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PDF GS2964 Data sheet ( Hoja de datos )
| Número de pieza | GS2964 | |
| Descripción | Adaptive Cable Equalizer | |
| Fabricantes | Gennum | |
| Logotipo |  |
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GS2964 Adaptive Cable Equalizer
Key Features
• SMPTE 424M, SMPTE 292M and SMPTE 259M
compliant
• Automatic cable equalization
• Multi-standard operation from 143Mb/s to 2.97Gb/s
• Performance optimized for 270Mb/s, 1.485Gb/s and
2.97Gb/s. Typical equalized length of Belden 1694A
cable:
100m at 2.97Gb/s
140m at 1.485Gb/s
180m at 270Mb/s
• Supports DVB-ASI at 270Mb/s
• Manual bypass (useful for low data rates with slow
rise/fall times)
• Programmable carrier detect with squelch threshold
adjustment
• Standard EIA/JEDEC logic control and status signal
levels
• Single 3.3V power supply operation
• 215mW power consumption (typical)
• Wide temperature range of -40ºC to +85ºC
• Small footprint QFN package (4mm x 4mm)
Drop-in compatible with the GS2974
• Pb-free and RoHS compliant
Applications
• SMPTE 424M, SMPTE 292M and SMPTE 259M coaxial
cable serial digital interfaces
Description
The GS2964 is a high-speed BiCMOS integrated circuit
designed to equalize and restore signals received over 75Ω
coaxial cable.
The device is designed to support SMPTE 424M,
SMPTE292M and SMPTE 259M, and is optimized for
performance at 270Mb/s, 1.485Gb/s and 2.97Gb/s.
The GS2964 features DC restoration to compensate for the
DC content of SMPTE pathological test patterns.
The Carrier Detect output pin (CD) indicates whether a
valid input signal has been detected. It can be connected
directly to the MUTE pin to mute the output on loss of
carrier. A voltage programmable threshold, which can be
changed via the SQ_ADJ pin, forces CD high when the
input signal amplitude falls below the threshold. This
allows the GS2964 to distinguish between low-amplitude
SDI signals and noise at the input of the device.
The equalizing and DC restore stages are disengaged when
the BYPASS pin is HIGH. No equalization occurs in Bypass
mode.
The differential outputs can be DC-coupled to Gennum
3.3V cable drivers and reclockers and to other
industry-standard 3.3V CML logic.
The GS2964 is footprint and drop-in compatible with
existing GS2974 designs, with no additional application
changes required.
The device is available in a 16-pin, 4mm x 4mm QFN
package.
Power consumption of the GS2964 is typically 215mW.
The GS2964 is Pb-free, and the encapsulation compound
does not contain halogenated flame retardant.
This component and all homogeneous subcomponents are
RoHS compliant.
GS2964 Adaptive Cable Equalizer
Data Sheet
51913 - 3
March 2010
www.gennum.com
1 of 17
1 page  
Table 1-1: GS2964 Pin Descriptions (Continued)
Pin Number
12
Name
VEE_D
Timing
Analog
Type
Power
13
VCC_D
Analog
Power
14
MUTE
Not
Input
Synchronous
15 CD Not Output
Synchronous
16
VCC_A
Analog
Power
–
Center Pad
–
Power
Description
Most negative power supply for the digital circuitry and output
buffer.
Connect to GND.
Most positive power supply for the digital I/O pins of the device.
Connect to +3.3V DC.
CONTROL SIGNAL INPUT
levels are LVCMOS/LVTTL compatible. (3.3V Tolerant)
Controls output behaviour on SDO and SDO. (Internal pull-down).
See Section 4.5.
STATUS SIGNAL OUTPUT
Signal levels are LVCMOS/LVTTL compatible.
Indicates the presence of an input signal.
See Section 4.5.
Most positive power supply for the analog circuitry of the device.
Connect to +3.3V DC.
Internally bonded to VEE_A.
GS2964 Adaptive Cable Equalizer
Data Sheet
51913 - 3
March 2010
5 of 17
5 Page 
SDO
SDO
50 50
+200mV
VCM = 2.9V
typical
-200mV
+200mV
VCM = 2.9V
typical
-200mV
Figure 4-1: Typical Output Voltage Levels
4.4 Programmable Squelch Adjust (SQ_ADJ)
The GS2964 incorporates a programmable Squelch Adjust (SQ_ADJ) threshold.
This feature can be useful in applications where there are multiple input channels using
the GS2964 and the maximum gain can be limited to avoid crosstalk.
The SQ_ADJ pin acts to change the threshold of the Carrier Detect (CD) pin, through
voltage level variances. When the input signal drops below a certain threshold, the CD
pin will be driven high, indicating that there is not a valid input signal. In order to enable
automatic muting of the output of the GS2964, the CD pin should be connected directly
to the MUTE pin. In applications where programmable squelch adjust is not required, the
SQ_ADJ pin may be left unconnected.
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.
4.5 Mute and Carrier Detect
The GS2964 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 GS2964. 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 1: 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 GS2964 when no valid input signal has been detected.
GS2964 Adaptive Cable Equalizer
Data Sheet
51913 - 3
March 2010
11 of 17
11 Page | ||
| Páginas | Total 17 Páginas | |
| PDF Descargar | [ Datasheet GS2964.PDF ] | |
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