MAX7438

Triple-Channel Video Reconstruction Filters with Back-Porch Clamp to GND

3-Channel Video Reconstruction Filters Eliminate the Need for Large-Output AC-Coupling Capacitors

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Overview

Back-Porch of Video Output Signal Clamped to Ground
Eliminates Input/Output AC-Coupling Capacitors
0.1% Line-Time Distortion
Stopband: 55dB at 27MHz
Passband: ±0.8dB out to 5MHz
Diff Gain = 0.05%, Diff Phase = 0.05 Degrees
Output Clamped to Ground with Loss of Input
Each Output Drives Two 150Ω Video Loads
Up to 2dB of High-Frequency Boost Control
Ideal for CVBS, Y/C (S-Video), and RGB (Y, P_b, P_r) Outputs for NTSC, PAL, and SDTV
Filter Bypass Mode
Small 20-Pin 5mm x 5mm Thin QFN Package

The MAX7438/MAX7439 three-channel, standard-definition video reconstruction filters include a back-porch clamp that sets the output blanking level of the video signal to ground. Each channel of the MAX7438/MAX7439 combines a lowpass filter with adjustable high-frequency boost levels and an output buffer capable of driving two standard 150Ω video loads. The blanking level of the output video signal on each channel is clamped to ground, eliminating the need for large AC-coupling output capacitors. Direct input-coupling circuitry eliminates the need for AC-coupling input capacitors. This DC-in/DC-out architecture results in extremely low line-time distortion. The MAX7438/MAX7439 are ideal for antialiasing and DAC smoothing in digital video devices such as STBs, DVDs, PVRs, and hard disk recorders. The MAX7438/MAX7439 operate from ±5V dual supplies.

The three-channel MAX7438/MAX7439 are ideal for Y, P_b, P_r, and RGB component video signals, three composite video signals, and also Y/C plus CVBS video signals. Each filter channel achieves 60dB of attenuation at 27MHz and a maximally flat passband from DC to 5MHz.

The MAX7438 offers an internal +2V/V gain, while the MAX7439 offers a +3V/V gain.

Applications