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COM20020-5 参数 Datasheet PDF下载

COM20020-5图片预览
型号: COM20020-5
PDF下载: 下载PDF文件 查看货源
内容描述: 通用局域网控制器2K ×8板载RAM [Universal Local Area Network Controller with 2K x 8 On-Board RAM]
分类和应用: 控制器局域网
文件页数/大小: 58 页 / 248 K
品牌: SMSC [ SMSC CORPORATION ]
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configuration recommended for applications like  
car-area networks or other cost-sensitive  
applications which do not require direct  
compatibility with existing ARCNET nodes and  
do not require isolation.  
COM20020-5 is disabled during reset and the  
nPULSE1, nPULSE2 and nTXEN pins are  
inactive.  
Programmable TXEN Polarity  
The Differential Driver Configuration cannot  
communicate directly with nodes utilizing the  
To accommodate transceivers with active high  
ENABLE pins, the COM20020-5 contains a  
programmable TXEN output. To program the  
TXEN pin for an active high pulse, the nPULSE2  
pin should be connected to ground. To retain  
the normal active low polarity, nPULSE2 should  
be left open. The polarity determination is made  
Traditional Hybrid Configuration.  
Like the  
Backplane Configuration, the Differential Driver  
Configuration does not isolate the node from the  
media.  
at power on reset and is  
Mode operation.  
remain grounded at all times if an active high  
polarity is desired.  
The Differential Driver interface includes a  
RS485 Driver/Receiver to transfer the data  
between the cable and the COM20020-5. The  
nPULSE1 signal transmits the data, provided  
the Transmit Enable signal is active. The  
nPULSE1 signal issues a 100nS negative pulse  
to transmit a logic "1". Lack of pulse indicates a  
logic "0". The RXIN signal receives the data. A  
negative pulse on this input indicates a logic "1".  
valid only for Backplane  
The nPULSE2 pin should  
Note: The COM20020-5 operates at a 5 Mbps  
data rate which is not compatible with previous  
ARCNET devices. The COM20020-5 should not  
be used with the HYC9088 or HYC9068 media  
interface hybrids.  
The  
transmitter  
portion  
of  
the  
RT  
RT  
+VCC  
+VCC  
+VCC  
RBIAS  
RBIAS  
RBIAS  
75ALS176B  
or Equiv.  
COM20020-5  
COM20020-5  
COM20020-5  
FIGURE 4 – COM20020-5 NETWORK USING RS-485 DIFFERENTIAL TRANSCEIVERS  
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