參數(shù)資料
型號: LTC491CS
廠商: LINEAR TECHNOLOGY CORP
元件分類: 通用總線功能
英文描述: Differential Driver and Receiver Pair
中文描述: LINE TRANSCEIVER, PDSO14
封裝: PLASTIC, SOIC-14
文件頁數(shù): 8/12頁
文件大?。?/td> 236K
代理商: LTC491CS
LTC491
8
U
S
A
O
PPLICATI
U
U
Thermal Shutdown
The LTC491 has a thermal shutdown feature which pro-
tects the part from excessive power dissipation. If the
outputs of the driver are accidently shorted to a power
supply or low impedance source, up to 250mA can flow
through the part. The thermal shutdown circuit disables
the driver outputs when the internal temperature reaches
150
°
C and turns them back on when the temperature
cools to 130
°
C. If the outputs of two or more LTC491
drivers are shorted directly, the driver outputs can not
supply enough current to activate the thermal shutdown.
Thus, the thermal shutdown circuit will not prevent con-
tention faults when two drivers are active on the bus at the
same time.
Cables and Data Rate
The transmission line of choice for RS485 applications is
a twisted pair. There are coaxial cables (twinaxial) made
for this purpose that contain straight pairs, but these are
less flexible, more bulky, and more costly than twisted
pairs. Many cable manufacturers offer a broad range of
120
cables designed for RS485 applications.
Losses in a transmission line are a complex combination
of DC conductor loss, AC losses (skin effect), leakage and
AC losses in the dielectric. In good polyethylene cables
such as the Belden 9841, the conductor losses and
dielectric losses are of the same order of magnitude,
leading to relatively low over all loss (Figure 11).
When using low loss cables, Figure 12 can be used as a
guideline for choosing the maximum line length for a given
data rate. With lower quality PVC cables, the dielectric loss
factor can be 1000 times worse. PVC twisted pairs have
terrible losses at high data rates (>100kBs), and greatly
reduce the maximum cable length. At low data rates
however, they are acceptable and much more economical.
DATA RATE (bps)
10k
10
C
100
1k
10k
100k
1M
10M
LTC491 TA13
2.5M
Figure 12. Cable Length vs Data Rate
Figure 11. Attenuation vs Frequency for Belden 9481
FREQUENCY (MH
Z
)
0.1
0.1
L
1.0
10
1.0
10
100
LTC491 TA12
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相關代理商/技術參數(shù)
參數(shù)描述
LTC491CS#PBF 功能描述:IC TXRX RS485 LOW POWER 14-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) 供應商設備封裝:16-SSOP 包裝:帶卷 (TR) 其它名稱:296-19849-2
LTC491CS#PBF 制造商:Linear Technology 功能描述:Driver/Receiver IC
LTC491CS#TR 功能描述:IC TXRX RS485 LOW POWER 14-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) 供應商設備封裝:28-SOIC 包裝:管件
LTC491CS#TRPBF 功能描述:IC TXRX RS485 LOW POWER 14-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) 供應商設備封裝:28-SOIC 包裝:管件
LTC491CSPBF 制造商:Linear Technology 功能描述:Differential driver & receiver,LTC491CS