VSC7216-02
Data Sheet
If using the VSC7216-02 as a replacement for the VSC7216, the termination scheme in
can be used. The
outputs will function normally, but with slightly increased jitter and power consumption.
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VSC7216-02
Z
O
= 50Ω
150Ω
Receiver Device
C
IN
V
SSD
150Ω
Z
O
= 50Ω
C
IN
100Ω
V
SSD
Figure 7. PECL Output Termination Scheme With Pull-Downs
Transmitter Pre-Emphasis
High-speed digital waveforms are subject to skin effect phenomena such as velocity dispersion and frequency
dependent attenuation of their fourier components. These effects cause the signal to become increasingly distorted
with increasing propagation distance along a transmission medium. The situation is exacerbated with increasing
frequency. Recognizing this, the VSC7216-02 provides the capability of signal predistortion, or pre-emphasis in its
transmitter section. When used, transmit pre-emphasis will cause the PECL transmitter outputs to be distorted in a
manner that is the inverse of skin effect distortion. When signal pre-emphasis is chosen, the effects of predistortion
and skin effect distortion will offset and a high quality waveform will be seen at the receiving device.
Control of the pre-emphasis feature is provided through the JTAG interface. By default, transmitter pre-emphasis is
off. To enable this feature, use the JTAG interface.
Reduced Transmitter Serial Output Swing
The VSC7216-02 provides a mode of operation in which the high-speed PECL transimtter output voltage swing is
reduced by approximately half. This mode may be useful driving signals over short distances. It carries the benefit of
a reduction in the total power consumption of the device.
Control of this function is provided through the JTAG interface. By default, the PECL output swing is FULL. To
configure the PECL outputs to reduced swing, use the JTAG interface.
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G52367 Revision 4.2
December 2006
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
