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TMDS Input Fail-Safe

TMDS

Receiver

TMDS

Driver

Y

Z

A

B

TMDS351

SLLS840 – MAY 2007

APPLICATION INFORMATION (continued)

Figure 15. Frequency Response Compensation Curve at EQ = H

Internal termination circuitry which can be switched on or off, provides 50-

Ω resistance to each differential input

pin when a port is selected. External terminations are not required. When the termination is switched on, current

will flow to the TMDS driver. When a port is not selected, the termination is open. This stops supply current

flowing from the input pins of the un-selected ports. This switchable termination provides the connected HDMI

source another method of determining the sink port status, and whether it is selected or not selected, without

referring to the HPD pin status.

The TMDS input does not incorporate a fail-safe circuit. To implement fail-safe, the input can be externally

resistor as shown in Figure 16.

Figure 16. TMDS Input Fail-Safe Recommendation

16

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