ip4778cz38/v NXP Semiconductors, ip4778cz38/v Datasheet - Page 16

• Manufacturer Part Number: ip4778cz38/v
• Description: Hdmi Esd Protection, Ddc Buffering And Hot Plug Control
• Manufacturer: NXP Semiconductors

NXP Semiconductors
IP4778CZ38_1
Objective data sheet
10.6 Backdrive protection
The combination of a TMDS switch and the IP4778CZ38 is a cost-effective way to attain
various HDMI ports by using a single input HDMI receiver device. The Enable signal
activates the HDMI DDC and hot plug lines at the port that is selected by the system
controller.
The HDMI contains various signals which can partly supply current into an HDMI device
that is powered down.
Typically, the DDC lines and the CEC signals can force 5 V into the switched off device.
The IP4778CZ38 ensures that at power-down, the critical signals are blocked to prevent
any damage to the HDMI sink and HDMI source.
Fig 12. Example of multiplexing both DDC and hot plug
Fig 13. Backdrive protection
HOT_PLUG_DET_IN
HOT_PLUG_DET_IN
HOT_PLUG_DET_IN
DDC_CLK_IN
DDC_DAT_IN
DDC_CLK_IN
DDC_DAT_IN
DDC_CLK_IN
DDC_DAT_IN
HDMI source
HDMI ASIC
Rev. 01 — 10 April 2008
HDMI ESD protection, DDC buffering and hot plug control
supply off
ENABLE
ENABLE
ENABLE
backdrive current
5 V
I
2
C-bus ASIC
input 1
input 2
input 3
DDC_CLK_IN
DDC_DAT_IN
HOT_PLUG_DET_IN
HDMI sink
001aag047
IP4778CZ38
001aag046
© NXP B.V. 2008. All rights reserved.
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