2.97Gb/s. Typical equalized length of Belden 1694A
cable up to:
210m at 2.97Gb/s
300m at 1.485Gb/s
550m at 270Mb/s
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Supports DVB-ASI at 270Mb/s
Supports MADI at 125Mb/s
Manual bypass (useful for low data rates with slow
rise/fall times)
Programmable carrier detect with squelch threshold
adjustment
Automatic power-down on loss of signal
Standby power <35mW (typical)
Differential output supports DC-coupling from 1.2V to
3.3V CML logic
Option to compensate for 6dB flat attenuation prior to
input of device
Selectable output de-emphasis: 2dB, 4dB and 6dB
Standard EIA/JEDEC logic control and status signal
levels
Single 3.3V power supply operation
180mW power consumption (typical)
Wide operating temperature range of -40ºC to +85ºC
Small footprint QFN package (4mm x 4mm)
Footprint compatible with the GS2974A, GS2974B,
GS2984 and GS2994
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Pb-free and RoHS compliant
Applications
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SMPTE ST 424, SMPTE ST 292 and SMPTE ST 259
coaxial cable serial digital interfaces
Description
The GS3440 is a high-speed BiCMOS device designed to
equalize and restore signals received over 75Ω coaxial
cable.
The device is designed to support SMPTE ST 424,
SMPTE ST 292 and SMPTE ST 259, and is optimized for
performance at 270Mb/s, 1.485Gb/s and 2.97Gb/s.
The GS3440 features DC restoration to compensate for the
DC content of SMPTE pathological signals.
The Carrier Detect output pin (CD) indicates whether an
input signal has been detected. It can be connected directly
to the SLEEP pin to enable automatic sleep on loss of carrier.
A voltage programmable threshold, set via the SQ_ADJ pin,
forces CD high when the input signal amplitude falls below
the threshold. This allows the GS3440 to distinguish
between low-amplitude SDI signals and noise at the input
of the device.
The equalizing and DC restore stages are disengaged and
no equalization occurs when the BYPASS pin is HIGH.
Setting the BYPASS pin HIGH is useful for signals launched
at the signal source with low data rates and/or slow rise/fall
times.
The GS3440 features a gain selection pin (GAIN_SEL) which
can be used to compensate for 6dB flat attenuation prior to
the input of the device.
The differential output can be DC-coupled to Semtech’s
reclockers and cable drivers, as well as industry-standard
1.2V, 1.8V, 2.5V and 3.3V CML logic by changing the voltage
applied to the VCC_O pin. In general, DC-coupling to any
termination voltage between 1.2V and 3.3V is supported.
The GS3440 also features programmable output
de-emphasis with three, user-selectable operating levels to
support long PCB traces at the output of the device.
GS3440 Adaptive Cable Equalizer
Final Data Sheet
Rev. 2
December 2012
www.semtech.com
1 of 23
Proprietary and Confidential
Description (continued)
The device comes in a 16-pin, 4mm x 4mm QFN package and is footprint compatible with Semtech’s GS2974A, GS2974B,
GS2984 and GS2994 equalizers.
Power consumption of the GS3440 is typically 180mW when DC-coupled at 1.2V.
The GS3440 is Pb-free, and the encapsulation compound does not contain halogenated flame retardant.
This component and all homogeneous subcomponents are RoHS compliant.
SQ_ADJ
BYPASS
SLEEP
CD
VCC_A
Squelch Adjust
Carrier Detect
Mute
VCC_O
SDI
SDI
GAIN_SEL
Equalizer
DC
Restore
Output
DDO
DDO
VEE_O
OP_CTL
AGC
VEE_A
AGC
AGC
GS3440 Functional Block Diagram
GS3440 Adaptive Cable Equalizer
Final Data Sheet
Rev. 2
December 2012
2 of 23
Proprietary and Confidential
Contents
Key Features ........................................................................................................................................................1
4.7 Adjustable Output Swing, De-Emphasis and Mute ............................................................ 15
5. Application Information .......................................................................................................................... 17
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