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参数资料
| 型号： | LTC2855CGN#PBF |
| 厂商： | Linear Technology |
| 文件页数： | 4/16页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS485/RS422 16-SSOP |
| 标准包装： | 100 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 1/1 |
| 规程： | RS422，RS485 |
| 电源电压： | 3 V ~ 3.6 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 16-SSOP |
| 包装： | 管件 |
| 产品目录页面： | 1355 (CN2011-ZH PDF) |
LTC2854/LTC2855
12
285455fb
285455 F14
DATA RATE (bps)
CABLE
LENGTH
(FT)
10k
1M
10M
100k
100M
100
1k
10
10k
RS485/RS422
MAX DATA RATE
LTC2854/LTC2855
MAX DATA RATE
Supply Current
The unloaded static supply currents in the LTC2854/
LTC2855 are very low —typically under 500μA for all
modes of operation. In applications with resistively ter-
minated cables, the supply current is dominated by the
driver load. For example, when using two 120Ω termina-
tors with a differential driver output voltage of 2V, the DC
current is 33mA, which is sourced by the positive voltage
supply. This is true whether the terminators are external
or internal such as in the LTC2854/LTC2855. Power sup-
ply current increases with toggling rate due to capacitive
loading and this term can increase signicantly at high
data rates. Figure 13 shows supply current vs data rate for
two different capacitive loads for the circuit conguration
of Figure 4.
High Speed Considerations
A ground plane layout is recommended for the LTC2854/
LTC2855. A 0.1μF bypass capacitor less than one-quarter
inch away from the VCC pin is also recommended. The PC
board traces connected to signals A/B and Z/Y (LTC2855)
should be symmetrical and as short as possible to maintain
good differential signal integrity. To minimize capacitive
effects, the differential signals should be separated by more
than the width of a trace and should not be routed on top
of each other if they are on different signal planes.
Care should be taken to route outputs away from any
sensitive inputs to reduce feedback effects that might
cause noise, jitter, or even oscillations. For example, in
the full duplex LTC2855, DI and A/B should not be routed
near the driver or receiver outputs.
The logic inputs of the LTC2854/LTC2855 have 150mV of
hysteresis to provide noise immunity. Fast edges on the
outputs can cause glitches in the ground and power supplies
which are exacerbated by capacitive loading. If a logic input
is held near its threshold (typically 1.5V), a noise glitch
from a driver transition may exceed the hysteresis levels
on the logic and data input pins causing an unintended
state change. This can be avoided by maintaining normal
logic levels on the pins and by slewing inputs through
their thresholds by faster than 1V/μs when transitioning.
Good supply decoupling and proper line termination also
reduces glitches caused by driver transitions.
Cable Length vs Data Rate
For a given data rate, the maximum transmission distance
is bounded by the cable properties. A typical curve of
cable length vs data rate compliant with the RS485/RS422
standards is shown in Figure 14. Three regions of this
curve reect different performance limiting factors in data
transmission. In the at region of the curve, maximum
distance is determined by resistive losses in the cable. The
downward sloping region represents limits in distance and
data rate due to AC losses in the cable. The solid vertical
line represents the specied maximum data rate in the
RS485/RS422 standards. The dashed lines at 20Mbps
show the maximum data rates of the LTC2854/LTC2855.
Figure 14. Cable Length vs Data Rate (RS485/
RS422 Standards Shown in Vertical Solid Line)
Figure 13. Supply Current vs Data Rate
DATA RATE (Mbps)
0.1
20
SUPPLY
CURRENT
(mA)
60
70
80
1
10
100
285455 F13
50
40
30
RDIFF = 54Ω
CL = 1000pF
CL = 100pF
APPLICATIONS INFORMATION
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC2855HDE#PBF | 功能描述:IC TXRX RS485/RS422 12-DFN RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 产品培训模块:RS-232 & USB Transceiver 标准包装:2,000 系列:- 类型:收发器 驱动器/接收器数:1/1 规程:RS232 电源电压:3 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:16-SSOP（0.209"，5.30mm 宽） 供应商设备封装:16-SSOP 包装:带卷 (TR) 其它名称:296-19849-2 |
| LTC2855HDE#TR | 制造商:Linear Technology 功能描述:Single Transmitter/Receiver RS-422/RS-485 12-Pin DFN EP T/R |
| LTC2855HDE#TRPBF | 功能描述:IC TXRX RS485/RS422 12-DFN RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LTC2855HGN#PBF | 功能描述:IC TXRX RS485/RS422 16-SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
| LTC2855HGN#TRPBF | 功能描述:IC TXRX RS485/RS422 16-SSOP RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:27 系列:- 类型:收发器 驱动器/接收器数:3/3 规程:RS232，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:28-SOIC（0.295"，7.50mm 宽） 供应商设备封装:28-SOIC 包装:管件 |
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