RTL8306SD/RTL8306SDM
Datasheet
7.2.6.
100Base-TX Receive Function
The receive path includes a receiver composed of an adaptive equalizer and DC restoration circuits (to
compensate for an incoming distorted MLT-3 signal), an MLT-3 to NRZI and NRZI to NRZ converter to
convert analog signals to digital bit-stream, and a PLL circuit to clock data bits with minimum bit error
rate. A De-scrambler, 5B/4B decoder, and serial-to-parallel conversion circuits are followed by the PLL
circuit. Finally, the converted parallel data is fed into the MAC.
7.2.7.
Power-Down Mode
The RTL8306SD/RTL8306SDM implements power-down mode on a per-port basis. Setting MII
Reg.0.11 forces the corresponding port of the RTL8306SD/RTL8306SDM to enter power-down mode.
This disables all transmit/receive functions, except SMI (Serial Management Interface: MDC/MDIO, also
known as MII Management Interface).
7.2.8.
Crossover Detection and Auto Correction
During the link setup phase, the RTL8306SD/RTL8306SDM checks whether it receives active signals on
every port in order to determine if a connection can be established. In cases where the receiver data pin
pair is connected to the transmitter data pin pair of the peer device and vice versa, the
RTL8306SD/RTL8306SDM automatically changes its configuration and swaps receiver/transmitter data
pins as required. If a port is connected to a PC or NIC with MDI-X interface with a crossover cable, the
RTL8306SD/RTL8306SDM will reconfigure the port to ensure proper connection. This replaces the DIP
switch commonly used for reconfiguring a port on a hub or switch.
By pulling-up EN_AUTOXOVER, the RTL8306SD/RTL8306SDM identifies the type of connected
cable and sets the port to MDI or MDIX:
• When switching to MDI mode, the RTL8306SD/RTL8306SDM uses TXOP/N as transmit pairs.
• When switching to MDIX mode, the RTL8306SD/RTL8306SDM uses RXIP/N as transmit pairs.
This function is port-based. Pulling-down EN_AUTOXOVER disables this function and the
RTL8306SD/RTL8306SDM operates in MDI mode, in which TXOP/N represents transmit pairs, and
RXIP/N represents receive pairs.
Note: IEEE 802.3 compliant forced mode 100M ports with Autoxover have link problems with NWay
(Auto-Negotiation) ports. It is recommended to not use Autoxover for forced 100M.
6-Port 10/100Mbps Single-Chip Dual MII/RMII Switch Controller
40
Track ID: JATR-1076-21 Rev. 1.1
REALTEK [ Realtek Semiconductor Corp. ]
