THS7376_14 Datasheet, PDF (40/62 Pages) Texas Instruments – 4-Channel Video Amplifier with One SD and Three HD 8th-Order Filters with 6-dB Gain

THS7376
SBOS692 – JUNE 2013
www.ti.com
TYPICAL CONFIGURATION AND VIDEO TERMINOLOGY
A typical application circuit using the THS7376 as a video buffer is shown in Figure 130. Figure 130 shows a
DAC or encoder driving the device input channels. The SD channel (CVBS IN pin) can be used for NTSC, PAL,
or SECAM signals. The other three channels are the component video Y’, P’_B, P’_R (sometimes labeled Y’U’V’ or
incorrectly labeled Y’, C’_B, C’_R) signals. These signals are typically 480i, 576i, 480p, 576p, 720p, 1080i, 1080p24,
1080p30, or up to 1080p60 signals.
Note that the Y’ term is used for the luma channels throughout this document rather than the more common
luminance (Y) term. This usage accounts for the definition of luminance as stipulated by the International
Commission on Illumination (CIE). Video departs from true luminance because a nonlinear term, gamma, is
added to the true RGB signals to form R’G’B’ signals. These R’G’B’ signals are then used to mathematically
create luma (Y’). Thus, luminance (Y) is not maintained, providing a difference in terminology.
CVBS
Y’, G’
P’_B, B’
P’_R, R’
R
37.4 W
R
37.4 W
R
37.4 W
R
37.4 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
To GPIO
+3 V to 5 V
Controller Or GND
75 W
75 W
75 W
75 W
CVBS
Out
Y’, G’
Out
P’_B, B’
Out
P’_R, R’
Out
Figure 130. Typical Four-Channel System Inputs from a DC-Coupled Encoder and DAC with
DC-Coupled Line Driving
75 W
75 W
75 W
75 W
R’G’B’ (commonly mislabeled RGB) is also called G’B’R’ (again commonly mislabeled as GBR) in professional
video systems. The Society of Motion Picture and Television Engineers (SMPTE) component standard stipulates
that the luma information is placed on the first channel, the blue color difference is placed on the second
channel, and the red color difference signal is placed on the third channel. This practice is consistent with the Y',
P'_B, P'_R nomenclature. Placing the green channel (G') first in the system makes logical sense because the luma
channel (Y') carries the sync information and the green channel (G') also carries sync information. Likewise,
because the blue color difference channel (P'_B) is next and the red color difference channel (P'_R) is last, placing
the B' signal on the second channel and the R' signal on the third channel (respectfully) also makes logical
sense. Thus, hardware compatibility is better achieved when using G'B'R' rather than R'G'B'. Note that for many
G'B'R' systems, sync is embedded on all three channels, but this configuration may not always be the case in all
systems.
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