Application information

HDMI2C2-14HD

10/31

DocID024813 Rev1

2.4

TMDS channels ESD protection

The TMDS (Transient Minimized Differential Signaling) channels are described by the HDMI

1.4 standard. A total of 4 unidirectional differential pairs are used to transmit the video data

to the sink device. There are 3 channels dedicated to the video data, and 1 channel

dedicated to the clock. The frequency of the TMDS clock is 1/10 of the video data frequency.

The HDMI2C2-14HD provides a simple PCB layout solution, directly compliant with HDMI

connector type A. It protects the application against the ESD according the IEC61000-4-2

level 4 standard (+/-8 kV contact). The high bandwidth of this ESD protection allows to

transmit HD video high speed data with no disturbance of the signal. The TDR is compliant

with the HDMI specification.

A capacitor can be optionally connected to the ESD_DISCH pin in order to enhance the

ESD protection performances.

Figure 8. TMDS lines ESD protection functional diagram

2.5

Application block diagrams

The Figure 9 shows a typical application block diagram proposal implementing all the

possible options. The TMDS channels are simply connected to the connector and to the

HDMI ASIC. The diagram shows that the CEC driver can be totally independent from the

HDMI ASIC. By this way, even if the +5 V power supply and/or if the HDMI ASIC is sleeping,

the CEC bus is still active in low power mode. The designer has then all the tools to optimize

the power consumption of the global application in stand-by mode, and has the possibility to

implement a smart wake-up through the CEC bus enhancing the final user experience.

DAT_D2+

DAT_D2 -

DAT_D1+

DAT_D1-

DAT_D0+

DAT_D0 -

DAT_CLK-

5V_IN

DAT_CLK+

ESD_DSICH

HDMI

ASIC

DAT_D2+_IC

DAT_D2 -_IC

DAT_D1+_IC

DAT_D1- _IC

DAT_D0+_IC

DAT_D0 - _IC

DAT_CLK- _IC

DAT_CLK+_IC

HDMI

connector

VDD_IC

1

3

5

7

9

11

13

15

17

19

12

14

16

18

2

4

6

8

10