SH7619 Datasheet, PDF (678/836 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7619 Series

Section 22 Ethernet Physical Layer Transceiver (PHY)
CODE
GROUP
00001
00010
00011
00101
01000
01100
10000
SYM
V
V
V
V
V
V
V
RECEIVER
INTERPRETATION (CO_MII_RXD)
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
INVALID, CO_RX_ER if during CO_RX_DV
TRANSMITTER
INTERPRETATION
(CO_MII_TXD)
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
INVALID
(3) Scrambling
Repeated data patterns (especially the IDLE code-group) can have power spectral densities with
large narrow-band peaks. Scrambling the data helps eliminate these peaks and spread the signal
power more uniformly over the entire channel bandwidth. This uniform spectral density is
required by FCC regulations to prevent excessive EMI from being radiated by the physical
routing.
The seed for the scrambler is generated from the PHY address. The scrambler also performs the
Parallel In Serial Out conversion (PISO) of the data.
(4) NRZI and MLT3 Encoding
The scrambler block passes the 5-bit wide parallel data to the NRZI converter where it becomes a
serial 125MHz NRZI data stream. The NRZI is encoded to MLT-3. MLT3 is a tri-level code
where a change in the logic level represents a code bit "1" and the logic output remaining at the
same level represents a code bit "0".
(5) 100M Transmit Driver
The MLT3 data is then passed to the analog transmitter, which launches the differential MLT-3
signal, on outputs TXP and TXM, to the twisted pair media via a 1:1 ratio isolation transformer.
The 10Base-T and 100Base-TX signals pass through the same transformer so that common
"magnetics" can be used for both. The transmitter drives into the 100 ohm impedance of the CAT-
5 cable. Cable termination and impedance matching require external components.
Rev. 5.00 Mar. 15, 2007 Page 640 of 794
REJ09B0237-0500