THS7376 Datasheet, PDF (50/61 Pages) Texas Instruments – 4-Channel Video Amplifier with One SD and Three HD 8th-Order Filters with 6-dB Gain

THS7376
SBOS692 – JUNE 2013
EVALUATION MODULE
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To evaluate the THS7376, an evaluation module (EVM) is available. The THS7376EVM allows for testing the
device in many different configurations. Inputs and outputs include BNC 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 2.85 V up to 5.5 V maximum.
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 clips the output signal. If
the input range is beyond this range, or 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, s-video Y', component
Y' signals, and R'G'B' signals, no other changes are needed. However, if a bias voltage is desired after the input
capacitor which is commonly needed for s-video C', component P'_B and P'_R signals, 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: RX1, RX3, RX5, or RX7. A common value to use is 3 MΩ. Note that even signals with an
embedded sync can also use bias mode if desired.
The THS7376EVM default output configuration sets all channels for dc-output coupling. This configuration is
commonly used for most modern systems today. However, if ac-coupling is desired, then replacing the 0-Ω
resistors at C12, C14, C16, and C17 with 0.1-µF capacitors works well along with the existing 470-µF capacitors
already populated. Removing the 470-µF capacitors is optional when dc-coupling is used. Removing these
capacitors eliminates a few picofarads of stray capacitance on each signal path, which may be desirable for
improved high-frequency response.
The THS7376 incorporates an easy method to configure the bypass and disable mode. The use of JP1 controls
the disable feature and JP4 controls the HD channels filter and bypass mode. While there is a space on the EVM
for JP2 and JP3, these components are not used for the THS7376.
Connecting JP1 to GND applies 0 V to the disable pin and the THS7376 operates normally. Moving JP1 to +V_S
causes all channels of the THS7376 to be in disable mode. If left open, the THS7376 defaults to 0 V and is fully
functional.
Connecting JP4 to GND places the THS7376 HD channels in filter mode; moving JP4 to +V_S places the
THS7376 HD channels in bypass mode. If left open, the THS7376 defaults to 0 V and is in filter mode operation.
The THS7376 has improved ESD performance on all video input and output pins. Refer to the Absolute
Maximum Ratings table for specific tested values of the device. When tested with the THS7376EVM, the
THS7376 has passed the IEC ±8-kV contact surge testing through the RCA connections. Note that every
complete system may not pass IEC testing because IEC is a system-level test and not a device-level test.
However, when a very small EVM with minimal parasitics is used, the THS7376 has been shown to pass IEC
surge testing. If further protection is desired, the EVM incorporates pads that can be populated with standard
dual-diode packaged parts (such as the BAV99 or BAT54S).
Figure 136 shows the THS7376EVM schematic. Figure 137 and Figure 138 illustrate the two layers of the EVM
PCB, incorporating standard high-speed layout practices. Table 2 lists the bill of materials as the board comes
supplied from Texas Instruments.
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