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0.65碌 Low Power CMOS
鈥?128-pin PQFP
Functional Description
The Cypress Semiconductor CY7C955 is a Transceiver chip
designed to carry ATM cells across SONET/SDH systems.
On the transmit side, ATM cells coming from the Utopia inter-
face are being mapped into SONET/SDH frames and then se-
rialized for transmission over fiber or twisted pair (through an
optical module or an equalizer chip).
On the receive side, serial SONET/SDH datastreams coming
from an optical module or an equalizer chip are being recov-
ered by the intergrated clock and data recovery phase-locked
loop, framed, processed, and presented as parallel ATM cells
on the Receive Utopia Interface.
The CY7C955 can be used in a Network Interface Card (NIC)
design to connect the segmentation and Reassembly (SAR)
chip to the optical modules or equalizer chip.
The CY7C955 can also be used in work group or enterprise
switches to connect the I/O FIFOs of the switch fabric to the
optical module or equalizer in the interface boards.
The applications of the CY7C955 include adapters, switches,
routers, hubs, and proprietary systems.
TABLE OF CONTENTS
Features
Functional Description
Pin Descriptions
Pin Configuration
Description
Transmit Section
Receive Section
Controller Interface (CI)
Loopback Operation
SONET Overhead Description
CY7C955 Register Map
Electrical Characteristics
Capacitance
AC Test Loads and Waveforms
Switching Characteristics
1
1
2
7
8
8
10
12
16
17
18
60
61
61
61
Cypress Semiconductor Corporation
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3901 North First Street
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San Jose
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CA 95134
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408-943-2600
November 29, 1999
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