MAX7461EUK+T - Maxim Integrated Products, Inc.

General Description

The MAX7461 single-channel loss-of-sync alarm (LOS)

provides composite video sync detection in NTSC,

PAL, and SECAM standard-definition television (SDTV)

systems. The MAX7461’s advanced detection circuitry

delivers robust performance by preventing false loss-

of-sync alarms due to noise. The device accepts an

AC-coupled composite (CVBS), luma (Y), or any other

video signal with sync, and outputs a logic-level signal.

The open-drain LOS output is low when no sync is

detected and high impedance when sync is detected.

The device operates from a single +5V supply.

The MAX7461 is available in a 5-pin SOT23 package

and is specified for operation over the -40°C to +85°C

temperature range.

Applications

Security Systems

Automotive Rear Seat Entertainment (RSE)

Systems

Consumer Electronics

Features

♦Accepts CVBS, Y, or Any Other Video with Sync

♦Loss-of-Sync Alarm Output

♦Robust Performance in Noisy Environments

♦Wire-OR Alarm Output

♦NTSC, PAL, and SECAM

♦Small 5-Pin SOT23 Package

MAX7461

Loss-of-Sync Alarm

________________________________________________________________ Maxim Integrated Products 1

19-0553; Rev 0; 5/06

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.

Ordering Information

PART

TEMP RANGE

PIN-

PACKAGE

CODE

MAX7461EUK

-40°C to +85°C

5 SOT23-5 U5-2

GND

LOSGND

15V

MAX7461

SOT23-5

TOP VIEW

Pin Configuration

CLAMP LPF

SYNC

DETECTOR

GND

LOS

75Ω

+5V

0.1µF

VCC

SYNC

SLICE

LEVEL

LOS

FILTER

VCC

0.1µF

1kΩ

SYNC

CIN IN

MAX7461

Functional Diagram

MAX7461

Loss-of-Sync Alarm

2_______________________________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

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..............................................................-0.3V to +6V

LOS to GND..............................................................-0.3V to +6V

IN to GND.................-0.3V to the lower of +6V and (VCC + 0.3V)

Continuous Power Dissipation (TA= +70°C)

5-Pin SOT23-5 (derate 7.1mW/°C above +70°C) ......571.0mW

Maximum Current Into Any Pin .........................................±50mA

Operating Temperature Range

MAX7461EUK ...................................................-40°C to +85°C

Storage Temperature Range .............................-65°C to +150°C

Lead Temperature (soldering, 10s) .................................+300°C

Junction Temperature......................................................+150°C

ELECTRICAL CHARACTERISTICS

(VCC = +4.5V to +5.5V, GND = 0, CIN = 0.1µF, RO = 500Ω, TA = -40°C to +85°C, unless otherwise noted. Typical values are at TA=

+25°C.)

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

AC CHARACTERISTICS

Minimum Input Sync Height

VIN-MIN

AC-coupled (Note 1) 105 130

mVP-P

Maximum Input Voltage

VIN-MAX

AC-coupled 2.4

VP-P

LOS Release Time tRT (Note 2) 1.7 2.2 2.7

LOS Detect Time tDT (Note 3) 1.9 3.4 4.9 ms

DIGITAL CHARACTERISTICS

Output Low Voltage VOL ISINK = 10mA 0.4 V

Logic High Leakage Current IOLEAK 1µA

POWER REQUIREMENTS

Supply Voltage VCC 4.5 5.0 5.5 V

Supply Current ICC 1.7 2.2 mA

Power-Supply Noise Immunity VPSNI 0 to 5MHz sinusoid on VCC (Note 4) 200

mVP-P

Note 1: Minimum input sync height is the voltage above which LOS is guaranteed to be in high-impedance mode after the maximum

LOS time-constant time.

Note 2: LOS release time is the time that the video input must be continuously present before LOS goes high (inactive state).

Note 3: The LOS detect time is the time that the video input must be continuously absent before LOS goes low (active state).

Note 4: The MAX7461 LOS output is accurate with a power-supply noise level below VPSNI.

MAX7461

Loss-of-Sync Alarm

_______________________________________________________________________________________ 3

500mV/div

t = 10ms/div

CVSB LOS ALERT TRANSIENT

MAX7461 toc01

LOS

5V/div

3.0

2.5

2.0

1.5

1.0

4.5 4.94.7 5.1 5.3 5.5

LOS DETECT TIME

vs. SUPPLY VOLTAGE

MAX7461 toc02

SUPPLY VOLTAGE (V)

TIME (ms)

4.0

3.5

3.0

2.5

2.0

4.5 4.94.7 5.1 5.3 5.5

LOS RELEASE TIME

vs. SUPPLY VOLTAGE

MAX7461 toc03

SUPPLY VOLTAGE (V)

TIME (ms)

0.20

0.15

0.10

0.05

4.5 4.94.7 5.1 5.3 5.5

SYNC HEIGHT LOS ALERT THRESHOLD

vs. SUPPLY VOLTAGE

MAX7461 toc04

SUPPLY VOLTAGE (V)

SYNC HEIGHT (V)

1.6

1.8

1.7

1.9

2.0

-40 0-20 20 40 60 80

SUPPLY CURRENT

vs. TEMPERATURE (CVBS INPUT)

MAX7461 toc05

TEMPERATURE (°C)

ICC (mA)

Typical Operating Characteristics

(VCC = 5V, GND = 0, CIN = 0.1µF, RO = 10kΩ, TA= +25°C, unless otherwise noted.)

MAX7461

Detailed Description

The MAX7461 single-channel LOS alarm is ideal for any

video system needing to verify the presence of a video

source. The device accepts an AC-coupled CVBS, Y,

or any video signal with sync, and pulls LOS low when

no composite sync signal is detected for more than the

LOS detect time (3.4ms, typ) at the input (IN).

Clamp

The MAX7461 features an input clamp that corrects any

DC shift, on a line-by-line basis. The external AC-cou-

pling capacitor provides DC isolation for the input.

Lowpass Filter

The MAX7461 integrates a lowpass filter for enhanced

sync detection. The lowpass filter prevents false sync

detection by reducing color burst, chroma, and noise.

Sync Detector/LOS Filter

The sync detector looks for sync pulses greater than

the minimum sync voltage (0.13VP-P). If the detector

does not detect any sync pulses for 3.4ms (typ), the

LOS filter pulls LOS low. After detecting sync for at

least 2.2ms (typ), the LOS filter returns LOS to a high-

impedance state. LOS is an open-drain output.

Connect a 1kΩpullup resistor between LOS and VCC.

Power-On Reset (POR)

At power-up, LOS is pulled low and the MAX7461

checks for 2.2ms (typ) of valid sync pulses before

releasing LOS.LOS remains high impedance while a

valid sync signal is detected at the input.

Applications Information

Input Considerations

Use 0.1µF ceramic capacitors to AC-couple the input.

The input cannot be DC-coupled. The input capacitor

stores a DC level so that the video signal is clamped to

an appropriate DC voltage for proper sync detection.

Power-Supply Bypassing

Careful PC board layout is important for optimal system

performance. Do not use wire-wrapped boards or

breadboards. When possible, use a multilayer board

with a dedicated low-inductance ground plane and

supply plane. Connect all GND inputs to a single

ground plane and VCC to a single-supply plane.

Bypass VCC to GND with a 0.1µF capacitor.

Wired-OR Application

The LOS open-drain output allows the MAX7461 to be

used in wired-OR applications as shown in the automo-

tive RSE typical application diagram of Figure 1.

Chip Information

PROCESS: BiCMOS

Loss-of-Sync Alarm

4_______________________________________________________________________________________

Pin Description

PIN NAME FUNCTION

1IN

Video Input. Accepts CVBS, luma (Y), or any video input with sync. AC-couple IN with a series 0.1µF

capacitor.

2, 3 GND Ground

4LOS

Loss-Of-Sync Output (Open Drain). LOS is in high impedance when sync pulses are detected, and is

pulled low when no horizontal sync signal is detected for more than the LOS detect time. LOS returns

high when sync pulses are detected for more than the LOS release time. Connect a 1kΩ pullup resistor

from LOS to VCC.

CC Power-Supply Input. Bypass to GND with a 0.1µF capacitor.

MAX7461

Loss-of-Sync Alarm

_______________________________________________________________________________________ 5

MONITOR 1

µC

SWITCH

MATRIX

AND

PROCESSING

MONITOR N

75Ω

CAMERA

RGB VIDEO SOURCE

TUNER

75Ω

1kΩ

0.1µF

VCC

MAX7461

Figure 1. Automotive RSE System

MAX7461

Loss-of-Sync Alarm

6_______________________________________________________________________________________

MONITOR 1

µC

SWITCH

MATRIX

AND

PROCESSING

MONITOR N

75Ω

1kΩ

75Ω

0.1µF

CAM 1

VCC

CAM 2

CAM N

MAX7461

Figure 2. Video Security System

MAX7461

Loss-of-Sync Alarm

Boblet

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

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.)

SOT-23 5L .EPS

21-0057

PACKAGE OUTLINE, SOT-23, 5L