KSZ9031MNX Datasheet, PDF (16/73 Pages) Micrel Semiconductor – The KSZ9031MNX is a completely integrated triple-speed (10Base-T/100Base-TX/1000Base-T) Ethernet physicallayer transceiver for transmission and reception of data on standard CAT-5 unshielded twisted pair (UTP) cable.

KSZ9031MNX
In 10BASE-T/100BASE-TX mode, the adaptive equalizer needs only to remove the inter-symbol interference and
recover the channel loss from the incoming data.
3.2.6 TRELLIS ENCODER AND DECODER
In 1000BASE-T mode, the transmitted 8-bit data is scrambled into 9-bit symbols and further encoded into 4D-PAM5
symbols. The initial scrambler seed is determined by the specific PHY address to reduce EMI when more than one
KSZ9031MNX is used on the same board. On the receiving side, the idle stream is examined first. The scrambler seed,
pair skew, pair order, and polarity must be resolved through the logic. The incoming 4D-PAM5 data is then converted
into 9-bit symbols and de-scrambled into 8-bit data.
3.3 Auto MDI/MDI-X
The Automatic MDI/MDI-X feature eliminates the need to determine whether to use a straight cable or a crossover cable
between the KSZ9031MNX and its link partner. This auto-sense function detects the MDI/MDI-X pair mapping from the
link partner, and assigns the MDI/MDI-X pair mapping of the KSZ9031MNX accordingly.
Table 3-1 shows the KSZ9031MNX 10/100/1000 pin configuration assignments for MDI/MDI-X pin mapping.
TABLE 3-1: MDI/MDI-X PIN MAPPING
Pin
(RJ-45 Pair)
1000BASE-T
MDI
100BASE-T
10BASE-T
1000BASE-T
MDI-X
100BASE-T
10BASE-T
TXRXP/M_A
(1, 2)
TXRXP/M_B
(3, 6)
TXRXP/M_C
(4, 5)
TXRXP/M_D
(7, 8)
A+/–
B+/–
C+/–
D+/–
TX+/–
RX+/–
Not Used
Not Used
TX+/–
RX+/–
Not Used
Not Used
B+/–
A+/–
D+/–
C+/–
RX+/–
TX+/–
Not Used
Not Used
RX+/–
TX+/–
Not Used
Not Used
Auto MDI/MDI-X is enabled by default. It is disabled by writing a one to Register 1Ch, Bit [6]. MDI and MDI-X mode is
set by Register 1Ch, Bit [7] if Auto MDI/MDI-X is disabled.
An isolation transformer with symmetrical transmit and receive data paths is recommended to support Auto MDI/MDI-X.
3.4 Pair-Swap, Alignment, and Polarity Check
In 1000BASE-T mode, the KSZ9031MNX
• Detects incorrect channel order and automatically restores the pair order for the A, B, C, D pairs (four channels).
• Supports 50 ns ±10 ns difference in propagation delay between pairs of channels in accordance with the IEEE
802.3 standard, and automatically corrects the data skew so the corrected four pairs of data symbols are synchro-
nized.
Incorrect pair polarities of the differential signals are automatically corrected for all speeds.
3.5 Wave Shaping, Slew-Rate Control, and Partial Response
In communication systems, signal transmission encoding methods are used to provide the noise-shaping feature and
to minimize distortion and error in the transmission channel.
• For 1000BASE-T, a special partial-response signaling method is used to provide the band-limiting feature for the
transmission path.
• For 100BASE-TX, a simple slew-rate control method is used to minimize EMI.
• For 10BASE-T, pre-emphasis is used to extend the signal quality through the cable.
3.6 PLL Clock Synthesizer
The KSZ9031MNX generates 125 MHz, 25 MHz, and 10 MHz clocks for system timing. Internal clocks are generated
from the external 25 MHz crystal or reference clock.
DS00002096C-page 16
 2016 Microchip Technology Inc.