GS1524A 데이터 시트보기 (PDF) - Gennum -> Semtech

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GS1524A

Adaptive Cable Equalizer

Gennum -> Semtech 

MCLADJ

In applications where there are multiple input channels using the GS1524A, it is

advantageous to have a programmable mute output to avoid signal crosstalk.

The output of the GS1524A can be muted when the input signal decreases below a

certain input level. This threshold is determined using the input voltage applied to the

MCLADJ pin. The MCLADJ pin may be left unconnected for applications where output

muting is not required.

This feature has been designed for use in applications such as routers where signal

crosstalk and circuit noise cause the equalizer to output erroneous data when no input

signal is present. The use of a Carrier Detect function with a fixed internal reference

does not solve this problem since the signal to noise ratio on the circuit board could be

significantly less than the default signal detection level set by the on chip reference.

NOTE: MCLADJ is only recommended for data rates up to 360Mb/s.

CLI

The output voltage of the CLI pin is an approximation of the amount of cable present at

the GS1524A input. With 0m of cable, 800mV input signal levels, and a data rate of

270Mb/s, the CLI output voltage is approximately 2.5V. As the cable length increases,

the CLI voltage decreases providing an approximate correlation between the CLI

voltage and cable length.

NOTE: CLI is only recommended for data rates up to 360Mb/s.

4.4 Mute and Carrier Detect

In addition to the programmable mute output and cable length indicator, the GS1524A

includes a multi-function CD/MUTE bidirectional pin that provides the following

functions:

INPUT (MUTE)

Applying a HIGH INPUT to the CD/MUTE pin forces the GS1524A outputs to a muted

condition. The minimum voltage required to force the outputs to a muted condition is

listed in the DC electrical characteristics table. In this condition the outputs will be

latched to the last logic level present at the output to avoid signal crosstalk.

Applying a LOW INPUT to the CD/MUTE pin will force the GS1524A outputs to remain

active regardless of the length of input cable and the voltage applied to the MCLADJ pin.

See the DC electrical characteristics table for voltage levels.

OUTPUT (CD)

When used as an OUTPUT, the CD/MUTE pin will indicate the presence of a valid input

signal. When CD/MUTE is LOW, a valid input signal has been detected at the input of the

device. When CD/MUTE is HIGH, the input signal is invalid. This pin will indicate loss of

carrier for data rates greater than 19Mb/s.

NOTE: The CD/MUTE pin is not functional in BYPASS mode.

GS1524A Adaptive Cable Equalizer

Data Sheet

28852 - 5

June 2009

12 of 16

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