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 ?db, 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 ?v or ?.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 150 ? video load with 0db or +6db gain ? dual-supply operation MAX7450 (5v) max7451 (3.3v) ? tiny 8-pin so package MAX7450/max7451/max7452 v ideo-signal conditioners with agc and back-porch clamp ________________________________________________________________ maxim integrated products 1 ordering information 19-3267; rev 1; 6/04 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. part ? temp range pin- package supply voltage (v) MAX7450 esa -40 c to +85 c8 so-ep** 5 max7451 esa* -40 c to +85 c8 so-ep** 3.3 max7452 esa -40 c to +85 c8 so-ep** +5 MAX7450 max7451 noise filter v cc v ss 75 ? 75 ? los sync separator and amplitude detector agcd in out video input gnd 6db 0 or +6db gain set (0db or +6db) functional diagram * future product?ontact factory for availability. ** ep = exposed pad. ? package code = s8e-12.
MAX7450/max7451/max7452 v ideo-signal conditioners with agc and back-porch clamp 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v supply = ?v ?% (MAX7450), v supply = ?.3v ?% (max7451), v supply = +5v ?% (max7452), r l =150 ? to gnd, c l = 0 to 20pf, gset = 1, agcd = 1, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) 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 MAX7450/max7452...........................................................+6v max7451 ...........................................................................+4v v ss to gnd MAX7450.............................................................................-6v max7451.............................................................................-4v out MAX7450/max7451 ..........................................-2.5v to +3.5v max7452 ................................................-0.3v to (v cc + 0.3v) gset, agcd, los .....................................-0.3v to (v cc + 0.3v) all other pins MAX7450/max7451...................(-0.3v + v ss ) to (v cc + 0.3v) max7452 ................................................-0.3v to (v cc + 0.3v) maximum current into any pin ............?0ma continuous power dissipation (t a = +70?) 8-pin so (derate 18.9mw/? above +70?)..............1509mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? junction temperature ......................................................+150? lead temperature (soldering, 10s) ..................................+300? parameter symbol conditions min typ max units MAX7450/max7451, relative to gnd ?0 clamp accuracy max7452, relative v bplvl = 1.5v ?0 mv gset = 0 1.0 3.0 back-porch level input range v bplvl max7452 gset = 1 1.2 2.4 v clamp response time t clamp blanking level at the output to 1% of final value 70 lines gset = 0, relative to v out = 1v p-p ?0 agc accuracy agcd = 0, v in = 0.5v p-p to 2v p-p gset = 1, relative to v out = 2v p-p ?0 % agc input range agcd = 0, relative to v in = 1v p-p -6.0 +6.0 db gain flatness g f f = 5mhz relative to 100khz -0.3 +0.3 db noise-filter cutoff fc 10 mhz gset = 0 0.95 1 1.05 low-frequency gain f = 100khz gset = 1 1.85 2 2.05 v/v group-delay deviation ? t g 3.58/4.43mhz relative to 100khz 15 ns differential gain dg five-step modulated staircase (v in = 1v p-p ) 0.2 0.6 % differential phase d
MAX7450/max7451/max7452 v ideo-signal conditioners with agc and back-porch clamp _______________________________________________________________________________________ 3 electrical characteristics (continued) (v supply = ?v ?% (MAX7450), v supply = ?.3v ?% (max7451), v supply = +5v ?% (max7452), r l =150 ? to gnd, c l = 0 to 20pf, gset = 1, agcd = 1, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) parameter symbol conditions min typ max units gset = 0, v out = 1v p-p 68 signal-to-noise ratio snr output signal peak-to-peak to rms noise (100hz to 5mhz) gset = 1, v out = 2v p-p 65 db line time distortion h dist 18?, 100 ire bar 0.2 % field time distortion v dist 130 lines, 18?, 100ire bar 0.5 % input leakage current i in 15 a output dynamic range v in = 1v p-p , dg / dp < 3% / degrees 2 2.4 v p-p agcd = 1 30 power-supply rejection ratio psrr v cc + 100mv p-p , f = 3.5mhz agcd = 0 with maximum gain 20 db MAX7450 35 supply current max7452 20 ma logic-high input v ih 0.7 x v cc v logic-low input v il 0.3 x v cc v logic-high output v oh i source = 500? v cc - 0.5 v logic-low output v ol i sink = 500? 0.4 v input current logic-high i ih logic input sink 10 a input current logic-low i il logic input source 10 a
MAX7450/max7451/max7452 v ideo-signal conditioners with agc and back-porch clamp 4 _______________________________________________________________________________________ t ypical operating characteristics v supply = ?v ?% (MAX7450), v supply = ?.3v ?% (max7451), v supply = +5v ?% (max7452), r l = 150 ? to gnd, c l = 0 to 20pf, gset = 1, agcd = 1. t a = +25 c, unless otherwise noted. group delay vs. frequency MAX7450 toc01 frequency (mhz) group delay (ns) 1 20 30 40 50 60 10 0.1 10 2t response MAX7450 toc02 t = 200ns/div in 200mv/div out 200mv/div differential gain MAX7450 toc03 differential phase (degrees) 1st 3rd 2nd 4th 5th 6th differential gain (%) 0.2 0.4 0 -0.2 -0.4 0.2 0.1 0.3 0 -0.2 -0.1 -0.3 differential phase 1st 3rd 2nd 4th 5th 6th passband amplitude vs. frequency MAX7450 toc04 frequency (mhz) amplitude (db) 1 -8 -6 -4 -2 0 2 4 6 8 -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 10 0.1 100 gain = 1v / v gain = 2v / v supply current vs. temperature MAX7450 toc06 temperature ( c) supply current (ma) 60 35 10 -15 27 29 31 33 35 25 -40 85 MAX7450 back-porch voltage vs. temperature MAX7450 toc07 temperature ( c) back-porch voltage (mv) 60 35 10 -15 -5 -4 -3 -2 -1 0 -6 -40 85 MAX7450
MAX7450/max7451/max7452 v ideo-signal conditioners with agc and back-porch clamp _______________________________________________________________________________________ 5 pin MAX7450/ max7451 max7452 name function 11 v cc positive power supply. connect +5v to v cc for the MAX7450/max7452. connect +3.3v to v cc for the max7451. bypass to gnd with 1? and 0.1? capacitors as close to the pin as possible. 22 in video input. ac-couple video signal through a 0.1? capacitor. 33 gnd ground 4 v ss negative power supply. connect -5v to v ss for the MAX7450. connect -3.3v to v ss for the max7451. bypass to gnd with 1? and 0.1? capacitors as close to the pin as possible. ? 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 v bplvl /1.5. 55 agcd automatic gain-control disable input. disable agc by driving agcd to v cc . enable agc by driving agcd to gnd. 66 out video output 77 gset gain-setting input. drive gset high to set buffer gain to +6db. drive gset low to set buffer gain to 0db. 88 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 v ss (MAX7450/max7451). connect to gnd (max7452). pin description output back-porch level (MAX7450) MAX7450 toc08 1 s in ac-coupled 200mv/div out 200mv/div back-porch = 0v agc response envelope (v in = 0.5v p-p ) MAX7450 toc09 400ms/div 500mv/div agcd = 0 v out = 2v p-p agc response envelope (v in = 2v p-p ) MAX7450 toc10 400ms/div 500mv/div agcd = 0 v out = 2v p-p t ypical operating characteristics (continued) v supply = ?v ?% (MAX7450), v supply = ?.3v ?% (max7451), v supply = +5v ?% (max7452), r l = 150 ? to gnd, c l = 0 to 20pf, gset = 1, agcd = 1. t a = +25 c, unless otherwise noted.
MAX7450/max7451/max7452 v ideo-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 (150 ? ) with a full 2v p-p video signal (gset = 1) or 1v p- 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?4,000 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 v bplvl (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. v bplvl sets the back-porch clamp level. the back-porch clamp-output level is defined by the following equations. gset = 1 (gain = 2v / v), v backporchlevel = v bplvl gset = 0 (gain = 1v / v), v backporchlevel = v bplvl / 1.5 max7452 noise filter v cc 75 ? 75 ? 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 v ideo-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 = v in 11v out = 2v in 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 v ideo-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 0.1? and 1? capacitors. these capacitors filter higher frequencies in the mhz range. place all external components as close to the devices as possible. connect ep to v ss 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 v cc v ss 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 v ss (MAX7450/max7451) bplvl (max7452) 1 2 8 7 los gset in gnd v cc so-ep* top view *connect ep to v ss for the MAX7450/max7451 3 4 6 5 MAX7450 max7451 max7452 pin configuration
MAX7450/max7451/max7452 v ideo-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 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 _____________________ 9 2004 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 info rmation, go to www.maxim-ic.com/packages .) 8l, soic exp. pad.eps b 1 1 21-0111 package outline 8l soic, .150" exposed pad
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