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January 1997

ML6680

Token Ring Copper-to-Fiber Converter

GENERAL DESCRIPTION

The ML6680 is a single-chip conversion between Token

Ring ISO/IEC8802-5 copper-based media and Token Ring

ISO/IEC8802-5 fiber-based media. The ML6680 fiber-optic

interface contains a data quantizer, circuitry for fiber optic

key signal generation and recognition, pin-selectable

signal switching, and current driven transmitter outputs.

The ML6680 copper interface consists of a twisted pair

line equalizer, receive squelch circuit, pin selectable

phantom wire fault detection and signal switching, and a

transmit driver. This section supports the ISO/IEC8802-5

standard requirements. The ML6680 provides an optional

PECL compatible interface.

The ML6680 may be configured to one of four modes:

1. Standard Media Converter

2. Concentrator Media Converter

3. Lobe or Ring Out Port Media Converter

4. Ring In Port Media Converter

FEATURES

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Single-chip copper-to-fiber converter for Token Ring

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16Mbps and 4Mbps data rates with the same

external components

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Four modes of operation covering a wide variety

of applications

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Full duplex operation

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Highly stable data quantizer with 55dB input

dynamic range

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Current driven fiber optic LED driver for accurate

launch power

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Current driven output for low RFI noise and low jitter

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Capable of driving 100

Ω UTP or 150Ω STP

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Pin selectable phantom wire fault detection and

signal switching

TWISTED PAIR

EQUALIZER

TWISTED PAIR

RECEIVE SQUELCH

TWISTED PAIR

DRIVER

PHANTOM

DRIVER

LED

DRIVER

FIBER OPTIC

RECEIVE SQUELCH

FIBER OPTIC

QUANTIZER

BIAS

CONTROL

LOGIC

CRYSTAL

OSCILLATOR

SIGNAL

MUX

TPINP

TPINN

OPVCC

OPOUT

TPOUTP

TPINOK

RTSETTP

TPOUTN

OPINP

OPINOK

OPINN

PHTM1

PHTM2

XTAL1

VDC

XTAL2

KEYGEN

INSERTED

EQA

EQB

RTSETOP

BLOCK DIAGRAM