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? 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? to +85? 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? website at www.maxim-ic.com. ordering information part temp range pin- package package code MAX7461euk -40? to +85? 5 sot23-5 u5-2 gnd los gnd 15v cc in MAX7461 sot23-5 top view 2 34 pin configuration clamp lpf sync detector gnd los 75 ? +5v 0.1 f v cc sync slice level los filter v cc 0.1 f 1k ? 1 5 3 4 sync c in in ro MAX7461 functional diagram
MAX7461 loss-of-sync alarm 2 _______________________________________________________________________________________ absolute maximum ratings stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. v cc to gnd ..............................................................-0.3v to +6v los to gnd..............................................................-0.3v to +6v in to gnd.................-0.3v to the lower of +6v and (v cc + 0.3v) continuous power dissipation (t a = +70?) 5-pin sot23-5 (derate 7.1mw/? above +70?) ......571.0mw maximum current into any pin .........................................?0ma operating temperature range MAX7461euk ...................................................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? junction temperature ......................................................+150? electrical characteristics (v cc = +4.5v to +5.5v, gnd = 0, c in = 0.1?, ro = 500 ? , t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) parameter symbol conditions min typ max units ac characteristics minimum input sync height v in-min ac-coupled (note 1) 105 130 mv p-p maximum input voltage v in-max ac-coupled 2.4 v p-p los release time t rt (note 2) 1.7 2.2 2.7 los detect time t dt (note 3) 1.9 3.4 4.9 ms digital characteristics output low voltage v ol i sink = 10ma 0.4 v logic high leakage current i oleak 1 a power requirements supply voltage v cc 4.5 5.0 5.5 v supply current i cc 1.7 2.2 ma power-supply noise immunity v psni 0 to 5mhz sinusoid on v cc (note 4) 200 mv p-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 v psni .
MAX7461 loss-of-sync alarm _______________________________________________________________________________________ 3 in 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 4.9 4.7 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 4.9 4.7 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 0 4.5 4.9 4.7 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) i cc (ma) t ypical operating characteristics (v cc = 5v, gnd = 0, c in = 0.1?, ro = 10k ? , t a = +25?, 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 (0.13v p-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 1k ? pullup resistor between los and v cc . 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 0.1? 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 v cc to a single-supply plane. bypass v cc to gnd with a 0.1? 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 0.1? capacitor. 2, 3 gnd ground 4 los 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 1k ? pullup resistor from los to v cc . 5v cc power-supply input. bypass to gnd with a 0.1? capacitor.
MAX7461 loss-of-sync alarm _______________________________________________________________________________________ 5 monitor 1 c switch matrix and processing monitor n 75 ? camera rgb video source tv tuner 75 ? 75 ? 1k ? 0.1 f 0.1 f 0.1 f v cc MAX7461 MAX7461 MAX7461 figure 1. automotive rse system
MAX7461 loss-of-sync alarm 6 _______________________________________________________________________________________ monitor 1 c switch matrix and processing monitor n 75 ? 75 ? 1k ? 1k ? 1k ? 75 ? 0.1 f 0.1 f 0.1 f cam 1 n 1 v cc v cc v cc cam 2 cam n MAX7461 MAX7461 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 circu it 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 2006 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation, go to www.maxim-ic.com/packages .) sot-23 5l .eps e 1 1 21-0057 package outline, sot-23, 5l
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