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VSC7123XQN 参数 Datasheet PDF下载

VSC7123XQN图片预览
型号: VSC7123XQN
PDF下载: 下载PDF文件 查看货源
内容描述: [暂无描述]
分类和应用: 光纤以太网
文件页数/大小: 18 页 / 210 K
品牌: VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
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VITESSE  
SEMICONDUCTOR CORPORATION  
Data Sheet  
10-Bit Transceiver for Fibre  
Channel and Gigabit Ethernet  
VSC7123  
serial data is retimed, deserialized and output on R(0:9). The parallel data will be captured by the adjoining  
protocol logic on the rising edges of RCLK and RCLKN.  
If serial input data is not present or does not meet the required baud rate, the VSC7123 will continue to  
produce a recovered clock, allowing downstream logic functionality to continue. Under these circumstances,  
the RCLK/RCLKN output frequency differ from its expected frequency by no more than +1%.  
Word Alignment  
The VSC7123 provides 7-bit comma character recognition and data word alignment. Word synchronization  
is enabled by asserting ENCDET HIGH. When synchronization is enabled, the receiver examines the recovered  
serial data for the presence of the “Commacharacter. This pattern is 0011111XXX, where the leading zero  
corresponds to the first bit received. The comma sequence is not contained in any normal 8B/10B coded data  
character or pair of adjacent characters. It occurs only within special characters, known as K28.1, K28.5 and  
K28.7, which are defined for synchronization purposes. Improper alignment of the comma character is defined  
as any of the following conditions:  
1) The comma is not aligned within the 10-bit transmission character such that R0...R6 = 0011111.”  
2) The comma straddles the boundary between two 10-bit transmission characters.  
3) The comma is properly aligned but occurs in the received character presented during the rising edge of  
RCLK rather than RCLKN.  
When ENCDET is HIGH and an improperly aligned comma is encountered, the recovered clock is  
stretched (never slivered) so that the comma character and recovered clocks are properly aligned to R(0:9). This  
results in proper character and word alignment. When the parallel data alignment changes in response to a  
improperly aligned comma pattern, some data which would have been presented on the parallel output port may  
be lost. Additionally, the first Comma pattern may also be lost or corrupted. Subsequent data will be output  
correctly and properly aligned. When ENCDET is LOW, the current alignment of the serial data is maintained  
indefinitely, regardless of data pattern.  
When encountering a comma character, COMDET is driven HIGH. The COMDET pulse is presented  
simultaneously with the comma character and has a duration equal to the data, or half of an RCLK period. The  
COMDET signal is timed such that it can be captured by the adjoining protocol logic on the rising edge of  
RCLKN. Functional waveforms for synchronization are given in Figure 2 and Figure 3. Figure 2 shows the case  
when a comma character is detected and no phase adjustment is necessary. Figure 2 illustrates the position of  
the COMDET pulse in relation to the comma character on R(0:9). Figure 3 shows the case where the K28.5 is  
detected, but it is misaligned so a change in the output data alignment is required. Note that up to three  
characters prior to the comma character may be corrupted by the realignment process.  
G52212-0, Rev 4.3  
03/25//01  
Page 3  
© VITESSE SEMICONDUCTOR CORPORATION 741 Calle Plano Camarillo, CA 93012  
Tel: (800) VITESSE FAX: (805) 987-5896 Email: prodinfo@vitesse.com  
Internet: www.vitesse.com  
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