THS7303 Datasheet, PDF (32/43 Pages) Texas Instruments – 3-Channel Low Power Video Amplifier with I2C Control, Selectable Filters, 6-dB Gain, SAG Correction, 2:1 Input MUX, and Selectable Input Bias Modes

THS7303
SLOS479 – OCTOBER 2005
www.ti.com
APPLICATION INFORMATION (continued)
The THS7303 bypass mode has a 190-MHz bandwidth (-3 dB) and a 300 V/µs slewrate to pass G’B’R’ (R’G’B’)
SXGA and UXGA signals with little degradation. This bypass mode is also useful for HDTV 1080p signals that
require a 60-MHz video signal bandwidth.
The I²C interface of the THS7303 allows each channel to be configured totally independent of the other
channels. One of the benefits is that a multiple output encoder (or DAC) can be routed through one THS7303
with the proper input configuration and low-pass filter required regardless of the signal. This is useful for a
portable system or in a low cost system where only one set (or 2 sets in parallel) is desired on the output of the
system. An update of the I²C commands changes the THS7303 channels. An example is shown in Figure 68
where the input MUX allows for one set of HDTV signals to be put into the THS7303, and then through an I²C
update, a SDTV set of signals is sent through the THS7303 with the proper input mode and low-pass filters.
3.3 V
Y’
R
P’_B
R
P’_R
DAC /
Encoder
R
S-Video
Y’
R
S-Video
C’
R
CVBS
R
DC + 135 mV
1 NC
NC 20
2
DC + 135 mV
3
DC + 135 mV
4
CH.1 IN A
CH.2 IN A
CH.3 IN A
DC + 135 mV
5 CH.1 IN B
DC + 135 mV
6 _{CH.2 IN B}
DC + 135 mV
7 _{CH.3 IN B}
CH.1 OUT 19
CH.1 SAG ¹⁸
CH.2 OUT ¹⁷
CH.2 SAG 16
CH.3 OUT 15
CH.3 SAG 14
8 I2C-A1
SCL 13
9 I2C-A0
10 GND
SDA 12
VS+ ¹¹
0.01 mF
330 mF
(See Note A)
+
Video
Out 1
75 W
330 mF
(See Note A)
+
Video
Out 2
75 W
330 mF
(See Note A)
+
Video
Out 3
75 W
+Vs
+
100 mF
2
IC
Controller
75 W
75 W
75 W
A. Due to the high frequency content of the video signal, it is recommended, but not required, to add a 0.01-µF capacitor
in parallel with these large capacitors.
Figure 68. Typical SD/ED/ and HD Video and SDTB Encoder DAC Driving a Single THS7303
Although the circuit of Figure 68 conserves space and cost, the reuse of the output connections may not be the
best solution. For a complete 6-channel system, it is better to use the THS7303 and the THS7313 (see
SLOS483) together as shown in Figure 69. The THS7313 is targeted for SDTV signals and is limited to an
8-MHz filter. As the I²C section discusses, it is easy to have both parts in one system as the I²C address of each
part can be one of 4 discrete addresses by the logic appearing on the I²C-A1 and I²C-A0 lines.
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