19-2989; Rev 1; 4/06
KIT
ATION
EVALU
BLE
AVAILA
4-Channel RGB Video Filter with
Asynchronous CVBS Input
Features
♦
4-Channel Filter and Buffer for RGB and CVBS
Video 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
General Description
The MAX7448, 4-channel, buffered video reconstruc-
tion filter is ideal for anti-aliasing and digital-to-analog
converter (DAC)-smoothing video applications or wher-
ever analog video is reconstructed from a digital data
stream (such as cable/satellite/terrestrial set-top boxes,
DVD players, hard-disk recorders (HDRs), and person-
al 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 MAX7448 processes RGB and asynchronous CVBS
video signals. The output video buffers have a fixed gain
of +6dB. The channel used for CVBS video has high-fre-
quency boost circuitry, which 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 MAX7448 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.
MAX7448
Ordering Information
PART
MAX7448EUD
TEMP
RANGE
-40°C to
+85°C
PIN-
PACKAGE
14 TSSOP-EP*
PACKAGE
CODE
U14E-3
Applications
Set-Top Boxes/HDRs
Game Consoles
Desktop Video Editors
DVD Players
Digital VCRs
*EP
= Exposed pad.
Pin Configuration appears at end of data sheet.
Functional Diagram
V
CC
ENCODER
0.1µF
G
D/A
(WITH SYNC)
INA
LOWPASS
FILTER
SYNC
DETECTOR
OUTA
75Ω
*
75Ω
75Ω
0.1µF
R D/A
*
INB
LOWPASS
FILTER
OUTB
75Ω
75Ω
0.1µF
B D/A
INC
LOWPASS
FILTER
OUTC
75Ω
75Ω
IND
LOWPASS
FILTER
SYNC
DETECTOR
OUTD
75Ω
*
*
*
*
*
75Ω
75Ω
75Ω
75Ω
75Ω
*
75Ω
75Ω
75Ω
0.1µF
CVBS
D/A
(WITH SYNC)
MAX7448
GND
DISABLE
*OPTIONAL CAPACITORS
________________________________________________________________
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.
4-Channel RGB Video Filter with
Asynchronous CVBS Input
MAX7448
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)
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
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-coupled load, R
L
= 75Ω to V
CC
/ 2 for AC-coupled load, C
IN_
= 0.1µF,
GAIN = +6dB,T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V, T
A
= +25°C.)
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
V
CC
I
CC
PSRR
No load
V
IN
= 100mV
P-P
, f = 0 to 3.5MHz
4.75
100
40
5.25
140
V
mA
dB
A
V
A
V(MATCH)
t
g(MATCH)
X
TALK
I
SC
I
IN
Channels A, D
Channels B, C
A
SB
dG
dθ
SNR
∆t
g
H
DIST
V
DIST
t
CLAMP
SYMBOL
CONDITIONS
f = 100kHz to 5MHz,
relative to 100kHz
f
≥
27MHz
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%
Channels A, D
Channels B, C
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 V
CC
2
60
70
10
1.2
0.9
0.6
1.1
-3
430
0.9
1.5
1.1
1.8
+3
4
Channels A, B, C
Channel D
Channels A, B, C
Channel D
MIN
+0.75
+0.9
39
TYP
+0.15
+1.2
43
0.15
0.15
80
11
17
20
30
0.3
0.5
0.50
0.50
MAX
+0.75
+1.5
UNITS
dB
dB
%
Degrees
dB
ns
%
%
Lines
V
%
%
ns
dB
mA
µA
V
P-P
2
_______________________________________________________________________________________
4-Channel RGB Video Filter with
Asynchronous CVBS Input
ELECTRICAL CHARACTERISTICS (continued)
(V
CC
= +5V ±5%, C
L
= 0 to 20pF, R
L
= 75Ω to GND for DC-coupled load, R
L
= 75Ω to V
CC
/ 2 for AC-coupled load, C
IN_
= 0.1µF,
GAIN = +6dB, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at V
CC
= +5V, T
A
= +25°C.)
PARAMETER
DISABLE
Output Impedance during
Disable
Disable Logic-Input High Voltage
Disable Logic-Input Low Voltage
Disable Logic-Input Current
Z
DISABLE
V
IH
V
IL
I
DISABLE
V
IL
= 0V (sink), V
IH
= V
CC
(source)
At 5MHz
2.0
0.8
±10
2
kΩ
V
V
µA
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
MAX7448
Typical Operating Characteristics
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
AMPLITUDE vs. FREQUENCY
MAX7448 toc01
PASSBAND AMPLITUDE vs. FREQUENCY
MAX7448 toc02
PHASE RESPONSE vs. FREQUENCY
150
100
PHASE (DEGREES)
50
0
-50
-100
-150
MAX7448 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
_______________________________________________________________________________________
3
4-Channel RGB Video Filter with
Asynchronous CVBS Input
MAX7448
Typical Operating Characteristics (continued)
(V
CC
= +5V, T
A
= +25°C, unless otherwise noted.)
GROUP DELAY vs. FREQUENCY
MAX7448 toc04
2T RESPONSE (1 IRE = 7.14mV)
MAX7448 toc05
MODULATED 12.5T RESPONSE
(1 IRE = 7.14mV)
MAX7448 toc06
100
90
GROUP DELAY (ns)
IN_
250mV/div
IN_
250mV/div
80
70
OUT_
60
250mV/div
50
0.1
1
FREQUENCY (MHz)
10
200ns/div
400ns/div
250mV/div
OUT_
SUPPLY CURRENT vs. TEMPERATURE
MAX7448 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
MAX7448 toc08
MULTIBURST RESPONSE
MAX7448 toc09
120
INPUTS BIASED TO +2V
NO LOAD
SUPPLY CURRENT (mA)
110
IN_
250mV/div
100
DIFFERENTIAL PHASE
OUT_
250mV/div
90
80
-40
-15
10
35
60
85
TEMPERATURE (°C)
10µs/div
4
_______________________________________________________________________________________
4-Channel RGB Video Filter with
Asynchronous CVBS Input
Pin Description
PIN
1
2
3
4
5
6–9
10
11
12
NAME
INA
INB
INC
IND
DISABLE
GND
V
CC
OUTD
OUTC
FUNCTION
Channel A Video Input. Use channel A for the green (G with sync) video signal. AC-couple INA with a series
0.1µF capacitor.
Channel B Video Input. Use channel B for the red (R) video signal. AC-couple INB with a series 0.1µF
capacitor.
Channel C Video Input. Use channel C for the blue (B) video signal. AC-couple INC with a series 0.1µF
capacitor.
Channel D Video Input. Use channel D for a CVBS (with sync) signal. AC-couple IND 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 buffer outputs and puts them in a high-impedance state.
Ground
+5V Supply Input
Channel D Buffer Output. This output can be either AC- or DC-coupled.
Channel C Buffer Output. This output can be either AC- or DC-coupled.
MAX7448
Detailed Description
The MAX7448 filters and buffers video-encoder DAC
outputs in applications such as set-top boxes, HDRs,
DVD players, and digital VCRs. The MAX7448 recon-
structs 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 150Ω video loads.
The MAX7448 is designed to process R, G (with sync),
B, and CVBS
ASYNC
video signals. The video signal
processed by channel A (G video signal) requires a
sync pulse. This sync pulse provides the required tim-
ing for channels A, B, and C. Channel D allows an
asynchronous video signal to be processed with its
own local sync separator.
This device operates from a single +5V supply and has
a nominal cutoff frequency of 5MHz optimized for
NTSC, PAL, and SDTV.
Filter
Filter Response
The reconstruction filter consists of two 2nd-order Sallen-
Key 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 D (CVBS
video signal) increases image sharpness by compensat-
ing for signal degradation and rolloff in the video encoder.
Channels A, B, and C do not boost high-frequency sig-
nals 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
MAX7448 can drive an AC load or drive the video load
directly without using a large output capacitor. The out-
put buffers drive DC loads with an output blanking level
of less than 1V.
_______________________________________________________________________________________
5
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