参数资料
型号: KSZ8851-16MLLI
厂商: Micrel Inc
文件页数: 9/84页
文件大小: 0K
描述: IC MAC CTLR 1PORT W/BUS 48-TQFP
标准包装: 250
控制器类型: 以太网控制器,MAC/PHY
接口: 总线
电源电压: 1.8V,2.5V,3.3V
工作温度: -40°C ~ 85°C
安装类型: 表面贴装
封装/外壳: 48-LQFP
供应商设备封装: 48-LQFP(7x7)
包装: 托盘
产品目录页面: 1081 (CN2011-ZH PDF)
其它名称: 576-3505
Micrel, Inc.
KSZ8851-16MLL/MLLI
March 11, 2014
17
Revision 2.2
Physical Layer Transceiver (PHY)
100BASE-TX Transmit
The 100BASE-TX transmit function performs parallel-to-serial conversion, 4B/5B coding, scrambling, NRZ-to-NRZI
conversion, and MLT3 encoding and transmission.
The circuitry starts with a parallel-to-serial conversion, which converts the MII data from the MAC into a 125MHz serial bit
stream. The data and control stream is then converted into 4B/5B coding, followed by a scrambler. The serialized data is
further converted from NRZ-to-NRZI format, and then transmitted in MLT3 current output. An external 3.01K
(1%)
resistor for the 1:1 transformer ratio sets the output current.
The output signal has a typical rise/fall time of 4ns and complies with the ANSI TP-PMD standard regarding amplitude
balance, overshoot, and timing jitter. The wave-shaped 10BASE-T output driver is also incorporated into the 100BASE-TX
driver.
100BASE-TX Receive
The 100BASE-TX receiver function performs adaptive equalization, DC restoration, MLT3-to-NRZI conversion, data and
clock recovery, NRZI-to-NRZ conversion, de-scrambling, 4B/5B decoding, and serial-to-parallel conversion.
The receiving side starts with the equalization filter to compensate for inter-symbol interference (ISI) over the twisted pair
cable. Since the amplitude loss and phase distortion is a function of the cable length, the equalizer has to adjust its
characteristics to optimize performance. In this design, the variable equalizer makes an initial estimation based on
comparisons of incoming signal strength against some known cable characteristics, and then tunes itself for optimization.
This is an ongoing process and self-adjusts against environmental changes such as temperature variations.
Next, the equalized signal goes through a DC restoration and data conversion block. The DC restoration circuit is used to
compensate for the effect of baseline wander and to improve the dynamic range. The differential data conversion circuit
converts the MLT3 format back to NRZI. The slicing threshold is also adaptive.
The clock recovery circuit extracts the 125 MHz clock from the edges of the NRZI signal. This recovered clock is then
used to convert the NRZI signal into the NRZ format. This signal is sent through the de-scrambler followed by the 4B/5B
decoder. Finally, the NRZ serial data is converted to an MII format and provided as the input data to the MAC.
PLL Clock Synthesizer (Recovery)
The internal PLL clock synthesizer can generate either 125MHz, 62.5MHz, 41.66MHz, or 25MHz clocks by setting the on-
chip bus control register (0x20) for KSZ8851-16MLL system timing. These internal clocks are generated from an external
25MHz crystal or oscillator.
Scrambler/De-scrambler (100BASE-TX only)
The purpose of the scrambler is to spread the power spectrum of the signal to reduce electromagnetic interference (EMI)
and baseline wander.
Transmitted data is scrambled through the use of an 11-bit wide linear feedback shift register (LFSR). The scrambler
generates a 2047-bit non-repetitive sequence. Then the receiver de-scrambles the incoming data stream using the same
sequence as at the transmitter.
10BASE-T Transmit
The 10BASE-T driver is incorporated with the 100BASE-TX driver to allow for transmission using the same magnetics.
They are internally wave-shaped and pre-emphasized into outputs with typical 2.4V amplitude. The harmonic contents are
at least 27dB below the fundamental frequency when driven by an all-ones Manchester-encoded signal.
10BASE-T Receive
On the receive side, input buffers and level detecting squelch circuits are employed. A differential input receiver circuit and
a phase-locked loop (PLL) perform the decoding function.
The Manchester-encoded data stream is separated into clock signal and NRZ data. A squelch circuit rejects signals with
levels less than 400mV or with short pulse widths to prevent noise at the RXP1 or RXM1 input from falsely triggering the
decoder. When the input exceeds the squelch limit, the PLL locks onto the incoming signal and the KSZ8851-16MLL
decodes a data frame. The receiver clock is maintained active during idle periods in between data reception.
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KSZ8851-16MLLJ_10 制造商:MICREL 制造商全称:Micrel Semiconductor 功能描述:Single-Port Ethernet MAC Controller with 8-Bit or 16-Bit Non-PCI Interface
KSZ8851-16MLLU 功能描述:以太网 IC Single-Port Ethernet Controller (Automotive Grade) RoHS:否 制造商:Micrel 产品:Ethernet Switches 收发器数量:2 数据速率:10 Mb/s, 100 Mb/s 电源电压-最大:1.25 V, 3.45 V 电源电压-最小:1.15 V, 3.15 V 最大工作温度:+ 85 C 封装 / 箱体:QFN-64 封装:Tray
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