THS7347 Datasheet, PDF (13/28 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
The THS7347 is targeted for RGB+HV video buffer applications. Although it can be used for numerous other
applications, the needs and requirements of the video signal were the most important design parameters of the
THS7347. Built on the revolutionary complementary silicon-germanium (SiGe) BiCom3 process, the THS7347
incorporates many features not typically found in integrated video parts while consuming very low power. Each
channel configuration is completely independent of the other channels. This architecture allows for any
configuration for each channel to be dictated by the end user, rather than the part dictating what the
configuration must be—resulting in a highly flexible system.
The THS7347 has the following features:
• I²C interface for easy interfacing to the system.
• Single-supply 2.7-V to 5-V operation with low quiescent current of 80 mA at 3.3 V.
• 2:1 input mux.
• Input configuration accepts dc, dc + shift, ac bias, or ac sync-tip clamp selection.
• 500-MHz unity-gain buffer amplifier to drive ADC/Scalar/Decoder.
• Monitor Pass-Through path has an internal fixed gain of 2 V/V (+6 dB) amplifier that can drive two video lines
per channel with dc coupling, traditional ac coupling, or SAG-corrected ac coupling.
• While disabled, the Monitor Pass-Through path has a very high output impedance (> 500 kΩ || 8 pF)
• Power-Up Control (PUC) allows the THS7347 to be fully disabled or have the Monitor Pass-Through function
(with ac-bias mode on all channels) enabled upon initial device power-up.
• Mux is controlled by either I²C or a general-purpose input/output (GPIO) pin, based on the MUX Mode pin
logic.
• H-Sync and V-Sync paths have an externally-adjustable Schmitt trigger threshold
• Disable mode reduces quiescent current to as low as 0.1-µA.
OPERATING VOLTAGE
The THS7347 is designed to operate from 2.7 V to 5 V over a -40°C to +85°C temperature range. The impact on
performance over the entire temperature range is negligible because of the implementation of thin film resistors
and high-quality, low temperature coefficient capacitors.
A 0.1-µF to 0.01-µF capacitor should be placed as close as possible to the power-supply pins. Failure to do so
may result in the THS7347 outputs ringing or oscillating. Additionally, a large capacitor, such as 100 µF, should
be placed on the power-supply line to minimize issues with 50-Hz/60-Hz line frequencies.
INPUT VOLTAGE
The THS7347 input range allows for an input signal range from ground to approximately (V_S+ – 1.6 V). However,
because of the internal fixed gain of 2 V/V (+6 dB), the output is generally the limiting factor for the allowable
linear input range. For example, with a 5-V supply, the linear input range is from GND to 3.4 V. As a result of the
gain, the linear output range limits the allowable linear input range from GND to 2.5 V at most.
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