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19-2951; Rev 0; 8/03
4-Channel Video Filter for RGB and CVBS Video
General Description
The MAX7446 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 MAX7446 processes CVBS and RGB video signals. The video output buffers have a fixed gain of +6dB. The channel for CVBS video has high-frequency boost circuitry that 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 MAX7446 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 RGB and CVBS 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 Small 14-Pin TSSOP Package
MAX7446
Ordering Information
PART MAX7446EUD TEMP RANGE -40C to +85C PIN-PACKAGE 14 TSSOP-EP*
Applications
Set-Top Boxes/HDRs Desktop Video Editors Digital VCRs Game Consoles DVD Players
*EP = Exposed pad.
Pin Configuration appears at end of data sheet.
Functional Diagram
VCC ENCODER 75 0.1F CVBS D/A * INA LOWPASS FILTER SYNC DETECTOR OUTA 75 75 0.1F R D/A * INB LOWPASS FILTER OUTB 75 75 0.1F G (WITHOUT SYNC) D/A INC LOWPASS FILTER OUTC 75 * * * * * 75 75 75 * 75 75 75
0.1F B D/A IND LOWPASS FILTER OUTD
75 75
75 75
*OPTIONAL CAPACITORS
MAX7446
GND DISABLE
________________________________________________________________ Maxim Integrated Products
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4-Channel Video Filter for RGB and CVBS Video MAX7446
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, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25C.)
PARAMETER Passband Response Stopband Attenuation Differential Gain Differential Phase Signal-to-Noise Ratio Group Delay Deviation Line-Time Distortion Field-Time Distortion Clamp Settling Time Output DC Clamp Level Low-Frequency Gain Accuracy Low-Frequency Gain Matching Group Delay Matching Channel-to-Channel Crosstalk Output Short-Circuit Current Input Leakage Current Input Dynamic Swing SUPPLY Supply Voltage Range Supply Current Power-Supply Rejection Ratio VCC ICC PSRR No load VIN = 100mVP-P, f = 0 to 3.5MHz 4.75 100 40 5.25 140 V mA dB AV AV(MATCH) tg(MATCH) XTALK ISC IIN Channel A Channels B, C, D ASB dG d SNR tg HDIST VDIST tCLAMP SYMBOL CONDITIONS f = 100kHz to 5MHz, relative to 100kHz f 27MHz 5-step modulated staircase 5-step modulated staircase Peak signal (2VP-P) to RMS noise, f = 100Hz to 50MHz Deviation from 100kHz to 4.1MHz 18s, 100 IRE bar 130 lines, 18s, 100 IRE bar To 1% Channel A Channels B, C, D f = 100kHz Low-frequency channel-to-channel matching, f = 100kHz Low-frequency channel-to-channel matching, f = 100kHz f = 100kHz to 3.58MHz OUT_ shorted to GND or VCC 2 60 70 10 1.2 0.9 0.6 1.1 -3 0.9 1.5 Channel A Channels B, C, D Channel A Channels B, C, D MIN 0.9 -0.75 39 TYP 1.2 +0.15 43 0.15 0.15 80 17 11 30 20 0.3 0.5 100 1.1 1.8 +3 4 0.50 0.50 MAX 1.5 +0.75 UNITS dB dB % Degrees dB ns % % Lines V % % ns dB mA A VP-P
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4-Channel Video Filter for RGB and CVBS Video
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, TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25C.)
PARAMETER 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 SYMBOL CONDITIONS MIN TYP MAX UNITS
MAX7446
Typical Operating Characteristics
(VCC = +5V, TA = +25C, unless otherwise noted.)
AMPLITUDE vs. FREQUENCY
MAX7446 toc01
PASSBAND AMPLITUDE vs. FREQUENCY
1.5 1.0
MAX7446 toc02
PHASE RESPONSE vs. FREQUENCY
150 100 PHASE (DEGREES) 50 0 -50 -100 -150
MAX7446 toc03
2.0 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
MAX7446 toc04
2T RESPONSE (1 IRE = 7.14mV)
MAX7446 toc05
MODULATED 12.5T RESPONSE (1 IRE = 7.14mV)
MAX7446 toc06
100
90 GROUP DELAY (ns)
IN_ 250mV/div
IN_
80
250mV/div
70 OUT_ OUT_ 60 250mV/div 50 0.1 1 FREQUENCY (MHz) 10 200ns/div 400ns/div 250mV/div
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4-Channel Video Filter for RGB and CVBS Video MAX7446
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
INPUTS BIASED TO +2V NO LOAD SUPPLY CURRENT (mA) 110
MAX7446 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 OUT_ 250mV/div
MAX7446 toc08
MULTIBURST RESPONSE
MAX7446 toc09
120
IN_ 250mV/div
100
DIFFERENTIAL PHASE
90
80 -40 -15 10 35 60 85 TEMPERATURE (C)
10s/div
Pin Description
PIN 1 2 3 4 5 6-9 10 11 12 13 14 NAME INA INB INC IND DISABLE GND VCC OUTD OUTC OUTB OUTA FUNCTION Channel A Video Input. Use channel A for the CVBS video signal. AC-couple INA with a series 0.1F capacitor. Channel B Video Input. Use channel B for the red (R) signal. AC-couple INB with a series 0.1F capacitor. Channel C Video Input. Use channel C for the green (G) (without sync) signal. AC-couple INC with a series 0.1F capacitor. Channel D Video Input. Use channel D for the blue (B) signal. AC-couple IND with a series 0.1F capacitor. Disable Logic Input. A logic-low on DISABLE enables the output buffers. A logic-high on DISABLE disables all output buffers and puts them in a high-impedance state. Ground +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 MAX7446 filters and buffers video-encoder DAC outputs in applications such as set-top boxes, harddisk recorders, DVD players, and digital VCRs. The MAX7446 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 drives two standard 150 video loads.
The MAX7446 is designed to process CVBS, R, G, and B video signals. The video signal processed by channel A (CVBS) must include a sync pulse. This sync pulse provides the required timing to all four channels. This device operates from a single +5V supply and has a nominal cutoff frequency of 5MHz optimized for NTSC, PAL, and SDTV.
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4-Channel Video Filter for RGB and CVBS Video
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). High-Frequency Boost The +1.2dB high-frequency boost on channel A increases image sharpness by compensating for signal degradation and roll-off in the video encoder. Channels B, C, and D (RGB) do not boost high-frequency signals and have a flat response over the video bandwidth.
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.
MAX7446
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 has a fixed gain of +6dB and can drive two 150 video loads with a 2VP-P signal. The MAX7446 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 MAX7446 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.
Output Clamp Level
When a sync pulse is detected on channel A, the DC restore loop is activated. The function of the loop is to set the DC value of the video signal to a specified voltage. See Table 1 for clamp levels.
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.
Table 1. Output Clamp Level
CHANNEL A B C D CLAMP LEVEL (V) 0.8 1.4 1.4 1.4
Pin Configuration
TOP VIEW
INA 1 INB INC 2 3 14 OUTA 13 OUTB 12 OUTC
IND 4 DISABLE 5 GND 6 GND 7
MAX7446
11 OUTD 10 VCC 9 8 GND GND
TSSOP
Chip Information
TRANSISTOR COUNT: 6300 PROCESS: BiCMOS
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4-Channel Video Filter for RGB and CVBS Video MAX7446
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.
6 _____________________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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