RTL8309N データシートの表示（PDF） - Realtek Semiconductor

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RTL8309N

SINGLE-CHIP 8-PORT 10/100MBPS ETHERNET SWITCH CONTROLLER

Realtek Semiconductor 

RTL8309N

Datasheet

5.2. 10Base-T Transmit Function

The output 10Base-T waveform is Manchester-encoded before it is driven onto the network media. The

internal filter shapes the driven signals to reduce EMI emissions, eliminating the need for an external

filter.

5.3. 10Base-T Receive Function

The Manchester decoder converts the incoming serial stream to NRZ data when the squelch circuit

detects the signal level is above squelch level.

5.4. 100Base-TX Transmit Function

The 100Base-TX transmit function performs parallel to serial conversion, 4B/5B coding, scrambling,

NRZ/NRZI conversion, and MLT-3 encoding. The 5-bit serial data stream after 4B/5B coding is then

scrambled as defined by the TP-PMD Stream Cipher function to flatten the power spectrum energy

such that EMI effects can be reduced significantly.

The scrambled seed is based on PHY addresses and is unique for each port. After scrambling, the bit

stream is driven into the network media in the form of MLT-3 signaling. The MLT-3 multi-level

signaling technology moves the power spectrum energy from high frequency to low frequency, which

also reduces EMI emissions.

5.5. 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.

5.6. 100Base-FX Function

All ports support 100Base-FX, which shares pins with UTP (TX+-/RX+-) and needs no SD+/- pins.

100Base-FX can be forced to full duplex with optional flow control ability.

Note: In compliance with IEEE 802.3u, 100Base-FX does not support Auto-Negotiation. In order to

operate correctly, both sides of the connection should be set to the same flow control ability.

A scrambler is not needed in 100Base-FX. Compared to common 100Base-FX applications, the

RTL8309N removes a pair of differential SD (Signal Detect) signals that provide a link monitoring

function, which reduces the pin count (Realtek patent).

8-Port 10/100M Layer2 Switch Controller

5

Track ID:

Rev. 1.0

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