VITESSE

SEMICONDUCTOR CORPORATION

G52028-0, Rev 4.1

Page 1

05/25/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com

Internet: www.vitesse.com

Data Sheet

VSC8021/VSC8022

8-Bit MUX/DEMUX Chipset

2.5Gb/s SONET-Compatible

Features

Functional Description

The VSC8021 and VSC8022 are high-speed SONET interface devices capable of handling serial data at

rates up to 2.5Gb/s. These devices can be used for STS-3 through STS-48 SONET applications.

These products are fabricated in gallium arsenide using the Vitesse H-GaAs

 E/D MESFET process which

achieves high-speed and low power dissipation. These products are packaged in a ceramic 52-pin leaded

ceramic chip carrier.

VSC8021

The VSC8021 contains an 8:1 multiplexer and a self-positioning timer. The 8:1 multiplexer accepts 8 paral-

lel differential ECL data inputs (D1-D8, D1N-D8N) at rates up to 312.5Mb/s and multiplexes them into a serial

differential bit stream output (DO, DON) at rates up to 2.5Gb/s.

The internal timing of the VSC8021 is built around the high-speed clock (up to 2.5GHz) delivered onto the

chip through a differential input (CLKI, CLKIN). This signal is subsequently echoed at the high-speed differen-

tial output (CO, CON).

The parallel data inputs are clocked to on-chip input registers with an externally supplied differential ECL

input (BYCLK, BYCLKN) operating at the same rate as the data inputs. An internal byte clock, which is a

divide-by-8 version of the high-speed clock, is used to transfer the data to a set of buffer registers. This internal

byte clock is brought off chip at the ECL output CLK8, CLK8N.

Internal circuitry monitors the internal and external byte clocks and generates an ERR signal if a timing

violation is detected. This signal can be gated to the SYNC input which is edge sensitive high. An active SYNC

input allows the VSC8021 timing to shift, positioning it properly against the external byte clock, CLK8,

CLK8N. When a CLK8 timing switch is made, normal data flow will be invalid for 1 byte.

There are two clock inputs, CLKI and BYCLK, going into the VSC8021. These two clocks serve as timing

references for different parts of the VSC8021. The BYCLK is used to trigger the input registers for the parallel

data inputs, while the CLKI is used to trigger the high-speed serial output register as well as some of the timing

circuitry for the parallel to serial conversion. Furthermore, in order to make this part easy to use, the user is not

required to assume a known phase relationship between CLKI and the BYCLK.

• Differential or Single-Ended Inputs and Outputs

• Low Power Dissipation: 2.3W (Typ Per Chip)

• Standard ECL Power Supplies:

• Available in Commercial (0

°C to +70°C) or Industrial

(-40

°C to +85°C) Temperature Ranges

• Proven E/D Mode GaAs Technology

• 52-Pin Leaded Ceramic Chip Carrier

• Serial Data Rates up to 2.5Gb/s

• Parallel Data Rates up to 312.5Mb/s

• ECL 100K Compatible Parallel Data I/Os

• Divide-by-8 Clock for Synchronization of

Parallel Data to Interfacing Chips

• SONET Frame Recovery Circuitry

(VSC8022)

• Compatible with STS-3 to STS-48

SONET Applications