TL2218-285_14 [TI]
EXCALIBUR CURRENT-MODE SCSI TERMINATOR;
| 型号： | TL2218-285_14 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | EXCALIBUR CURRENT-MODE SCSI TERMINATOR |
| 文件： | 总9页 (文件大小：171K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
PW PACKAGE
(TOP VIEW)
available features
•
Fully Integrated 9-Channel SCSI
Termination
1
20
19
18
17
16
15
14
13
12
11
TERMPWR
NC
TERMPWR
DISABLE
NC
2
•
•
No External Components Required
3
NC
Maximum Allowed Current Applied at First
High-Level Step
4
D0
D8
5
D1
D7
•
•
6-pF Typical Power-Down Output
Capacitance
6
D2
NC
7
D3
D6
†
Wide V
(Termination Voltage)
term
8
D4
D5
Operating Range, 3.5 V to 5.5 V
TTL-Compatible Disable Feature
Compatible With Active Negation
Thermal Regulation
9
NC
NC
•
•
•
10
GND
GND
NC – No internal connection
description
The TL2218-285 is a current-mode 9-channel monolithic terminator specially designed for single-ended
small-computer-systems-interface (SCSI) bus termination. A user-controlled disable function is provided to
reduce standby power. No impedance-matching resistors or other external components are required for its
operation as a complete terminator.
†
The device operates over a wide termination-voltage (V
) range of 3.5 V to 5.5 V, offering an extra 0.5 V of
term
operating range when compared to the minimum termination voltage of 4 V required by other integrated active
terminators. The TL2218-285 functions as a current-sourcing terminator and supplies a constant output current
of23mAintoeachassertedline. Whenalineisdeasserted, thedevicesensestherisingvoltagelevelandbegins
to function as a voltage source, supplying a fixed output voltage of 2.85 V. The TL2218-285 features
compatibility with active negation drivers and has a typical sink current capability of 20 mA.
The TL2218-285 is able to ensure that maximum current is applied at the first high-level step. This performance
means that the device should provide a first high-level step exceeding 2 V even at a 10-MHz rate. Therefore,
noise margins are improved considerably above those provided by resistive terminators.
A key difference between the TL2218-285 current-mode terminator and a Boulay terminator is that the
TL2218-285 does not incorporate a low dropout regulator to set the output voltage to 2.85 V. In contrast with
the Boulay termination concept, the accuracy of the 2.85 V is not critical with the current-mode method used
in the TL2218-285 because this voltage does not determine the driver current. Therefore, the primary device
specifications are not the same as with a voltage regulator but are more concerned with output current.
The DISABLE terminal is TTL compatible and must be taken low to shut down the outputs. The device is
normally active, even when DISABLE is left floating. In the disable mode, only the device startup circuits remain
active, thereby reducing the supply current to just 500 µA. Output capacitance in the shutdown mode is typically
6 pF.
The TL2218-285 has on-board thermal regulation and current limiting, thus eliminating the need for external
protection circuitry. A thermal regulation circuit that is designed to provide current limiting, rather than an actual
thermal shutdown, is included in the individual channels of the TL2218-285. When a system fault occurs that
leads to excessive power dissipation by the terminator, the thermal regulation circuit causes a reduction in the
asserted-line output current sufficient to maintain operation. This feature allows the bus to remain active during
a fault condition, which permits data transfer immediately upon removal of the fault. A terminator with thermal
shutdown does not allow for data transfer until sufficient cooling has occurred. Another advantage offered by
the TL2218-285 is a design that does not require costly laser trimming in the manufacturing process.
The TL2218-285 is characterized for operation over the virtual junction temperature range of 0°C to 125°C.
†
This symbol is not presently listed within EIA/JEDEC standards for letter symbols.
Copyright 1995, 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.
8–1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
AVAILABLE OPTIONS
SURFACE MOUNT
CHIP FORM
(Y)
T
J
†
(PW)
0°C to 125°C
TL2218-285PWLE
TL2218-285Y
†
The PW package is only available left-end taped and reeled.
TL2218-285Y chip information
This chip, when properly assembled, displays characteristics similar to the TL2218-285. Thermal compression
or ultrasonic bonding may be used on the doped aluminum bonding pads. The chip may be mounted with
conductive epoxy or a gold-silicon preform.
BONDING PAD ASSIGNMENTS
(20)
(1)
(19)
1, 20
TERMPWR
Feedback
19
(17)
(4)
(5)
Active
Negation
Clamp
DISABLE
V
ref
4
D0
(16)
Thermal
Regulation
Common to All Channels
161
(6)
CHIP THICKNESS: 11 MILS TYPICAL
BONDING PADS: 4 × 4 MILS MINIMUM
(14)
(7)
T max = 150°C
J
TOLERANCES ARE ±10%.
ALL DIMENSIONS ARE IN MILS.
(13)
(8)
(10)(11)
84
8–2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
functional block diagram (each channel)
1, 20
TERMPWR
Feedback
Active
Negation
Clamp
19
DISABLE
V
ref
4
D0
Thermal
Regulation
Common to All Channels
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
†
(see Figures 1, 2, and 3)
Continuous termination voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 V
Continuous output voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 5.5 V
Continuous disable voltage range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 V to 5.5 V
Continuous total power dissipation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . See Dissipation Rating Table
Operating virtual junction temperature range, T . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –55°C to 150°C
J
Storage temperature range, T
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –60°C to 150°C
stg
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.
DISSIPATION RATING TABLE
POWER RATING
AT
T ≤ 25°C
POWER RATING
DERATING FACTOR
ABOVE T = 25°C
T = 70°C
T = 85°C
T = 125°C
PACKAGE
POWER RATING POWER RATING POWER RATING
T
828 mW
4032 mW
2475 mW
6.62 mW/°C
32.2 mW/°C
19.8 mW/°C
530 mW
2583 mW
1584 mW
430 mW
2100 mW
1287 mW
166 mW
812 mW
495 mW
A
PW
T
C
‡
T
L
‡
R
is the thermal resistance between the junction and device lead. To determine the virtual junction temperature (T ) relative to the device lead
J
θJL
temperature, the following calculations should be used: T = P x R
the device lead temperature at the point of contact to the printed wiring board. R
+ T , where P is the internal power dissipation of the device and T is
J
D
θJL
L
D
L
is 50.5°C/W.
θJL
8–3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
FREE-AIR TEMPERATURE
CASE TEMPERATURE
DISSIPATION DERATING CURVE
DISSIPATION DERATING CURVE
2400
2200
2000
1800
1600
1400
1200
1000
800
4800
4400
4000
3600
3200
2800
2400
2000
1600
1200
800
600
R
= 31°C/W
θJC
400
200
400
R
= 151°C/W
θJA
0
0
25
50
75
100
125
150
25
50
75
100
125
150
T
A
– Free-Air Temperature – °C
T
C
– Case Temperature – °C
Figure 1
Figure 2
LEAD TEMPERATURE
DISSIPATION DERATING CURVE
4800
4400
4000
3600
3200
2800
2400
2000
1600
1200
800
†
R
= 50.5°C/W
θJL
400
0
25
50
75
100
125
150
T
L
– Lead Temperature – °C
Figure 3
†
R
is the thermal resistance between the junction and device lead. To determine the virtual junction temperature (T ) relative to the device lead
J
θJL
temperature, the following calculations should be used: T = P x R
the device lead temperature at the point of contact to the printed wiring board. R
+ T , where P is the internal power dissipation of the device, and T is
J
D
θJL
L
D
L
is 50.5°C/W.
θJL
8–4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
recommended operating conditions
MIN
3.5
2
MAX
UNIT
V
Termination voltage
5.5
High-level disable input voltage, V
V
term
0.8
V
IH
Low-level disable input voltage, V
IL
Operating virtual junction temperature, T
0
V
0
125
°C
J
electrical characteristics, V
= 4.75 V, V = 0.5 V, T = 25°C
O J
term
PARAMETER
TEST CONDITIONS
MIN
TYP
2.85
9
MAX
UNIT
Output high voltage
TERMPWR supply current
Output current
2.5
V
All data lines open
All data lines = 0.5 V
DISABLE = 0 V
mA
228
500
–23
µA
–20.5
–24
1
mA
DISABLE = 4.75 V
DISABLE = 0 V
DISABLE = 0 V
Disable input current (see Note 1)
µA
600
Output leakage current
100
6
nA
pF
Output capacitance, device disabled
Termination sink current, total
V
V
= 0 V,
= 4 V
1 MHz
O
20
mA
O
NOTE 1: When DISABLE is open or high, the terminator is active.
8–5
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
THERMAL INFORMATION
The need for smaller surface-mount packages for use on compact printed-wiring boards (PWB) causes an
increasingly difficult problem in the area of thermal dissipation. In order to provide the systems designer with a better
approximation of the junction temperature rise in the thin-shrink small-outline package (TSSOP), the junction-to-lead
thermal resistance (R ) is provided along with the more typical values of junction-to-ambient and junction-to-case
θJL
θJA
thermal resistances, R
and R
.
θJC
R
is used to calculate the device junction temperature rise measured from the leads of the unit. Consequently, the
θJL
junction temperature is dependent upon the board temperature at the leads, R , and the internal power dissipation
of the device. The board temperature is contingent upon several variables, including device packing density,
θJL
thickness, material, area, and number of interconnects. The R
value depends on the number of leads connecting
θJL
to the die-mount pad, the lead-frame alloy, area of the die, mount material, and mold compound. Since the power level
at which the TSSOP can be used is highly dependent upon both the temperature rise of the PWB and the device itself,
the systems designer can maximize this level by optimizing the circuit board. The junction temperature of the device
can be calculated using the equation T = (P × R ) + T where T = junction temperature, P = power dissipation,
J
D
θJL
L
L
J
D
R
= junction-to-lead thermal resistance, and T = board temperature at the leads of the unit.
θJL
The values of thermal resistance for the TL2218-285 PW are as follows:
Thermal Resistance
Typical Junction Rise
151°C/W
R
R
θJA
31 °C/W
θJC
R
50.5°C/W
θJL
TYPICAL CHARACTERISTICS
Table of Graphs
FIGURE
I
Output current vs Input voltage
4
5
6
7
O
V
Output voltage vs Input voltage
O
I
O
Output current vs Junction temperature
Output voltage vs Junction temperature
V
O
8–6
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
TL2218-285, TL2218-285Y
EXCALIBUR CURRENT-MODE SCSI TERMINATOR
SLVS072C – DECEMBER 1992 – REVISED OCTOBER 1995
TYPICAL CHARACTERISTICS
OUTPUT CURRENT
vs
OUTPUT VOLTAGE
vs
INPUT VOLTAGE
INPUT VOLTAGE
24
22
20
4
3
2
T
J
= 25°C
T
J
= 25°C
18
16
14
1
0
3
3.5
4
4.5
5
5.5
3
3.5
4
4.5
5
5.5
V – Input Voltage – V
I
V – Input Voltage – V
I
Figure 4
Figure 5
OUTPUT CURRENT
vs
OUTPUT VOLTAGE
vs
JUNCTION TEMPERATURE
JUNCTION TEMPERATURE
4
25
20
15
10
V
T
A
= 4.75 V
J
V
= 4.75 V
J
term
= T
term
T = T
A
3.5
3
2.5
2
5
0
25
50
75
100
125
0
25
T
50
75
100
125
T
J
– Junction Temperature – °C
– Junction Temperature – °C
J
Figure 6
Figure 7
8–7
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
8–8
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