MAXIM MAX7447

19-2950; Rev 0; 8/03
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
The MAX7447 processes S-Video and CVBS video signals. The video output buffers have a fixed gain of +6dB.
Each channel has high-frequency boost circuitry that provides picture sharpness with up to +1.2dB of gain boost
without degradation in the stopband. The output video
drivers can be disabled with an external pin.
The MAX7447 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
Features
♦ 4-Channel Filter and Buffer for S-Video 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 Output <1V
♦ Each Channel Drives Two 150Ω Video Loads
♦ +5V Single-Supply Voltage
♦ Small 14-Pin TSSOP Package
Ordering Information
PART
TEMP RANGE
PIN-PACKAGE
MAX7447EUD
-40°C to +85°C
14 TSSOP-EP*
*EP = Exposed pad.
DVD Players
Digital VCRs
Functional Diagram
VCC
ENCODER
75Ω
0.1µF
CVBS
D/A
75Ω
*
INA
LOWPASS
FILTER
OUTA
SYNC
DETECTOR
75Ω
*
75Ω
0.1µF
Y
D/A
LOWPASS
FILTER
OUTB
LOWPASS
FILTER
OUTC
75Ω
75Ω
INC
D/A
D/A
75Ω
75Ω
0.1µF
CVBS
75Ω
*
INB
0.1µF
C
75Ω
IND
LOWPASS
FILTER
OUTD
SYNC
DETECTOR
75Ω
*
*
*
*
*
75Ω
75Ω
75Ω
75Ω
75Ω
*OPTIONAL CAPACITORS
MAX7447
GND
DISABLE
Pin Configuration appears at end of data sheet.
________________________________________________________________ Maxim Integrated Products
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.
1
MAX7447
General Description
The MAX7447 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.
MAX7447
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
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 = +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
(VCC = +5V ±5%, CL = 0 to 20pF, RL = 75Ω to GND for DC-coupled load, RL = 75Ω to VCC / 2 for AC-coupled load, CIN_ = 0.1µF,
TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25°C.)
PARAMETER
SYMBOL
Passband Response
CONDITIONS
MIN
TYP
MAX
1.5
UNITS
f = 100kHz to 5MHz, relative to 100kHz
0.9
1.2
Stopband Attenuation
ASB
f ≥ 27MHz
39
43
Differential Gain
dG
5-step modulated staircase
0.15
0.50
%
Differential Phase
dθ
5-step modulated staircase
0.15
0.50
Degrees
Signal-to-Noise Ratio
SNR
Peak signal (2VP-P) to RMS noise,
f = 100Hz to 50MHz
Group Delay Deviation
∆tg
Deviation from 100kHz to 4.1MHz
80
17
dB
dB
dB
30
ns
Line-Time Distortion
HDIST
18µs, 100 IRE bar
0.3
%
Field-Time Distortion
VDIST
130 lines, 18µs, 100 IRE bar
0.5
%
Clamp Settling Time
tCLAMP
100
Lines
Output DC Clamp Level
Low-Frequency Gain Accuracy
AV
To ±1%
Channel A, B, D
0.6
0.9
1.1
Channel C
1.25
1.60
1.95
f = 100kHz, relative to a gain of +6dB
Low-Frequency Gain Matching
Low-frequency channel-to-channel matching,
AV(MATCH)
f = 100kHz
Group Delay Matching
tg(MATCH)
Channel-to-Channel Crosstalk
XTALK
Output Short-Circuit Current
ISC
Input Leakage Current
IIN
Input Dynamic Swing
-3
Low-frequency channel-to-channel matching,
f = 100kHz
V
+3
%
4
%
2
ns
f = 100kHz to 3.58MHz
60
dB
OUT_ shorted to GND or VCC
70
mA
10
Channel A, B, D
1.2
Channel C
0.9
µA
VP-P
SUPPLY
Supply Voltage Range
VCC
Supply Current
ICC
Power-Supply Rejection Ratio
2
PSRR
4.75
No load
100
VIN = 100mVP-P, f = 0 to 3.5MHz
40
_______________________________________________________________________________________
5.25
V
140
mA
dB
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
(VCC = +5V ±5%, CL = 0 to 20pF, RL = 75Ω to GND for DC-coupled load, RL = 75Ω to VCC / 2 for AC-coupled load, CIN_ = 0.1µF,
TA = TMIN to TMAX, unless otherwise noted. Typical values are at VCC = +5V, TA = +25°C.)
PARAMETER
SYMBOL
CONDITIONS
MIN
TYP
MAX
UNITS
DISABLE
Output Impedance During Disable
ZDISABLE
Disable Logic-Input High Voltage
VIH
Disable Logic-Input Low Voltage
Disable Logic-Input Current
At 5MHz
2
kΩ
2.0
V
VIL
IDISABLE
VIL = 0V (sink), VIH = VCC (source)
0.8
V
±10
µA
Typical Operating Characteristics
(VCC = +5V, TA = +25°C, unless otherwise noted.)
PASSBAND AMPLITUDE vs. FREQUENCY
0
PHASE RESPONSE vs. FREQUENCY
200
MAX7447 toc02
MAX7447 toc01
2.0
1.5
HIGH-FREQUENCY BOOST
150
-40
100
PHASE (DEGREES)
AMPLITUDE (dB)
AMPLITUDE (dB)
1.0
-20
0.5
0
-0.5
-1.0
-60
-50
-150
-2.0
10
-200
0.1
100
10
1
0.1
10
1
FREQUENCY (MHz)
FREQUENCY (MHz)
FREQUENCY (MHz)
GROUP DELAY vs. FREQUENCY
2T RESPONSE (1 IRE = 7.14mV)
MODULATED 12.5T RESPONSE
(1 IRE = 7.14mV)
MAX7447 toc06
MAX7447 toc05
MAX7447 toc04
100
90
GROUP DELAY (ns)
0
NORMALIZED TO 0dB
-80
1
50
-100
-1.5
NORMALIZED TO 0dB
MAX7447 toc03
AMPLITUDE vs. FREQUENCY
80
IN-
IN-
250mV/div
250mV/div
OUT-
OUT-
250mV/div
250mV/div
70
60
50
0.1
1
10
200ns/div
400ns/div
FREQUENCY (MHz)
_______________________________________________________________________________________
3
MAX7447
ELECTRICAL CHARACTERISTICS (continued)
Typical Operating Characteristics (continued)
(VCC = +5V, TA = +25°C, unless otherwise noted.)
SUPPLY CURRENT vs. TEMPERATURE
110
100
90
80
-40
-15
10
35
60
85
TEMPERATURE (°C)
MAX7447 toc09
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
MAX7447 toc08
DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%)
INPUTS BIASED TO +2V
NO LOAD
MULTIBURST RESPONSE
DIFFERENTIAL GAIN
MAX7447 toc07
120
SUPPLY CURRENT (mA)
MAX7447
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
250mV/div
1st
2nd
3rd
4th
5th
6th
DIFFERENTIAL PHASE
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
250mV/div
1st
2nd
3rd
4th
5th
6th
10µs/div
Pin Description
PIN
NAME
1
INA
Channel A Video Input. Use channel A for a CVBS video signal. AC-couple INA with a series 0.1µF capacitor.
FUNCTION
2
INB
Channel B Video Input. Use channel B for the luma (Y) video signal. AC-couple INB with a series 0.1µF
capacitor.
3
INC
Channel C Video Input. Use channel C for the chroma (C) video signal. AC-couple INC with a series 0.1µF
capacitor.
4
IND
Channel D Video Input. Use channel D for a second CVBS video signal. AC-couple IND with a series 0.1µF
capacitor.
5
DISABLE
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.
6–9
GND
Ground
10
VCC
+5V Supply Input
11
OUTD
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 D Video Output. This output can be either AC- or DC-coupled.
Detailed Description
The MAX7447 filters and buffers video-encoder DAC
outputs in applications such as set-top boxes, harddisk recorders, DVD players, and digital VCRs. The
MAX7447 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.
4
The MAX7447 is designed to process S-Video and
CVBS video signals. The video signal processed by
channel A (CVBS video signal) must include a sync
pulse. This sync pulse provides the required timing for
channels A, B, and C. Channel D allows an asynchronous CVBS 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.
_______________________________________________________________________________________
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
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 and
above (see the Typical Operating Characteristics).
High-Frequency Boost
Each channel has a +1.2dB high-frequency boost that
increases image sharpness by compensating for signal
degradation and rolloff in the video encoder.
Output Buffers
Each output buffer has a fixed gain of +6dB and can
drive two 150Ω video loads with a 2VP-P signal. The
MAX7447 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 (CVBS),
the DC restore loop is activated for channels A, B, and
C. Channel D’s DC restore loop is activated by the sync
pulse on channel D.The function of the loop is to set the
DC level of the video signal to a specified voltage. See
Table 1 for clamp levels and sync source.
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 MAX7447 operates from a single +5V supply.
Bypass VCC to 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.
Pin Configuration
Table 1. Output Clamp Level and Sync
Source
CHANNEL
CLAMP LEVEL (V)
SYNC SOURCE (V)
A
0.8
Channel A
TOP VIEW
INA 1
14 OUTA
2
13 OUTB
3
12 OUTC
B
0.8
Channel A
INB
C
1.6
Channel A
INC
D
0.8
Channel D
IND 4
MAX7447
DISABLE 5
11 OUTD
10 VCC
GND 6
9
GND
GND 7
8
GND
TSSOP
Chip Information
TRANSISTOR COUNT: 6300
PROCESS: BiCMOS
_______________________________________________________________________________________
5
MAX7447
Filter
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
MAX7447
4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input
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.