參數(shù)資料
型號(hào)： KS8993F
廠商： Micrel Inc
文件頁(yè)數(shù)： 28/99頁(yè)
文件大?。?/td> 0K
描述： IC CONV MED 10/100 3PORT 128PQFP
標(biāo)準(zhǔn)包裝： 66
系列： *
類型： *
應(yīng)用： *
安裝類型： 表面貼裝
封裝/外殼： 128-BFQFP
供應(yīng)商設(shè)備封裝： 128-PQFP（14x20）
配用： KS8993F-EVAL-ND - EVAL KIT EXPERIMENTAL KS8993F
KS8993F
Micrel
August 26, 2004
Revision 1.0
- 34 -
On the transmit side, the KS8993F has intelligent and efficient means to determine when to invoke flow control. The
flow control is based on the availability of system resources, including available buffers, available transmit queues and
available receive queues.
The KS8993F will flow control a port, which just received a packet, if the destination port resource is being used up.
The KS8993F will issue a flow control frame (XOFF), containing the maximum pause time defined in IEEE standard
802.3x. Once the resource is freed up, the KS8993F will send out the other flow control frame (XON) with zero pause
time to turn off the flow control (turn on transmission to the port). A hysteresis feature is provided to prevent the flow
control mechanism from being activated and deactivated too many times.
The KS8993F will flow control all ports if the receive queue becomes full.
2.4.12 Half Duplex Back Pressure
A half-duplex back-pressure option (Note: not in IEEE 802.3 standards) is also provided.
The activation and
deactivation conditions are the same as the above in full duplex mode. If back-pressure is required, the KS8993F will
send preambles to defer the other stations' transmission (carrier sense deference). To avoid jabber and excessive
deference defined in 802.3 standard, after a certain time it will discontinue the carrier sense but it will raise the carrier
sense quickly. This short silent time (no carrier sense) is to prevent other stations from sending out packets and
keeps other stations in carrier sense deferred state. If the port has packets to send during a back-pressure situation,
the carrier sense type back-pressure will be interrupted and those packets will be transmitted instead. If there are no
more packets to send, carrier sense type back-pressure will be active again until switch resources free up. If a collision
occurs, the binary exponential back-off algorithm is skipped and carrier sense is generated immediately, reducing the
chance of further colliding and maintaining carrier sense to prevent reception of packets.
To ensure no packet loss in 10 BASE-T or 100 BASE-TX half duplex modes, the following should be enabled:
1.
Aggressive back off (set Global Register 3 (0x03), bit 0 to ‘1’, or pull high SMAC (pin 69))
2.
No excessive collision drop (set Global Register 4 (0x04), bit 3 to ‘1’, or pull high SMAC (pin 69))
These bits are not set as defaults because the settings are not part of the IEEE standard.
2.4.13 Broadcast Storm Protection
The KS8993F has an intelligent option to protect the switch system from receiving too many broadcast packets.
Broadcast packets will be forwarded to all ports except the source port, and thus use too many switch resources
(bandwidth and available space in transmit queues). The KS8993F 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. The rate is based on a 50ms interval for 100BT and a 500 ms 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 Global Registers 6 (0x06) and 7 (0x07).
The default setting for
registers 6 and 7 is 0x63, which is 99 decimal. This is equal to a rate of 1 %, calculated as follows:
148,800 frames/sec * 67 ms/interval * 1% = 99 frames/interval (approx.) = 0x63h
This means the KS8993F accepts only 1% of broadcast data and filters out 99%.
2.5
MII Interface Operation
The MII (Media Independent Interface) is specified by the IEEE 802.3 committee and provides a common interface
between physical layer and MAC layer devices. The MII Interface provided by the KS8993F is connected to the
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KS8993F-A1 功能描述:IC CONV MED 10/100 3PORT 128PQFP RoHS:否 類別:集成電路 (IC) >> 專用 IC 系列:* 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 類型:調(diào)幀器 應(yīng)用:數(shù)據(jù)傳輸 安裝類型:表面貼裝 封裝/外殼:400-BBGA 供應(yīng)商設(shè)備封裝:400-PBGA（27x27） 包裝:散裝
KS8993FA5 功能描述:IC SWITCH 3-PORT 10/100 128-PQFP RoHS:否 類別:集成電路 (IC) >> 專用 IC 系列:* 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 類型:調(diào)幀器 應(yīng)用:數(shù)據(jù)傳輸 安裝類型:表面貼裝 封裝/外殼:400-BBGA 供應(yīng)商設(shè)備封裝:400-PBGA（27x27） 包裝:散裝
KS8993F-EVAL 功能描述:EVAL KIT EXPERIMENTAL KS8993F RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評(píng)估演示板和套件 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 主要目的:電源管理，電池充電器 嵌入式:否 已用 IC / 零件:MAX8903A 主要屬性:1 芯鋰離子電池 次要屬性:狀態(tài) LED 已供物品:板
KS8993FL 功能描述:IC CONV MED 10/100 SGL 128PQFP RoHS:否 類別:集成電路 (IC) >> 專用 IC 系列:* 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 類型:調(diào)幀器 應(yīng)用:數(shù)據(jù)傳輸 安裝類型:表面貼裝 封裝/外殼:400-BBGA 供應(yīng)商設(shè)備封裝:400-PBGA（27x27） 包裝:散裝
KS8993FL-EVAL 功能描述:BOARD EVAL EXPERIMENT KS8993F RoHS:否 類別:編程器，開發(fā)系統(tǒng) >> 評(píng)估演示板和套件 系列:- 產(chǎn)品培訓(xùn)模塊:Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:1 系列:- 主要目的:電源管理，電池充電器 嵌入式:否 已用 IC / 零件:MAX8903A 主要屬性:1 芯鋰離子電池 次要屬性:狀態(tài) LED 已供物品:板
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