SN75976A, SN55976A
9-CHANNEL DIFFERENTIAL TRANSCEIVER
SLLS218B – MAY 1995 – REVISED MAY 1997
SN75976A DGG or DL
SN55976A WD
(TOP VIEW)
Improved Speed and Package Replacement
for the SN75LBC976
Designed to Operate at up to 20 Million
Data Transfers per Second (Fast-20 SCSI)
GND
BSR
CDE2
CDE1
CDE0
9B+
1
56
55
54
53
52
51
50
49
48
47
46
45
Nine Differential Channels for the Data and
Control Paths of the Small Computer
Systems Interface (SCSI) and Intelligent
Peripheral Interface (IPI)
2
CRE
3
1A
4
1DE/RE
2A
9B–
5
SN75976A Packaged in Shrink
8B+
6
Small-Outline Package with 25-Mil Terminal
Pitch (DL) and Thin Shrink Small-Outline
Package with 20-Mil Terminal Pitch (DGG)
2DE/RE
3A
8B–
7
7B+
8
3DE/RE
4A
7B–
9
SN55976A Packaged in a 56-Pin Ceramic
Flat Pack (WD)
6B+
10
11
12
4DE/RE
6B–
V
V
Two Skew Limits Available
CC
CC
GND 13
GND 14
44 GND
43 GND
ESD Protection on Bus Terminals
Exceeds 12 kV
15
16
17
18
19
20
21
22
23
24
25
26
27
28
42
41
40
39
38
37
36
35
34
33
32
31
30
29
GND
GND
GND
GND
GND
GND
Low Disabled Supply Current 8 mA Typ
Thermal Shutdown Protection
Positive- and Negative-Current Limiting
Power-Up/Down Glitch Protection
V
V
CC
5A
CC
5B+
5B–
4B+
4B–
3B+
3B–
2B+
2B–
1B+
1B–
5DE/RE
6A
description
6DE/RE
7A
The SN75976A is an improved replacement for
the industry’s first 9-channel RS-485
7DE/RE
8A
transceiver — the SN75LBC976. The A version
offers improved switching performance, a smaller
package, and higher ESD protection. The
SN75976A is offered in two versions. The ’976A2
skew limits of 4 ns for the differential drivers and
5 ns for the differential receivers complies with the
recommended skew budget of the Fast-20 SCSI
standard for data transfer rates up to 20 million
transfers per second. The ’976A1 supports the
Fast SCSI skew budget for 10 million
8DE/RE
9A
9DE/RE
Terminals 13 through 17 and 40 through 44 are
connected together to the package lead frame
and signal ground.
transferspersecond. Theskewlimitensuresthatthepropagationdelaytimes, notonlyfromchannel-to-channel
but from device-to-device, are closely matched for the tight skew budgets associated with high-speed parallel
data buses.
The patented thermal enhancements made to the 56-pin shrink small-outline package (SSOP) of the SN75976
have been applied to the new, thin shrink, small-outline package (TSSOP). The TSSOP package offers even
less board area requirements than the SSOP while reducing the package height to 1 mm. This provides more
board area and allows component mounting to both sides of the printed circuit boards for low-profile,
space-restricted applications such as small form-factor hard disk drives.
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.
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265