TMDS361 datasheet(28/42 Pages) TI

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A DTV Supporting a Passive CEC Link

E-EDID Reading Configurations in Standby Mode

HPD1

SDA1

SCL1

HPD2

SDA2

SCL2

HPD3

SDA3

SCL3

HPD_SINK

SDA_SINK

SCL_SINK

Y1/Z1

Y2/Z2

Y3/Z3

Y4/Z4

VSADJ

E-EDID

HDMIRX

DDC_SDA

DDC_SCL

47kW

mController

3.3V

4.7kW

CEC

4.02 kW 10%

GND

1kW

HPD

SDA

SCL

CEC

CLK

D 0

HPD

SDA

SCL

CEC

CLK

HPD

SDA

SCL

CEC

CLK

SINK

HPD

SDA

SCL

CEC

CLK

SOURCE1

HPD

SDA

SCL

CEC

CLK

SOURCE2

HPD

SDA

SCL

CEC

CLK

SOURCE3

A11/B11

A12/B12

A13/B13

A14/B14

VDD

(5V)

VCC

(3.3V)

A21/B21

A22/B22

A23/B23

A24/B24

A31/B31

A32/B32

A33/B33

A34/B34

Y1/Z1

Y2/Z2

Y3/Z3

Y4/Z4

TMDS361

SLLS919 – DECEMBER 2008............................................................................................................................................................................................ www.ti.com

In Figure 34, the DTV does not have the capability of handling CEC signals, but allows CEC signals to pass over

the CEC bus. The source selection is done by the control command of the DTV. The user cannot force the

command from any audio/video product on the CEC bus. The selected source reads the E-EDID data after

receiving an asserted HPD signal. The microcontroller loads different CEC physical addresses while changing

the source by means of the S1 and S2 pins.

When the DTV system is in standby mode, the sources do not read the E-EDID memory because the 1-k

Ω

pulldown resistor keeping the HPD_SINK input at logic low forces all HPD pins to output logic-low to all sources.

The source does not read the E-EDID data with a low on HPD signal. However, if reading the E-EDID data in the

system standby mode is preferred, then TMDS361 can still support this need.

The recommended configuration sequences are:

1. Apply the same 3.3-V power to the VCC of TMDS361 and the TMDS line termination at the HDMI receiver

2. Because the TMDS361 has clock-detect circuitry and there is no valid input TMDS clock in the standby

mode, TMDS361 draws significanty less current.

3. Set S1 and S2 to select the source port which is allowed to read the E-EDID memory.

Note that if the source has a time-out limitation between the 5-V and the HPD signals, the foregoing configuration

is not applicable. Uses individual EEPROMs assigned for each input port, see Figure 35. The solution uses

E-EDID data to be readable during system power-off or standby-mode operations.

Figure 34. Three-Port HDMI-Enabled DTV With TMDS361 – CEC Commands Passing Through

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