GS3490 Datasheet, PDF (16/22 Pages) Semtech Corporation – Configurable Adaptive Cable Equalizer/Cable Driver

When muted, the output swing is set to 425mV_ppd and the DDO/DDO outputs are
latched.
Automatic muting of the output can be enabled by connecting the CD pin to the
EQ_OP_CTL pin.
If the connection is made directly, as shown in Figure 4-3, the output would be in its
default mode (850mV_ppd swing with no De-emphasis) when there is a signal present.
Figure 4-3: Direct Loopback
4.2 Cable Driver Mode
4.2.1 Cable Driver Mode Enable
To enable Cable Driver Mode, EQ_DISABLE and CD_ENABLE must be set to logic HIGH.
These two pins may be tied together and controlled from a single logic signal.
4.2.2 Differential Digital Data Inputs (DDI/DDI)
The GS3490 features a differential input buffer (DDI/DDI) with on-chip 100Ω differential
termination.
The differential data input signal is connected to the DDI and DDI input pins of the
device.
The serial data input buffer is capable of operation with any binary coded signal that
meets the input signal level requirements, in the range of 270Mb/s to 2.97Gb/s in Cable
Driver Mode. The input circuit is self-biasing to allow for simple AC or DC-coupling of
input signals to the device.
4.2.3 Serial Data Outputs (SDO/SDO)
The GS3490 features a current-mode differential output driver capable of achieving
output swings up to 1040mV_pp using a 3.3V termination supply (V_TERM).
The output signal amplitude or swing is set using an external R_SET resistor. For the most
commonly used output swing configurations, please refer to Section 4.2.5.
The SDO/SDO pins of the device provide the serial data outputs.
Please refer to Section 5.1 for the correct way to implement the bi-directional serial
input/output. Other application circuits are not supported.
GS3490
Final Data Sheet
GENDOC-058568
Rev. 1
April 2014
www.semtech.com
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