TMDS261 datasheet(27/42 Pages) TI

27 / 42 page

HPD Pins

1kW

TMDS261

HPD_SINK

VCC/5V_source

1 k

(internal

series resistor)

VCC

HPD_SINK

HPD[1:2]

HPD_SOURCE

OFF

VCC

HPD[1:2]

HPD_SOURCE

S0387-02

1kW

10kW

5V_Source (5VcomingfromHDMI source)

Layout Considerations

Using the TMDS261 in Systems with Different CEC Link Requirements

TMDS261

www.ti.com............................................................................................................................................................................................ SLLS953 – DECEMBER 2008

Obviously, to accommodate the 3-mA drive current specification, a narrower threshold voltage range is required

to support a maximum 800-pF load capacitance for a standard-mode I2C bus.

When the input low- and high-level threshold voltages, Vth– and Vth+, are 0.7 V and 1.9 V, respectively, which is

0.15 VDD and 0.4 VDD, approximately. With VDD = 5 V from Table 5, the maximum pullup resistor is 3.59 kΩ. The

allowable pullup resistor is in the range of 1.83 k

Ω and 3.59 kΩ.

The HPD circuits are powered by the 3.3-V VCC supply. This provides maximum VOH = VCC and maximum VOL=

0.4-V output signals to the SOURCE with a typical 1-k

Ω output resistance. An external 1-kΩ resistor is not

needed here. The HPD output of the selected source port follows the logic level of the HPD_SINK input.

Unselected HPD outputs are kept low. When the device is in standby mode, all HPD outputs follow HPD_SINK.

If VOH greater than VCC is desired, then an external circuit as shown in Figure 33 can be used. In this case, the

max VOH can be equal to the 5 V coming from the HDMI source.

Figure 33. External Circuit to Drive 5-V VOH on HPD[1:2]

The high-speed differential TMDS inputs are the most critical paths for the TMDS261. There are several

considerations to minimize discontinuities on these transmission lines between the connectors and the device:

• Maintain 100-Ω differential transmission line impedance into and out of the TMDS261.

• Keep an uninterrupted ground plane beneath the high-speed I/Os.

• Keep the ground-path vias to the device as close as possible to allow the shortest return current path.

• Keep the trace lengths of the TMDS signals between connector and device as short as possible.

The TMDS261 supports a DTV with up to two HDMI inputs when used in conjunction with a signal-port HDMI

receiver. Figure 34 and Figure 35 through Figure 37 show simplified application block diagrams for the TMDS261

Submit Documentation Feedback

Product Folder Link(s) :TMDS261

TMDS261 Datasheet(PDF) 27 Page - Texas Instruments

TMDS261 Datasheet(HTML) 27 Page - Texas Instruments

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

Datasheet Download

Link URL