19-2749; Rev 1; 1/06
KIT
ATION
EVALU
E
BL
AVAILA
Triple-Channel Video Reconstruction Filter and
Buffer for Composite and Y/C Outputs
General Description
The MAX7443/MAX7444 are low-cost, triple-channel
video reconstruction filters for S-video and CVBS video
signals. These devices are ideal for anti-aliasing and
DAC smoothing video applications such as set-top
boxes, DVD players, hard-disk recorders (HDRs), and
personal video recorders. These filters operate from a
single +5V supply. They are optimized for NTSC, PAL,
and standard-definition digital TV (SDTV) video systems.
Each channel consists of a lowpass filter and an
adjustable-gain output buffer capable of driving two
standard 150Ω video loads. The output buffers can drive
either an AC or a DC load such that the blanking level
voltage after the backmatch resistor is less than 1V. The
Y and C video inputs are summed to produce the com-
posite video output. The MAX7444 offers high-
frequency boost to improve picture sharpness. The
MAX7443 has a maximum flat-frequency response.
The MAX7443/MAX7444 are available in a tiny 8-pin thin
QFN and an 8-pin SO package with exposed pad, and
are fully specified over the -40°C to +85°C extended
temperature range.
Features
♦
Triple-Channel Filter and Buffer for CVBS and
Y/C (S-Video)
♦
Filter Response Ideal for NTSC, PAL, and
Interlaced SDTV Signals
♦
41dB (typ) Stopband Attenuation at 27MHz
♦
-0.3dB (typ) Passband Response
♦
Low Blanking Level Voltage Allows DC-Coupled
Output
♦
Each Channel Drives Two 150Ω Video Loads
♦
+5V Single-Supply Voltage
♦
Tiny 8-Pin Thin QFN or 8-Pin SO Packages
MAX7443/MAX7444
Ordering Information
PART
MAX7443ETA
MAX7443ESA
MAX7444ETA
MAX7444ESA
PIN-PACKAGE
8 Thin QFN-EP*
8 SO-EP*
8 Thin QFN-EP*
8 SO-EP*
TOP
MARK
AFX
—
AFY
—
PKG
CODE
T833-1
S8E-12
T833-1
S8E-12
Applications
Set-Top Boxes/HDR/DVD
Security Cameras/Digital
Cameras
Game Consoles
Digital VCRs
Every Composite,
S-Video Output for NTSC,
PAL, SDTV
Note:
All devices specified over -40°C to +85°C temperature
range.
*EP
= Exposed pad.
Selector Guide appears at end of data sheet.
Functional Diagram
V
CC
*
ENCODER
YIN
D/A
LOWPASS
FILTER
6dB/
9.5dB/
12dB
YOUT
*
*
MAX7443
MAX7444
Σ
6dB/
9.5dB/
12dB
CVOUT
*
D/A
CIN
LOWPASS
FILTER
GND
6dB/
9.5dB/
12dB
COUT
*
*
GSET
*OPTIONAL
________________________________________________________________
Maxim Integrated Products
1
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.
Triple-Channel Video Reconstruction Filter and
Buffer for Composite and Y/C Outputs
MAX7443/MAX7444
ABSOLUTE MAXIMUM RATINGS
V
CC
to 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)
8-Pin Thin QFN (derate 24.4mW/°C above +70°C) ...1951mW
8-Pin SO (derate 18.9mW/°C above +70°C)..............1509mW
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
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
(V
CC
= +5V ±5%, C
L
= 0 to 20pF, R
L
= 75Ω to GND for DC-couple, R
L
= 75Ω to V
CC
/2 for AC-couple, C
YIN
= C
CIN
= 0.1µF,
T
A
= T
MIN
to T
MAX
, GSET = GND (6dB) and V
CC
(9.5dB), unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Passband Response
Stopband Attenuation
Boost Amplitude
Differential Gain
Differential Phase
dG
dθ
A
SB
SYMBOL
CONDITIONS
f = 100kHz to 4.2MHz,
relative to 100kHz
f = 27MHz
f = 4.2MHz, MAX7444
5-step modulated
staircase
5-step modulated
staircase
Peak signal (2V
P-P
) to
RMS noise, f = 100Hz to
50MHz
Deviation from 100kHz to
4.1MHz
18µs, 100 IRE bar
130 lines, 18µs, 100 IRE bar
To ±1%
YOUT
Output DC Clamp Level
Low-Frequency Gain Accuracy
Group Delay Matching
Channel-to-Channel Crosstalk
Input Leakage Current
A
V
t
g(MATCH)
X
TALK
I
IN
CVOUT
COUT
f = 100kHz, relative to 6dB
Low-frequency channel-to-channel matching,
f = 100kHz for YOUT and COUT
f = 100kHz to 3.58MHz, gain = 6dB
0.6
0.6
1.44
-3.5
2
61
10
430
0.8
0.8
1.6
1.0
1.0
1.97
+2
%
ns
dB
µA
V
Gain = 6dB,
9.5dB, 12dB
Gain = 6dB,
9.5dB, 12dB
Gain = 6dB,
9.5dB, 12dB
MAX7443
MAX7444
67
MAX7443
MAX7444
MIN
-0.8
-0.1
39
TYP
-0.3
+0.6
41
0.6
0.15
0.15
0.4
0.4
MAX
+0.1
+0.92
UNITS
dB
dB
dB
%
Degrees
Signal-to-Noise Ratio
SNR
73
8
12
20
30
0.3
0.5
dB
Group Delay Deviation
Line-Time Distortion
Field-Time Distortion
Clamp Settling Time
∆t
g
H
DIST
V
DIST
ns
%
%
Lines
2
_______________________________________________________________________________________
Triple-Channel Video Reconstruction Filter and
Buffer for Composite and Y/C Outputs
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V ±5%, C
L
= 0 to 20pF, R
L
= 75Ω to GND for DC-couple, R
L
= 75Ω to V
CC
/2 for AC-couple, C
YIN
= C
CIN
= 0.1µF,
T
A
= T
MIN
to T
MAX
, GSET = GND (6dB) and V
CC
(9.5dB), unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
Input Dynamic Swing
SUPPLY
Supply Voltage Range
Supply Current
Power-Supply Rejection Ratio
V
CC
I
CC
PSRR
V
CC
= +5.25V, no load
V
IN
= 100mV
P-P
, f = 0 to 3.5MHz
4.75
88
33
5.25
110
V
mA
dB
SYMBOL
Y
INP-P
C
INP-P
CONDITIONS
GSET = GND (6dB)
GSET = GND (6dB)
MIN
TYP
MAX
1.2
0.9
UNITS
V
P-P
MAX7443/MAX7444
Typical Operating Characteristics
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
AMPLITUDE vs. FREQUENCY
MAX7443/44 toc01
PASSBAND AMPLITUDE vs. FREQUENCY
MAX7443/44 toc02
PHASE RESPONSE vs. FREQUENCY
150
100
PHASE (DEGREES)
50
0
-50
-100
-150
MAX7443/44 toc03
2.0
1.5
1.0
AMPLITUDE (dB)
0.5
0
-0.5
-1.0
MAX7443
MAX7444
200
0
AMPLITUDE (dB)
-20
-40
-60
NORMALIZED TO 0dB
-80
1
10
FREQUENCY (MHz)
100
-1.5
NORMALIZED TO 0dB
-2.0
0.1
1
FREQUENCY (MHz)
10
-200
0.1
1
FREQUENCY (MHz)
10
GROUP DELAY vs. FREQUENCY
MAX7443/44 toc04
2T RESPONSE (1 IRE = 7.14mV)
MAX7443/44 toc05
MODULATED 12.5T RESPONSE
(1 IRE = 7.14mV)
MAX7443/44 toc06
90
80
GROUP DELAY (ns)
70
Y
IN
200mV/div
Y
IN
200mV/div
60
Y
OUT
200mV/div
50
Y
OUT
400mV/div
0.1
1
FREQUENCY (MHz)
10
40
200ns/div
400ns/div
_______________________________________________________________________________________
3
Triple-Channel Video Reconstruction Filter and
Buffer for Composite and Y/C Outputs
MAX7443/MAX7444
Typical Operating Characteristics (continued)
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
SUPPLY CURRENT
vs. TEMPERATURE
DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%)
MAX7443/44 toc07
DIFFERENTIAL GAIN
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
1
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
1
2
3
4
5
6
7
2
3
4
5
6
7
YOUT
200mV/div
MAX7443/44 toc08
MULTIBURST RESPONSE
YIN
200mV/div
MAX7443/44 toc09
90
85
SUPPLY CURRENT (mA)
80
DIFFERENTIAL PHASE
75
70
65
-40
-15
10
35
60
85
TEMPERATURE (°C)
10µs/div
Pin Description
PIN
1
2
3
4
5
6
7
8
NAME
YIN
GSET
CIN
GND
V
CC
COUT
CVOUT
YOUT
FUNCTION
Luma (Y) Input
Gain-Setting Control Input. See Table 1
for values.
Chroma (C) Input
Ground
5V Power Supply
Chroma (C) Output
Composite Video Output
Luma (Y) Output
These devices operate from a single +5V supply. The
filters have a nominal cutoff frequency optimized for
NTSC, PAL, and SDTV.
Filter
Filter Response
The reconstruction filter consists of two 2nd-order
Sallen-Key stages. The Butterworth-type response fea-
tures a maximally flat passband for NTSC and PAL
bandwidths. The stopband offers 41dB (typ) of attenua-
tion at sampling frequencies of 27MHz and above (see
Typical Operating Characteristics).
High-Frequency Boost
The high-frequency boost available in the MAX7444
compensates for signal degradation and rolloff in the
video encoder, which increases the image sharpness.
The MAX7443 has a flat response over the video band-
width.
Detailed Description
The primary function of the MAX7443/MAX7444 is to fil-
ter and buffer the encoder DAC outputs that contain
digital video information in applications such as set-top
boxes, hard-disk recorders, DVD players, and digital
VCRs. These devices reconstruct and clean up analog
video signals. Each MAX7443/MAX7444 consists of a
lowpass filter and an adjustable-gain output video
buffer that is capable of driving two standard 150Ω
video loads. The luma (YIN) and chroma (CIN) video
inputs are summed internally to provide the composite
(CVOUT) video output.
Output Buffer
The output buffer drives two 150Ω video loads with a
2V
P-P
signal. The adjustable gain of the output buffer
provides a gain of 6dB, 9.5dB, and 12dB, which are
selected by tying the GSET pin to GND, V
CC
, or float-
ing, respectively. The MAX7443/MAX7444 can drive an
AC load or drive the video load directly without using
the large output capacitor. The output buffer drives a
DC load with an output blanking level of less than 1V.
4
_______________________________________________________________________________________
Triple-Channel Video Reconstruction Filter and
Buffer for Composite and Y/C Outputs
Table 1. Gain-Setting Control
GSET
GND
V
CC
Open
GAIN (dB)
6
9.5
12
PART
MAX7443ETA
MAX7443ESA
MAX7444ETA
MAX7444ESA
Selector Guide
HIGH-FREQUENCY BOOST
No
No
Yes
Yes
MAX7443/MAX7444
12dB Gain Setting
The GSET pin is biased internally to V
CC
/2 through two
100kΩ resistors from V
CC
to GND. The internal imped-
ance at the node is 50kΩ. No additional connection is
necessary since the pin offers a minimum noise margin
immunity of 1V
P-P
.
Pin Configurations
TOP VIEW
Output Clamp Level
When sync pulses in the luma signal (Y) are detected,
the DC restore loop is activated. The function of the
loop is to set the sync tip of the video signal to the
desired DC level of 0.8V for YOUT and COUT and the
average DC voltage of COUT at 1.6V.
YIN
GSET
CIN
GND
1
2
3
4
MAX7443
MAX7444
8
7
6
5
YOUT
CVOUT
COUT
V
CC
Applications Information
THIN QFN
Input Considerations
Use a 0.1µF ceramic capacitor to AC-couple the input
to the MAX7443/MAX7444. This input capacitor stores
a DC level such that the outputs are clamped to the
appropriate DC voltage level.
YIN
GSET
CIN
GND
1
2
3
4
MAX7443
MAX7444
8
7
6
5
YOUT
CVOUT
COUT
V
CC
Output Considerations
The outputs of the MAX7443/MAX7444 are typically
connected to a 75Ω series back-match resistor fol-
lowed by the video cable. Because of the inherent
divide by two of this configuration, the blanking level of
the video cable is always less than 1V, which complies
with industry-standard video requirements. The video
buffer can also drive an AC-coupled video load. Good
video performance is achieved with an output capacitor
as low as 220µF.
SO
Chip Information
TRANSISTOR COUNT: 4252
PROCESS: BiCMOS
Power-Supply Bypassing and Layout
The MAX7443/MAX7444 operate from a single +5V
supply. Bypass V
CC
to GND with a 0.1µF capacitor.
Place all external components as close to the device as
possible. Refer to the MAX7443 evaluation kit for a
proven PC board layout example.
Exposed Pads
Both the SO and thin QFN packages of the MAX7443/
MAX7444 have exposed pads on the bottom of the
packages. These pads are electrically connected to
GND and should be connected to the ground plane for
improved thermal conductivity. Do not route signals
under these packages.
_______________________________________________________________________________________________________
5
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