SN74F1018 [TI]
18-BIT SCHOTTKY BARRIER DIODE R-C BUS-TERMINATION ARRAY; 18位肖特基势垒二极管RC总线 - 终端阵列
| 型号： | SN74F1018 |
| 厂家： | 
TEXAS INSTRUMENTS |
| 描述： | 18-BIT SCHOTTKY BARRIER DIODE R-C BUS-TERMINATION ARRAY |
| 文件： | 总5页 (文件大小：89K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
SN74F1018
18-BIT SCHOTTKY BARRIER DIODE
R-C BUS-TERMINATION ARRAY
SDFS094 – NOVEMBER 1992 – REVISED DECEMBER 1993
DW PACKAGE
(TOP VIEW)
• Designed to Reduce Reflection Noise
• Repetitive Peak Forward
Current . . . 300 mA
GND
GND
A1
A2
A3
A4
A5
A6
A7
GND
GND
A18
A17
A16
A15
A14
A13
A12
1
24
23
22
21
20
19
18
17
16
• 18-Bit Array Structure Suited for
2
Bus-Oriented Systems
3
4
description
5
6
This bus-termination array is designed to reduce
reflection noise and minimize ringing on
high-performance bus lines. The SN74F1018
features an 18-bit R-C network and Schottky
barrier diode array. These Schottky diodes
provide clamp-to-ground functionality and serve
to minimize overshoot and undershoot of
high-speed switching buses.
7
8
9
A8
A9
GND
15 A11
10
11
12
A10
GND
14
13
The SN74F1018 is characterized for operation
from 0°C to 70°C.
schematic diagram
GND GND
24 23
A18
22
A17
21
A16
20
A15
19
A14
18
A13
17
A12
16
A11
15
A10
14
GND
13
1
2
3
4
5
6
7
8
9
10
A8
11
A9
12
GND GND
A1
A2
A3
A4
A5
A6
A7
GND
Resistor
= 50 Ω ± 10%
Capacitor = 47 pF ± 10%, V = 2.5 V, f = 1 MHz
R
Diode
= Schottky
Copyright 1993, 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.
2–1
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN74F1018
18-BIT SCHOTTKY BARRIER DIODE
R-C BUS-TERMINATION ARRAY
SDFS094 – NOVEMBER 1992 – REVISED DECEMBER 1993
†
absolute maximum ratings over operating free-air temperature range (unless otherwise noted)
Steady-state reverse voltage, V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
R
Continuous forward current, I : Any D terminal from GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 mA
F
Total through all GND terminals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 170 mA
‡
Repetitive peak forward current, I
: Any D terminal from GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . 300 mA
Total through all GND terminals . . . . . . . . . . . . . . . . . . . . . . . . . 1.2 A
FRM
Continuous total power dissipation at (or below) 25°C free-air temperature . . . . . . . . . . . . . . . . . . . . 500 mW
Operating free-air temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0°C to 70°C
Storage temperature range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to 150°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.
These values apply for t ≤ 100 µs, duty cycle ≤ 20%.
w
electrical characteristics over recommended operating free-air temperature range (unless
otherwise noted)
single-diode operation (see Note 1)
†
PARAMETER
TEST CONDITIONS
= 7 V
MIN TYP
MAX
2
UNIT
I
R
Static reverse current
V
µA
R
I
F
I
F
I
F
= 18 mA
= 50 mA
= 200 mA
0.8
1
1
V
Static forward voltage
Peak forward voltage
V
V
F
1.2
V
FM
1.25
V
R
V
R
V
R
= 0
80
60
55
C
Total capacitance
= 2 V
= 3 V
pF
t
†
All typical values are at T = 25°C.
A
NOTE 1: Test conditions and limits apply separately to each of the diodes. The diodes not under test are open-circuited during the measurement
of these characteristics.
multiple-diode operation
†
PARAMETER
TEST CONDITIONS
Total GND current = 1.2 A,
MIN TYP
MAX
UNIT
I
x
Internal crosstalk current
See Note 2
10
50
µA
NOTE 2: I is measured under the following conditions with one diode static, all others switching:
x
Switching diodes: t = 100 µs, duty cycle = 20%;
w
Static diode: V = 5 V; the static diode input current is the internal crosstalk current I .
R
x
switching characteristics, T = 25°C
A
†
PARAMETER
TEST CONDITIONS
= 10 mA,
MIN TYP
MAX
UNIT
t
rr
Reverse recovery time
I
F
= 10 mA,
I
I
= 1 mA,
R = 100 Ω
L
8
10
ns
RM(REC)
R(REC)
undershoot characteristics
†
PARAMETER
TEST CONDITIONS
MIN TYP
MAX
UNIT
t = 2 ns, t = 50 ns, V = 5 V, V = 0, Z = 25 Ω, Z = 50 Ω,
L = 36-inch coaxial cable
f
w
IH IL
S
O
V
US
Undershoot voltage
0.7
0.8
V
2–2
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN74F1018
18-BIT SCHOTTKY BARRIER DIODE
R-C BUS-TERMINATION ARRAY
SDFS094 – NOVEMBER 1992 – REVISED DECEMBER 1993
APPLICATION INFORMATION
Large negative transients occurring at the inputs of memory devices (DRAMs, SRAMs, EPROMs, etc.) or on the
CLOCK lines of many clocked devices can result in improper operation of the devices. The SN74F1018 diode
termination array helps suppress negative transients caused by transmission line reflections, crosstalk, andswitching
noise.
Diode terminations have several advantages when compared to resistor termination schemes. Split resistor or
Thevenin equivalent termination can cause a substantial increase in power consumption. The use of a single resistor
togroundtoterminatealineusuallyresultsindegradationoftheoutputhighlevel, resultinginreducednoiseimmunity.
Series damping resistors placed on the outputs of the driver will reduce negative transients, but they can also increase
propagation delays down the line, as a series resistor reduces the output drive capability of the driving device. Diode
terminations have none of these drawbacks.
The operation of the diode arrays in reducing negative transients is explained in Figure 1. The diode conducts current
whenever the voltage reaches a negative value large enough for the diode to turn on. Suppression of negative
transients is tracked by the current-voltage characteristic curve for that diode. A typical current voltage for the
SN74F1018 is shown in Figure 1.
The maximum effectiveness of the diode arrays in suppressing negative transients occurs when they are placed at
the end of a line and/or the end of a long stub branching off a main transmission line. The diodes can also be used
to reduce the negative transients that occur due to discontinuities in the middle of a line. An example of this is a slot
in a backplane that is provided for an add-on card.
DIODE FORWARD CURRENT
vs
DIODE FORWARD VOLTAGE
–100
Variable 1:
T
A
= 25°C
V
IN
–Ch1
–90
–80
–70
–60
–50
–40
–30
–20
–10
0
Linear Sweep:
Start
Stop
Step
0.000 V
–2.000 V
– 0.010 V
Constants:
V
V
–Vs1
–Vs2
3.5000 V
0.0000 V
HI
LO
0
0.2 0.4 0.6 0.8
1
1.2 1.4 1.6 1.8
2
V
F
– Forward Voltage – V
Figure 1
2–3
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
SN74F1018
18-BIT SCHOTTKY BARRIER DIODE
R-C BUS-TERMINATION ARRAY
SDFS094 – NOVEMBER 1992 – REVISED DECEMBER 1993
Z
= 50 Ω
O
Length = 36 in
S1
Z
S
= 25Ω
(a) UNDERSHOOT TEST SETUP
243.500 ns
218.500 ns
268.500 ns
S1 Open
S1 Closed
Vmarker 1
Vmarker 2
–2.0 V
Ch. 1
=
=
=
=
1.00 V/div
5.00 ns/div
0.00 V
Offset
Delay
Delta V
=
=
=
– 20.00 mV
243.5 ns
–640.00 mV
Timebase
Vmarker 1
Vmarker 2
–640.00 mV
(b) SCOPE DISPLAY
Figure 2. Undershoot Test Setup and Scope Display
2–4
POST OFFICE BOX 655303 • DALLAS, TEXAS 75265
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pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
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In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
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Copyright 1998, Texas Instruments Incorporated
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