THS7368 Datasheet, PDF (21/39 Pages) Texas Instruments – 6-Channel Video Amplifier with 3-SD and 3-SD/ED/HD/Full-HD Filters and 6-dB Gain

THS7368
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TYPICAL CONFIGURATION AND VIDEO
TERMINOLOGY
A typical application circuit using the THS7368 as a
video buffer is shown in Figure 37. It shows a DAC or
encoder driving the input channels of the THS7368.
One channel is a CVBS connection while two other
channels are for the S-Video Y’/C’ signals of an SD
video system. These signals can be 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, or up to 1080p60 signals. Because the filters
can be bypassed, other formats such as R'G'B' video
up to QXGA or UWXGA can also be supported with
the THS7368.
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
SBOS497 – DECEMBER 2009
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.
This rationale is also used for the chroma (C’) term.
Chroma is derived from the nonlinear R’G’B’ terms
and, thus, it is nonlinear. Chominance (C) is derived
from linear RGB, giving the difference between
chroma (C’) and chrominance (C). The color
difference signals (P’_B/P’_R/U’/V’) are also referenced
in this manner to denote the nonlinear (gamma
corrected) signals.
CVBS
S-Video Y’
S-Video C’
Y'/G'
P'_B/B'
P'_R/R'
THS7368
1 SD1 IN
SD1 OUT 20
R
2 SD2 IN
SD2 OUT 19
3 SD3 IN
SD3 OUT 18
4 NC
R
+2.7 V to
+5 V
5 V_S+
6 NC
Disable SD 17
GND 16
Disable SF 15
Disable SD
Disable SF
7 SF1 IN
SF1 OUT 14
R
8 SF2 IN
SF2 OUT 13
9 SF3 IN
SF3 OUT 12
10 Bypass SD Bypass SF 11
R
Bypass
SD LPF
R
Bypass
SF LPF
R
CVBS
75 W
S-Video Y' Out
75 W
S-Video C' Out
75 W
Y'/G' Out
75 W
P'_B/B' Out
75 W
P'_R/R' Out
75 W
75 W
75 W
75 W
75 W
75 W
75 W
(1) SF indicates selectable filter.
Figure 37. Typical Six-Channel System Inputs from DC-Coupled Encoder/DAC with DC-Coupled Line
Driving
Copyright © 2009, Texas Instruments Incorporated
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