VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC8114
Features
•
Operates at STS-12/STM-4 (622.08Mb/s)
Data Rate
ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux
with Integrated Clock Generation and Clock Recovery
• Loss of Signal (LOS) Input & LOS Detection
• +3.3V/5V Programmable PECL Serial Interface
• Provides Equipment, Facilities and Split Loop-
back Modes as well as Loop Timing Mode
• Provide PECL Reference Clock Inputs
• Meets Bellcore, ITU and ANSI Specifications
for Jitter Performance
• Low Power - 0.9Watts Typical
• 100 PQFP Package
• Compatible with Industry ATM UNI Devices
• On Chip Clock Generation of the 622.08MHz
High Speed Clock (Mux)
• On Chip Clock Recovery of the 622.08MHz
High Speed Clock (Demux)
• 8-Bit Parallel TTL Interface with Parity Error
Detection and Generation
• SONET/SDH Frame Recovery
General Description
The VSC8114 is an ATM/SONET/SDH compatible transceiver integrating an on-chip Clock Multiplication
Unit (PLL) for high speed clock generation as well as a Clock and data Recovery Unit (CRU) with 8-bit serial-
to-parallel and parallel-to-serial data conversion. The PLL clock is used for serialization in the transmit direc-
tion (Mux). The recovered clock is used for deserialization in the receive direction (Demux). The demultiplexer
contains SONET/SDH frame detection and recovery. In addition, the device provides both facility and equip-
ment loopback modes and a loop time mode. The part is packaged in a 100PQFP with an integrated heat
spreader for optimum thermal performance and reduced cost. The VSC8114 provides an integrated solution for
ATM physical layers and SONET/SDH systems applications.
Functional Description
The VSC8114 is designed to provide a SONET/SDH compliant interface between the high speed optical
networks and the lower speed User Network Interface devices such as the PM5355 S/UNI-622. The VSC8114
converts 8 bit parallel data at 77.76Mb/s to a serial bit stream at 622.08Mb/s. The device also provides a Facility
Loopback function which loops the received high speed data and clock (optionally recovered on-chip) directly
to the high speed transmit outputs. A Clock Multiplier Unit (CMU) is integrated into the transmit circuit to gen-
erate the high speed clock for the serial output data stream from input reference frequencies of 19.44 or 77.76
MHz. The CMU can be bypassed with the received/recovered clock in loop timing mode, thus synchronizing
the entire part to a single clock. The block diagram on page 2 shows the major functional blocks associated with
the VSC8114.
The receive section provides the serial-to-parallel conversion, converting 622Mb/s bit stream to an 8 bit par-
allel output at 77.76MHz. A Clock Recovery Unit (CRU) is integrated into the receive circuit to recover the high
speed clock from the received serial data stream. The receive section provides an Equipment Loopback function
which will loop the low speed transmit data and clock back through the receive section to the 8 bit parallel out-
puts. The VSC8114 also provides the option of selecting between either its internal CRU’s clock and data sig-
nals, or optics containing a CRU clock and data signals. The receive section also contains a SONET/SDH frame
G52185-0, Rev 4.0
11/1/99
©
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
Page 1
VITESSE
SEMICONDUCTOR CORPORATION
ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux
with Integrated Clock Generation and Clock Recovery
Data Sheet
VSC8114
detector circuit which is used to provide frame pluses during the A1, A2 boundary in the serial to parallel con-
verter. This only occurs when OOF is high. Both internal and external LOS functions are supported.
The VSC8114 provides the parity error detection and generation for the 8 bit data bus. On the receive side,
the parity of the 8 bit data outputs is generated. On the transmit side, the parity of the 8 bit data input is calcu-
lated and compared with the received parity input.
VSC8114 Block Diagram
EQULOOP
RESET
D Q
0
1
0
1
Divide-by-8
Parity Chk
TXDATAOUT+/-
Q D
1
0
1
0
FACLOOP
Divide-by-8
8:1
MUX
REG
8
TXIN[7:0]
TXLSCKIN
TXLSCKOUT
RXLSCKOUT
TXPERR
TXINP
1:8
DEMUX
Parity/
REG
8
RXOUT[7:0]
RXOUTP
FRAMER
OOF
FP
1
0
LOOPTIM0
0
1
RXDATAIN+/-
CRUEQLP
0
CRU
REC-CLK
RXCLKIN+/-
DSBLCRU
losdet
0
1
REC-DATA
1
0
1
CMU
REFCLKP+/-
REFSEL
LOSPECL
LOSTTL
LOSDETEN_
0
1
CRUREFCLK
CRUREFSEL
Transmit Section
Byte-wide data is presented to TXIN[7:0] and is clocked into the part on the rising edge of TXLSCKIN.
See Figure 1. The data is then serialized (MSB leading) and presented to the TXDATAOUT+/- pins. The serial
output stream is synchronized to the CMU generated clock which is a phase locked and frequency scaled ver-
Page 2
©
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
G52185-0, Rev 4.0
11/1/99
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC8114
ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux
with Integrated Clock Generation and Clock Recovery
sion of the input reference clock. External control input REFSEL selects the multiply ratio of the CMU (see
table 11). A divide-by-8 version of the CMU clock (TXLSCKOUT) should be used to synchronize the transmit
interface of the UNI device to the transmit input registers on the VSC8114 (see Application Notes, p. 20).
Figure 1: Data and Clock Transmit Block Diagram
VSC8114
PM5355
TXDATAOUT+
TXDATAOUT-
Q D
Q D
TXIN[7:0]
Q D
TXLSCKIN
REFCLK
CMU
Divide-by-8
TXLSCKOUT
Receive Section
High speed Non-Return to Zero (NRZ) serial data at 622Mb/s are received by the RXDATAIN inputs. The
CRU recovers the high speed clock from the serial data input. The serial data is converted to byte-wide parallel
data and presented on RXOUT[7:0] pins. A divide-by-8 version of the high-speed clock (RXLSCKOUT)
should be used to synchronize the byte-serial RXOUT[7:0] data with the receive portion of the UNI device. The
on-chip CRU is by-passed by setting the DSBLCRU input high. In this mode, the serial input data and corre-
sponding clock are received by the RXDATAIN and RXCLKIN inputs respectively. RXDATAIN is clocked in
on the rising edge of RXCLKIN+. See Figure 2.
The receive section also includes frame detection and recovery circuitry which detects the SONET/SDH
frame, aligns the received serial data on byte boundaries, and initiates a frame pulse on FP coincident with the
byte aligned data. The frame recovery is initiated when OOF is held high which must occur at least 4 byte clock
cycles before the A1A2 boundary. The OOF input control is a level-sensitive signal, and the VSC8114 will con-
tinually perform frame detection and recovery as long as this pin is held high even if 1 or more frames has been
detected. Frame detection and recovery occurs when a series of three A1 bytes followed by three A2 bytes has
been detected. The parallel output data on RXOUT[7:0] will be byte aligned starting on the third A2 byte. When
a frame is detected, a single byte clock period long pulse is generated on FP which is synchronized with the
byte-aligned third A2 byte on RXOUT[7:0]. The frame detector sends an FP pulse only if OOF is high.
Loss of Signal
The VSC8114 features Loss of Signal (LOS) detection. Loss of Signal is detected if the incoming serial
data stream has no transition continuously for more than 128 bits. During an LOS condition, the VSC8114
forces the receive data low which is an indication for any downstream equipment that an optical interface failure
has occurred. The receive section continues to be clocked by the CRU as it is now locked to the CRUREFCLK
unless DSBLCRU is active, in which case it will be clocked by the CMU. This LOS condition will be removed
when the part detects more than 16 transitions in a 128 bit time window. This LOS detection feature can be dis-
abled by applying a high level to the LOSDETEN_ input. The VSC8114 also has a TTL input LOSTTL and a
G52185-0, Rev 4.0
11/1/99
©
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
Page 3
VITESSE
SEMICONDUCTOR CORPORATION
ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux
with Integrated Clock Generation and Clock Recovery
Data Sheet
VSC8114
PECL input LOSPECL to force the part into a Loss of Signal state. Most optics have a PECL output usually
called “SD” or “FLAG” indicating the presence or lack of optical power. Depending on the optics manufacturer
this signal is either active high or active low. The LOSTTL and LOSPECL inputs are XNOR’d to generate an
internal LOS control signal. See Figure 2. The optics “SD” output should be connected to LOSPECL. The
LOSTTL input should be tied to low if the optics “SD” is active high. If it’s active low tie LOSTTL to a high.
The inverse is true if the optics use “FLAG” for loss of signal
Figure 2: Data and Clock Receive Block Diagram
VSC8114
LOSPECL
LOSTTL
LOSDETEN_
DSBLCRU
RXDATAIN+/-
Losdet
PM5355
D Q
D Q
RXOUT[7:0]
D Q
1
0
CRU
0
Divide-by-8
0
1
CMU
D Q
FP
D Q
RXLSCKOUT
RXCLKIN+/-
1
Facility Loopback
The Facility Loopback function is controlled by the FACLOOP signal. When the FACLOOP signal is set
high, the Facility Loopback mode is activated and the high speed serial receive data (RXDATAIN) is presented
to the high speed transmit output (TXDATAOUT). See Figure 3. In Facility Loopback mode the high speed
receive data (RXDATAIN) is also converted to parallel data and presented to the low speed receive data output
pins (RXOUT[7:0]). The receive clock (RXCLKIN) is also divided down and presented to the low speed clock
output (RXLSCKOUT).
Figure 3: Facility Loopback Data Path
RXDATAIN
CRU
Recovered
Clock
D
Q
1:8
Serial to
Parallel
D
Q
RXOUT[7:0]
0
1
Q
D
RXCLKIN
TXDATAOUT
1
0
8:1
Parallel to
Serial
Q
D
TXIN[7:0]
1
0
PLL
FACLOOP
Page 4
©
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
G52185-0, Rev 4.0
11/1/99
VITESSE
SEMICONDUCTOR CORPORATION
Data Sheet
VSC8114
ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux
with Integrated Clock Generation and Clock Recovery
Equipment Loopback
The Equipment Loopback function is controlled by the EQULOOP signal. When the EQULOOP signal is
set high, the Equipment Loopback mode is activated and the high speed transmit data generated from the paral-
lel to serial conversion of the low speed data (TXIN[7:0]) is selected and converted back to parallel data in the
receiver section and presented to the low speed parallel outputs (RXOUT[7:0]). See Figure 4. The internally
generated 622MHz clock is used to generate the low speed receive clock output (RXLSCKOUT). In Equipment
Loopback mode the transmit data (TXIN[7:0]) is serialized and presented to the high speed output
(TXDATAOUT) using the clock generated by the on-chip clock multiplier unit.
CRU Equipment Loopback
Exactly the same as equipment loopback, the point where the transmit data is looped back is moved all the
way back to the high speed I/O. When the CRUEQLP signal is set high, transmit data is looped back to the
CRU, replacing RXDATAIN±
Figure 4: Equipment Loopback Data Path
D Q
D
Q
RXDATAIN
EQULOOP
0
1
1:8
Serial to
Parallel
RXOUT[7:0]
÷
8
Q
D
8:1
Parallel to
Serial
Q
D
RXLSCKOUT
TXIN[7:0]
TXLSCKIN
÷
8
TXLSCKOUT
TXDATAOUT
PLL
Split Loopback
Equipment and facility loopback modes can be enabled simultaneously. In this case, high-speed serial data
received (RXDATAIN) is mux’d through to the high-speed serial outputs (TXDATAOUT). The low-speed trans-
mit byte-wide bus (TXIN[7:0]) and (TXLSCKIN) is mux’d into the low-speed byte-wide receive output bus
(RXOUT[7:0]) and (RXLSCKOUT). See Figure 5.
Figure 5: Split Loopback Datapath
RXDATAIN
Recovered
Clock
CRU
D
Q
1:8
Serial to
Parallel
D
Q
RXOUT[7:0]
0
1
Q
D
8:1
Parallel to
Serial
Q
D
RXLSCKOUT
TXIN[[7:0]
RXCLKIN
DSBLCRU
TXDATAOUT
TXLSCKIN
G52185-0, Rev 4.0
11/1/99
©
VITESSE
SEMICONDUCTOR CORPORATION
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896
Page 5
模拟与混合信号
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
