Texas Instruments SN55976A1WD, SN75976A1DGG, SN75976A1DGGR, SN75976A1DL, SN75976A1DLR Datasheet

SN75976A, SN55976A

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

D

Improved Speed and Package Replacement
for the SN75LBC976

D

Designed to Operate at up to 20 Million
Data Transfers per Second (Fast-20 SCSI)

D

Nine Differential Channels for the Data and
Control Paths of the Small Computer
Systems Interface (SCSI) and Intelligent
Peripheral Interface (IPI)

D

SN75976A Packaged in Shrink
Small-Outline Package with 25-Mil Terminal
Pitch (DL) and Thin Shrink Small-Outline
Package with 20-Mil Terminal Pitch (DGG)

D

SN55976A Packaged in a 56-Pin Ceramic
Flat Pack (WD)

D

Two Skew Limits Available

D

ESD Protection on Bus Terminals
Exceeds 12 kV

D

Low Disabled Supply Current 8 mA Typ

D

Thermal Shutdown Protection

D

Positive- and Negative-Current Limiting

D

Power-Up/Down Glitch Protection

description

The SN75976A is an improved replacement for
the industry’s first 9-channel RS-485
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

SN75976A DGG or DL

SN55976A WD

(TOP VIEW)

GND

BSR
CRE

1DE/RE

2DE/RE

3DE/RE

4DE/RE

V
GND
GND
GND
GND
GND

V

5DE/RE

6DE/RE

7DE/RE

8DE/RE

9DE/RE

1A

2A

3A

4A

CC

CC

5A

6A

7A

8A

9A

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28

56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29

CDE2
CDE1
CDE0
9B+

–

9B
8B+

–

8B
7B+
7B

–

6B+
6B

–

V

CC

GND
GND
GND
GND
GND
V

CC

5B+

–

5B
4B+
4B

–

3B+
3B

–

2B+
2B

–

1B+

–

1B

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

Terminals 13 through 17 and 40 through 44 are
connected together to the package lead frame
and signal ground.

transfers per second. The ’976A1 supports the
Fast SCSI skew budget for 10 million
transfers per second. The skew limit ensures that the propagation delay times, not only from channel-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 of fers 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.

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.

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

Copyright  1997, Texas Instruments Incorporated

1

SN75976A, SN55976A

T

0°C to 70°C

55°C to 125°C

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

description (continued)

In addition to speed improvements, the ’976A can withstand electrostatic discharges exceeding 12 kV using
the human-body model, and 600 V using the machine model of MIL-PRF-38535, Method 3015.7 on the RS-485
I/O terminals. This is six times the industry standard and provides protection from the noise that can be coupled
into external cables. The other terminals of the device can withstand discharges exceeding 4 kV and 400 V
respectively.

Each of the nine channels of the ’976A typically meet or exceed the requirements of EIA RS-485 (1983) and
ISO 8482-1987/TIA TR30.2 referenced by American National Standard of Information (ANSI) Systems,
X3.131-1994 (SCSI-2) standard, X2.277-1996 (Fast-20 Parallel Interface), and the Intelligent Peripheral
Interface Physical Layer-ANSI X3.129-1986 standard.

The SN75976A is characterized for operation over an ambient air temperature range of 0°C to 70°C. The
SN55976A is characterized for operation over an ambient air temperature range of –55°C to 125°C.

AVAILABLE OPTIONS

Skew Limit

A

°

°

°

–

†

The R suffix indicates taped and reeled packages.

°

(ns)

Driver Receiver

8 9

4 5
8 9 — — SN55976A1WD

4 5 — — SN55976A2WD

TSSOP

(DGG)

SN75976A1DGG
SN75976A1DGGR

SN75976A2DGG
SN75976A2DGGR

PACKAGE

SN75976A1DL
SN75976A1DLR

SN75976A2DL
SN75976A2DLR

SSOP

(DL)

†

CERAMIC FLAT PACK

(WD)

—

—

2

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9-CHANNEL DIFFERENTIAL TRANSCEIVER

g

I/O

Termination

DESCRIPTION

Terminal Functions

SN75976A, SN55976A

SLLS218B – MAY 1995 – REVISED MAY 1997

TERMINAL

NAME NO.

1A to 9A 4,6,8,10,

1B– to 9B– 29,31,33,

1B+ to 9B+ 30,32,34,

BSR 2 TTL Input Pullup BSR is the bit significant response. BSR disables receivers 1 through 8 and

CDE0 54 TTL Input Pulldown CDE0 is the common driver enable 0. Its input signal enables all drivers

CDE1 55 TTL Input Pulldown CDE1 is the common driver enable 1. Its input signal enables drivers

CDE2 56 TTL Input Pulldown CDE2 is the common driver enable 2. When CDE2 is high and BSR is low,

CRE 3 TTL Input Pullup CRE is the common receiver enable. When high, CRE disables receiver

1DE/RE to
9DE/RE

GND 1,13,14,

V

CC

†

Terminal 1 must be connected to signal ground for proper operation.

19,21,23,

25,27

35,37,.46,

48,50,52

36,38,47,

49,51,53

5,7,9,1 1,

20,22,24,

26,28

15,16,17,
40,41,42,

43,44

12,18,39,

45

Logic
Level

TTL I/O Pullup 1A to 9A carry data to and from the communication controller.

RS-485 I/O Pulldown 1B – to 9B – are the inverted data signals of the balanced pair to/from

RS-485 I/O Pullup 1B+ to 9B+ are the noninverted data signals of the balanced pair to/from

TTL Input Pullup 1DE/RE–9DE/RE are direction controls that transmit data to the bus when

NA Power NA GND is the circuit ground. All GND terminals except terminal 1 are

NA Power NA Supply voltage

the bus.

the bus.

enables wired-OR drivers when BSR and DE/RE
high. Channel 9 is placed in a high-impedance state with BSR high.

when CDE0 and 1DE/RE

1 to 4 when CDE1 is high and BSR is low.

drivers 5 to 8 are enabled.

channels 5 to 9.

it and CDE0 are high. Data is received from the bus when
1DE/RE

–9DE/RE and CRE and BSR are low and CDE1 and CDE2 are

low.

physically tied to the die pad for improved thermal conductivity.

– 9DE/RE are high.

and CDE1 or CDE2 are

†

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3

SN75976A, SN55976A
9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

logic diagram (positive logic)

54

CDE0

55

CDE1

2

BSR

4

1A

30
29

1B+
1B–

1DE/RE

2A

2DE/RE

3A

3DE/RE

4A

4DE/RE

CDE2

CRE

5A

5DE/RE

6A

6DE/RE

7A

7DE/RE

8A

8DE/RE

9A

9DE/RE

5

6
7
8
9

10
11

56

3

19

20

21
22
23
24
25
26

27

28

Channel 2

Channel 3

Channel 4

Channel 6

Channel 7

Channel 8

2354

BSRBSR

CRE CDE0

32
31
34
33

36
35

38
37

47
46
49
48
51
50

53
52

2B+
2B–
3B+
3B–

4B+
4B–

5B+
5B–

6B+
6B–
7B+
7B–

8B+
8B–

9B+
9B–

4

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schematics of inputs and outputs

SN75976A, SN55976A

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

Input

V

CC

Input

16 V

DE/RE, CRE, BSR, AND

A Inputs

100 kΩ

1 kΩ

8 V

B+ Input B– Input

100 kΩ
18 kΩ

4 kΩ

16 V

B+ AND B– Outputs

2 kΩ

18 kΩ

2 kΩ

V

CC

16 V

V

CC

Output

Input

Input

CDE0, CDE1, AND CDE2 Inputs

1 kΩ

100 kΩ

18 kΩ

100 kΩ

4 kΩ

A Output

V

8 V

16 V

16 V

CC

40 Ω

2 kΩ

V

CC

Output

V

CC

4 kΩ

16 V

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

8 V

5

SN75976A, SN55976A

Junction-to-ambient thermal resistance, R

Junction-to-case thermal resistance, R

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

absolute maximum ratings over operating free-air temperature range (unless otherwise noted)

Supply voltage range, V

Bus voltage range –10 V to 15 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data I/O and control (A side) voltage range –0.3 V to V

Electrostatic discharge:B side and GND, Class 3, A: (see Note 2) 12 kV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Continuous total power dissipation (see Note 3) internally limited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Storage temperature range, T

Lead temperature 1,6 mm (1/16 inch) from case for 10 seconds 260°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

†

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, and
functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not
implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability.

NOTES: 1. All voltage values are with respect to the GND terminals.

2. This absolute maximum rating is tested in accordance with MIL-PRF-38535, Method 3015.7.

3. The maximum operating junction temperature is internally limited. Use the Dissipation Rating Table to operate below this
temperature.

PACKAGE

DGG 2500 mW 20 mW/°C 1600 mW —

DL 2500 mW 20 mW/°C 1600 mW —

WD 1300 mW 10.5 mW/°C 827 mW 250 mW

‡

This is the inverse of the junction-to-ambient thermal resistance when board-mounted and with no air flow.

(see Note 1) –0.3 V to 6 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

CC

CC

B side and GND, Class 3, B: (see Note 2) 400 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

All terminals, Class 3, A: 4 kV. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

All terminals, Class 3, B: 400 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

–65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

stg

DISSIPATION RATING TABLE

TA ≤ 25°C

OPERATING FACTOR

ABOVE TA = 25°C

‡

TA = 70°C

POWER RATING

TA = 125°C

POWER RATING

+0.5 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

†

package thermal characteristics

θJA

Junction-to-ambient thermal resistance, R

Junction-to-case thermal resistance, R
Thermal-shutdown junction temperature, T

θJA

θJC

θJC

JS

MIN NOM MAX UNIT

DGG, board-mounted, no air flow 50 °C/W
DL, board-mounted, no air flow 50 °C/W
WD 95.4 °C/W
DGG 27 °C/W
DL 12 °C/W
WD 5.67 °C/W

165 °C

6

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recommended operating conditions

Voltage at any bus terminal (separately or common-mode), V

V

V

nB+ or nB

High-level output current, I

Low-level output current, I

Operating free-air temperature, T

Supply voltage, V
High-level input voltage, V
Low-level input voltage, V

Operating case temperature, T

p

†

n = 1 – 9

CC

IH

IL

p

p

p

OH

OL

C

p

A

SN75976A, SN55976A

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

MIN NOM MAX UNIT

4.75 5 5.25 V
Except nB+, nB–
Except nB+, nB–

,

, or

O

I

IC

Driver –60 mA
Receiver –8 mA
Driver 60 mA
Receiver 8 mA
SN75976A 0 125 °C
SN75976A 0 70 °C

SN55976A –55 125 °C

†
†

–

2 V

0.8 V
12 V

–7 V

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7

SN75976A, SN55976A

PARAMETER

TEST CONDITIONS

UNIT

level out ut voltage

level out ut voltage

OH

age

OL

age

IIBus input current

I

g

IILLow-level input current

I

g

C

capacitance

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)

SN55976A SN75976A

MIN TYP†MAX MIN TYP†MAX

S1 to A, VT = 5 V, See Figure 1 0.7 1 1.8 V

V

V

V

V

V

V

V

I

I

C

†
NOTE 4: Cpd determines the no-load dynamic supply current consumption, IS = CPD × VCC × f + I

Driver differential high-

ODH

ODL

IT+

IT–

hys

IH

OS

OZ

CC

O

pd

All typical values are at VCC = 5 V, TA = 25°C.

p

Driver differential low-

p

High-level output volt-

Low-level output volt-

Receiver positive-go­ing differential input
threshold voltage

Receiver negative­going differential input
threshold voltage

Receiver input
hysteresis
(V

– V

IT+

High-level input cur­rent

Short circuit output
current

High-impedance-state
output current

Supply current

Output capacitance nB+ or nB– to GND 18 18 25 pF
Power dissipation

p

(see Note 4)

)

IT–

p

p

S1 to B,
TC ≥ 25°C

S1 to B,
See Figure 1

S1 to A,
TC ≥ 25°C

S1 to B, VT = 5 V, See Figure 1 0.7 –1.8 –1 –1.8 V
S1 to A,

See Figure 1
A side,

IOH = –8 mA
B side, VT = 5 V, See Figure 1 3 3 V
A side,

IOH = 8 mA
A side, VT = 5 V, See Figure 1 1 1 V

IOH = –8 mA, See Figure 3 0.2 0.2 V

IOL = 8 mA, See Figure 3 –0.2 –0.2 V

VCC = 5 V, TA = 25°C 24 45 24 45 mV

VIH = 12 V, VCC = 5 V, Other input at 0 V 0.4 1 0.4 1 mA
VIH = 12 V, VCC = 0, Other input at 0 V 0.5 1 0.5 1 mA
VIH = –7 V, VCC = 5 V, Other input at 0 V –0.4 –0.8 –0.4 –0.8 mA
VIH = –7 V, VCC = 0, Other input at 0 V –0.3 –0.8 –0.3 –0.8 mA
A, BSR, DE/RE, and CRE, VIH = 2 V –100 –100 µA
CDE0, CDE1, and CDE2,
A, BSR, DE/RE, and CRE, VIL = 0.8 V –100 –100 µA
CDE1, CDE1, and CDE2, VIL = 0.8 V 100 100 µA

nB+ or nB– ±260 ±260 mA
A See IIH and I

nB+ or nB–
Disabled 10 10 mA
All drivers enabled, no load
All receivers enabled, no load 45 45 mA

Receiver 40 40 pF
Driver 100 100 pF

VT = 5 V,
See Figure 1

VT = 5 V,

VT = 5 V,
See Figure 1

VT = 5 V,

VID = 200 mV,
See Figure 3

VID = –200 mV,
See Figure 3

VIH = 2V 100 100 µA

0.7 0.8 V

0.7 –1.4 –1 –1.4 V

–0.8 –1.4 –0.8 –1.4 V

4 4.5 4 4.5 V

0.6 0.8 0.6 0.8 V

IL

See I

I

60 60 mA

CC

1 1.4 V

See IIH and I

See I

IL

I

8

POST OFFICE BOX 655303 • DALLAS, TEXAS 75265

SN75976A, SN55976A

PARAMETER

TEST CONDITIONS

UNIT

t

gy,

PHL PLH

t

,

dd

See Figures 5 and 6

PARAMETER

TEST CONDITIONS

UNIT

t

gy,

PHL PLH

t

,

dd

See Figures 5 and 6

9-CHANNEL DIFFERENTIAL TRANSCEIVER

SLLS218B – MAY 1995 – REVISED MAY 1997

driver switching characteristics over recommended operating conditions (unless otherwise
noted)

SN75976A

MIN TYP†MAX

2.5 13.5 ns

’976A1

pd

sk(lim)

t

sk(p)

t

f

t

r

t

en

t

dis

t

PHZ

t

PLZ

t

PZH

t

PZL

†

All typical values are at VCC = 5 V, TA = 25°C.

NOTE 5: This parameter is applicable at one VCC and operating temperature within the recommended operating conditions and to any two

Propagation delay time, t
(see Figures 1 and 2)

Skew limit, maximum tp – minimum tp
(see Note 5)

Pulse skew, |t
Fall time S1 to B, See Figure 2 4 ns
Rise time See Figure 2 8 ns
Enable time, control inputs to active output 50 ns
Disable time, control inputs to high-impedance output 100 ns
Propagation delay time, high-level to high-impedance output 17 100 ns
Propagation delay time, low-level to high-impedance output
Propagation delay time, high-impedance to high-level output
Propagation delay time, high-impedance to low-level output 17 50 ns

devices.

PHL

– t

or t

’976A2

’976A1 8 ns
’976A2

| 4 ns

PLH

VCC = 5 V, TC = 25°C 3 11 ns
VCC = 5 V, TC = 100°C 5 13 ns

4.5 11.5 ns
VCC = 5 V, TC = 25°C 5 9 ns
VCC = 5 V, TC = 100°C 7 11 ns

4 ns

25 100 ns
17 50 ns

driver switching characteristics over recommended operating conditions (unless otherwise
noted)

SN55976A

MIN TYP†MAX

pd

sk(lim)

t

sk(p)

t

f

t

r

t

en

t

dis

t

PHZ

t

PLZ

t

PZH

t

PZL

†

All typical values are at VCC = 5 V, TA = 25°C.

NOTE 5. This parameter is applicable at one VCC and operating temperature within the recommended operating conditions and to any two

Propagation delay time, t
(see Figures 1 and 2)

Skew limit, maximum tp – minimum tp
(see Note 5)

Pulse skew, |t
Fall time S1 to B, See Figure 2 4 ns
Rise time See Figure 2 8 ns
Enable time, control inputs to active output 60 ns
Disable time, control inputs to high-impedance output 140 ns
Propagation delay time, high-level to high-impedance output 120 ns
Propagation delay time, low-level to high-impedance output
Propagation delay time, high-impedance to high-level output
Propagation delay time, high-impedance to low-level output 60 ns

devices.

PHL

– t

or t

| 4 ns

PLH

’976A1 VCC = 5 V, TA = 25°C 15 ns
’976A2
’976A1 8 ns
’976A2

VCC = 5 V, TA = 25°C 13.5 ns

4 ns

120 ns

60 ns

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9