G52154-0, Rev 4.2

© VITESSE SEMICONDUCTOR CORPORATION

Page 3

3/19/99

741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: 805/987-5896

VITESSE

SEMICONDUCTOR CORPORATION

Data Sheet

VSC8113

ATM/SONET/SDH 622 Mb/s Transceiver Mux/Demux

with Integrated Clock Generation and Clock Recovery

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 at the TXDATAOUT+/- pins.

TXDATAOUT is clocked out on the falling edge of TXCLKOUT+. The serial output stream is synchronized to

the CMU generated clock which is a phase locked and frequency scaled version of the input reference clock.

External control inputs B0-B2 and STS-12 select the multiply ratio of the CMU for either STS-3 (155MbS) or

STS-12 (622Mb/s) transmission (see Table 12). 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

VSC8113 (see Application Notes, p. 20).

Figure 1: Data and Clock Transmit Block Diagram

Receive Section

High speed Non-Return to Zero (NRZ) serial data at 155Mb/s or 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 corresponding 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 VSC8113 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 a FP pulse only if OOF is high.

D

Q

D

Q

Divide-by-8

CMU

D

Q

TXIN[7:0]

TXLSCKIN

TXLSCKOUT

TXDATAOUT+

TXDATAOUT-

TXCLKOUT+

TXCLKOUT-

REFCLK

VSC8113

PM5355