VSC8140QR VITESSE [Vitesse Semiconductor Corporation], VSC8140QR Datasheet - Page 12

• Manufacturer Part Number: VSC8140QR
• Description: 2.48832Gb/s 16:1 SONET/SDH Transceiver with Integrated Clock Generator
• Manufacturer: VITESSE [Vitesse Semiconductor Corporation]

Transceiver with Integrated Clock Generator
2.48832Gb/s 16:1 SONET/SDH
Page 12
High-Speed Clock and High-Speed Data Inputs
RXCLKIN. The inputs are internally biased to accommodate AC-coupling.
DC-coupling, the network is terminated to the appropriate termination voltage V
termination for both true and complement inputs. For differential input AC-coupling, the network is terminated
to V
where this does not hold, direct DC connection is possible. All serial data and clock inputs have the same circuit
topology, as shown in Figure 16. The reference voltage is created by a resistor divider as shown. If the input sig-
nal is driven differentially and DC-coupled to the part, the mid-point of the input signal swing should be cen-
tered about this reference voltage and not exceed the maximum allowable amplitude. For single-ended, DC-
coupling operations, it is recommended that the user provides an external reference voltage which has better
temperature and power supply noise rejection than the on-chip resistor divider. The external reference should
have a nominal value equivalent to the common-mode switch point of the DC-coupled signal, and can be con-
nected to either side of the differential gate.
In most situations, these inputs will have high transition density and little DC offset. However, in cases
The incoming high-speed data and high-speed clock are received by high-speed inputs RXIN and
The data input receiver is internally terminated by a center-tapped resistor network. For differential input
TERM
via a blocking capacitor.
C
C
IN
AC
741 Calle Plano, Camarillo, CA 93012 • 805/388-3700 • FAX: [phone]
TYP = 100nF
TYP = 100nF
Figure 16: High-Speed Clock and High-Speed Data Inputs
Z
Z
O
O
V
TERM
VITESSE
SEMICONDUCTOR CORPORATION
VITESSE SEMICONDUCTOR CORPORATION
C
C
C
IN
AC
IN
1.65V
Chip Boundary
50
50
3k
3k
V
V
CC
EE
= 3.3V
= 0V
TERM
providing a 50 to
3k
3k
1.65V
VSC8140
Data Sheet
G52251-0, Rev. 4.0
V
TERM
9/6/00