THS7347 Datasheet, PDF (15/28 Pages) Texas Instruments – 3-Channel RGBHV Video Buffer with I2C™ Control, 2:1 Input Mux, Monitor Pass-Through, and Selectable Input Bias Modes

THS7347
www.ti.com
SLOS531 – MAY 2007
APPLICATIONS INFORMATION (continued)
R'G'B' (commonly labeled RGB) is also called G'B'R' (again commonly labeled as GBR) in professional video
systems. The 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 approach is consistent with the Y'P'_BP'_R nomenclature. Because the luma channel (Y') carries the
sync information and the green channel (G') also carries the sync information, it makes logical sense that G' be
placed first in the system. Since the blue color difference channel (P'_B) is next and the red color difference
channel (P'_R) is last, then it also makes logical sense to place the B' signal on the second channel and the R'
signal on the third channel, respectively. 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; this
configuration may not always be the case for all systems.
Monitor Output
Red
75 W
Green
2.2 mF
2.2 mF
75 W
Y’
75 W
Blue
2.2 mF
75 W
P’_B
75 W
H-Sync 806 W
V_A
75 W
P’_R
V_A
Component
480i
576i
480p
576p
720p
1080i
1080p
G’B’R’
1.4 kW
V-Sync 806 W
1.4 kW
0.1 mF
Y’
75 W
2.2 mF
P’_B
75 W
48 47 46 45 44 43 42 41 40 39 38 37
1
36
2
35
3
34
4
33
5
32
6
31
7
THS7347
30
8
29
9
28
10
27
11
26
12
25
13 14 15 16 17 18 19 20 21 22 23 24
P’_R
2.2 mF
75 W
H-Sync and
V-Sync 0.1 mF
Not Used
3.3 V
22 pF
3.3 V
22 pF
0.1 mF
V_A
0.1 mF
V_A
0.1 mF
+3.3 V +1.8 V
ADC
Scalar/
Decoder
100
100
V_A = 3.3 V to 5 V
2
IC
(1) Inputs and/or outputs can be ac- or dc-coupled if desired.
(2) H-Sync and V-Sync input resistance as shown above = 2.2kΩ, but may be changed to any desired resistance.
(3) If the Monitor or Buffer PCB trace is >25 mm, it is recommended to place at least a 10-Ω resistor in series with each
signal to reduce PCB parasitic issues
Figure 4. Typical R'G'B'HV and Y'P'_BP'_R AC-Coupled Inputs and DC-Coupled Output Configuration
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