TMDS261B Datasheet, PDF (32/48 Pages) Texas Instruments – TWO-PORT HDMI SWITCH

TMDS261B
SLLS987A – SEPTEMBER 2009 – REVISED JULY 2011
www.ti.com
E-EDID Reading Configurations in Standby Mode
When the DTV system is in standby mode, the sources do not read the E-EDID memory because the 1-kΩ
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 TMDS261B can still support this need.
The recommended configuration sequences are:
1. Apply the same 3.3-V power to the VCC of TMDS261B and the TMDS line termination at the HDMI receiver.
2. Because the TMDS261B has clock-detect circuitry and there is no valid input TMDS clock in the standby
mode, TMDS261B 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 47 through Figure 49. The
solution uses E-EDID data to be readable during system power-off or standby-mode operations.
SINK
HPD
5V
SDA
SOURCE 1 ^SCL
CEC
CLK
D0
D1
D2
HPD
5V
SDA
SOURCE 2 ^SCL
CEC
CLK
D0
D1
D2
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
5V
47kW
CEC
HPD
5V
SDA
SCL
CEC
CLK
D0
D1
D2
5V
47kW
CEC
HPD1
SDA1
SCL1
A21/B11
A22/B12
A23/B13
A24/B14
HPD2
SDA2
SCL2
A21/B21
A22/B22
A23/B23
A24/B24
VDD
VCC
(5V)
(3.3V)
EQ
S1
S2
mController
GND
HPD_SINK
SDA_SINK
SCL_SINK
Y1/Z1
Y2/Z2
Y3/Z3
Y4/Z4
VSadj
1kW
E-EDID
3.3V
4.7kW
4.7kW
DDC_SDA
DDC_SCL
HDMI RX
Y1/Z1
Y2/Z2
Y3/Z3
Y4/Z4
4.02kW 10%
Figure 46. Two-Port HDMI-Enabled DTV With TMDS261B – CEC Commands Passing Through
32
Copyright © 2009–2011, Texas Instruments Incorporated