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19-2948; Rev 0; 8/03
4-Channel Video Reconstruction Filter
General Description
The MAX7445 4-channel, buffered video reconstruction filter is ideal for anti-aliasing and DAC-smoothing video applications or wherever analog video is reconstructed from a digital data stream (such as cable/satellite/terrestrial set-top boxes, DVD players, hard-disk recorders (HDRs), and personal video recorders (PVRs)). This device operates from a single +5V supply and has a flat passband out to 5MHz with a stopband attenuation of 43dB at 27MHz. This makes it ideal for use with NTSC, PAL, and standard-definition digital TV (SDTV) video systems. Each output is capable of driving two standard 150 video loads. The MAX7445 has three modes of operation. Mode 1 processes CVBS and RGB video signals. Mode 2 processes CVBS, Y, and C signals, as well as a second asynchronous CVBS video signal. Mode 3 processes RGB and CVBS (asynchronous) video signals. An external pin adjusts the gain of the video buffer to either +6dB, +9.5dB, or +12dB to accommodate video-encoder DAC output signals of <1V. High-frequency boost circuitry provides picture sharpness with +1.2dB of gain boost without degradation in the stopband. The output video drivers can be disabled with an external pin. The MAX7445 is available in a 14-pin TSSOP package with an exposed pad, and is specified over the -40C to +85C extended temperature range.
Features
o 4-Channel Filter and Buffer for CVBS, RGB, or Y/C Video Signals o Filter Response Ideal for NTSC, PAL, and Interlaced SDTV Video Signals o 43dB (typ) Stopband Attenuation at 27MHz o 0.75dB (max) Passband Ripple Out to 5MHz o Blanking Level Voltage on Cable <1V o Each Channel Drives Two 150 Video Loads o +5V Single-Supply Voltage o Selectable Gain: +6dB, +9.5dB, and +12dB o Small 14-Pin TSSOP Package
MAX7445
Ordering Information
PART MAX7445EUD TEMP RANGE -40C to +85C PIN-PACKAGE 14 TSSOP-EP*
*EP = Exposed pad.
Applications
Set-Top Boxes/HDRs Game Consoles Desktop Video Editors
VCC ENCODER 0.1F D/A INA LOWPASS FILTER SYNC DETECTOR OUTA 75 * 75 75 0.1F D/A * INB LOWPASS FILTER OUTB 75 75 0.1F D/A INC LOWPASS FILTER OUTC 75 * * * 75 75 75 * 75 75 75
DVD Players Digital VCRs
Pin Configuration appears at end of data sheet.
Functional Diagram
SELECT
MAX7445
0.1F D/A IND LOWPASS FILTER SYNC DETECTOR OUTD
75 75
* *
75 75
*OPTIONAL CAPACITORS GND DISABLE GAIN
________________________________________________________________ Maxim Integrated Products
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4-Channel Video Reconstruction Filter MAX7445
ABSOLUTE MAXIMUM RATINGS
VCC to GND ...........................................................................+6V All Other Pins to GND.................................-0.3V to (VCC + 0.3V) Maximum Current into Any Pin Except VCC and GND .....50mA Continuous Power Dissipation (TA = +70C) TSSOP-EP (derate 20.8mW/C above +70C) ...........1667mW Operating Temperature Range ...........................-40C to +85C Storage Temperature Range .............................-65C to +150C Junction Temperature ......................................................+150C Lead Temperature (soldering, 10s) .................................+300C
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VCC = +5V 5%, CL = 0 to 20pF, RL = 75 to GND for DC-coupled load, RL = 75 to VCC / 2 for AC-coupled load, CIN_ = 0.1F, GAIN = GND (+6dB) or VCC (+9.5dB), TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25C.)
PARAMETER SYMBOL CONDITIONS f = 100kHz to 5MHz, relative to 100kHz ASB dG f 27MHz 5-step modulated staircase Gain = +6dB, +9.5dB Gain = +12dB Differential Phase d 5-step modulated staircase Peak signal (2VP-P) to RMS noise, f = 100Hz to 50MHz Gain = +6dB, +9.5dB Gain = +12dB Signal-to-Noise Ratio SNR Gain = +6dB, +9.5dB, +12dB Channel without boost (see Table 2) Channel with boost (see Table 2) 69 Channel without boost (see Table 2) Channel with boost (see Table 2) MIN -0.75 +0.9 39 TYP +0.15 +1.2 43 0.15 0.25 0.15 0.15 75 0.50 0.90 0.50 0.60 dB Degrees MAX +0.75 dB +1.5 dB % UNITS
Passband Response
Stopband Attenuation Differential Gain
11 17
20 ns 30 0.3 0.5 100 % % Lines
Group Delay Deviation
tg
Deviation from 100kHz to 4.1MHz 18s, 100 IRE bar
Line-Time Distortion Field-Time Distortion Clamp Settling Time
HDIST VDIST tCLAMP
130 lines, 18s, 100 IRE bar To 1% SELECT = GND Channel A Channels B, C, D Channels A, B, D Channel C Channels A, D Channels B, C 0.6 1.1 0.6 1.25 0.6 1.1 -3 0.9 1.5 0.9 1.6 0.9 1.5
1.1 1.8 1.1 1.95 1.1 1.8 +3 4 % % V
Output DC Clamp Level
SELECT = VCC SELECT = floating
Low-Frequency Gain Accuracy Low-Frequency Gain Matching
AV AV(MATCH)
f = 100kHz, relative to a gain of +6dB Low-frequency channel-to-channel matching, f = 100kHz
2
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4-Channel Video Reconstruction Filter
ELECTRICAL CHARACTERISTICS (continued)
(VCC = +5V 5%, CL = 0 to 20pF, RL = 75 to GND for DC-coupled load, RL = 75 to VCC / 2 for AC-coupled load, CIN_ = 0.1F, GAIN = GND (+6dB) or VCC (+9.5dB), TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25C.)
PARAMETER Group Delay Matching Channel-to-Channel Crosstalk Output Short-Circuit Current Input Leakage Current SYMBOL tg(MATCH) XTALK ISC IIN SELECT = GND Input Dynamic Swing for Gain of +6dB SELECT = VCC SELECT = floating SUPPLY Supply Voltage Range Supply Current Power-Supply Rejection Ratio DISABLE Output Impedance During Disable Disable Logic-Input High Voltage Disable Logic-Input Low Voltage Disable Logic Input Current ZDISABLE VIH VIL IDISABLE VIL = 0V (sink), VIH = VCC (source) At 5MHz 2.0 0.8 10 2 k V V A VCC ICC PSRR No load VIN = 100mVP-P, f = 0 to 3.5MHz 4.75 100 40 5.25 140 V mA dB Channel A Channels B, C, D Channels A, B, D Channel C Channels A, D Channels B, C CONDITIONS Low-frequency channel-to-channel matching, f = 100kHz f = 100kHz to 3.58MHz OUT_ shorted to GND or VCC MIN TYP 2 60 70 10 1.2 0.9 1.2 0.9 1.2 0.9 VP-P MAX UNITS ns dB mA A
MAX7445
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4-Channel Video Reconstruction Filter MAX7445
Typical Operating Characteristics
(VCC = +5V, VGAIN = 0V, TA = +25C, unless otherwise noted.)
AMPLITUDE vs. FREQUENCY
MAX7445 toc01
PASSBAND AMPLITUDE vs. FREQUENCY
MAX7445 toc02
PHASE RESPONSE vs. FREQUENCY
150 100 PHASE (DEGREES) 50 0 -50 -100 -150
MAX7445 toc03
2.0 1.5 1.0 HIGH-FREQUENCY BOOST
200
0
AMPLITUDE (dB)
AMPLITUDE (dB)
-20
0.5 0 -0.5 FLAT PASSBAND RESPONSE -1.0 -1.5
-40
-60 NORMALIZED TO 0dB -80 1 10 FREQUENCY (MHz) 100
NORMALIZED TO 0dB -2.0 0.1 1 FREQUENCY (MHz) 10 -200 0.1 1 FREQUENCY (MHz) 10
GROUP DELAY vs. FREQUENCY
MAX7445 toc04
2T RESPONSE (1 IRE = 7.14mV)
MAX7445 toc05
MODULATED 12.5T RESPONSE (1 IRE = 7.14mV)
MAX7445 toc06
100
90 GROUP DELAY (ns)
IN_ 250mV/ div
IN_ 250mV/ div
80
70 OUT_ 60 250mV/ div 0.1 1 FREQUENCY (MHz) 10 200ns/div OUT_ 250mV/ div 400ns/div
50
SUPPLY CURRENT vs. TEMPERATURE
INPUTS BIASED TO +2V NO LOAD SUPPLY CURRENT (mA) 110
MAX7445 toc07
DIFFERENTIAL GAIN
DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%) 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 1st 0.3 0.2 0.1 0 -0.1 -0.2 -0.3 1st 2nd 3rd 4th 5th 6th 2nd 3rd 4th 5th 6th
MAX7445 toc08
MULTIBURST RESPONSE
MAX7445 toc09
120
IN_ 250mV/ div
100
DIFFERENTIAL PHASE
OUT_ 250mV/ div 10s/div
90
80 -40 -15 10 35 60 85 TEMPERATURE (C)
4
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4-Channel Video Reconstruction Filter
Pin Description
PIN 1 2 3 4 5 6, 8 7 9 10 11 12 13 14 NAME INA INB INC IND FUNCTION Channel A Video Input. AC-couple INA with a series 0.1F capacitor. Channel B Video Input. AC-couple INB with a series 0.1F capacitor. Channel C Video Input. AC-couple INC with a series 0.1F capacitor. Channel D Video Input. AC-couple IND with a series 0.1F capacitor.
MAX7445
Disable Logic Input. A logic-low on DISABLE enables the output buffers. A logic-high on DISABLE disables DISABLE all output buffers and puts them in a high-impedance state. GND GAIN SELECT VCC OUTD OUTC OUTB OUTA Ground Gain-Control Input. Connect GAIN to GND for a gain of +6dB (+2V/V), to VCC for a gain of +9.5dB (+3V/V), or leave unconnected for a gain of +12dB (+4V/V). Mode Select Input. Connect to GND for CVBS/RGB processing, to VCC for CVBS/Y/C/CVBSASYNC processing, or leave floating for RGB/CVBSASYNC (G with sync) processing. +5V Supply Input Channel D Video Output. This output can be either AC- or DC-coupled. Channel C Video Output. This output can be either AC- or DC-coupled. Channel B Video Output. This output can be either AC- or DC-coupled. Channel A Video Output. This output can be either AC- or DC-coupled.
Detailed Description
The MAX7445 filters and buffers video-encoder DAC outputs in applications such as set-top boxes, harddisk recorders, DVD players, and digital VCRs. The MAX7445 reconstructs and cleans up analog video signals from the output of DAC video encoders. Each channel consists of a lowpass filter and an output video buffer that can drive two standard 150 video loads. This device operates from a single +5V supply and has a nominal cutoff frequency of 5MHz optimized for NTSC, PAL, and SDTV. The MAX7445 has three modes of operation allowing different video signals to be processed. The modes are shown in Table 1. Mode 1 requires that channel A is a video signal that includes a sync pulse. A sync separator uses this signal to extract the timing required to clamp all four channels. Modes 2 and 3 require that channel A and channel D have a sync pulse to provide the required timing information. Channel A provides the required timing for channels A, B, and C while channel D provides its own sync separator to extract the sync signal from an asynchronous video signal.
Table 1. Operating Modes
MODE MODE 1 CVBS/RGB SELECT CHANNEL A GND B C D A MODE 2 CVBS/Y/C/ CVBSASYNC VCC B C D A MODE 3 RGB/CVBSASYNC FLOATING (G with sync) B C D R G B CVBS Y C CVBSASYNC G (with sync) R B CVBSASYNC SIGNAL CVBS
Filter
Filter Response The reconstruction filter consists of two 2nd-order SallenKey stages. The Butterworth-type response features a maximally flat passband for NTSC and PAL bandwidths. The stopband offers at least 43dB (typ) of attenuation at a video-encoder DAC sampling frequency of 27MHz (see the Typical Operating Characteristics).
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4-Channel Video Reconstruction Filter MAX7445
Table 2. High-Frequency Boost for Each Mode
CHANNEL A B C D HIGH-FREQUENCY BOOST (dB) MODE 1 +1.2 - - - MODE 2 +1.2 +1.2 +1.2 +1.2 MODE 3 - - - +1.2
12dB Gain Setting GAIN is biased internally to V CC / 2 with a resistordivider pair of 100k resistors from VCC to GND such that the internal impedance at the node is 50k. No additional connection is necessary since the input offers a minimum noise-margin immunity of 1VP-P.
Output Clamp Level
When sync pulses are detected in either a CVBS or G video signal, the DC restore loop is activated. The function of the loop is to set the DC level of the video signal to a specified voltage. See Table 4 for clamp levels.
Table 3. Gain Setting Control
GAIN GND VCC Floating BUFFER GAIN (dB) +6 +9.5 +12
Applications Information
Input Considerations
Use 0.1F ceramic capacitors to AC-couple the inputs. These input capacitors store a DC level so the outputs are clamped to an appropriate DC voltage level.
High-Frequency Boost The high-frequency boost available on the CVBS, Y, and C video channels increases image sharpness by compensating for signal degradation and roll-off in the video encoder. Table 2 shows the channels that have the highfrequency boost option for the three operating modes. The channels without high-frequency boost have a flat response over the video bandwidth.
Output Considerations
The outputs are typically connected to a 75 series back-match resistor followed by the video cable. Because of the inherent divide-by-two of this configuration, the voltage on the video cable is always less than 1V, complying with industry-standard video requirements such as the European SCART standard (which allows up to 2V of DC on the video cable). The video buffer can also drive an AC-coupled video load. Good video performance is achieved with an output capacitor as low as 220F.
Output Buffers
Each output buffer can drive two 150 video loads with a 2VP-P signal. The output buffer gain is selectable between +6dB, +9.5dB, or +12dB by using GAIN (see Table 3). The MAX7445 can drive an AC load or drive the video load directly without using a large output capacitor. The output buffers drive DC loads with an output blanking level of less than 1V.
Power-Supply Bypassing and Layout
The MAX7445 operates from a single +5V supply. Bypass VCC to GND with a 0.1F capacitor. Place all external components as close to the device as possible.
Table 4. Output Clamp Level
CHANNEL A B C D MODE 1: SELECT = GND CLAMP LEVEL (V) 0.8 1.4 1.4 1.4 SYNC SOURCE Channel A Channel A Channel A Channel A MODE 2: SELECT = VCC CLAMP LEVEL (V) 0.8 0.8 1.6 0.8 SYNC SOURCE Channel A Channel A Channel A Channel D MODE 3: SELECT = FLOATING CLAMP LEVEL (V) 0.8 1.4 1.4 0.8 SYNC SOURCE Channel A Channel A Channel A Channel D
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4-Channel Video Reconstruction Filter
Pin Configuration
TOP VIEW
INA 1 INB INC 2 3 14 OUTA 13 OUTB 12 OUTC
Exposed Pads
The TSSOP-EP package has an exposed pad on the bottom of the package. This pad is electrically connected to GND and should be connected to the ground plane for improved thermal conductivity. Do not route signals under this package.
MAX7445
IND 4 DISABLE 5 GND 6 GAIN 7
MAX7445
11 OUTD 10 VCC 9 8 SELECT GND
Chip Information
TRANSISTOR COUNT: 6300 PROCESS: BiCMOS
TSSOP
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4-Channel Video Reconstruction Filter MAX7445
Package Information
(The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)
TSSOP 4.4mm BODY.EPS
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 (c) 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.

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