THS7327 Datasheet, PDF (14/26 Pages) Texas Instruments – 3-Channel RGBHV Video Buffer with I2C Control, Selectable Filters, Monitor Pass-Thru,2:1 Input MUX, and Selectable Input Bias Modes

THS7327
SLOS502 – SEPTEMBER 2006
APPLICATION INFORMATION
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The THS7327 is targeted for RGB + HV sync video buffer applications. Although it can be used for numerous
other applications, the needs and requirements of the video signal is the most important design parameter of the
THS7327. Built on the complimentary Silicon Germanium (SiGe) BiCom-3 process, the THS7327 incorporates
many features not typically found in integrated video parts while consuming low power. Each channel
configuration is completely independent of the other channels. This allows for ANY configuration for each
channel to be dictated by the end user rather than the device — resulting in a highly flexible system. The
THS7327 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 100-mA at 3.3-V
• 2:1 input MUX
• Input configuration accepting dc, dc + shift, ac bias, or ac sync-tip clamp selection.
• Unity Gain Buffer path to drive ADC/Scalar/Decoder.
• Selectable 5^th-order low-pass filter on buffer path for DAC reconstruction or ADC image rejection:
– 9-MHz for SDTV NTSC and 480i, PAL/SECAM and 576i, and S-Video signals.
– 16-MHz for EDTV 480p and 576p Y'P'_BP'_R signals and R'G'B' (G'B'R') VGA signals.
– 35-MHz for HDTV 720p and 1080i Y’P’_BP’_R signals and R'G'B' SVGA and XGA signals.
– 75-MHz for HDTV 1080p and R’G’B’ SXGA signals.
– Bypass mode for passing R'G'B' UXGA, QXGA or higher signals.
• Monitor Pass-thru path has an internal fixed gain of 2V/V (6 dB) amplifier that can drive 2 video lines with dc
coupling, traditional ac coupling, or SAG corrected ac coupling.
• While disabled, the Monitor Pass-Thru path has a high output impedance (>500 kΩ || 8 pF)
• Power Up Control (PUC) allows the THS7327 to be fully disabled or have the Monitor Pass-Thru function
(with AC-Bias mode on all channels) enabled upon initial power-up.
• MUX is controlled by either I²C or GPIO pin based on the MUX Mode pin logic.
• H and V Sync paths have an externally adjustable Schmitt Trigger threshold
• Disable mode which reduces quiescent current to as low as 0.1-µA.
OPERATING VOLTAGE
The THS7327 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 due to the implementation of thin film resistors and
low-temperature coefficient capacitors.
The power supply pins should have a 0.1-µF to 0.01-µF capacitor placed as close as possible to these pins.
Failure to do so may result in the THS7327 outputs ringing or oscillating. Additionally, a large capacitor, such as
22 µF to 100 µF, should be placed on the power supply line to minimize issues with 50-Hz/60-Hz line
frequencies.
INPUT VOLTAGE
The THS7327 input range allows for an input signal range from ground to about (V_S+ - 1.6 V). But, due to the
internal fixed gain of 2V/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. But due to the gain, the linear
output range limits the allowable linear input range to be from GND to at most 2.5 V.
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