SN75971B Datasheet, PDF (1/15 Pages) Texas Instruments – SCSI DIFFERENTIAL CONVERTER-DATA

SN75971B
SCSI DIFFERENTIAL CONVERTER-DATA
SLLS322A – NOVEMBER 1999 – REVISED JANUARY 2000
D Provides High-Voltage Differential SCSI
From Single-Ended Controller When Used
DGG OR DL PACKAGE
(TOP VIEW)
With the SN75970B Control Transceiver
D Meets or Exceeds the Requirements of EIA
Standard RS-485 and ISO-8482 Standards
D ESD Protection on Bus Pins to 12 kV
D Packaged in Shrink Small-Outline Package
with 25 mil Terminal Pitch and Thin
Small-Package with 20 mil Terminal Pitch
D Low Disabled-Supply Current 32 mA Typ
D Thermal Shutdown Protection
D Positive- and Negative-Current Limiting
D Power-Up/-Down Glitch Protection
D Open-Circuit Failsafe Receivers
SDB 1
DRVBUS 2
GND 3
ADBP – 4
NC 5
ADB7 – 6
NC 7
ADB6 – 8
NC 9
ADB5 – 10
NC 11
V_CC 12
GND 13
56 DSENS
55 RESET
54 GND
53 BDBP –
52 BDBP +
51 BDB7 –
50 BDB7 +
49 BDB6 –
48 BDB6 +
47 BDB5 –
46 BDB5 +
45 V_CC
44 GND
description
GND 14
GND 15
43 GND
42 GND
The SN75971B SCSI differential converter-data is a
9-channel RS-485 transceiver. When used in conjunc-
tion with its companion control transceiver, the
SN75970B, the resulting chip set provides the superior
electrical performance of differential SCSI from a
single-ended SCSI bus or controller. A 16-bit
Ultra-SCSI (or Fast-20) SCSI bus can be implemented
GND 16
GND 17
V_CC 18
ABD4 – 19
NC 20
ADB3 – 21
NC 22
41 GND
40 GND
39 V_CC
38 BDB4 –
37 BDB4 +
36 BDB3 –
35 BDB3 +
with just three devices (two data and one control) in the
ADB2 – 23 34 BDB2 –
space efficient, 56-pin, shrink small-outline package
NC 24 33 BDB2 +
(SSOP) or thin shink small outline package (TSSOP)
ADB1 – 25 32 BDB1 –
and a few external components. An 8-bit SCSI bus
NC 26 31 BDB1 +
requires only one data and one control transceiver.
ADB0 – 27 30 BDB0 –
The SN75971B is available in a B2 (20 Mxfer)
NC 28 29 BDB0 +
version and a B1 (10 Mxfer) version.
Pins 13 – 17 and 40 – 44 are connected
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
together to the package lead frame and
to signal ground.
NC – No internal connection
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 SCSIcontrol signals, the SN75970B control transceiver decodes the
state of the bus and enables the SN75971B 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.
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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Copyright © 2000, Texas Instruments Incorporated
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