TLF10385

February 1991

DP83241 CDD

(FDDI Clock Distribution Device)

General Description

The CDD device is a clock generation and distribution de-

vice intended for use in FDDI (Fiber Distributed Data Inter-

face) networks The device provides the complete set of

clocks required to convert byte wide data to serial format for

fiber medium transmission and to move byte wide data be-

tion configurations 125 MHz and 125 MHz differential ECL

clocks are generated for the conversion of data to serial

format and 125 MHz and 25 MHz TTL clocks are generated

for the byte wide data transfers

Features

Y

Provides 125 MHz and 25 MHz TTL clocks

Y

125 MHz and 125 MHz ECL clocks

Y

5 phase TTL local byte clocks eliminate clock

skew problems in concentrators

Y

Internal VCO requires no varactors coils or

adjustments

Y

Option for use of High Q external VCO

Y

125 MHz clock generated from a 125 MHz crystal

Y

External PLL synchronizing reference for

concentrator configurations

Y

28-pin PLCC package

Y

BiCMOS processing

TLF10385 – 1

FIGURE 1-1 FDDI Chip Set Block Diagram

TRI-STATE

is a registered trademark of National Semiconductor Corporation

C1995 National Semiconductor Corporation

RRD-B30M105Printed in U S A