Rainbow Electronics MAX7447 User Manual

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.

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 DVD Players
Game Consoles Digital VCRs
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

MAX7447

4-Channel S-Video, CVBS Video Filter with

Asynchronous CVBS Input

________________________________________________________________ Maxim Integrated Products 1

Functional Diagram

Ordering Information

19-2950; 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.

ENCODER

0.1µF

CVBS

CVBS

INA

INC

IND

LOWPASS

FILTER

INB

LOWPASS

FILTER

LOWPASS

FILTER

LOWPASS

FILTER

D/A

Y

C

0.1µF

D/A

0.1µF

D/A

0.1µF

D/A

SYNC

DETECTOR

SYNC

DETECTOR

GND

PART TEMP RANGE PIN-PACKAGE

MAX7447EUD -40°C to +85°C 14 TSSOP-EP*

V

CC

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

MAX7447

DISABLE

75Ω

OUTA

75Ω

75Ω

OUTB

75Ω

75Ω

OUTC

75Ω

75Ω

OUTD

75Ω

*OPTIONAL CAPACITORS

*

*

*

*

*

*

*

*

MAX7447

4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input

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 f = 100kHz to 5MHz, relative to 100kHz 0.9 1.2 1.5 dB

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 ≥ 27MHz 39 43 dB

SB

Peak signal (2V
f = 100Hz to 50MHz

∆t

g Deviation from 100kHz to 4.1MHz 17 30 ns

DIST

DIST

CLAMP

V ( M ATC H )

t

g(MATCH)

TALK

18µs, 100 IRE bar 0.3 %

130 lines, 18µs, 100 IRE bar 0.5 %

To ±1% 100 Lines

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 -3 +3 %

V

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, B, D 1.2

Channel C 0.9

CC

No load 100 140 mA

CC

= 100mV

IN

P-P

) to RMS noise,

P-P

CC

4.75 5.25 V

, f = 0 to 3.5MHz 40 dB

80 dB

2ns

70 mA

4%

10 µA

V

V

P-P

MAX7447

4-Channel S-Video, CVBS Video Filter with

Asynchronous CVBS Input

_______________________________________________________________________________________ 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

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 eV

D i sab l e Log i c- Inp ut Low V ol tag eV

Disable Logic-Input Current I

DISABLE

At 5MHz 2 kΩ

IH

IL

VIL = 0V (sink), VIH = VCC (source) ±10 µA

AMPLITUDE vs. FREQUENCY

0

-20

-40

AMPLITUDE (dB)

-60

NORMALIZED TO 0dB

-80
1 100

10

FREQUENCY (MHz)

MAX7447 toc01

PASSBAND AMPLITUDE vs. FREQUENCY

2.0

1.5

1.0

0.5

0

-0.5

AMPLITUDE (dB)

-1.0

-1.5

-2.0

0.1 10

HIGH-FREQUENCY BOOST

NORMALIZED TO 0dB

1

FREQUENCY (MHz)

2.0 V

PHASE RESPONSE vs. FREQUENCY

200

150

MAX7447 toc02

100

50

0

-50

PHASE (DEGREES)

-100

-150

-200

0.1 10

0.8 V

1

FREQUENCY (MHz)

MAX7447 toc03

GROUP DELAY vs. FREQUENCY

100

90

80

70

GROUP DELAY (ns)

60

50

0.1 10

1

FREQUENCY (MHz)

MAX7447 toc04

250mV/div

250mV/div

OUT-

2T RESPONSE (1 IRE = 7.14mV)

IN-

200ns/div

MAX7447 toc05

IN-

250mV/div

OUT-

250mV/div

MODULATED 12.5T RESPONSE

(1 IRE = 7.14mV)

400ns/div

MAX7447 toc06

MAX7447

4-Channel S-Video, CVBS Video Filter with
Asynchronous CVBS Input

4 _______________________________________________________________________________________

Pin Description

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.

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.

SUPPLY CURRENT vs. TEMPERATURE

MAX7447 toc07

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

603510-15

90

100

110

120

80

-40 85

INPUTS BIASED TO +2V
NO LOAD

DIFFERENTIAL GAIN

MAX7447 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

MAX7447 toc09

10µs/div

250mV/div

250mV/div

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 a C V BS video signal. AC - coup l e IN A w i th a ser i es 0.1µF cap aci tor .

2 INB

3INC

4IND

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 B Video Input. Use channel B for the luma (Y) video signal. AC-couple INB with a series 0.1µF
capacitor.

Channel C Video Input. Use channel C for the chroma (C) video signal. AC-couple INC with a series 0.1µF
capacitor.

Channel D Video Input. Use channel D for a second CVBS video 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 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 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 2V

P-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 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.

MAX7447

4-Channel S-Video, CVBS Video Filter with

Asynchronous CVBS Input

_______________________________________________________________________________________ 5

Pin Configuration

Chip Information

TRANSISTOR COUNT: 6300

PROCESS: BiCMOS

Table 1. Output Clamp Level and Sync
Source

CHANNEL CLAMP LEVEL (V) SYNC SOURCE (V)

A 0.8 Channel A

B 0.8 Channel A

C 1.6 Channel A

D 0.8 Channel D

TOP VIEW

1

INA

2

INB

3

INC

4

MAX7447

DISABLE

GND

5

6

7

TSSOP

14

OUTA

13

OUTB

12

OUTC

11

OUTDIND

V

10

CC

9

GND

GNDGND

8

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.

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