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 150Ω 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 -40°C to
+85°C extended temperature range.
Applications
Set-Top Boxes/HDRs Game Consoles
Desktop Video Editors DVD Players
Digital VCRs
Features
♦ 4-Channel Filter and Buffer for RGB and
CVBS Signals
♦ Filter Response Ideal for NTSC, PAL, and
Interlaced SDTV Video Signals
♦ 43dB (typ) Stopband Attenuation at 27MHz
♦ ±0.75dB (max) Passband Ripple Out to 5MHz
♦ Blanking Level Voltage on Cable <1V
♦ Each Channel Drives Two 150Ω Video Loads
♦ +5V Single-Supply Voltage
♦ Small 14-Pin TSSOP Package
MAX7446
4-Channel Video Filter for RGB and CVBS Video
________________________________________________________________ Maxim Integrated Products 1
Functional Diagram
Ordering Information
19-2951; Rev 0; 8/03
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
*EP = Exposed pad.
Pin Configuration appears at end of data sheet.
PART TEMP RANGE PIN-PACKAGE
MAX7446EUD -40°C to +85°C 14 TSSOP-EP*
*
*
*
*
*
*
*
*
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
75Ω
ENCODER
CVBS
(WITHOUT SYNC)
V
CC
0.1µF
0.1µF
0.1µF
0.1µF
INA
INB
INC
IND
D/A
R
D/A
G
D/A
B
D/A
LOWPASS
FILTER
LOWPASS
FILTER
LOWPASS
FILTER
LOWPASS
FILTER
SYNC
DETECTOR
GND
MAX7446
DISABLE
75Ω
OUTA
75Ω
75Ω
OUTB
75Ω
75Ω
OUTC
75Ω
75Ω
OUTD
75Ω
*OPTIONAL CAPACITORS
MAX7446
4-Channel Video Filter for RGB and CVBS Video
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS
(V
CC
= +5V ±5%, CL= 0 to 20pF, RL= 75Ω to GND for DC-coupled load, RL= 75Ω to V
CC
/ 2 for AC-coupled load, C
IN_
= 0.1µF,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VCC= +5V, TA= +25°C.)
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.
VCCto GND ...........................................................................+6V
All Other Pins to GND.................................-0.3V to (V
CC
+ 0.3V)
Maximum Current into Any Pin Except V
CC
and GND .....±50mA
Continuous Power Dissipation (T
A
= +70°C)
TSSOP-EP (derate 20.8mW/°C above +70°C)...........1667mW
Operating Temperature Range ...........................-40°C to +85°C
Storage Temperature Range .............................-65°C to +150°C
Junction Temperature......................................................+150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Passband Response
Stopband Attenuation A
Differential Gain dG 5-step modulated staircase 0.15 0.50 %
Differential Phase dθ 5-step modulated staircase 0.15 0.50 D eg r ees
Signal-to-Noise Ratio SNR
Group Delay Deviation
Line-Time Distortion H
Field-Time Distortion V
Clamp Settling Time t
Output DC Clamp Level
Low-Frequency Gain Accuracy A
Low-Frequency Gain Matching A
Group Delay Matching
Channel-to-Channel Crosstalk X
Output Short-Circuit Current I
Input Leakage Current I
Input Dynamic Swing
SUPPLY
Supply Voltage Range V
Supply Current I
Power-Supply Rejection Ratio PSRR V
f = 100kHz to 5MHz,
relative to 100kHz
f ≥ 27MHz 39 43 dB
SB
Peak signal (2V
f = 100Hz to 50MHz
∆t
DIST
DIST
CLAMP
Deviation from 100kHz
g
to 4.1MHz
18µs, 100 IRE bar 0.3 %
130 lines, 18µs, 100 IRE bar 0.5 %
To ±1% 100 Lines
Channel A 0.6 0.9 1.1
Channels B, C, D 1.1 1.5 1.8
f = 100kHz -3 +3 %
V
V ( M ATC H )
t
g(MATCH)
TALK
Low-frequency channel-to-channel matching,
f = 100kHz
Low-frequency channel-to-channel matching,
f = 100kHz
f = 100kHz to 3.58MHz 60 dB
OUT_ shorted to GND or V
SC
IN
Channel A 1.2
Channels B, C, D 0.9
CC
No load 100 140 mA
CC
= 100mV
IN
P-P
Channel A 0.9 1.2 1.5
Channels B, C, D -0.75 +0.15 +0.75
) to RMS noise,
P-P
80 dB
Channel A 17 30
Channels B, C, D 11 20
4%
2ns
CC
70 mA
10 µA
4.75 5.25 V
, f = 0 to 3.5MHz 40 dB
dB
ns
V
V
P-P
MAX7446
4-Channel Video Filter for RGB and CVBS Video
_______________________________________________________________________________________ 3
Typical Operating Characteristics
(VCC= +5V, TA = +25°C, unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V ±5%, CL= 0 to 20pF, RL= 75Ω to GND for DC-coupled load, RL= 75Ω to V
CC
/ 2 for AC-coupled load, C
IN_
= 0.1µF,
T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at VCC= +5V, TA= +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DISABLE
At 5MHz 2 kΩ
V
IH
2.0 V
V
IL
0.8 V
Disable Logic-Input Current
VIL = 0V (sink), VIH = VCC (source) ±10 µA
Outp ut Im p ed ance D ur i ng D i sab l eZ
DISABLE
D i sab l e Log i c- Inp ut H i g h V ol tag e
D i sab l e Log i c- Inp ut Low V ol tag e
I
DISABLE
-20
-40
AMPLITUDE (dB)
-60
-80
AMPLITUDE vs. FREQUENCY
0
NORMALIZED TO 0dB
1 100
10
FREQUENCY (MHz)
MAX7446 toc01
PASSBAND AMPLITUDE vs. FREQUENCY
2.0
1.5
1.0
0.5
0
-0.5
AMPLITUDE (dB)
-1.0
-1.5
NORMALIZED TO 0dB
-2.0
0.1 10
HIGH-FREQUENCY BOOST
FLAT PASSBAND RESPONSE
1
FREQUENCY (MHz)
PHASE RESPONSE vs. FREQUENCY
200
150
MAX7446 toc02
100
50
0
-50
PHASE (DEGREES)
-100
-150
-200
0.1 10
1
FREQUENCY (MHz)
MAX7446 toc03
GROUP DELAY vs. FREQUENCY
100
90
80
70
GROUP DELAY (ns)
60
50
0.1 10
MODULATED 12.5T RESPONSE
1
FREQUENCY (MHz)
MAX7446 toc04
250mV/div
250mV/div
OUT_
2T RESPONSE (1 IRE = 7.14mV)
IN_
200ns/div
MAX7446 toc05
IN_
250mV/div
OUT_
250mV/div
(1 IRE = 7.14mV)
400ns/div
MAX7446 toc06
MAX7446
4-Channel Video Filter for RGB and CVBS Video
4 _______________________________________________________________________________________
Pin Description
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 150Ω 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.
SUPPLY CURRENT vs. TEMPERATURE
MAX7446 toc07
TEMPERATURE (°C)
SUPPLY CURRENT (mA)
603510-15
90
100
110
120
80
-40 85
INPUTS BIASED TO +2V
NO LOAD
DIFFERENTIAL GAIN
MAX7446 toc08
DIFFERENTIAL PHASE (DEGREES)
1st
3rd2nd 4th 5th
6th
1st
3rd2nd 4th 5th
6th
0.2
0.3
0.1
0
-0.1
-0.2
-0.3
DIFFERENTIAL GAIN (%)
0.2
0.3
0.1
0
-0.1
-0.2
-0.3
DIFFERENTIAL PHASE
MULTIBURST RESPONSE
MAX7446 toc09
10µs/div
250mV/div
250mV/div
IN_
OUT_
Typical Operating Characteristics (continued)
(VCC= +5V, TA = +25°C, unless otherwise noted.)
PIN NAME FUNCTION
1 INA C hannel A V i d eo Inp ut. U se channel A for the C V BS vi d eo si g nal . AC - coup l e IN A w i th a ser i es 0.1µF cap aci tor .
2 INB Channel B Video Input. Use channel B for the red (R) signal. AC-couple INB with a series 0.1µF capacitor.
3INC
4 IND Channel D Video Input. Use channel D for the blue (B) signal. AC-couple IND with a series 0.1µF capacitor.
5 DISABLE
6–9 GND Ground
10 V
11 OUTD Channel D Video Output. This output can be either AC- or DC-coupled.
12 OUTC Channel C Video Output. This output can be either AC- or DC-coupled.
13 OUTB Channel B Video Output. This output can be either AC- or DC-coupled.
14 OUTA Channel A Video Output. This output can be either AC- or DC-coupled.
Channel C Video Input. Use channel C for the green (G) (without sync) signal. AC-couple INC with a series
0.1µF 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.
+5V Supply Input
CC
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.
Output Buffers
Each output buffer has a fixed gain of +6dB and can
drive two 150Ω video loads with a 2V
P-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.
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.
Applications Information
Input Considerations
Use 0.1µF 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.
Output Considerations
The outputs are typically connected to a 75Ω 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 220µF.
Power-Supply Bypassing and Layout
The MAX7446 operates from a single +5V supply.
Bypass VCCto GND with a 0.1µF capacitor. Place all
external components as close to the device as possible.
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.
MAX7446
4-Channel Video Filter for RGB and CVBS Video
_______________________________________________________________________________________ 5
Pin Configuration
Chip Information
TRANSISTOR COUNT: 6300
PROCESS: BiCMOS
Table 1. Output Clamp Level
CHANNEL CLAMP LEVEL (V)
A 0.8
B 1.4
C 1.4
D 1.4
TOP VIEW
1
INA
2
INB
3
INC
4
MAX7446
DISABLE
5
GND
6
7
TSSOP
14
OUTA
13
OUTB
12
OUTC
11
OUTDIND
V
10
CC
9
GND
GNDGND
8
MAX7446
4-Channel Video Filter for RGB and CVBS Video
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
© 2003 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
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
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