Datasheet

HPD1
SDA1
SCL1
HPD2
SDA2
SCL2
HPD3
SDA3
SCL3
EQ
S1
S2
HPD_SINK
SDA_SINK
SCL_SINK
Y1/Z1
Y2/Z2
Y3/Z3
Y4/Z4
VSADJ
E-EDID
HDMIRX
DDC_SDA
DDC_SCL
5V
5V
5V
47kW
47kW
47kW
mController
3.3V
4.7kW 4.7kW
CEC
CEC
CEC
4.02 kW 10%
GND
1kW
HPD
5V
SDA
SCL
CEC
CLK
D 0
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
SINK
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
SOURCE1
HPD
5V
SDA
SCL
CEC
CLK
D0
1D
D2
D1
D2
SOURCE2
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
SOURCE3
A11/B11
A12/B12
A13/B13
A14/B14
VDD
(5V)
VCC
(3.3V)
A21/B21
A22/B22
A23/B23
A24/B24
A31/B31
A32/B32
A33/B33
A34/B34
Y1/Z1
Y2/Z2
Y3/Z3
Y4/Z4
TMDS351
www.ti.com SLLS840B –MAY 2007– REVISED JULY 2011
Figure 18. Three-Port HDMI Enabled DTV with TMDS351 – CEC Commands Passing Through
A DTV Supporting an Active CEC Link
In Figure 19, the CEC PHY and CEC LOGIC functions are added. The DTV can initiate and/or react to CEC
signals from its remote control or other audio/video products on the same CEC bus. All sources must have their
own CEC physical address to support the full functionality of the CEC link.
A source reads its CEC physical address stored its E-EDID memory after receiving a logic-high from the HPD
feedback. When HPD is high, the sink-assigned CEC physical address should be maintained. Otherwise, when
HPD is low the source sets CEC physical address value to (F.F.F.F).
Case 1 – AC Coupled Source (See Figure 19, Port 1)
When the source TMDS lines are AC coupled or when the source cannot detect the TMDS termination provided
in the connected sink, the indication of the source selection can only come from the HPD signal. The TMDS351
HPD1 pin should be applied directly as the HPD signal back to the source.
Case 2 – DC Coupled Source (See Figure 19, Port 2)
When the source TMDS lines are DC coupled, there are two methods to inform the source that it is the active
source to the sink. One is checking the HPD signal from the sink, and the other is checking the termination
condition in the sink.
In a full CEC operation mode, the HPD signal is set high whether the port is selected or not. The source loads
and maintains the CEC physical address when HPD is high. As soon as HPD goes low, the source loses the
CEC physical address. To keep the CEC physical address to the source, the HPD signal is looping back from the
source provided 5-V signal through a 1-kΩ pull-up resistor in the sink. This method is acceptable in application
where the HDMI transmitter can detect the receiver termination by current sensing, and the receiver has
switchable termination on the TMDS inputs. The internal termination resistors are connected to the termination
voltage when the port is selected, or they are disconnected when the port is not selected. The TMDS351
features switchable termination on the TMDS inputs.
Copyright © 2007–2011, Texas Instruments Incorporated 19