gs2914 Gennum Corporation, gs2914 Datasheet - Page 9

• Manufacturer Part Number: gs2914
• Description: Gs2914 Hd-linx? Iii Serial Digital Dc Restorer For Fibre-optic Receivers
• Manufacturer: Gennum Corporation

4.3 Mute and Carrier Detect
The GS2914 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 GS2914. 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: The MUTE pin may be connected directly to the CD pin to allow mute on loss of
carrier.
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 GS2914 when no valid input signal has been detected.
NOTE: If the minimum input signal strength is not achieved and the device is not in
bypass mode, the GS2914 will not assert the CD pin even if a carrier is present.
Table 4-1: Mute Input Table
Table 4-2: CD Output Table
5. Application Information
5.1 PCB Layout
Special attention must be paid to component layout when designing serial digital
interfaces for HDTV. An FR-4 dielectric can be used, however, controlled impedance
transmission lines are required for PCB traces longer than approximately 1cm. Note the
following PCB artwork features used to optimize performance:
•
•
GS2914 HD-LINX™ III Serial Digital DC Restorer for
Fibre-Optic Receivers
Data Sheet
50864 - 0
Mute
CD
PCB trace width for HD rate signals is closely matched to SMT component width to
minimize reflections due to change in trace impedance.
The PCB ground plane is removed under the GS2914 input components to minimize
parasitic capacitance.
0
1
0
1
Function
SDO and SDO operate normally
SDO and SDO are forced to a steady
state
Input Status
Valid Input on SDI, SDI pins
Input is not valid
February 2009
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