MAX7452ESA+ - MAXIM INTEGRATED PRODUCTS

General Description

The MAX7450/MAX7451/MAX7452 complete front-end

video-signal conditioners are designed to improve the

quality of standard-definition video signals. The devices

restore the DC level of the video input, correct for

amplitude errors up to ±6dB, detect fault conditions,

and filter out-of-band noise. The MAX7450/MAX7451/

MAX7452 optimize the signal quality for further video

processing through a crosspoint switch or video

decoder (ADC). Each device integrates an input video

clamp, automatic gain control (AGC), loss-of-sync

(LOS) detector, and an out-of-band noise/lowpass filter.

These devices also incorporate a user-selectable

buffer gain (0 or +6dB) and an AGC-disable function.

The MAX7450 and MAX7451 operate from dual power

supplies of ±5V or ±3.3V respectively, and they restore

the video blanking level to GND. The MAX7452 operates

from a single +5V supply and features a user-adjustable

clamp level.

The devices are available in an 8-pin SO package with

an exposed pad and are specified for operation over

the extended (-40°C to +85°C) temperature range.

Applications

Signal Conditioner for Standard-Definition

Video Inputs

Security Video Systems

Video-Switching Systems

Features

♦Back-Porch Clamp to GND (MAX7450/MAX7451)

♦Adjustable Back-Porch Clamp (MAX7452)

♦Automatic Gain Control (±6dB Range) Normalizes

Signals to Standard Video Level

♦Input Fault Detection with LOS Output

♦Inherent 50Hz/60Hz Input Rejection of 60dB

♦Single-Supply Operation: MAX7452 (+5V)

♦Out-of-Band Noise Filter

♦Output Buffer Drives Standard 150ΩVideo Load

with 0dB or +6dB Gain

♦Dual-Supply Operation

MAX7450 (±5V)

MAX7451 (±3.3V)

♦Tiny 8-Pin SO Package

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

________________________________________________________________ Maxim Integrated Products 1

Ordering Information

19-3267; Rev 2; 11/04

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.

EVALUATION KIT

AVAILABLE

PART†

TEMP RANGE

PIN-

PACKAGE

SUPPLY

VOLTAGE (V)

MAX7450ESA

-40°C to +85°C

8 SO-EP* ±5

MAX7451ESA

-40°C to +85°C

8 SO-EP* ±3.3

MAX7452ESA

-40°C to +85°C

8 SO-EP* +5

MAX7450

MAX7451

NOISE

FILTER

VSS

75Ω

LOS

SYNC SEPARATOR

AND AMPLITUDE

DETECTOR AGCD

IN OUT

VIDEO

INPUT

GND

±6dB 0 OR +6dB

GAIN SET (0dB OR +6dB)

Functional Diagram

*EP = Exposed pad.

†Package code = S8E-12.

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

2 _______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

ELECTRICAL CHARACTERISTICS

(VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL=150Ωto GND, CL = 0 to

20pF, GSET = 1, AGCD = 1, TA = TMIN to TMAX, unless otherwise noted. Typical values are at 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.

VCC to GND

MAX7450/MAX7452...........................................................+6V

MAX7451 ...........................................................................+4V

VSS to GND

MAX7450.............................................................................-6V

MAX7451.............................................................................-4V

OUT

MAX7450/MAX7451 ..........................................-2.5V to +3.5V

MAX7452................................................-0.3V to (VCC + 0.3V)

GSET, AGCD, LOS.....................................-0.3V to (VCC + 0.3V)

All Other Pins

MAX7450/MAX7451...................(-0.3V + VSS) to (VCC + 0.3V)

MAX7452................................................-0.3V to (VCC + 0.3V)

Maximum Current into Any Pin ............……………………±50mA

Continuous Power Dissipation (TA= +70°C)

8-Pin SO (derate 18.9mW/°C above +70°C)..............1509mW

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

MAX7450/MAX7451, relative to GND

±50

Clamp Accuracy MAX7452, relative VBPLVL = 1.5V

±50

GSET = 0 1.5 2.4

Back-Porch Level Input Range VBPLVL MAX7452 GSET = 1 1.2 2.0 V

Clamp Response Time tCLAMP Blanking level at the output to 1% of final

value 70

Lines

GSET = 0, relative

to VOUT = 1VP-P

±10

AGC Accuracy AGCD = 0,

VIN = 0.5VP-P to 2VP-P

GSET = 1, relative

to VOUT = 2VP-P

±10

AGC Input Range AGCD = 0, relative to VIN = 1VP-P

-6.0 +6.0

Gain Flatness GFf = 5MHz relative to 100kHz

-0.3 +0.3

Noise-Filter Cutoff Fc 10

MHz

GSET = 0

0.95

1.05

Low-Frequency Gain f = 100kHz GSET = 1

1.85

2.05

V/V

Group-Delay Deviation ΔtG3.58/4.43MHz relative to 100kHz 15 ns

Differential Gain dG

Five-step modulated staircase (VIN = 1VP-P)

0.2 0.6 %

Differential Phase dθ

Five-step modulated staircase (VIN = 1VP-P)

0.2 0.6

Degrees

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

_______________________________________________________________________________________ 3

ELECTRICAL CHARACTERISTICS (continued)

(VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL=150Ωto GND, CL = 0 to

20pF, GSET = 1, AGCD = 1, TA = TMIN to TMAX, unless otherwise noted. Typical values are at TA = +25°C.)

PARAMETER

SYMBOL

CONDITIONS

MIN TYP MAX

UNITS

GSET = 0,

VOUT = 1VP-P 68

Signal-to-Noise Ratio SNR

Output signal

peak-to-peak to RMS

noise (100Hz to 5MHz)

GSET = 1,

VOUT = 2VP-P 65

Line Time Distortion HDIST 18µs, 100 IRE bar 0.2 %

Field Time Distortion VDIST 130 lines, 18µs, 100IRE bar 0.5 %

Input Leakage Current IIN 15µA

Output Dynamic Range VIN = 1VP-P, dG / dP < 3% / degrees 2 2.4

VP-P

AGCD = 1 30

Power-Supply Rejection Ratio PSRR VCC + 100mVP-P,

f = 3.5MHz AGCD = 0 with

maximum gain 20 dB

MAX7450 35

MAX7451 30

Supply Current

MAX7452 20

Logic-High Input VIH 0.7 x

VCC

Logic-Low Input VIL 0.3 x

VCC

Logic-High Output VOH ISOURCE = 500µA VCC -

0.5 V

Logic-Low Output VOL ISINK = 500µA 0.4 V

Input Current Logic-High IIH Logic input sink 10 µA

Input Current Logic-Low IIL Logic input source 10 µA

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

4 _______________________________________________________________________________________

Typical Operating Characteristics

VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL= 150Ωto GND, CL = 0 to

20pF, GSET = 1, AGCD = 1. TA = +25°C, unless otherwise noted.

GROUP DELAY vs. FREQUENCY

MAX7450 toc01

FREQUENCY (MHz)

GROUP DELAY (ns)

0.1 10

2T RESPONSE

MAX7450 toc02

t = 200ns/div

200mV/div

OUT

200mV/div

DIFFERENTIAL GAIN

MAX7450 toc03

DIFFERENTIAL PHASE (DEGREES)

1st 3rd2nd 4th 5th 6th

DIFFERENTIAL GAIN (%)

0.2

0.4

-0.2

-0.4

0.2

0.1

0.3

-0.2

-0.1

-0.3

DIFFERENTIAL PHASE

1st 3rd2nd 4th 5th 6th

PASSBAND AMPLITUDE vs. FREQUENCY

MAX7450 toc04

FREQUENCY (MHz)

AMPLITUDE (dB)

-8

-6

-4

-2

-10

0.1 10

GAIN = 2V / V

GAIN = 1V / V

AMPLITUDE vs. FREQUENCY

MAX7450 toc05

FREQUENCY (MHz)

AMPLITUDE (dB)

110

-70

-60

-50

-40

-30

-20

-10

0.1 100

GAIN = 1V / V

GAIN = 2V / V

SUPPLY CURRENT vs. TEMPERATURE

MAX7450 toc06

TEMPERATURE (°C)

SUPPLY CURRENT (mA)

603510-15

-40 85

MAX7450

BACK-PORCH VOLTAGE

vs. TEMPERATURE

MAX7450 toc07

TEMPERATURE (°C)

BACK-PORCH VOLTAGE (mV)

603510-15

-5

-4

-3

-2

-1

-6

-40 85

MAX7450

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

_______________________________________________________________________________________ 5

MAX7450/

MAX7451 MAX7452 NAME

FUNCTION

VCC

Positive Power Supply. Connect +5V to VCC for the MAX7450/MAX7452. Connect +3.3V to VCC

for the MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible.

2 2 IN Video Input. AC-couple video signal through a 0.1µF capacitor.

GND

Ground

4—V

SS Negative Power Supply. Connect -5V to VSS for the MAX7450. Connect -3.3V to VSS for the

MAX7451. Bypass to GND with 1µF and 0.1µF capacitors as close to the pin as possible.

—4

BPLVL

Back-Porch Level Input. When gain = 2V/V (GSET = 1), output back-porch level is equal to

BPLVL input. When gain = 1V/V (GSET = 0), output back-porch level is equal to VBPLVL/1.5.

AGCD

Automatic Gain-Control Disable Input. Disable AGC by driving AGCD to VCC. Enable AGC by

driving AGCD to GND.

OUT

Video Output

GSET

Gain-Setting Input. Drive GSET high to set buffer gain to +6dB. Drive GSET low to set buffer

gain to 0dB.

LOS

Loss-of-Sync Logic Output. LOS is high when video sync is lost for more than 15 horizontal

lines. LOS goes low when video sync is present.

— — EP Exposed Pad. Connect to VSS (MAX7450/MAX7451). Connect to GND (MAX7452).

Pin Description

OUTPUT BACK-PORCH LEVEL (MAX7450)

MAX7450 toc08

1μs

AC-COUPLED

200mV/div

OUT

200mV/div BACK-PORCH = 0V

AGC RESPONSE ENVELOPE (VIN = 0.5VP-P)

MAX7450 toc09

400ms/div

500mV/div

AGCD = 0

VOUT = 2VP-P

AGC RESPONSE ENVELOPE (VIN = 2VP-P)

MAX7450 toc10

400ms/div

500mV/div

AGCD = 0

VOUT = 2VP-P

Typical Operating Characteristics (continued)

VSUPPLY = ±5V ±5% (MAX7450), VSUPPLY = ±3.3V ±5% (MAX7451), VSUPPLY = +5V ±5% (MAX7452), RL= 150Ωto GND, CL = 0 to

20pF, GSET = 1, AGCD = 1. TA = +25°C, unless otherwise noted.

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

6 _______________________________________________________________________________________

Detailed Description

As shown in Figure 1, the devices include a 2nd-order

lowpass filter intended to reject out-of-band noise. The

MAX7450/MAX7451 clamp the back-porch voltage to

ground, and the MAX7452 clamps to a user-supplied

reference voltage. These devices also include an auto-

matic gain control (AGC), which automatically adjusts

the gain to ensure the sync amplitude is normalized to

a standard video level; an AGC disable function; and

an output driver that drives a standard video load

(150Ω) with a full 2VP-P video signal (GSET = 1) or 1VP-

P video signal (GSET = 0).

The clamp and the AGC work concurrently. Interaction

between the two different control loops is eliminated by

the large difference in time constants. The time con-

stant of the clamp settles within 100 lines, while the

AGC loop is digitally stepped so that it settles between

1000–64,000 lines.

The AGC control works independently of the gain set-

ting of the output buffer. The overall gain is the multipli-

cation of the AGC gain and the output buffer gain. The

maximum overall gain is +12dB and the minimum gain

is -6dB.

Back-Porch Clamp

The MAX7450/MAX7451/MAX7452 feature a back-

porch clamp to set the output blanking level. The

devices sense the voltage during back porch and feed

back into a control system. The control system provides

the appropriate DC-level shift to clamp the output to

ground (MAX7450/MAX7451) or to a voltage set by

VBPLVL (MAX7452). This restores the DC level for fur-

ther video processing such as on-screen display (OSD)

insertion and analog-to-digital conversion. The back-

porch clamp to ground also eliminates the need for

large output-coupling capacitors that can introduce

unwanted line-time distortion (tilt) and cost. This can

also reduce board space. The feedback network and

the on-chip capacitors introduce a finite settling time

after power-up or after any dramatic shift in input volt-

age (see the Electrical Characteristics section).

Back-Porch Level Input (MAX7452)

The MAX7452 features an adjustable back-porch level

at the output as shown in Figure 1. VBPLVL sets the

back-porch clamp level. The back-porch clamp-output

level is defined by the following equations.

GSET = 1 (Gain = 2V / V), VBACKPORCHLEVEL = VBPLVL

GSET = 0 (Gain = 1V / V), VBACKPORCHLEVEL =

VBPLVL / 1.5

MAX7452

NOISE

FILTER

VCC

75Ω

LOS

SYNC SEPARATOR

AND AMPLITUDE

DETECTOR

AGCD

IN OUT

VIDEO

INPUT

BPLVL

±6dB 0 OR +6dB

GAIN SET (0dB OR +6dB)

GND

Figure1. MAX7452 Functional Diagram

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

_______________________________________________________________________________________ 7

Automatic Gain Control (AGC)

The MAX7450/MAX7451/MAX7452 have an integrated

automatic gain-control circuit to ensure the sync ampli-

tude is normalized to the standard level, thus normalizing

the overall amplitude to a standard level. The accuracy

of the normalized amplitude assumes the ratio of active

video to sync amplitude is correct in the input video sig-

nal. The gain is adjusted automatically by detecting and

comparing the amplitude of the sync pulse to a fixed

internal reference. If the sync amplitude is less than this

value, the overall gain is increased until the sync ampli-

tude equals this reference. However, if the sync ampli-

tude is high, the overall gain is reduced accordingly.

Disable the AGC loop by driving AGCD high.

When designing the overall system, it is important to note

that the AGC can correct for termination problems. First,

disable the AGC and verify that the terminations are cor-

rect, and then enable the AGC for proper operation.

Output Buffer

The output buffer of the MAX7450/MAX7451/MAX7452

is designed to drive either standard video loads or

high-impedance loads, independent of the buffer gain.

Logic levels on GSET and AGCD set the gain of the

MAX7450/MAX7451/MAX7452. Table 1 shows the dif-

ferent gain-setting configurations.

Noise Filter

The MAX7450/MAX7451/MAX7452 feature a simple 2nd-

order lowpass filter to reject out-of-band noise that may

be introduced by the long cable connection between the

cameras and the switching matrix.

LOS Detector

The LOS detector of the MAX7450/MAX7451/MAX7452

outputs a logic high when the sync is not present (loss

of video signal) for at least 15 horizontal lines on the

input. This can be used to indicate a fault condition of

the camera or cable.

Applications Information

Connecting the MAX7450/MAX7451 to a

Crosspoint Switch

The MAX7450/MAX7451/MAX7452 are designed to

directly interface to a video crosspoint switching device

such as those used in security systems (see Figure 2).

The MAX7450/MAX7451 clamp the video output to

GND, making the devices an ideal interface to the

MAX4358 crosspoint switches and the MAX4455 OSD.

The MAX7450/MAX7451 and the MAX4455 have their

outputs referenced to ground, ensuring the amplitudes

and the brightness of the OSD relative to the video

signal are accurate.

Interfacing the MAX7452 to an ADC

The MAX7452 can be directly connected to an ADC or

video decoder as shown in Figure 3. The video output

of the MAX7452 is DC-coupled to a single-ended video

input on the ADC. The voltage on the BPLVL pin sets

the black level of the video signal at the output of the

MAX7452. Use a stable voltage reference for the

BPLVL voltage, ideally the same reference that is used

AGCD GSET OUTPUT

001V

P-P fixed

012V

P-P fixed

10V

OUT = VIN

11V

OUT = 2VIN

Table 1. Gain-Control Settings

MAX7450

MAX7451

MAX7450

MAX7451

CAM 1

MAX4358

32 x 16

CROSSPOINT

MAX4455

OSD

MAX4455

OSD

CAM 32

MONITOR 1

MONITOR 16

Figure 2. MAX7450/MAX7451 in a 32 x 16 Crosspoint Application

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

8 _______________________________________________________________________________________

for the analog-to-digital conversion. This voltage must

be scaled by a ratio of two resistors to set the black

level of the video signal to the appropriate level (to

match the input range of the converter).

If the ADC or video decoder has a built-in clamp circuit,

the output of the MAX7452 must be AC-coupled into

the ADC with the capacitor value recommended for the

converter. In this situation, set the BPLVL on the

MAX7452 to the midpoint of the specified range for

optimum performance. In addition, the stability of this

voltage is not critical, provided that it stays within the

specified range.

Power-Supply Bypassing and Layout

Bypass all supply pins to GND with 0.1µF and 1µF

capacitors. These capacitors filter higher frequencies in

the MHz range. Place all external components as close to

the devices as possible. Connect EP to VSS for the

MAX7450/MAX7451. Connect EP to GND for the

MAX7452. Placing the IC onto a copper area the size of

the pad is recommended for proper power dissipation.

Refer to the MAX7450 Evaluation Kit for a proven PC-

board layout example.

Chip Information

TRANSISTOR COUNT: 6316

PROCESS: BiCMOS

MAX7452

NOISE

FILTER

VCC

VSS

LOS

SYNC SEPARATOR

AND AMPLITUDE

DETECTOR

AGCD

IN OUT

VIDEO

INPUT

BPLVL

±6dB 0 OR +6dB

GAIN SET (0dB OR +6dB)

ADC

DSP

REF

VIDEO DECODER

Figure 3. MAX7452 Interfaced to a Video Decoder

OUT

AGCD

VSS (MAX7450/MAX7451)

BPLVL (MAX7452)

LOS

GSETIN

GND

VCC

SO-EP*

TOP VIEW

*CONNECT EP TO VSS FOR THE MAX7450/MAX7451

MAX7450

MAX7451

MAX7452

Pin Configuration

MAX7450/MAX7451/MAX7452

Video-Signal Conditioners with AGC

and Back-Porch Clamp

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 _____________________ 9

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.)

8L, SOIC EXP. PAD.EPS

21-0111

PACKAGE OUTLINE

8L SOIC, .150" EXPOSED PAD