MAXIM MAX7446

19-2951; Rev 0; 8/03
4-Channel Video Filter for RGB and CVBS Video
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
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
Ordering Information
PART
MAX7446EUD
TEMP RANGE
PIN-PACKAGE
-40°C to +85°C
14 TSSOP-EP*
*EP = Exposed pad.
Pin Configuration appears at end of data sheet.
Digital VCRs
Functional Diagram
VCC
ENCODER
75Ω
0.1µF
CVBS
D/A
75Ω
*
INA
LOWPASS
FILTER
OUTA
SYNC
DETECTOR
75Ω
*
75Ω
0.1µF
R
D/A
LOWPASS
FILTER
OUTB
LOWPASS
FILTER
OUTC
LOWPASS
FILTER
OUTD
75Ω
75Ω
INC
D/A
D/A
75Ω
75Ω
0.1µF
B
75Ω
*
INB
0.1µF
G
(WITHOUT SYNC)
75Ω
IND
75Ω
*
*
*
*
*
75Ω
75Ω
75Ω
75Ω
75Ω
*OPTIONAL CAPACITORS
MAX7446
GND
DISABLE
________________________________________________________________ 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
MAX7446
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.
MAX7446
4-Channel Video Filter for RGB and CVBS Video
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
CONDITIONS
f = 100kHz to 5MHz,
relative to 100kHz
Passband Response
Channel A
Channels B, C, D
MIN
TYP
MAX
0.9
1.2
1.5
-0.75
+0.15
+0.75
39
43
UNITS
dB
Stopband Attenuation
ASB
f ≥ 27MHz
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
dB
80
dB
Channel A
17
30
Channels B, C, D
11
20
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
To ±1%
100
Lines
Output DC Clamp Level
Channel A
0.6
0.9
1.1
Channels B, C, D
1.1
1.5
1.8
f = 100kHz
-3
Low-Frequency Gain Accuracy
AV
Low-Frequency Gain Matching
AV(MATCH)
Low-frequency channel-to-channel matching,
f = 100kHz
Group Delay Matching
tg(MATCH)
Low-frequency channel-to-channel matching,
f = 100kHz
Channel-to-Channel Crosstalk
XTALK
Output Short-Circuit Current
ISC
Input Leakage Current
IIN
Input Dynamic Swing
%
V
+3
%
4
%
2
ns
f = 100kHz to 3.58MHz
60
dB
OUT_ shorted to GND or VCC
70
mA
10
Channel A
1.2
Channels B, C, D
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 Video Filter for RGB and CVBS Video
(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
VIL
Disable Logic-Input Current
At 5MHz
2
kΩ
2.0
IDISABLE
V
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
1.5
PHASE RESPONSE vs. FREQUENCY
200
MAX7446 toc02
MAX7446 toc01
2.0
HIGH-FREQUENCY BOOST
150
-40
100
PHASE (DEGREES)
AMPLITUDE (dB)
AMPLITUDE (dB)
1.0
-20
0.5
0
-0.5
FLAT PASSBAND RESPONSE
-1.0
-60
-50
-150
-2.0
10
-200
0.1
100
10
1
FREQUENCY (MHz)
FREQUENCY (MHz)
GROUP DELAY vs. FREQUENCY
2T RESPONSE (1 IRE = 7.14mV)
0.1
MAX7446 toc04
90
80
10
1
FREQUENCY (MHz)
MODULATED 12.5T RESPONSE
(1 IRE = 7.14mV)
MAX7446 toc05
100
GROUP DELAY (ns)
0
NORMALIZED TO 0dB
-80
1
50
-100
-1.5
NORMALIZED TO 0dB
MAX7446 toc03
AMPLITUDE vs. FREQUENCY
MAX7446 toc06
IN_
IN_
250mV/div
250mV/div
70
OUT_
OUT_
60
250mV/div
250mV/div
50
0.1
1
10
200ns/div
400ns/div
FREQUENCY (MHz)
_______________________________________________________________________________________
3
MAX7446
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)
MAX7446 toc09
0.3
0.2
0.1
0
-0.1
-0.2
-0.3
MAX7446 toc08
DIFFERENTIAL PHASE (DEGREES) DIFFERENTIAL GAIN (%)
INPUTS BIASED TO +2V
NO LOAD
MULTIBURST RESPONSE
DIFFERENTIAL GAIN
MAX7446 toc07
120
SUPPLY CURRENT (mA)
MAX7446
4-Channel Video Filter for RGB and CVBS Video
IN_
250mV/div
1st
2nd
3rd
4th
5th
6th
DIFFERENTIAL PHASE
OUT_
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
FUNCTION
2
INB
Channel B Video Input. Use channel B for the red (R) signal. AC-couple INB with a series 0.1µF capacitor.
3
INC
Channel C Video Input. Use channel C for the green (G) (without sync) signal. AC-couple INC with a series
0.1µF capacitor.
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
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
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 A Video Input. Use channel A for the CVBS video signal. AC-couple INA with a series 0.1µF capacitor.
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.
4
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.
_______________________________________________________________________________________
4-Channel Video Filter for RGB and CVBS Video
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 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.
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 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
CHANNEL
CLAMP LEVEL (V)
A
0.8
B
1.4
C
1.4
D
1.4
TOP VIEW
INA 1
14 OUTA
INB
2
13 OUTB
INC
3
12 OUTC
IND 4
MAX7446
11 OUTD
10 VCC
DISABLE 5
GND 6
9
GND
GND 7
8
GND
TSSOP
Chip Information
TRANSISTOR COUNT: 6300
PROCESS: BiCMOS
_______________________________________________________________________________________
5
MAX7446
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
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.
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Printed USA
is a registered trademark of Maxim Integrated Products.