THS7372 Datasheet, PDF (39/49 Pages) Texas Instruments – 4-Channel Video Amplifier with One CVBS and Three Full-HD Filters with 6-dB Gain

THS7372
www.ti.com
EVALUATION MODULE
SBOS578 – AUGUST 2011
To evaluate the THS7372, an evaluation module (EVM) is available. The THS7372EVM allows for testing the
THS7372 in many different configurations. Inputs and outputs include BNC connectors and RCA connectors
commonly found in video systems, along with 75-Ω input termination resistors, 75-Ω series source termination
resistors, and 75-Ω characteristic impedance traces. Several unpopulated component pads are found on the
EVM to allow for different input and output configurations as dictated by the user. This EVM is designed to be
used with a single supply from 2.6 V up to 5 V.
The EVM default input configuration sets all channels for dc input coupling. The input signal must be within 0 V
to approximately 1.4 V for proper operation. Failure to be within this range saturates and/or clips the output
signal. If the input range is beyond this, if the signal voltage is unknown, or if coming from a current sink DAC,
then ac input configuration is desired. This option is easily accomplished with the EVM by simply replacing the Z₁
through Z₄ 0-Ω resistors with 0.1-μF capacitors.
For an ac-coupled input and sync-tip clamp (STC) functionality commonly used for CVBS, component Y' signals,
and R'G'B' signals, no other changes are needed. However, if a bias voltage is needed after the input capacitor
which is commonly needed for component P'_B, and P'_R, then a pull-up resistor should be added to the signal on
the EVM. This configuration is easily achieved by simply adding a resistor to any of the following resistor pads;
RX4 to RX6 for the FHD channels and RX8 for the CVBS channel. A common value to use is 3.3 MΩ. Note that
even signals with embedded sync can also use bias mode if desired.
The EVM default output configuration sets all channels for ac output coupling. The 470-μF and 0.1-μF capacitors
work well for most ac-coupled systems. However, if dc-coupled output is desired, then replacing the 0.1-μF
capacitors (C24, C26, C28, and/or C30) with 0-Ω resistors works well. Removing the 470-μF capacitors is
optional, but removing them from the EVM eliminates a few picofarads of stray capacitance on each signal path
which may be desirable.
The THS7372 incorporates an easy method to configure the disable modes. The use of JP1 controls the SD
channel disable feature; JP3 controls the FHD channels disable feature.
Connection of JP1 and JP3 to GND applies 0 V to the disable pins and the THS7372 operates normally. Moving
JP1 to +V_S causes the THS7372 SD channel to be in disable mode, while moving JP3 to +V_S causes the
THS7372 FHD channels to be in disable mode.
Figure 90 shows the THS7372EVM schematic. Figure 92 and Figure 93 illustrate the two layers of the EVM PCB,
incorporating standard high-speed layout practices. Table 7 lists the bill of materials as the board comes supplied
from Texas Instruments.
Copyright © 2011, Texas Instruments Incorporated
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