16-bit, single-ended controller to only an

8-bit differential bus. Using the standard nine SCSI

control signals, the SN75LBC970A control transceiver decodes the state of the bus and enables the

SN75LBC971A data transceiver to transmit the single-ended SCSI input signals (A side) differentially to the

cable or receive the differential cable signals (B side) and drive the single-ended outputs to the controller.

A reset function, which disables all outputs and clears internal latches, can be accomplished from two external

inputs and two internally-generated signals. RESET (reset) and DSENS (differential sense) are available to

external circuits for a bus reset or to disable all outputs should a single-ended cable be inadvertently connected

to a differential connector. Internally-generated power-up and thermal-shutdown signals have the same affect

when the supply voltage is below approximately 3.5 V or the junction temperature exceeds 175

°C.

Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of

Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet.

Copyright

© 1997, Texas Instruments Incorporated

PRODUCTION DATA information is current as of publication date.

Products conform to specifications per the terms of Texas Instruments

standard warranty. Production processing does not necessarily include

testing of all parameters.

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SDB

DRVBUS

GND

ADBP –

NC

ADB7 –

NC

ADB6 –

NC

ADB5 –

NC

GND

GND

GND

GND

GND

ABD4 –

NC

ADB3 –

NC

ADB2 –

NC

ADB1 –

NC

ADB0 –

NC

DSENS

RESET

GND

BDBP –

BDBP +

BDB7 –

BDB7 +

BDB6 –

BDB6 +

BDB5 –

BDB5 +

GND

GND

GND

GND

GND

BDB4 –

BDB4 +

BDB3 –

BDB3 +

BDB2 –

BDB2 +

BDB1 –

BDB1 +

BDB0 –

BDB0 +

DL PACKAGE

(TOP VIEW)

NC – No internal connection

Pins 13 – 17 and 40 – 44 are connected

together to the package lead frame and

to signal ground.