XRT91L80 Datasheet, PDF (1/41 Pages) Exar Corporation – 2.488/2.666GBPS OC-48/STM-16 SONET/SDH TRANSCEIVER

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PRELIMINARY
XRT91L80
2.488/2.666GBPS OC-48/STM-16 SONET/SDH TRANSCEIVER
MARCH 2005
GENERAL DESCRIPTION
The XRT91L80 is a fully integrated SONET/SDH
transceiver for SONET OC-48 allowing 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 slower external clock references. 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 input
clock 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 control of the
REV. P1.0.4
AUTORST pin can automatically recover from an
overflow condition. The operation of the device can
be monitored by checking the status of the LOCKDET
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, Routers and
Switch/Routers
• DSLAMS
• SONET/SDH Test Equipment
• DWDM Termination Equipment
FIGURE 1. BLOCK DIAGRAM OF XRT91L80
FIFO_RST
FIFO_AUTORST
TxDI0P/N
TxDI1P/N
TxDI2P/N
TxDI3P/N
TxCLKIP/N
TXPCLKOP/N
TXCLKO16P/N
TRITXCLKO16
OC-48 TRANSCEIVER
WP
RP
RLOOPP
PISO
(Parallel Input
Serial Output)
Re-Timer
CMU
DLOOP RLOOPS
RxDO0P/N
RxDO1P/N
RxDO2P/N
RxDO3P/N
RxCLKP/N
RXCLK16P/N
DISRD
SIPO
(Serial Input
Parallel Output)
CDR
TDO
TDI
TCK
TMS
TRST
JTAG
Serial
Microprocessor
Hardware
Control
TXOP/N
PFD
& Charge Pump
RXIP/N
TRIRXD
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • [phone] • FAX [phone] • www.exar.com