HD3SS214_16 Datasheet, PDF (13/25 Pages) Texas Instruments – 8.1 Gbps DisplayPort 1.3 2:1/1:2 Differential Switch

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8.2.4 DP++ Support
The HD3SS214 supports DP++ implementations.
HD3SS214
SLAS907A – DECEMBER 2015 – REVISED JULY 2016
Figure 6. DP++ Docking Station Support
8.2.4.1 Design Requirements
For this example, use the parameters shown in Table 3
Table 3. Design Parameters
PARAMETER
V_DD
Source
Sink
AUX_SEL Level
DP++ Support
VALUE
3.3 V
DP x1
DP x2
M
Yes
8.2.4.2 Detailed Design Procedure
For applications involving DP++ support, following design procedures must be followed.
8.2.4.2.1 AUX and DDC Switching
The HD3SS214 supports DP++ implementations.
According to the DP++ standard, the DP AUX line is repurposed as the DDC line when HDMI signals are being
transmitted. Unfortunately, the AUX and DDC signals have very different electrical requirements. AUX is a
differential signal that requires AC coupling, while DDC uses I²C protocol, which needs pull-up resistors. As a
result, these signals are electrically incompatible if extra circuitry is not designed to accommodate the signals.
The source selection design block uses conditional pull-up resistors to support AUX and DDC signals on a
unified line.Figure 7 illustrates the circuit that was used to enable the signal.
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