KSZ8851-16MLLJ_10 MICREL [Micrel Semiconductor], KSZ8851-16MLLJ_10 Datasheet - Page 20

• Manufacturer Part Number: KSZ8851-16MLLJ_10
• Description: Single-Port Ethernet MAC Controller with 8-Bit or 16-Bit Non-PCI Interface
• Manufacturer: MICREL [Micrel Semiconductor]

10BASE-T Receive
On the receive side, input buffers and level detecting squelch circuits are employed. A differential input receiver circuit and
a phase-locked loop (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 to prevent noise at the RXP1 or RXM1 input from falsely triggering the
decoder. When the input exceeds the squelch limit, the PLL locks onto the incoming signal and the KSZ8851-16MLLJ
decodes a data frame. The receiver clock is maintained active during idle periods in between data reception.
MDI/MDI-X Auto Crossover
To eliminate the need for crossover cables between similar devices, the KSZ8851-16MLLJ supports HP-Auto MDI/MDI-X
and IEEE 802.3u standard MDI/MDI-X auto crossover. HP-Auto MDI/MDI-X is the default.
The auto-sense function detects remote transmit and receive pairs and correctly assigns the transmit and receive pairs for
the KSZ8851-16MLLJ device. This feature is extremely useful when end users are unaware of cable types in addition to
saving on an additional uplink configuration connection. The auto-crossover feature can be disabled through the port
control registers. The IEEE 802.3u standard MDI and MDI-X definitions are as below:
Straight Cable
A straight cable connects an MDI device to an MDI-X device or an MDI-X device to an MDI device. The following diagram
shows a typical straight cable connection between a network interface card (NIC) and a switch, or hub (MDI-X).
March 2010
Micrel, Inc.
Media Dependent Interface
Transmit Pair
Receive Pair
Modular Connector
RJ45 Pins
10/100 Ethernet
(RJ-45)
Figure 3. Typical Straight Cable Connection
1
2
3
6
NIC
Table 2. MDI/MDI-X Pin Definitions
MDI
1
2
3
4
5
6
7
8
Signals
TD+
RD+
RD-
TD-
Straight
Cable
RJ45 Pins
20
1
2
3
6
Media Dependent Interface
MDI-X
(Repeater or Switch)
Modular Connector
1
2
3
4
5
6
7
8
10/100 Ethernet
Signals
(RJ-45)
HUB
Transmit Pair
Receive Pair
RD+
TD+
RD-
TD-
M9999-030210-1.0
KSZ8851-16MLLJ