IP4778CZ38_2

© NXP B.V. 2009. All rights reserved.

Product data sheet

Rev. 02 — 12 February 2009

18 of 26

NXP Semiconductors

IP4778CZ38

HDMI ESD protection, DDC buffering and hot plug control

10.8 Typical application

This application ensures that the EDID (stored in the EEPROM) can be read out in

Standby mode, even if long cables are used, to guarantee correct CEC wake-up handling.

To wake up the system from Standby to normal operation, the HDMI source has to first

read the EDID in order to hand over the port ID via the CEC protocol. This ensures that

the HDMI starts up and switches to the correct HDMI port to display the HDMI source

which initiated the CEC wake-up sequence.

The RF routing optimized pin position variant allows optimum design layout of the RF

routing micro strips to ensure that the impedance of the TMDS lines remain within the

specification limits. Part of the microstrips comprise a solid ground plane which is located

beneath the device.

Fig 15. Application showing optimized PCB microstrip lines

8765

1234

EDID

001aag049

IP4778CZ38

HDMI

connector

1

2

3

4

5

6

7

8

9

10

TMDS_D2+

TMDS_D2

−

TMDS_D1+

TMDS_D1

−

TMDS_D0+

TMDS_D0

−

TMDS_CLK+

TMDS_CLK

−

CEC_IN

DDC_CLK_IN

DDC_DAT_IN

HOT_PLUG_DET_IN

11

12

13

14

15

16

17

18

+3.3 V

19

19

1

Rdata

1.5 k

Ω

Rclock

1.5 k

Ω

RCEC

100 k

Ω

RCEC

27 k

Ω

Rdata

47 k

Ω

Rclock

47 k

Ω

38

37

36

35

34

33

32

31

30

29

28

27

26

25

24

23

22

21

20

ENABLE

TMDS_D2+

TMDS_GND

TMDS_D2

−

TMDS_D1+

TMDS_GND

TMDS_D1

−

TMDS_D0+

TMDS_GND

TMDS_D0

−

TMDS_CLK+

TMDS_GND

TMDS_CLK

−

CEC

n.c.

DDC_CLK

DDC_DAT

GND

+5 V

HOTPLUG_DET

RDDC

100

Ω

RHP

1 k

Ω

+5.0 V