Datasheet MAX7448 Datasheet (MAXIM)

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General Description

The MAX7448, 4-channel, buffered video reconstruc­tion filter is ideal for anti-aliasing and digital-to-analog
converter (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 standard­definition 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-fre­quency 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.

Applications

Set-Top Boxes/HDRs DVD Players

Game Consoles Digital VCRs

Desktop Video Editors

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

MAX7448

4-Channel RGB Video Filter with

Asynchronous CVBS Input

________________________________________________________________ Maxim Integrated Products 1

Functional Diagram

Ordering Information

19-2989; Rev 0; 10/03

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.

EVALUATION KIT

AVAILABLE

Pin Configuration appears at end of data sheet.

PART TEMP RANGE PIN-PACKAGE

MAX7448EUD -40°C to +85°C 14 TSSOP-EP*

*

*

*

*

*

*

*

*

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

(WITH SYNC)

CVBS

(WITH SYNC)

ENCODER

G

D/A

D/A

R

D/A

B

D/A

0.1µF

0.1µF

0.1µF

0.1µF

INA

INB

INC

IND

LOWPASS

FILTER

LOWPASS

FILTER

LOWPASS

FILTER

LOWPASS

FILTER

V

CC

SYNC

DETECTOR

SYNC

DETECTOR

MAX7448

GND

DISABLE

OUTA

OUTB

OUTC

OUTD

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

75Ω

*OPTIONAL CAPACITORS

MAX7448

4-Channel RGB Video Filter with
Asynchronous CVBS Input

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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, C

IN_

= 0.1µF,

GAIN = +6dB,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

)

Passband Response

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 Degrees

Signal-to-Noise Ratio SNR

Group Delay Deviation ∆tg

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

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

f = 100kHz to 5MHz,
relative to 100kHz

f ≥ 27MHz 39 43 dB

SB

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

Deviation from 100kHz
to 4.1MHz

DIST

DIST

CLAMP

V(MATCH

g(MATCH)

t

TALK

SC

CC

CC

18µs, 100 IRE bar 0.3 %

130 lines, 18µs, 100 IRE bar 0.5 %

To ±1% 100 Lines

Channels A, D 0.6 0.9 1.1

Channels B, C 1.1 1.5 1.8

f = 100kHz -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

IN

Channels A, D 1.2

Channels B, C 0.9

No load 100 140 mA

= 100mV

IN

Channels A, B, C +0.75 +0.15 +0.75

Channel D +0.9 +1.2 +1.5

) to RMS noise,

P-P

Channels A, B, C 11 20

Channel D 17 30

CC

4.75 5.25 V

, f = 0 to 3.5MHz 40 dB

P-P

80 dB

4%

2ns

70 mA

10 µA

dB

ns

V

V

P-P

MAX7448

4-Channel RGB Video Filter with

Asynchronous CVBS Input

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VCC= +5V ±5%, CL= 0 to 20pF, RL= 75Ω to GND for DC-coupled load, RL= 75Ω to VCC/ 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 VCC= +5V, TA= +25°C.)

Typical Operating Characteristics

(VCC= +5V, TA = +25°C, unless otherwise noted.)

AMPLITUDE vs. FREQUENCY

MAX7448 toc01

FREQUENCY (MHz)

AMPLITUDE (dB)

10

-80

-60

-40

-20

0

1 100

NORMALIZED TO 0dB

PASSBAND AMPLITUDE vs. FREQUENCY

FREQUENCY (MHz)

AMPLITUDE (dB)

1

-1.5

-1.0

-0.5

0

0.5

1.0

1.5

2.0

-2.0

0.1 10

MAX7448 toc02

NORMALIZED TO 0dB

FLAT PASSBAND RESPONSE

HIGH-FREQUENCY BOOST

PHASE RESPONSE vs. FREQUENCY

MAX7448 toc03

FREQUENCY (MHz)

PHASE (DEGREES)

1

-150

-100

-50

0

50

100

150

200

-200

0.1 10

DISABLE

Output Impedance during
Disable

Disable Logic-Input High Voltage V

Disable Logic-Input Low Voltage V

Disable Logic-Input Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

Z

DISABLE

DISABLEVIL

At 5MHz 2 kΩ

IH

IL

= 0V (sink), VIH = V

(source) ±10 µA

CC

2.0 V

0.8 V

MAX7448

4-Channel RGB Video Filter with
Asynchronous CVBS Input

4 _______________________________________________________________________________________

Typical Operating Characteristics (continued)

(VCC= +5V, TA = +25°C, unless otherwise noted.)

GROUP DELAY vs. FREQUENCY

100

2T RESPONSE (1 IRE = 7.14mV)

MAX7448 toc05

MODULATED 12.5T RESPONSE

(1 IRE = 7.14mV)

MAX7448 toc06

90

80

70

GROUP DELAY (ns)

60

50

0.1 10
FREQUENCY (MHz)

SUPPLY CURRENT vs. TEMPERATURE

120

INPUTS BIASED TO +2V
NO LOAD

110

100

SUPPLY CURRENT (mA)

90

80

-40 85
TEMPERATURE (°C)

MAX7448 toc04

1

IN_

250mV/div

OUT_

250mV/div

200ns/div

DIFFERENTIAL GAIN

0.3

0.2

MAX7448 toc07

0.1
0

-0.1

-0.2

-0.3

DIFFERENTIAL GAIN (%)

2nd1st 3rd 4th

5th

6th

250mV/div

250mV/div

MAX7448 toc08

250mV/div

IN_

OUT_

IN_

400ns/div

MULTIBURST RESPONSE

MAX7448 toc09

DIFFERENTIAL PHASE

0.3

0.2

0.1
0

-0.1

-0.2

603510-15

-0.3
2nd1st 3rd 4th

DIFFERENTIAL PHASE (DEGREES)

5th

6th

OUT_

250mV/div

10µs/div

MAX7448

4-Channel RGB Video Filter with

Asynchronous CVBS Input

_______________________________________________________________________________________ 5

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 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 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 tim­ing 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 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 D (CVBS
video signal) increases image sharpness by compensat­ing for signal degradation and rolloff in the video encoder.
Channels A, B, and C 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 2V

P-P

signal. The
MAX7448 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.

Pin Description

PIN NAME FUNCTION

1 INA

2 INB

3 INC

4 IND

5 DISABLE

6–9 GND Ground

10 V

11 OUTD Channel D Buffer Output. This output can be either AC- or DC-coupled.

12 OUTC Channel C Buffer Output. This output can be either AC- or DC-coupled.

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.

+5V Supply Input

CC

MAX7448

4-Channel RGB Video Filter with
Asynchronous CVBS Input

6 _______________________________________________________________________________________

Output Clamp Level

When a sync pulse is detected on channel A, the DC
restore loop is activated for channel 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 the specified level of
the signal type (R, G, B, CVBS). See Table 1 for clamp
levels and sync sources.

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 MAX7448 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.

Pin Configuration

Chip Information

TRANSISTOR COUNT: 6300

PROCESS: BiCMOS

Table 1. Output Clamp Level and Sync
Source

CHANNEL

A 0.9 Channel A

B 1.5 Channel A

C 1.5 Channel A

D 0.9 Channel D

CLAMP LEVEL

(V)

SYNC SOURCE

TOP VIEW

INA

INB

INC

DISABLE

GND

1

2

3

4

MAX7448

5

6

7

TSSOP

14

OUTA

13

OUTB

12

OUTC

11

OUTDIND

V

10

CC

9

GND

GNDGND

8

MAX7448

4-Channel RGB 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.

Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 _____________________ 7

© 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

PACKAGE OUTLINE, TSSOP, 4.40 MM BODY
EXPOSED PAD

21-0108

1

C

1