KSZ8851SNLI Micrel Inc, KSZ8851SNLI Datasheet - Page 17

• Manufacturer Part Number: KSZ8851SNLI
• Manufacturer: Micrel Inc

Specifications of KSZ8851SNLI

• Operating Supply Voltage (typ): 3.3V
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 32
• Lead Free Status / RoHS Status: Supplier Unconfirmed

MDI/MDI-X Auto Crossover
To eliminate the need for crossover cables between similar devices, the KSZ8851SNL 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 KSZ8851SNL 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).
Crossover Cable
A crossover cable connects an MDI device to another MDI device, or an MDI-X device to another MDI-X device. The
following diagram shows a typical crossover cable connection between two chips or hubs (two MDI-X devices).
August 2009
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
17
RJ45 Pins
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
(RJ-45)
HUB
Signals
Transmit Pair
Receive Pair
RD+
TD+
RD-
TD-
KSZ8851SNL/SNLI
M9999-083109-2.0