KS8999I Micrel Inc, KS8999I Datasheet - Page 20

• Manufacturer Part Number: KS8999I
• Description: IC SWITCH 9-PORT 10/100 208-PQFP
• Manufacturer: Micrel Inc

Specifications of KS8999I

• Applications: *
• Mounting Type: Surface Mount
• Package / Case: 208-MQFP, 208-PQFP
• Fiber Support: Yes
• Integrated Led Drivers: Yes
• Phy/transceiver Interface: MII/SNI
• Power Supply Type: Analog/Digital
• Package Type: PQFP
• Data Rate (typ): 10/100Mbps
• Vlan Support: Yes
• Operating Temperature (max): 85C
• Operating Temperature (min): -40C
• Mounting: Surface Mount
• Jtag Support: No
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• For Use With: 576-1023 - BOARD EVAL EXPERIMENT FOR KS8999
• Lead Free Status / RoHS Status: Not Compliant, Contains lead / RoHS non-compliant

Micrel, Inc.
KS8999
and a 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 in order to prevent
noises at the RXP or RXM input from falsely triggering the decoder. When the input exceeds the squelch limit,
the PLL locks onto the incoming signal and the KS8999 decodes a data frame. The receiver clock is maintained
active during idle periods in between data reception.
Power Management
Power Save Mode
The KS8999 will turn off everything except for the Energy Detect and PLL circuits when the cable is not installed on
an individual port basis. In other words, the KS8999 will shutdown most of the internal circuits to save power if there
is no link.
MDI/MDI-X Auto Crossover
The KS8999 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 MDI/MDI-X can be disabled by pulling the pin 87 (AUTOMDIX) to low.
Auto-Negotiation
The
KS8999
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 KS8999 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.
Figure 2. Auto-Negotiation
20
January 2005
KS8999