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參數(shù)資料
| 型號： | KSZ8842-16MBL |
| 廠商： | Micrel Inc |
| 文件頁數(shù)： | 72/141頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC MAC CTLR 2PORT ETH 100-LFBGA |
| 標準包裝： | 260 |
| 控制器類型： | 以太網(wǎng)開關(guān)控制器 |
| 接口： | PCI |
| 電源電壓： | 3.1 V ~ 3.5 V |
| 工作溫度： | 0°C ~ 70°C |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 100-LBGA |
| 供應(yīng)商設(shè)備封裝： | 100-LFBGA |
| 包裝： | 托盤 |
| 產(chǎn)品目錄頁面： | 1081 (CN2011-ZH PDF) |
| 配用： | 576-1635-ND - BOARD EVALUATION KSZ8842-16MVL 576-1634-ND - BOARD EVALUATION KSZ8842-16MQL |
| 其它名稱： | 576-3076 |
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Micrel, Inc.
KSZ8842-16/32 MQL/MVL/MVLI/MBL
October 2007
36
M9999-102207-1.9
To avoid jabber and excessive deference (as defined in the 802.3 standard), after a certain time, the KSZ8842M
discontinues the carrier sense and then raises it again quickly. This short silent time (no carrier sense) prevents other
stations from sending out packets thus keeping other stations in a carrier sense deferred state. If the port has packets to
send during a backpressure situation, the carrier sense type backpressure is interrupted and those packets are
transmitted instead. If there are no additional packets to send, carrier sense type backpressure is reactivated again until
switch resources free up. If a collision occurs, the binary exponential back-off algorithm is skipped and carrier sense is
generated immediately, thus reducing the chance of further collisions and carrier sense is maintained to prevent packet
reception.
To ensure no packet loss in 10 BASE-T or 100 BASE-TX half-duplex modes, the user must enable the following:
1.
Aggressive back off (bit 8 in SGCR1)
2.
No excessive collision drop (bit 3 in SGCR2)
Note: These bits are not set in default, since this is not the IEEE standard.
Broadcast Storm Protection
The KSZ8842M has an intelligent option to protect the switch system from receiving too many broadcast packets. As the
broadcast packets are forwarded to all ports except the source port, an excessive number of switch resources (bandwidth
and available space in transmit queues) may be utilized. The KSZ8842M has the option to include “multicast packets” for
storm control. The broadcast storm rate parameters are programmed globally, and can be enabled or disabled on a per
port basis in P1CR1[7] and P2CR1[7]. The rate is based on a 67ms interval for 100BT and a 670ms interval for 10BT. At
the beginning of each interval, the counter is cleared to zero and the rate limit mechanism starts to count the number of
bytes during the interval. The rate definition is described in SGCR3[2:0][15:8]. The default setting is 0x63 (99 decimal).
This is equal to a rate of 1%, calculated as follows:
148,800 frames/sec X 67 ms/interval X 1% = 99 frames/interval (approx.) = 0x63
Note: 148,800 frames/sec is based on 64-byte block of packets in 100BASE-T with 12 bytes of IPG and 8 bytes of
preamble between two packets.
Repeater Mode
When the KSZ8842M is set to repeater mode (SGCR3[7] = 1), it only works on 100BT half-duplex mode. In repeater
enabled mode, all ingress packets will be broadcast to the other two ports without MAC address checking and learning.
Before setting to the repeater mode, the user has to set bit 13 (100Mbps), bit 12 (auto-negotiation disabled) and bit 8 (half
duplex) in both P1MBCR and P2MBCR registers as well as set bit 6 (host half duplex) in SGCR3 register for the repeater
mode.
The latency in repeater mode is defined from the 1st bit of DA into the ingress port 1 to the 1st bit of DA out of the egress
port 2. The minimum is 270 ns and the maximum is 310 ns (one clock skew of 25 MHz between TX and RX).
Clock Generator
The X1 and X2 pins are connected to a 25 MHz crystal. X1 can also serve as the connector to a 3.3V, 25 MHz oscillator
(as described in the pin description).
The bus interface unit (BIU) uses BCLK (Bus Clock) for synchronous accesses. The maximum host port frequency is 50
MHz for VLBus-like and burst mode (32-bit interface only).
Bus Interface Unit (BIU)
The host interface of the BIU is designed to communicate with embedded processors. The host interface of the
KSZ8842M is a generic bus interface. Some glue logic may be required when the interface talks to various buses and
processors.
In terms of transfer type, the BIU can support two transfers: asynchronous transfer and synchronous transfer. To support
these transfers (asynchronous and synchronous), the BIU provides three groups of signals:
1.
Synchronous signals
2.
Asynchronous signals
3.
Common signals are used for both synchronous and asynchronous transfers.
Since both synchronous and asynchronous signals are independent of each other, synchronous burst transfer and
asynchronous transfer can be mixed or interleaved but cannot be overlapped (due to the sharing of the common signals).
In terms of physical data bus size, the KSZ8842M supports 8, 16, and 32 bit host/industrial standard data bus sizes.
Given a physical data bus size, the KSZ8842M supports 8, 16, or 32-bit data transfers depending on the size of the
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| KSZ8842-16MBL-EVAL | 制造商:MICREL 制造商全稱:Micrel Semiconductor 功能描述:2-Port Ethernet Switch with Non-PCI Interface |
| KSZ8842-16MBLI | 功能描述:以太網(wǎng) IC 2-Port Ethernet Switch + Generic (8, 16-Bit) Bus Interface (I-Temp, Lead Free) RoHS:否 制造商:Micrel 產(chǎn)品:Ethernet Switches 收發(fā)器數(shù)量:2 數(shù)據(jù)速率:10 Mb/s, 100 Mb/s 電源電壓-最大:1.25 V, 3.45 V 電源電壓-最小:1.15 V, 3.15 V 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-64 封裝:Tray |
| KSZ8842-16MBLI TR | 功能描述:以太網(wǎng) IC 2-Port Ethernet Switch + Generic (8, 16-Bit) Bus Interface (I-Temp, Lead Free) RoHS:否 制造商:Micrel 產(chǎn)品:Ethernet Switches 收發(fā)器數(shù)量:2 數(shù)據(jù)速率:10 Mb/s, 100 Mb/s 電源電壓-最大:1.25 V, 3.45 V 電源電壓-最小:1.15 V, 3.15 V 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-64 封裝:Tray |
| KSZ8842-16MQL | 功能描述:以太網(wǎng) IC 2-Port Ethernet Switch/Repeater + Generic (8, 16-bit) bus interface(Lead Free) RoHS:否 制造商:Micrel 產(chǎn)品:Ethernet Switches 收發(fā)器數(shù)量:2 數(shù)據(jù)速率:10 Mb/s, 100 Mb/s 電源電壓-最大:1.25 V, 3.45 V 電源電壓-最小:1.15 V, 3.15 V 最大工作溫度:+ 85 C 封裝 / 箱體:QFN-64 封裝:Tray |
| KSZ8842-16MQL-EVAL | 功能描述:以太網(wǎng)開發(fā)工具 KSZ8842-16MQL Evaluation Board RoHS:否 制造商:Micrel 產(chǎn)品:Evaluation Boards 類型:Ethernet Transceivers 工具用于評估:KSZ8873RLL 接口類型:RMII 工作電源電壓: |
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