GS9074A HD-LINX® II Adaptive Cable Equalizer

Data Sheet

34166 - 4

November 2009

13 of 17

Proprietary & Confidential

6.3 Programmable Mute Output

The GS9074A incorporates a programmable threshold output mute (MCLADJ).

In applications where there are multiple input channels using the GS9074A, it is

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

The output of the GS9074A 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.

6.4 Mute and Carrier Detect

The GS9074A includes a MUTE input pin that allows the application interface to mute

the serial digital output at any time. Set the MUTE pin HIGH to mute SDO and SDO. In

this case, the outputs will mute regardless of the setting of the BYPASS pin.

A Carrier Detect output pin (CD) indicates the presence of a valid signal at the input of

the GS9074A. When CD is LOW, the device has detected a valid input on SDI and SDI.

When CD is HIGH, the device has not detected a valid input.

NOTE: CD will only detect loss of carrier for data rates greater than 19Mb/s.

The CD output pin may be connected directly to the MUTE input pin to enable automatic

muting of the GS9074A when no valid input signal has been detected.

NOTE: If the maximum cable length is exceeded and the device is not in bypass mode

the GS1574A will not assert the CD pin even if a carrier is present.