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參數(shù)資料
| 型號： | LTC1487CS8 |
| 廠商： | LINEAR TECHNOLOGY CORP |
| 元件分類： | 通用總線功能 |
| 英文描述： | Ultra-Low Power RS485 with Low EMI, Shutdown and High Input Impedance |
| 中文描述： | LINE TRANSCEIVER, PDSO8 |
| 封裝： | 0.150 INCH, PLASTIC, SO-8 |
| 文件頁數(shù)： | 8/8頁 |
| 文件大小： | 224K |
| 代理商： | LTC1487CS8 |
8
LTC1487
APPLICATIU
effects of noise on the line signals. If the line is terminated
or the receiver inputs are shorted together, the receiver
output will retain the last valid line signal due to the 45mV
of hysteresis incorporated in the receiver circuit. If the
LTC1487 transceiver inputs are left floating (unterminated),
an internal pull-up of 10
μ
A at the A input will force the
receiver output to a known high state.
U
W
U
Low Power Operation
The LTC1487 draws very little supply current whenever
the driver outputs are disabled. In shutdown mode, the
quiescent current is typically less than 1
μ
A. With the
receiver active and the driver outputs disabled, the LTC1487
will typically draw 80
μ
A quiescent current. With the driver
outputs enabled but unterminated, quiescent current will
rise slightly as one of the two outputs sources current into
the internal receiver input resistance. With the minimum
receiver input resistance of 70k and the maximum output
swing of 5V, the quiescent current will rise by a maximum
of 72
μ
A. Typical quiescent current rise with the driver
enabled is about 40
μ
A.
The quiescent current rises significantly if the driver is
enabled when it is externally terminated. With 1/2
termination load (120
between the driver outputs), the
quiescent current will jump to at least 13mA as the drivers
force a minimum of 1.5V across the termination resistance.
With a fully terminated 60
line attached, the current will
rise to greater than 25mA with the driver enabled,
completely overshadowing the extra 40
μ
A drawn by the
internal receiver inputs.
Shutdown Mode
Both the receiver output (RO) and the driver outputs (A, B)
can be placed in three-state mode by bringing RE HIGH
and DE LOW respectively. In addition, the LTC1487 will
enter shutdown mode when RE is HIGH and DE is LOW.
In shutdown the LTC1487 typically draws only 1
μ
A of
supply current. In order to guarantee that the part goes
into shutdown, RE must be HIGH and DE must be LOW for
at least 600ns simultaneously. If this time duration is less
than 50ns the part will not enter shutdown mode. Toggling
either RE or DE will wake the LTC1487 back up within
3.5
μ
s.
If the driver is active immediately prior to shutdown, the
supply current will not drop to 1
μ
A until the driver
outputs have reached a steady state; this can take as long
as 2.6
μ
s under worst case conditions. If the driver is
disabled prior to shutdown the supply current will drop
to 1
μ
A immediately.
Slew Rate and Propagation Delay
Many digital encoding schemes are dependent upon the
difference in the propagation delay times of the driver and
receiver. Figure 11 shows the test circuit for the LTC1487
propagation delay.
Figure 11. Receiver Propagation Delay Test Circuit
D
BR
R
RECEIVER
OUT
R
100
100pF
100pF
TTL IN
t
r
, t
f
< 6ns
LTC1487 F11
The receiver delay times are:
t
PLH
– t
PHL
= 13ns Typ, V
CC
= 5V
The LTC1487 drivers feature controlled slew rate to reduce
system EMI and improve signal fidelity by reducing reflec-
tions due to misterminated cables.
The driver’s skew times are:
Skew = 250ns Typ, V
CC
= 5V
600ns Max, V
CC
= 5V, T
A
= –40
°
C to 85
°
C
For package descriptions consult the 1994 Linear Databook Volume III
PACKAGE DESCRIPTIO
N
U
LINEAR TECHNOLOGY CORPORATION 1995
LT/GP 0395 10K PRINTED IN THE USA
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, CA 95035-7487
(408) 432-1900
G
FAX
: (408) 434-0507
G
TELEX
: 499-3977
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| LTC1487CS8#PBF | 功能描述:IC TXRX RS485 LOW EMI LOPWR8SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發(fā)器 系列:- 產品培訓模塊:RS-232 & USB Transceiver 標準包裝:2,000 系列:- 類型:收發(fā)器 驅動器/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） 供應商設備封裝:16-SSOP 包裝:帶卷 (TR) 其它名稱:296-19849-2 |
| LTC1487CS8#TR | 功能描述:IC TXRX RS485 LO EMI SHTDN 8SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發(fā)器 系列:- 標準包裝:121 系列:- 類型:收發(fā)器 驅動器/接收器數(shù):1/1 規(guī)程:RS422，RS485 電源電壓:3 V ~ 3.6 V 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:管件 |
| LTC1487CS8#TRPBF | 功能描述:IC TXRX RS485 LOW EMI LOPWR8SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅動器，接收器，收發(fā)器 系列:- 標準包裝:121 系列:- 類型:收發(fā)器 驅動器/接收器數(shù):1/1 規(guī)程:RS422，RS485 電源電壓:3 V ~ 3.6 V 安裝類型:表面貼裝 封裝/外殼:10-WFDFN 裸露焊盤 供應商設備封裝:10-DFN（3x3） 包裝:管件 |
| LTC1487CS8PBF | 制造商:Linear Technology 功能描述:RS485 differential transceiverLTC1487CS8 |
| LTC150-1 | 制造商:Thomas & Betts 功能描述:APC CONDUIT |
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