VSC8021FC VITESSE [Vitesse Semiconductor Corporation], VSC8021FC Datasheet - Page 9

• Manufacturer Part Number: VSC8021FC
• Description: 2.5Gb/s SONET-Compatible 8-Bit MUX/DEMUX Chipset
• Manufacturer: VITESSE [Vitesse Semiconductor Corporation]

Data Sheet
VSC8021/VSC8022
G52028-0, Rev 4.1
05/25/01
High-Speed Inputs
frequencies greater than 1GHz, were specified with absolute minimum and maximum voltage values. Since
these inputs are intended for AC-coupled applications, they have been re-specified in terms of a voltage swing
( V
have high transition density and contain no DC offsets, making them candidates for AC-coupling as well. How-
ever, it is possible to employ DC-Pcoupling when the serial input data contains a DC component.
ate this input provided that the input swing is centered around the reference voltage. It is recommended that, in
single-ended DC-coupling situations, the user provide an external reference which has better temperature and
power supply rejection than the simple on-chip voltage divider. This external reference should have a nominal
value of -3.5V and can be connected to the complementary input. This complication can be avoided in DC-cou-
pled situations by using differential signals.
9 Rows
IN
In the past, the high-speed inputs, which are typically used for serial data and high-speed clock inputs with
High-speed clocks are intended for AC-coupled operation. In most situations high-speed serial data will
The structure of the high-speed input circuit is shown in Figure 6. DC-coupled circuits may be used to oper-
).
3 A1s
3 x 3 Bytes
Overhead
Transport
3 A2s
© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012
V
3 C1s
TT
STS-3 Frame
V
3 x 90 Bytes
50•
150 pF
TT
Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]
125 s
150 pF
Figure 6: High-Speed Input Circuit Structure
VITESSE
SEMICONDUCTOR CORPORATION
STS-3 Envelope
Chip Boundary
Figure 5: SONET Frame Structure
DATA
Capacity
A1s and A2s: SONET Framing Sequence
Internet: www.vitesse.com
-3.5 V
C1s: STS Frame ID
V
V
CC
EE
9 Rows
= GND
= -5.2V
48 A1s
-3.5 V
3 x 48 Bytes
Overhead
Transport
48 A2s
48 C1s
2.5Gb/s SONET-Compatible
STS-48 Frame
48 x 90 Bytes
8-Bit MUX/DEMUX Chipset
125 s
R • 1k•
STS-48 Envelope
DATA
Capacity
Page 9