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參數(shù)資料
| 型號： | LTC1686 |
| 廠商： | Linear Technology Corporation |
| 英文描述： | 52Mbps Precision Delay RS485 Fail-Safe Transceivers |
| 中文描述： | 52Mbps的精密延遲485故障安全收發(fā)器 |
| 文件頁數(shù)： | 9/12頁 |
| 文件大?。?/td> | 285K |
| 代理商： | LTC1686 |
9
LTC1686/LTC1687
(the converse applies for the “B” output). The outputs then
appear as
±
10mA current sources. Note that under normal
operation, the output drivers can sink/source >50mA. A
time-out period of about 50ns is used in order to maintain
normal high frequency operation, even under heavy ca-
pacitive loads.
If the cable is shorted at a large distance from the device
outputs, it is possible for the short to go unnoticed at the
driver outputs due to parasitic cable resistance. Addition-
ally, when the cable is shorted, it no longer appears as a
simple transmission line impedance, and the parasitic L’s
and C’s might give rise to ringing and even oscillation. All
these conditions disappear once the device comes out of
short-circuit mode.
For cables with the typical RS485 termination (no DC bias
on the cable, such as Figure 10), the LTC1686/LTC1687
will automatically come out of short-circuit mode once the
physical short has been removed.
Cable Termination
The recommended cable termination for the LTC1686/
LTC1687 is a single resistor across the two wires at each
end of the twisted-pair line (see Figure 10). The LTC1687
can also be used with cable terminations with a DC bias
(such as Fast-20 and Fast-40 differential SCSI termina-
tors). When using a biased termination with the LTC1687,
however, the DE pin must be held low for at least 200ns
after the part has been powered up. This ensures proper
start-up into the DC load of the biased termination. Fur-
thermore, when the LTC1687 output is shorted, the DE pin
APPLICATIO
S I
FOR
ATIO
U
W
U
U
should be pulsed low for at least 200ns after the short has
been removed. Since the LTC1686 driver is always
enabled, the LTC1686 should only be used with single
resistor termination, as shown in Figure 10.
HIGH SPEED TWISTED-PAIR TRANSMISSION
Data rates up to 52Mbps can be transmitted over 100 feet
of category 5 twisted pair. Figure 10 shows the LTC1687
receiving differential data from another LTC1687 trans-
ceiver. Figure 11a shows a 26MHz (52Mbps) square wave
propagated over 100 feet of category 5 UTP. Figure 11b
shows a more stringent case of propagating a 20ns pulse
over 100 feet of category 5 UTP. Figure 12 shows a 2MHz
(4Mbps) square wave propagated over 1000 feet of
category 5 unshielded twisted pair. Note that the LTC1686/
LTC1687 can still perform reliably at this distance and
speed. Very inexpensive unshielded telephone grade
twisted pair is shown in Figure 13. Despite the noticeable
loss at the receiver input, the LTC1686/LTC1687 can still
transfer at 30Mbps over 100 feet of telephone grade UTP.
Note that under all these conditions, the LTC1686/LTC1687
can pass through a single data pulse equal to the inverse
of the data rate (e.g., 20ns for 50Mbps data rate).
TRANSMISSION OVER LONG DISTANCES
1Mbps Over 4000 Feet Category 5 UTP
The LTC1685/LTC1686/LTC1687 family of high speed
transceivers is capable of 1Mbps transmission over 4000
feet of category 5 UTP. High quality cable provides lower
Figure 10
LTC1686/87 F10
100
100
100
100
LTC1687
R
D
R
D
5
2
11
12
10
9
4
DE
3
RE
DE
RE
CATEGORY 5 UTP
RECEIVER
LTC1687
DRIVER
RECEIVER
DRIVER
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LTC1686CS8 | 52Mbps Precision Delay RS485 Fail-Safe Transceivers |
| LTC1687 | 52Mbps Precision Delay RS485 Fail-Safe Transceivers |
| LTC1687CS | 12-Bit, 2.5 us Dual DAC, Serial Input, Pgrmable Settling Time, Simultaneous Update, Low Power 8-SOIC -40 to 125 |
| LTC1688CS | 100Mbps RS485 Hot Swapable Quad Drivers |
| LTC1689CS | 100Mbps RS485 Hot Swapable Quad Drivers |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1686CS8 | 功能描述:IC TXRX RS485 PREC DELAY 8-SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅(qū)動器，接收器，收發(fā)器 系列:- 標準包裝:27 系列:- 類型:收發(fā)器 驅(qū)動器/接收器數(shù):3/3 規(guī)程:RS232，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC 包裝:管件 |
| LTC1686CS8#PBF | 功能描述:IC TXRX RS485 PREC DELAY 8-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動器，接收器，收發(fā)器 系列:- 產(chǎn)品培訓模塊:RS-232 & USB Transceiver 標準包裝:2,000 系列:- 類型:收發(fā)器 驅(qū)動器/接收器數(shù):1/1 規(guī)程:RS232 電源電壓:3 V ~ 5.5 V 安裝類型:表面貼裝 封裝/外殼:16-SSOP（0.209"，5.30mm 寬） 供應(yīng)商設(shè)備封裝:16-SSOP 包裝:帶卷 (TR) 其它名稱:296-19849-2 |
| LTC1686CS8#PBF | 制造商:Linear Technology 功能描述:IC, RS-485 TRANSCEIVER, 5V, SOIC-8 |
| LTC1686CS8#TR | 功能描述:IC TXRX RS485 PREC DELAY 8SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅(qū)動器，接收器，收發(fā)器 系列:- 標準包裝:27 系列:- 類型:收發(fā)器 驅(qū)動器/接收器數(shù):3/3 規(guī)程:RS232，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC 包裝:管件 |
| LTC1686CS8#TRPBF | 功能描述:IC TXRX RS485 PREC DELAY 8-SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動器，接收器，收發(fā)器 系列:- 標準包裝:27 系列:- 類型:收發(fā)器 驅(qū)動器/接收器數(shù):3/3 規(guī)程:RS232，RS485 電源電壓:4.75 V ~ 5.25 V 安裝類型:表面貼裝 封裝/外殼:28-SOIC（0.295"，7.50mm 寬） 供應(yīng)商設(shè)備封裝:28-SOIC 包裝:管件 |
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