THS7376_14 Datasheet, PDF (37/62 Pages) Texas Instruments – 4-Channel Video Amplifier with One SD and Three HD 8th-Order Filters with 6-dB Gain

THS7376
www.ti.com
SBOS692 – JUNE 2013
Sometimes the input must be ac-coupled to the THS7376 with current-sinking video DACs. The configuration
shown in Figure 125 allows for these DACs to interface properly with the device. The CVBS channel and the
component Y channel have bottom-level syncs that function perfectly with the device built-in sync-tip clamps. The
component P'_B and P'_R channel syncs are not the lowest voltage because the active video is allowed to be below
the sync voltage. Under some video frames and signals, this voltage can cause issues when trying to use the
sync-tip clamp function. The bias coupling mode shown in Figure 125 is preferable for these signals. Note that
the RGB signals can be coupled using the sync-tip clamp function without issue, even if sync is not present.
+1.8 V to +3.3 V
CVBS
Y’
P’_B
P’_R
0.1 mF
R
0.1 mF
+3.3 V
R
3.3 MW
0.1 mF
+3.3 V
R
3.3 MW
0.1 mF
R
1 CVBS IN
CVBS OUT 14
2 HD CH1 IN ^{HD CH1 OUT} 13
3 HD CH2 IN HD CH2 OUT 12
4 ^{HD CH3 IN HD CH3 OUT} 11
5 ^GND
VS+ ₁₀
6 ^DISABLE HD BYPASS 9
7 ^NC
NC ₈
75 W
75 W
75 W
75 W
CVBS
Out
Y’, G’
Out
P’_B, B’
Out
P’_R, R’
Out
To GPIO
+3 V to 5 V
Controller Or GND
Figure 125. Typical CVBS, Y, P'_B, P'_R AC Input Coupled System Configuration for a DAC Input
Figure 126 shows a similar configuration to Figure 125, except that the inputs come from an external source. The
same information for Figure 125 applies to Figure 126 as well.
CVBS
Input
Y’, G’
Input
P’_B, B’
Input
P’_R, R’
Input
0.1 mF
75 W
0.1 mF
75 W
+3.3 V
3.3 MW
0.1 mF
75 W
+3.3 V
3.3 MW
0.1 mF
75 W
1 CVBS IN
CVBS OUT 14
2 HD CH1 IN ^{HD CH1 OUT} 13
3 HD CH2 IN HD CH2 OUT 12
4 ^{HD CH3 IN HD CH3 OUT} 11
5 ^GND
VS+ ₁₀
6 ^DISABLE HD BYPASS 9
7 ^NC
NC ₈
75 W
75 W
75 W
75 W
CVBS
Out
Y’, G’
Out
P’_B, B’
Out
P’_R, R’
Out
To GPIO
+3 V to 5 V
Controller Or GND
Figure 126. Typical CVBS, Y, P_B, P_R AC Input Coupled System Configuration for External Source Inputs
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