DP83241 Datasheet, PDF (1/20 Pages) National Semiconductor (TI) – CDD Device (FDDI Clock Distribution Device)

February 1991
DP83241 CDD^TM Device
(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-
tween the PLAYER^TM and BMAC^TM devices in various sta-
tion configurations 12 5 MHz and 125 MHz differential ECL
clocks are generated for the conversion of data to serial
format and 12 5 MHz and 25 MHz TTL clocks are generated
for the byte wide data transfers
Features
Y _{Provides 12 5 MHz and 25 MHz TTL clocks}
Y _{12 5 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 12 5 MHz crystal}
Y _{External PLL synchronizing reference for}
concentrator configurations
Y _{28-pin PLCC package}
Y _{BiCMOS processing}
FIGURE 1-1 FDDI Chip Set Block Diagram
TL F 10385 – 1
TRI-STATE is a registered trademark of National Semiconductor Corporation
BMACTM BSITM CDDTM CRDTM and PLAYERTM are trademarks of National Semiconductor Corporation
C1995 National Semiconductor Corporation TL F 10385
RRD-B30M105 Printed in U S A