THS7320 Datasheet, PDF (20/35 Pages) Texas Instruments – 3-Channel ED Filter Video Amplifier with 4-V/V Gain

THS7320
SBOS565B – JULY 2011 – REVISED SEPTEMBER 2012
APPLICATION INFORMATION
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The THS7320 includes a triple-channel video output amplifier and filter that supports three enhanced-definition
(ED) video and/or RGB video output buffers. The THS7320 also supports standard definition (SD) video for
oversampled systems with a DAC sampling frequency of 54 MHz or greater. Although the THS7320 can be used
for numerous other applications, the needs and requirements of the video signal are the most important design
parameters. Built on the revolutionary, complementary silicon germanium (SiGe) BiCom3X process, the
THS7320 incorporates many attributes not typically found in integrated video parts while consuming very low
power. The THS7320 video portion includes these features:
• Single-supply 2.6-V to 5-V operation with low total quiescent current of 3.4 mA at 3.3 V
• Enable mode for shutting down the THS7320 video amplifiers to save system power in power-sensitive
applications
• DC input configuration with internal 150-mV dc level shifting to prevent sync crushing and saturation effects
• Third-order, 20-MHz (–3-dB) low-pass filter for DAC reconstruction or ADC image rejection; ideal for:
– NTSC/PAL 480p/576p Y’P’_BP’_R or G’B’R’ (R’G’B’) signals
– NTSC/PAL/SECAM composite video (CVBS), S-Video Y’/C’, 480i/576i Y’P’_BP’_R, and G’B’R’ (R’G’B’)
signals for oversampled systems
• Internally-fixed gain of 4-V/V (+12-dB) amplifiers that allow for dc-coupling or traditional ac-coupling
OPERATING VOLTAGE
The THS7320 is designed to operate from 2.6 V to 5 V over the –40°C to +85°C temperature range. The impact
on performance over the entire temperature range is negligible as a result of the implementation of thin film
resistors and high-quality, low-temperature coefficient capacitors. The design of the THS7320 allows operation
down to 2.5 V, but it is recommended to use at least a 2.7-V supply to ensure that no issues arise with headroom
or clipping with 100% color-saturated CVBS signals. If only 75% color saturated CVBS is supported, then the
output voltage requirements are reduced to 2 V_PP on the output, allowing a 2.6-V supply to be used without
issues.
A 0.1-μF capacitor should be placed as close as possible to each power-supply pin to avoid potential ringing or
oscillation. Additionally, a large capacitor (such as 4.7 μF to 100 μF) should be placed on the power-supply line
to minimize interference with 50-Hz/60-Hz line frequencies.
VIDEO INPUT VOLTAGE
The THS7320 input range allows for an input signal range from –0.06 V to approximately (V_S+ – 1.5 V). However,
because of the internal fixed gain of 4 V/V (+12 dB) and the internal output level shift of 150 mV (typical), the
output is generally the limiting factor for the allowable linear input range. For example, with a 3-V supply, the
linear input range is from 0.15 V to 0.75 V. However, because of the gain and level shift, the linear output range
limits the allowable linear input range from approximately –0.03 V to 0.65 V.
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