VSC8140 查看數據表（PDF） - Vitesse Semiconductor

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VSC8140

2.48832Gb/s 16:1 SONET/SDH Transceiver with Integrated Clock Generator

Vitesse Semiconductor 

VITESSE

SEMICONDUCTOR CORPORATION

2.48832Gb/s 16:1 SONET/SDH

Transceiver with Integrated Clock Generator

Figure 16: High-Speed Clock and High-Speed Data Inputs

Data Sheet

VSC8140

Chip Boundary

VCC = 3.3V

1.65V

3kΩ

ZO

CIN

CAC

VTERM

CIN

ZO

CIN TYP = 100nF

CAC TYP = 100nF

50Ω

3kΩ

50Ω

VEE = 0V

3kΩ 1.65V

3kΩ

High-Speed Clock and High-Speed Data Inputs

The incoming high-speed data and high-speed clock are received by high-speed inputs RXIN and

RXCLKIN. The inputs are internally biased to accommodate AC-coupling.

The data input receiver is internally terminated by a center-tapped resistor network. For differential input

DC-coupling, the network is terminated to the appropriate termination voltage VTERM providing a 50Ω to VTERM

termination for both true and complement inputs. For differential input AC-coupling, the network is terminated

to VTERM via a blocking capacitor.

In most situations, these inputs will have high transition density and little DC offset. However, in cases

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.

Page 12

© VITESSE SEMICONDUCTOR CORPORATION

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

G52251-0, Rev. 4.0

9/6/00

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