KS8993M datasheet(22/85 Pages) MICREL | Integrated 3-Port 10/100 Managed Integrated 3-Port 10/100 Managed

22 / 85 page

Micrel, Inc.

KS8993M/ML/MI

April 2005

M9999-041205

magnetic. They are internally wave-shaped and pre-emphasized into outputs with a typical 2.3V amplitude. The

harmonic contents are at least 27dB below the fundamental when driven by an all-ones Manchester-encoded

signal.

10BASE-T Receive

On the receive side, input buffers and level detecting squelch circuits are employed. A differential input receiver

circuit 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 400 mV 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 KS8993M decodes a data frame. The receiver clock

is maintained active during idle periods in between data reception.

Power Management

The KS8993M features a per-port power down mode. To save power, the user can power down ports that are not

in use by setting the port control registers, or MII control registers. In addition, there is a full chip power down

mode. When activated, the entire chip will be shut down.

MDI /MDI-X Auto Crossover

The KS8993M supports MDI/ DI-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 KS8993M device. This feature can be extremely useful

when end users are unaware of cable types and can also save on an additional uplink configuration connection.

The auto-crossover feature can be disabled through the port control registers.

Based on the IEEE 802.3 standard, the MDI and MDI-X definitions are as follows:

MDI

MDI-X

RJ45 Pins

Signals

RJ-45 Pins

Signals

TD+

RD+

TD-

RD-

RD+

TD+

RD-

TD-

Table 2. MDI/MDI-X Pin Definitions

KS8993M Datasheet(PDF) 22 Page - Micrel Semiconductor