KS8997 Micrel Inc, KS8997 Datasheet - Page 16

• Manufacturer Part Number: KS8997
• Description: IC SWITCH 10/100 8PORT 128PQFP
• Manufacturer: Micrel Inc

Specifications of KS8997

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 128-MQFP, 128-PQFP
• Fiber Support: No
• Integrated Led Drivers: Yes
• Phy/transceiver Interface: MII
• Power Supply Type: Analog/Digital
• Package Type: PQFP
• Data Rate (typ): 10/100Mbps
• Vlan Support: Yes
• Operating Temperature (max): 70C
• Operating Temperature (min): 0C
• Pin Count: 128
• Mounting: Surface Mount
• Jtag Support: No
• Operating Temperature Classification: Commercial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Micrel, Inc.
KS8997/KSZ8997
MDI/MDI-X Auto Crossover
The KS8997 supports MDI/MDI-X auto crossover. This facilitates the use of either a straight connection CAT-5 cable
or a crossover CAT-5 cable. The auto-sense function will detect remote transmit and receive pairs, and correctly
assign the transmit and receive pairs from the Micrel device. This can be highly useful when end users are unaware
of cable types and can also save on an additional uplink configuration connection.
The auto MDI/MDI-X is achieved by the Micrel device listening for the far end transmission channel and assigning
transmit/receive pairs accordingly.
Auto-Negotiation
The KS8997 conforms to the auto-negotiation protocol as described by the 802.3 committee. Auto-negotiation allows
UTP (Unshielded Twisted Pair) link partners to select the best common mode of operation. In auto-negotiation the
link partners advertise capabilities across the link to each other. If auto-negotiation is not supported or the link partner
to the KS8997 is forced to bypass auto-negotiation, then the mode is set by observing the signal at the receiver. This
is known as parallel mode because while the transmitter is sending auto-negotiation advertisements, the receiver is
listening for advertisements or a fixed signal protocol.
The flow for the link set up is depicted below. Note that the KS8997 only supports auto-negotiation and not forced
modes.
Figure 4. Auto-Negotiation
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February 2007
M9999-022807-1.1