75 W
S-VideoY'Out
CVBS
R
SOC/DAC/Encoder
S-Video Y’
R
S-Video C’
R
Y'/G'
R
1
2
3
4
5
6
7
8
9
10
20
19
18
17
16
15
14
13
12
11
SD1OUT
SD2OUT
SD3OUT
DisableSD
GND
DisableSF
SF1OUT
SF2OUT
SF3OUT
BypassSF
SD1IN
SD2IN
SD3IN
NC
V
S+
NC
SF1IN
SF2IN
SF3IN
BypassSD
THS7368
Bypass
SDLPF
Bypass
SFLPF
P' /B'
B
R
CVBS
P' /R'
R
75 W
S-VideoC'Out
75 W
Y'/G'Out
75 W
P' /B'Out
B
75 W
P' /R'Out
R
75 W
+2.7Vto
+5V
DisableSF
DisableSD
www.ti.com
SBOS497 – DECEMBER 2009
TYPICAL CONFIGURATION AND VIDEO
departs from true luminance because a nonlinear
TERMINOLOGY
term, gamma, is added to the true RGB signals to
form R’G’B’ signals. These R’G’B’ signals are then
A typical application circuit using the THS7368 as a
used to mathematically create luma (Y’). Thus,
video buffer is shown in
Figure 37. It shows a DAC or
luminance
(Y)
is
not
maintained,
providing
a
encoder driving the input channels of the THS7368.
difference in terminology.
One channel is a CVBS connection while two other
channels are for the S-Video Y’/C’ signals of an SD
This rationale is also used for the chroma (C’) term.
video system. These signals can be NTSC, PAL, or
Chroma is derived from the nonlinear R’G’B’ terms
SECAM signals. The other three channels are the
and, thus, it is nonlinear. Chominance (C) is derived
component
video
Y’/P’B/P’R (sometimes labeled
from linear RGB, giving the difference between
Y’U’V’ or incorrectly labeled Y’/C’B/C’R) signals. These
chroma
(C’)
and
chrominance
(C).
The
color
signals are typically 480i, 576i, 480p, 576p, 720p,
difference signals (P’B/P’R/U’/V’) are also referenced
1080i, or up to 1080p60 signals. Because the filters
in this manner to denote the nonlinear (gamma
can be bypassed, other formats such as R'G'B' video
corrected) signals.
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
(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
21