DS90UB914ATRHSTQ1 Datasheet, PDF (56/68 Pages) Texas Instruments – DS90UB913A-Q1/DS90UB914A-Q1 25 to100 MHz 10/12-Bit

DS90UB913A-Q1, DS90UB914A-Q1
SNLS443A – MAY 2013 – REVISED JUNE 2013
APPLICATION INFORMATION
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AC Coupling
The SER/DES supports only AC-coupled interconnects through an integrated DC-balanced decoding scheme.
External AC coupling capacitors must be placed in series in the FPD-Link III signal path as illustrated in
Figure 44. For applications utilizing single-ended 50Ω coaxial cable, the unused data pin (DOUT-, RIN-) should
utilize a 0.047µF capacitor and should be terminated with a 50Ω resistor.
SER
D_OUT+
D_OUT-
R_IN+
R_IN-
DES
Figure 44. AC-Coupled Connection (STP)
SER
D_OUT+
R_IN+
DES
D_OUT-
50Q
50Q
R_IN-
Figure 45. AC-Coupled Connection (Coaxial)
For high-speed FPD–Link III transmissions, the smallest available package should be used for the AC coupling
capacitor. This will help minimize degradation of signal quality due to package parasitics. The I/O’s require a
0.1µF AC coupling capacitors to the line.
Adaptive Equalizer – Loss Compensation
The receiver inputs provide an adaptive equalization filter in order to compensate for signal degradation from the
interconnect components. There are limits to the amount of loss that can be compensated – these limits are
defined by the gain curve of the equalizer. In addition, there is a minimum tolerance for loss defined by the delta
between the serializer’s minimum VOD and the input threshold of the deserializer (Vswing). In order to determine
the maximum cable reach, factors that affect signal integrity such as jitter, skew, ISI, crosstalk, etc. need to be
taken into consideration. Figure 46 illustrates the maximum allowable interconnect loss for coax/STP cable with
the
adaptive
equalizer
at
various
gain
settings.
The level of equalization can also be manually selected via register controls. The adaptive equalized output can
be seen using the CMLOUTP/CMLOUTN pins in the Deserializer.
Figure 46. Adaptive Equalizer – Interconnect Loss Compensation (Coax/STP)
Figure 47 shows the typical connection of a DS90UB913A-Q1 Serializer using a coax interface.
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