Datasheet
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-18
-16
-14
-12
-10
-8
-6
-4
-2
0
0 250 500 750 1000 1250 1500 1750 2000
f-Frequency-MHz
Loss-dB
spec
10mcable
EQ=High
V
CC
R
INT
R
INT
TMDS
Receiver
TMDS
Driver
R
T
R
T
Y
Z
A
B
AV
CC
TMDS351
SLLS840B – MAY 2007– REVISED JULY 2011
www.ti.com
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.
TMDS Input Fail-Safe
The TMDS input does not incorporate a fail-safe circuit. To implement fail-safe, the input can be externally biased
to prevent output oscillation. One pin can be pulled high to V
CC
with the other grounded through a 1-kΩ resistor
as shown in Figure 16.
Figure 16. TMDS Input Fail-Safe Recommendation
TMDS Outputs
A 10% precision resistor, 4.02-kΩ, is recommended to control the output swing to the HDMI compliant 400 mV to
600 mV range (500 mV typical). The TMDS outputs are high impedance under standby mode operation, S1 = H
and S2 = L.
16 Copyright © 2007–2011, Texas Instruments Incorporated