HDMI2C1-14HD Datasheet, PDF (9/32 Pages) STMicroelectronics – HPD pull down and signal conditioning

HDMI2C1-14HD
Application information
2.3
HEAC link and HPD line description
The HDMI2C1-14HD proposes a unique solution in order to manage and protect both the
HEAC and the HPD links. The Figure 8 shows an overview of the function diagram of the
integrated block.
Figure 8. HEAC / HPD / Utility functional block diagram
VDD_IC
HDMI
ASIC
or
IC
HPD_IC
HEAC -
HEAC+
VDD_IC
matching
HDMI
connector
HPD
HPD / HEAC- 1
2
3
4
5
6
7
8
9
10
11
Utility
13
12
14
15
17
16
Utility / HEAC+
19
18
2.3.1
This block simplifies the design and the PCB layout of the HPD and HEAC functions. Simply
connect the 2 pins from the HDMI connector to one side of the device, and then use the 3
dedicated outputs on the other side of the device to manage separately the HPD and the
HEAC links.
Both HPD and Utility inputs (cable side) integrate a protection against ESD which is
compliant with IEC61000-4-2 standard, level 4 (8 kV contact).
HPD line description
The HPD line is described in the HDMI™ standards as the Hot Plug Detect function. This
line is used by the Source device in order to detect if a Sink device is connected through an
HDMI cable.
The integrated HPD block is pulling down the line via a current source. When the input
voltage is detected to be higher than a threshold level V_{TH_HPD}, the signal is converted into
a high state level on the ASIC side, at the voltage level of the ASIC power supply V_{DD_IC}.
Otherwise, HPD_IC pin remains in low state.
The electrical parameters relevant to the HPD block and specified by theTable 7 are
illustrated in the Figure 9.
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