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HDMI2C2-14HD

Application information

31

2.3

HEAC link and HPD line protection

The HDMI2C2-14HD proposes a unique solution in order to manage and protect both the

HEAC and the HPD links.

The HPD line is describe in the HDMI standards as a Hot Plug Defect function.This line is

used by the source device in order to detect if a sink device is connected through an HDMI

cable.

The HEAC link is described in the HDMI 1.4 standards as the HDMI ethernet and audio

return channel. It corresponds physically to one differential wired pair made of the utility line

and the HPD line. Two signals are transmitted through this link.

The first signal corresponds to the HDMI Ethernet Channel (HEC). The signal is transmitted

in differential mode (bidirectional) through the HEAC link. It is specified by the

100Base TX IEEE 802.3 standard (Fast Ethernet 100Mbps over twisted pair). Therefore,

the HEC integrates an Ethernet link into the video cable, enabling IP-based applications

over the HDMI cable.

The second signal corresponds to the Audio Return Channel (ARC). The signal is

transmitted in common mode (unidirectional, from sink to source) through the HEAC link. It

is specified by the IEC 60958-1 standard. The ARC integrates an upstream audio capability,

simplifying the cabling of the audiovisual equipments. It is no more necessary to use a

coaxial cable from TV to audio amplifier.

The HDMI2C1-14HD helps the designer to implement this high added value HEAC function

in the application, protecting the link against the ESD with no disturbance of the signal,

thanks to the integrated matching circuitry on HEAC+ line. It provides 2 distinct outputs

HEAC+ and HEAC- in order to ease as much as possible the PCB layout.

Both HPD and utility inputs (cable side) integrate a protection against ESD which is

compliant with IEC61000-4-2 standard, level 4 (8kV contact).

Figure 7. HEAC / HPD / utility functional block diagram

HPD

Utility

HDMI

ASIC

or

IC

VDD_IC

Utility / HEAC+

HEAC+

HPD

1

3

5

7

9

2

4

6

8

HDMI

connector

HEAC+

HDMI2C2-14HD

10

11

15

13

19

17

12

16

14

18