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LAN8700IC-AEZG 参数 Datasheet PDF下载

LAN8700IC-AEZG图片预览
型号: LAN8700IC-AEZG
PDF下载: 下载PDF文件 查看货源
内容描述: [LAN Controller, 4 Channel(s), 12.5MBps, CMOS, 6 X 6 MM, 0.90 MM HEIGHT, ROHS COMPLIANT, QFN-36]
分类和应用: 通信时钟局域网数据传输外围集成电路
文件页数/大小: 83 页 / 687 K
品牌: SMSC [ SMSC CORPORATION ]
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±15kV ESD Protected MII/RMII 10/100 Ethernet Transceiver with HP Auto-MDIX Support and flexPWR® Technology in a Small Footprint  
Datasheet  
If the full capabilities of the PHY are advertised (100M, Full Duplex), and if the link partner is capable  
of 10M and 100M, then auto-negotiation selects 100M as the highest performance mode. If the link  
partner is capable of Half and Full duplex modes, then auto-negotiation selects Full Duplex as the  
highest performance operation.  
Once a capability match has been determined, the link code words are repeated with the acknowledge  
bit set. Any difference in the main content of the link code words at this time will cause auto-negotiation  
to re-start. Auto-negotiation will also re-start if not all of the required FLP bursts are received.  
The capabilities advertised during auto-negotiation by the PHY are initially determined by the logic  
levels latched on the MODE[2:0] bus after reset completes. This bus can also be used to disable auto-  
negotiation on power-up.  
Writing register 4 bits [8:5] allows software control of the capabilities advertised by the PHY. Writing  
register 4 does not automatically re-start auto-negotiation. Register 0, bit 9 must be set before the new  
abilities will be advertised. Auto-negotiation can also be disabled via software by clearing register 0,  
bit 12.  
The LAN8700/LAN8700i does not support “Next Page” capability.  
4.7.1  
Parallel Detection  
If the LAN8700/LAN8700i is connected to a device lacking the ability to auto-negotiate (i.e. no FLPs  
are detected), it is able to determine the speed of the link based on either 100M MLT-3 symbols or  
10M Normal Link Pulses. In this case the link is presumed to be Half Duplex per the IEEE standard.  
This ability is known as “Parallel Detection.” This feature ensures interoperability with legacy link  
partners. If a link is formed via parallel detection, then bit 0 in register 6 is cleared to indicate that the  
Link Partner is not capable of auto-negotiation. The controller has access to this information via the  
management interface. If a fault occurs during parallel detection, bit 4 of register 6 is set.  
Register 5 is used to store the Link Partner Ability information, which is coded in the received FLPs.  
If the Link Partner is not auto-negotiation capable, then register 5 is updated after completion of parallel  
detection to reflect the speed capability of the Link Partner.  
4.7.2  
Re-starting Auto-negotiation  
Auto-negotiation can be re-started at any time by setting register 0, bit 9. Auto-negotiation will also re-  
start if the link is broken at any time. A broken link is caused by signal loss. This may occur because  
of a cable break, or because of an interruption in the signal transmitted by the Link Partner. Auto-  
negotiation resumes in an attempt to determine the new link configuration.  
If the management entity re-starts Auto-negotiation by writing to bit 9 of the control register, the  
LAN8700/LAN8700i will respond by stopping all transmission/receiving operations. Once the  
break_link_timer is done, in the Auto-negotiation state-machine (approximately 1200ms) the auto-  
negotiation will re-start. The Link Partner will have also dropped the link due to lack of a received  
signal, so it too will resume auto-negotiation.  
4.7.3  
4.7.4  
Disabling Auto-negotiation  
Auto-negotiation can be disabled by setting register 0, bit 12 to zero. The device will then force its  
speed of operation to reflect the information in register 0, bit 13 (speed) and register 0, bit 8 (duplex).  
The speed and duplex bits in register 0 should be ignored when auto-negotiation is enabled.  
Half vs. Full Duplex  
Half Duplex operation relies on the CSMA/CD (Carrier Sense Multiple Access / Collision Detect)  
protocol to handle network traffic and collisions. In this mode, the carrier sense signal, CRS, responds  
to both transmit and receive activity. In this mode, If data is received while the PHY is transmitting,  
a collision results.  
Revision 2.3 (04-12-11)  
SMSC LAN8700/LAN8700i  
DATA3S0HEET