參數(shù)資料
型號: LTC486ISW
廠商: Linear Technology
文件頁數(shù): 2/14頁
文件大小: 0K
描述: IC DVR RS485 LOW PWR QUAD 16SOIC
標(biāo)準(zhǔn)包裝: 47
類型: 驅(qū)動(dòng)器
驅(qū)動(dòng)器/接收器數(shù): 4/0
規(guī)程: RS422,RS485
電源電壓: 4.75 V ~ 5.25 V
安裝類型: 表面貼裝
封裝/外殼: 16-SOIC(0.295",7.50mm 寬)
供應(yīng)商設(shè)備封裝: 16-SOIC
包裝: 管件
LTC486
10
486fc
APPLICATIONS INFORMATION
Thecouplingcapacitorallowshighfrequencyenergytoflow
to the termination, but blocks DC and low frequencies. The
dividing line between high and low frequency depends on
the length of the cable. The coupling capacitor must pass
frequencies above the point where the line represents an
electrical one-tenth wavelength. The value of the coupling
capacitorshouldthereforebesetat16.3pFperfootofcable
length for 120 cables. With the coupling capacitors in
place, power is consumed only on the signal edges, not
when the driver output is idling at a 1 or 0 state. A 100nF
capacitor is adequate for lines up to 4000 feet in length.
Be aware that the power savings start to decrease once
the data rate surpasses 1/(120
× C).
486 F11
140
RECEIVER
RX
5V
1.5k
RECEIVER
RX
5V
110
130
110
130
120
RECEIVER
RX
C
5V
100k
1.5k
Figure 11. Forcing “0” When All Drivers Are Off
Receiver Open-Circuit Fail-Safe
Some data encoding schemes require that the output of
the receiver maintains a known state (usually a logic 1)
when the data is finished transmitting and all drivers on
the line are forced into three-state. All LTC RS485 receivers
have a fail-safe feature which guarantees the output to be
in a logic 1 state when the receiver inputs are left floating
(open-circuit). However, when the cable is terminated with
120, the differential inputs to the receiver are shorted
together, not left floating.
If the receiver output must be forced to a known state, the
circuits of Figure 11 can be used.
The termination resistors are used to generate a DC bias
which forces the receiver output to a known state, in this
case a logic 0. The first method consumes about 208mW
andthesecondabout8mW.Thelowestpowersolutionisto
use an AC termination with a pull-up resistor. Simply swap
the receiver inputs for data protocols ending in logic 1.
Fault Protection
All of LTC’s RS485 products are protected against ESD
transients up to ±2kV using the human body model
(100pF, 1.5k). However, some applications need greater
protection. The best protection method is to connect a
bidirectional TransZorb from each line side pin to ground
(Figure 12).
A TransZorb is a silicon transient voltage suppressor that
has exceptional surge handling capabilities, fast response
time, and low series resistance. They are available from
General Semiconductor Industries and come in a variety
of breakdown voltages and prices. Be sure to pick a break-
down voltage higher than the common-mode voltage
required for your application (typically 12V). Also, don’t
forget to check how much the added parasitic capacitance
will load down the bus.
486 F12
120
DRIVER
Z
Y
Figure 12. ESD Protection
相關(guān)PDF資料
PDF描述
IDT72V3611L20PF8 IC FIFO SYNC 64X36 20NS 120-TQFP
MS27656E17A35SD CONN RCPT 55POS WALL MNT W/SCKT
MS27497T10B99S CONN RCPT 7POS WALL MNT W/SCKT
IDT7285L15PAI8 IC FIFO 4096X18 15NS 56TSSOP
LT1794CSW#TR IC OPAMP 200MHZ DUAL 20-SOIC
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
LTC486ISW#PBF 功能描述:IC DVR RS485 LOW PWR QUAD 16SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器,接收器,收發(fā)器 系列:- 標(biāo)準(zhǔn)包裝:27 系列:- 類型:收發(fā)器 驅(qū)動(dòng)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
LTC486ISW#PBF 制造商:Linear Technology 功能描述:Differential Bus/Line Driver IC
LTC486ISW#TR 功能描述:IC DRIVER RS485 QUAD LP 16SOIC RoHS:否 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器,接收器,收發(fā)器 系列:- 標(biāo)準(zhǔn)包裝:27 系列:- 類型:收發(fā)器 驅(qū)動(dòng)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
LTC486ISW#TRPBF 功能描述:IC DVR RS485 LOW PWR QUAD 16SOIC RoHS:是 類別:集成電路 (IC) >> 接口 - 驅(qū)動(dòng)器,接收器,收發(fā)器 系列:- 標(biāo)準(zhǔn)包裝:27 系列:- 類型:收發(fā)器 驅(qū)動(dòng)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
LTC486ISWPBF 制造商:Linear Technology 功能描述:RS-485 Quad Transmitter 110uA SOIC16W