Texas Instruments SN75LBC968DL, SN75LBC968DLR Datasheet
SN75LBC968
9-CHANNEL BUS TRANSCEIVER
WITH ACTIVE TERMINATION
SLLS179C – APRIL 1994 – REVISED JANUARY 1999
1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
D
Nine Single-Ended SCSI Transceiver
Channels With Active Termination
D
Programmable Drivers Provide Active
Negation (Totem Pole) or Wired-OR (Open
Drain) Outputs
D
24-mA Current-Mode Active Termination
With Common Nine-Channel Bus Enable
D
Low Output Capacitance Presented to SCSI
Bus, 13.5 pF Typ
D
3.3 V Compatible Logic Inputs Provide
Bridge from 3 V Controllers to 5 V SCSI
Bus
D
Designed to Operate at 10-Million Data
Transfers Per Second (Fast-SCSI)
D
Controlled Driver Rise and Fall Times
5 ns Min
D
High-Receiver Input-Voltage Hysteresis
500 mV Typ
D
Receiver Input-Noise Pulse Filter
5 ns Typ
D
Each Driver and Receiver Meets ANSI
X3.131-1994 (SCSI-2) and the Proposed
SCSI-3 Standards
D
Power-Up/Power-Down Glitch Protection
D
High Impedance Driver With VCC at 0 V
description
The SN75LBC968 is a nine-channel transceiver
with active termination that drives and receives
the signals from the single-ended, parallel data
buses such as the Small Computer-Systems
Interface (SCSI) bus. The features of the line drivers, receivers, and active-termination circuits provide the
optimum signal-to-noise ratios for reliable data transmission. Integration of the termination and transceivers in
the LinBiCMOS process provides the necessary analog-circuit performance, has low quiescent power, and
reduces the capacitance presented to the bus over separate termination and I/O circuits.
The transceivers of the SN75LBC968 can be enabled to function as totem-pole or open-drain outputs. The
open-drain mode drives the wired-OR lines of SCSI (BSY, SEL, and RST) by inputting the data to the direction
control input DE/RE instead of the A input. When driving the data through the A input, the outputs become totem
poles and provide active signal negation for a higher voltage level on low-to-high signal transitions on heavily
loaded buses. In either mode, the turn-on and turn-off output transition times are limited to minimize crosstalk
through capacitive coupling to adjacent lines and RF emissions from the cable. The receivers are also designed
for optimum analog performance by precisely controlling the input-voltage thresholds, providing wide
input-voltage hysteresis and including an input-noise filter. These features significantly increase the likelihood
of detecting only the desired data signal and rejecting noise.
LinBiCMOS is a trademark of Texas Instruments Incorporated.
Copyright 1999, 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
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
GND
TE
GND
1A
1DE/RE
2A
2DE/RE
3A
3DE/RE
4A
4DE/RE
V
CC1
GND
GND
GND
GND
GND
V
CC
5A
5DE/RE
6A
6DE/RE
7A
7DE/RE
8A
8DE/RE
9A
9DE/RE
8B
GND
CE
NC
NC
NC
7B
NC
6B
NC
5B
V
CC
GND
GND
GND
GND
GND
V
CC
NC
4B
NC
3B
NC
2B
NC
1B
NC
9B
DL PACKAGE
(TOP VIEW)
NC – No internal connection
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.
SN75LBC968
9-CHANNEL BUS TRANSCEIVER
WITH ACTIVE TERMINATION
SLLS179C – APRIL 1994 – REVISED JANUARY 1999
2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
description (continued)
The communication between the SN75LBC968 and the controller can be accomplished at 3.3-V logic levels
provided that the V
CC1
input connects to the same supply rail as the controller. This provides a bridge from the
lower-voltage circuit and the 5-V SCSI bus. The SN75LBC968 also removes the need for special I/O buffers
(and associated power dissipation) on the controller itself. The SN75LBC968 must be used with a SCSI
controller with support for Differential SCSI.
The integrated, current-mode, active termination supplies a constant 24 mA of current (TERMPWR) to the bus
when the bus voltage falls below 2.5 V . This makes the next low-to-high (negation) signal transition independent
of the low-level (asserted) bus voltage, unlike voltage-mode terminators. The termination current is provided
through the TE input and from TERMPWR and can be disabled by letting the TE input float or by connecting
it to ground. The termination circuitry is independent from the line drivers and receivers and V
CC
or V
CC1
.
Operational termination is present as long as TERMPWR is applied.
The switching speeds of the SN75LBC968 are sufficient to transfer data over the data bus at ten million transfers
per second (Fast-SCSI). The specification, t
sk(lim)
, is for system skew budgeting and maintenance of bus set-up
and hold times. The device is available in the space-efficient shrink-small-outline package (SSOP) with 25-mil
lead pitch. The SN75LBC968 meets or exceeds the requirements of ANSI X3.131–1994 (SCSI-2) and the
proposed SPI (SCSI-3) standards, and is characterized for operation from 0°C to 70°C.
logic diagram (positive logic)
31
1B
56
37
35
33
2B
3B
4B
11
10
9
8
7
6
4
2
54
5
Channel 4
Channel 3
Channel 2
4DE/RE
4A
3DE/RE
3A
2DE/RE
2A
1A
TE
50
48
46
5B
6B
7B
24
23
22
21
20
19
Channel 7
Channel 6
Channel 5
7DE/RE
7A
6DE/RE
6A
5DE/RE
5A
29
8B
9B
28
27
26
25
Channel 9
Channel 8
9DE/RE
9A
8DE/RE
8A
CE
1DE/RE
Active Terminator
DE/RE BA
Z
H
L
Z
Z
H
Z
Z
Z
Z
H
L
Z
L
BA
INPUTS OUTPUTS
H = high level L = low level
X = irrelevant Z = high impedance
TERMINATION FUNCTION
OUTPUT
B
INPUT
TE
GND
V
TE
Open
Z
24-mA source
Z
CE
Function Tables
L
H
H
H
H
H
H
TRANSCEIVER FUNCTIONS
X
L
L
H
H
L
H
X
X
X
L
H
X
Open
X
L
H
X
X
Open
X
SN75LBC968
9-CHANNEL BUS TRANSCEIVER
WITH ACTIVE TERMINATION
SLLS179C – APRIL 1994 – REVISED JANUARY 1999
3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
schematics
TEV
CC
DRIVER ACTIVE TERMINATOR
2.85 V
10 Ω
50 Ω
2.85 V
V
CC
V
ref
B
RECEIVER
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
Supply voltage range, V
CC
, V
CC1
, VTE (see Note 1) –0.5 V to 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Input voltage range, V
I
(A-side) V
CC1
+ 0.3 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Bus voltage range (B-side) –0.5 V to 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Data I/O and control (A-side) voltage range –0.5 V to 7 V. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Continuous power dissipation (see Note 2) Internally Limited. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Operating free-air temperature range, T
A
0°C to 70°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Storage temperature range, T
stg
65°C to 150°C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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 GND.
2. The maximum operating-junction temperature is internally limited. Use the dissipation rating table to operate below this temperature.
SN75LBC968
9-CHANNEL BUS TRANSCEIVER
WITH ACTIVE TERMINATION
SLLS179C – APRIL 1994 – REVISED JANUARY 1999
4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
DISSIPATION RATING TABLE
PACKAGE
TA ≤ 25°C
POWER RATING
DERATING FACTOR
†
ABOVE TA = 25°C
TA = 70°C
POWER RATING
DL 2500 mW 20 mW/°C 1600 mW
†
Derating factors are the inverse of the junction-to-ambient thermal resistance when
board-mounted with no air flow .
recommended operating conditions
MIN NOM MAX UNIT
Supply voltage, V
CC
4.75 5 5.25 V
Supply voltage, V
CC1
(see Note 3) 3 5.25 V
Termination voltage, V
TE
4.25 5.25 V
High-level input voltage, V
IH
DE/RE, CE, A, B 2 V
Low-level input voltage, V
IL
DE/RE, CE, A, B 0.8 V
High-level output current, I
OH
A –8 mA
p
B 48
Low-level output current, I
OL
A 8
mA
Operating free-air temperature, T
A
0 70 °C
NOTE 3: All electrical characteristics are measured with V
CC1
= VCC unless otherwise noted.
driver electrical characteristics over recommended operating conditions (unless otherwise noted)
(see Figure 1)
PARAMETER TEST CONDITIONS MIN MAX UNIT
V
OH
High-level output voltage IOH = –20 mA 2 V
V
OL
Low-level output voltage IOL = 48 mA 0.5 V
I
IH
High-level input current VIH = 2 V, VCC = V
CC1
= 5.25 V –100 µA
I
IL
Low-level input current, A VIL = 0.5 V, VCC = V
CC1
= 5.25 V –100 µA
p
p
VO = 5.25 V , VCC = V
CC1
= 5.25 V –100
IOZHigh-impedance-state output current
VO = 0 V, VCC = V
CC1
= 5.25 V –100
µ
A
termination electrical characteristics over recommended operating conditions (unless otherwise
noted) (see Figure 2)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
O(OC)
Open-circuit output voltage IO = 0 mA, VCC = V
CC1
= 0 V 2.5 2.85 3.24 V
VO = 0 V, VCC = V
CC1
= 0 V –24 mA
p
VO = 0.5 V, VCC = V
CC1
= 0 V –20 –24 mA
IOOutput current
VO = 3 V, VCC = V
CC1
= 0 V 100 µA
VO = 4 V, VCC = V
CC1
= 0 V 2 12 mA
SN75LBC968
9-CHANNEL BUS TRANSCEIVER
WITH ACTIVE TERMINATION
SLLS179C – APRIL 1994 – REVISED JANUARY 1999
5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
receiver electrical characteristics over recommended operating conditions (unless otherwise
noted) (see Figure 3)
PARAMETER TEST CONDITIONS MIN TYP MAX UNIT
V
OH
High-level output voltage IOH = –8 mA 2 2.5 V
V
OL
Low-level output voltage IOL = 8 mA 0.8 V
V
IT+
Positive-going input threshold voltage
1.2 1.6 2 V
V
IT–
Negative-going input threshold voltage
V
CC
=
V
CC1
0.8 1.1 1.4 V
V
hys
Input hysteresis voltage (V
IT+
– V
IT–
) 0.2 0.5 V
I
IH
High-level input current VIH = 2 V 100 µA
I
IL
Low-level input current VIL = 0.5 V 100 µA
p
p
VO = 0 V –100
IOZHigh-impedance-state output current
VO = 5.25 V –100
µ
A
device electrical characteristics over recommended operating conditions (unless otherwise
noted)
PARAMETER TEST CONDITIONS MIN TYP†MAX UNIT
All drivers, receivers, and terminator
disabled
All inputs at 0 V 1.3 3
Supply current to V
All receivers enabled, termination and
drivers disabled, No load
CE at VCC,DE/RE at 0 V,
TE at 0 V
14 21
I
CC
y
CC
and V
CC1
All drivers enabled, termination and
DE/RE and CE at VCC,
A and TE at 0 V
33 45
mA
,
receivers disabled, No load
DE/RE and CE at VCC,
VTE = 0 V, A at V
CC1
15 21
I
CC
Supply current to TE
Termination and receivers enabled,
No load
TE at VTE,DE/RE at 0 V 33 45
CoBus port capacitance (see Note 4) 13.5 16.5 pF
I
IH
High-level input current DE/RE, CE VIH = VCC or 2 V 100 µA
I
IL
Low-level input current DE/RE, CE VIL = 0.5 V 100 µA
†
All typical values are at VCC = V
CC1
= 5 V, TA = 25°C.
NOTE 4: Tested in accordance with Annex G X3T9.2/855D, revision 14
Loading...