xr
XRT91L80
2.488/2.666 GBPS STS-48/STM-16 SONET/SDH TRANSCEIVER
JANUARY 2007
REV. 1.0.0
control of the FIFO_AUTORST pin can automatically
recover from an overflow condition. The operation of
GENERAL DESCRIPTION
The XRT91L80 is a fully integrated SONET/SDH
transceiver for SONET OC-48/STM-16 applications
supporting the use of Forward Error Correction (FEC)
capability. The transceiver includes an on-chip Clock
Multiplier Unit (CMU), which uses a high frequency
Phase-Locked Loop (PLL) to generate the high-
speed transmit serial clock from a slower external
clock reference. It also provides Clock and Data
Recovery (CDR) functions by synchronizing its on-
chip Voltage Controlled Oscillator (VCO) to the
incoming serial data stream. The chip provides serial-
to-parallel and parallel-to-serial converters and 4-bit
LVDS system interfaces in both receive and transmit
directions. The transmit section includes a 4x9 Elastic
Buffer (FIFO) to absorb any phase differences
between the transmitter clock input and the internally
generated transmitter reference clock. In the event of
an overflow, an internal FIFO control circuit outputs
an OVERFLOW indication. The FIFO under the
the device can be monitored by checking the status of
the LOCKDET_CMU, LOCKDET_CDR, and
LOSDET output signals. An on-chip phase/frequency
detector and charge-pump offers the ability to form a
de-jittering PLL with an external VCXO that can be
used in loop timing mode to clean up the recovered
clock in the receive section.
APPLICATIONS
•
•
•
•
•
•
•
SONET/SDH-based Transmission Systems
Add/Drop Multiplexers
Cross Connect Equipment
ATM and Multi-Service Switches and Routers
DSLAMS
SONET/SDH Test Equipment
DWDM Termination Equipment
FIGURE 1. BLOCK
D
IAGRAM OF XRT91L80
STS-48 TRANSCEIVER
WP
FIFO_RST
FIFO_AUTORST
TXDI0P/N
TXDI1P/N
TXDI2P/N
TXDI3P/N
PISO
(Parallel Input
Serial Output)
TXOP/N
Re-Timer
RP
TXPCLKIP/N
TXPCLKOP/N
TXCLKO16P/N
Div by 4
Div by 16
CMU
TXCLKO16DIS
DLOOP RLOOPS
RLOOPP
RXDO0P/N
RXDO1P/N
RXDO2P/N
RXDO3P/N
SIPO
(Serial Input
Parallel Output)
CDR
RXIP/N
RXPCLKOP/N
RXCLKO16P/N
Div by 4
Div by 16
LOSDMUTE
DISRD
TDO
TDI
TCK
TMS
TRST
PFD
& Charge Pump
Serial
Microprocessor
Hardware
Control
JTAG
Exar Corporation 48720 Kato Road, Fremont CA, 94538
•
(510) 668-7000
•
FAX (510) 668-7017
•
www.exar.com