MAX7438 Datasheet, PDF (1/10 Pages) Maxim Integrated Products – Triple-Channel Video Reconstruction Filters with Back-Porch Clamp to GND

19-2857; Rev 0; 4/03
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Triple-Channel Video Reconstruction Filters with
Back-Porch Clamp to GND
General Description
The MAX7438/MAX7439 three-channel standard defini-
tion 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 capa-
ble of driving two standard 150Ω video loads. The
blanking level of the output video signal on each chan-
nel 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 oper-
ate from ±5V dual supplies.
The three-channel MAX7438/MAX7439 are ideal for Y,
P_b, P_r, and RGB component video signals, three com-
posite video signals, and also Y/C plus CVBS video sig-
nals. Each filter channel achieves 60dB of attenuation at
27MHz and a maximally flat passband from DC to 5MHz.
The MAX7438 offers an internal gain of +2V/V, while the
MAX7439 offers a gain of +3V/V.
Set-Top Boxes/HDR/DVD
Game Consoles
Camcorders
Applications
Composite, Component,
S-Video Output for
NTSC, PAL, SDTV
Features
o Back-Porch of Video Output Signal Clamped to
Ground
o Eliminates Input/Output AC-Coupling Capacitors
o 0.1% Line-Time Distortion
o Stopband: 55dB at 27MHz
o Passband: ±0.8dB out to 5MHz
o Diff Gain = 0.05%, Diff Phase = 0.05 Degrees
o Output Clamped to Ground with Loss of Input
o Each Output Drives Two 150Ω Video Loads
o Up to 2dB of High-Frequency Boost Control
o Ideal for CVBS, Y/C (S-Video), and RGB (Y, P_b, P_r)
Outputs for NTSC, PAL, and SDTV
o Filter Bypass Mode
o Small 20-Pin 5mm ✕ 5mm Thin QFN Package
Ordering Information
PART
TEMP RANGE
MAX7438ETP
-40°C to +85°C
MAX7439ETP
-40°C to +85°C
*EP = Exposed paddle
PIN-PACKAGE
20 Thin QFN-EP*
20 Thin QFN-EP*
Pin Configuration appears at end of data sheet.
Functional Diagram
ENCODER
IN1
DAC1
IN2
DAC2
IN3
DAC3
HFB1
HFB2
HFB3
LOWPASS
FILTER
BACK-PORCH
DETECTOR
LOWPASS
FILTER
MAX7438
MAX7439
LOWPASS
FILTER
HIGH-FREQUENCY
BOOST CONTROL/
BYPASS
VCC = +5V VSS = -5V
GAIN/LEVEL
SHIFT
GAIN/LEVEL
SHIFT
GAIN/LEVEL
SHIFT
BIAS
GENERATOR
GND EXT
10kΩ
OUT1 ^75Ω
Z0 = 75Ω
Z0 = 75Ω
75Ω
75Ω
75Ω
OUT2 ^75Ω
Z0 = 75Ω
Z0 = 75Ω
75Ω
75Ω
75Ω
OUT3 ^75Ω
Z0 = 75Ω
Z0 = 75Ω
75Ω
75Ω
75Ω
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