SN75LBC970A_05 Datasheet, PDF (1/21 Pages) Texas Instruments – SCSI DIFFERENTIAL CONVERTER-CONTROL

SN75LBC970A
SCSI DIFFERENTIAL CONVERTER-CONTROL
SLLS215B – MAY 1995 – REVISED JANUARY 1999
D Provides Differential SCSI from Single-
Ended Controller When Used With the
DL PACKAGE
(TOP VIEW)
SN75LBC971A Data Transceiver
D Designed to Operate at Fast-SCSI Speeds
of 10 Million Data Transfers per Second
D Nine Transceivers Meet or Exceed the
Requirements of ANSI Standard EIA-485
and ISO-8482 Standards
D Packaged in Shrink Small-Outline Package
with 25 mil Terminal Pitch
D Low Disabled Supply Current
22 mA Typ
D Thermal Shutdown Protection
D Positive- and Negative-Current Limiting
D Power-Up/-Down Glitch Protection
RSTFLTR ₁
RESET ₂
DSENS ₃
CLK40 4
GND 5
AATN – 6
TEST 7
AACK – 8
TIMEOUT 9
AREQ – 10
AC/D – 11
V_CC 12
GND 13
GND 14
56 ^X2
55 ^X1/CLK20
54 ^NC
53 BATN –
52 BATN+
51 BACK –
50 BACK+
49 BREQ –
48 BREQ+
47 BC/D –
46 BC/D+
45 V_CC
44 GND
43 GND
description
The SN75LBC970A SCSI differential converter-
control is an adaptation of the industry’s first
9-channel RS-485 transceiver, the SN75LBC976.
When used in conjunction with one or more of its
companion data transceiver(s), SN75LBC971A,
the chip set provides the superior electrical
performance of differential SCSI from a single-en-
ded SCSI bus controller. A 16-bit, Fast-SCSI bus
can be implemented with just three devices (two
for data and one for control) in the space-efficient,
56-pin, shrink small-outline package (SSOP) and
a few external components.
GND 15
GND 16
GND 17
V_CC 18
DRVBUS 19
SDB 20
AMSG – 21
AI/O – 22
ASEL– 23
NC ²⁴
ABSY – ²⁵
NC ²⁶
ARST – ²⁷
NC ²⁸
42 GND
41 GND
40 GND
39 V_CC
38 BMSG –
37 BMSG+
36 BI/O –
35 BI/O+
34 BSEL+
33 BSEL –
32 _BBSY+
31 _{BBSY –}
30 _BRST+
29 _{BRST –}
In a typical differential SCSI node, the SCSI
controller provides the enables for each external
NC – no internal connection
RS-485 transceiver. This could require as many
as 27 additional terminals for a 16-bit differential
bus controller or relegate a 16-bit single-ended
Terminals 13 through 17 and 40 through 44 are
connected together to the package lead frame and
signal ground.
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(s) to transmit
the single-ended SCSI input signals differentially to the cable or receive the differential cable signals and drive
the single-ended outputs to the controller.
The single-ended SCSI bus interface consists of CMOS bidirectional inputs and outputs. The drivers are rated
at ±16 mA of output current. The receiver inputs are pulled high with approximately 4 mA to eliminate the need
for external pullup resistors for the open-drain outputs of most single-ended SCSI controllers. The single-ended
side of the device is not intended to drive the SCSI bus directly.
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 © 1999, Texas Instruments Incorporated
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