Datasheet

TMDS141
V
CC
GND
TMDS
Driver
AV
CC
Z
O
= R
T
Z
O
= R
T
R
T
R
T
TMDS
Receiver
TMDS141
www.ti.com SLLS737D –JUNE 2006– REVISED SEPTEMBER 2011
APPLICATION INFORMATION
Supply Voltage
All V
CC
pins can be tied to a single 3.3-V power source. A 0.01-μF capacitor is connected from each V
CC
pin
directly to ground to filter supply noise.
TMDS Inputs
Standard TMDS terminations are integrated on all TMDS inputs. External terminations are not required. Each
input channel contains an 8-dB equalization circuit to compensate for cable losses. The voltage at the TMDS
input pins must be limited per the absolute maximum ratings. An unused input should not be connected to
ground as this would result in excessive current flow damaging the device. TMDS input pins do not incorporate
failsafe circuits. An unused input channel can be externally biased to prevent output oscillation. The
complementary input pin is recommended to be grounded through a 1-kΩ resistor and the other pin left open.
TMDS Outputs
A 1% precision resistor, 4.64-kΩ, connected from VSADJ to ground is recommended to allow the differential
output swing to comply with TMDS signal levels. The differential output driver provides a typical 10-mA current
sink capability, which provides a typical 500-mV voltage drop across a 50-Ω termination resistor.
Figure 18. TMDS Driver and Termination Circuit
Referring to Figure 18, if both V
CC
(TMDS141 supply) and AV
CC
(sink termination supply) are both powered, the
TMDS output signals is high impedance when OEB = high. Both supplies being active is the normal operating
condition.
Again refer to Figure 18, if V
CC
is on and AV
CC
is off, the TMDS outputs source a typical 5-mA current through
each termination resistor to ground. A total of 10-mW of power is consumed by the terminations independent of
the OEB logical selection. When AV
CC
is powered on, normal operation (OEB controls output impedance) is
resumed.
When the power source of the device is off and the power source to termination is on, the I
O(off)
, output leakage
current, specification ensures the leakage current is limited 10-μA or less.
The PRE pin provides 3dB de-emphasis, allowing output signal pre-conditioning to offset interconnect losses
from the TMDS141 outputs to a TMDS receiver. PRE is recommended to be set low while connecting to a
receiver throw short PCB route.
I
2
C Function Description
The RSCL/RSDA and TSCL/TSDA pins are 5-V tolerant when the device is powered off and high impedance
under low supply voltage, 1.5 V or below. If the device is powered up and the I
2
C circuits are enabled, and
I2CEN = high, the driver T (see Figure 19) is turned on or off depending up on the corresponding R side voltage
level.
When the R side is pulled low below 1.5 V, the corresponding T side driver turns on and pulls the T side down to
a low level output voltage, V
OL
. The value of V
OL
depends on the input to the OVS pin. When OVS is left floating
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