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________________general description the max976/max978/max998 dual/quad/single, high- speed, low-power comparators are optimized for +3v/+5v single-supply applications. they achieve a 20ns propagation delay while consuming only 225? supply current per comparator. the max998 features a low-power shutdown mode that places the output in a high-impedance state and reduces supply current to 1na. the max976/max978/max998 inputs have a common- mode voltage range that extends 200mv below ground. their outputs are capable of rail-to-rail operation with- out external pullup circuitry, making these devices ideal for interface with cmos/ttl logic. all inputs and out- puts can tolerate a continuous short-circuit fault condi- tion to either rail. the comparators?internal hysteresis ensures clean output switching, even with slow-moving input signals. for space-critical applications, the single max998 is available in a 6-pin sot23 package, the dual max976 is available in an 8-pin ?ax package, and the quad max978 is available in a 16-pin qsop package. ________________________applications battery-powered systems threshold detectors/discriminators 3v systems ir receivers digital line receivers ____________________________features ? single-supply operation down to 2.7v ? 20ns propagation delay ? 225a supply current ? 1na shutdown supply current ? rail-to-rail outputs ? ground-sensing inputs ? internal hysteresis ensures clean switching ? available in space-saving packages sot23 (max998) max (max976) qsop (max978) max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators ________________________________________________________________ maxim integrated products 1 top view gnd in- in+ 16 v cc 5 shdn out max998 sot23 2 34 + - __________________pin configurations v cc v cc v cc v cc r d shdn r1 r2 ir receiver out 0.1 f max998 v cc gnd ___________typical operating circuit 19-1299; rev 3; 3/09 part* max976 esa max976eua max978 ese 16 narrow so 8 ?ax 8 so pin-package sot top mark _______________ordering information pin configurations continued at end of data sheet ?ax a registered trademark of maxim integrated products, inc. max978eee max998 esa max998eut-t 6 sot23 8 so 16 qsop aaao * all devices are specified over the -40? to +85? temper- ature range. for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim's website at www.maxim-ic.com.
mv max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +2.7v to +5.5v, v cm = 0v, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) 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. supply voltage (v cc ).............................................................+6v shdn (max998) .........................................................-0.3v to 6v all other pins..............................................-0.3v to (v cc + 0.3v) current into input pins ......................................................?0ma duration of output short circuit to gnd or v cc ........continuous continuous power dissipation (t a = +70?) 6-pin sot23-6 (derate 7.1mw/? above +70?) .........571mw 8-pin ?ax (derate 4.10mw/? above +70?) ............330mw 8-pin so (derate 5.88mw/? above +70?).................471mw 16-pin narrow so (derate 8.70mw/? above +70?) ..696mw 16-pin qsop (derate 8.33mw/? above +70?)..........667mw operating temperature range ..........................-40? to +85? storage temperature range .............................-65? to +160? lead temperature (soldering, 10s) .................................+300? v cc = 5.5v max998 only, shdn = gnd i sink = 2ma v cc = 5.5v inferred from psrr test v cc = 5v (note 4) 2.7v < v cc < 5.5v conditions ma 90 out short-circuit current 74 i sh v 0.1 0.4 v ol out output-voltage low na ? ?00 i os input offset current mv v hys 0.5 1.5 4.0 input-referred hysteresis na 1 500 i sd shutdown supply current 300 650 v 2.7 5.5 v cc supply voltage range db 63 100 psrr power-supply rejection ratio units min typ max symbol parameter c load =10pf (note 6) ns 2 t skew propagation-delay skew max976/max978 only ns 1 t pd propagation-delay matching between channels sinking sourcing overdrive = 50mv ns 20 40 t pd propagation delay i source = 2ma, v cc - v oh v 0.1 0.4 v oh out output-voltage high (note 2) v -0.2 v cc - 1.2 v cmr common-mode voltage range -0.2v v cm (v cc - 1.2v) db 66 95 cmrr common-mode rejection ratio v cc = 5v (note 3) mv 0.2 ? v os input offset voltage t a = +25? t a = t min to t max ? pf input capacitance 3 c in 28 c load =10pf, v cc = 5v (note 5) overdrive = 5mv max998 only v shdn input-voltage high 0.65 x v cc v ih max998 only v shdn input-voltage low 0.2 x v cc v il max998 only, shdn = gnd, v out = 0v to v cc na out leakage current 1 200 i out max998 only na shdn input current 1 200 i shdn c load =10pf ns 1.6 t r /t f output rise/fall time max998 only, v cc = 5v, i cc = 10% of typical ? 5 t sd shutdown delay time v cc = 2.7v ? 225 i cc supply current per comparator 0.3 1.5 5.0 na i b 75 300 input bias current all others max976eua, max998eut
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = +2.7v to +5.5v, v cm = 0v, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) note 1: the max998eut specifications are 100% tested at t a = +25?. limits over the extended temperature range are guaran- teed by design, not production tested. note 2: inferred from cmrr test. either input can be driven to the absolute maximum limit without false output inversion, as long as the other input is within the common-mode voltage range. note 3: v os is defined as the mean of trip points. the trip points are the extremities of the differential input voltage required to make the comparator output change state (figure 1). note 4: the difference between the upper and lower trip points is equal to the width of the input-referred hysteresis zone (figure 1). note 5: propagation delay is guaranteed by design. for low overdrive conditions, v trip (figure 1) is added to the overdrive. note 6: propagation-delay skew is the difference between the positive-going and the negative-going propagation delay. note 7: for design purposes, the t en can be as high as 60?. conditions max998 only, v cc = 5v, i cc = 90% of typical (note 7) ? 15 t en wake-up from shutdown units min typ max symbol parameter v cc = 0v to 5v step, output valid ? 3 t pu power-up delay __________________________________________typical operating characteristics (v cc = +5v, v cm = 0v, t a = +25?, unless otherwise noted.) 125 175 275 225 325 375 -60 -20 0 -40 20406080100 supply current per comparator vs. temperature max976 toc01 temperature (?) supply current per comparator ( a) v cc = 5.5v, v out = low v cc = 5.5v, v out = high v cc = 2.7v, v out = high v cc = 2.7v, v out = low 10 30 20 50 40 70 60 80 100 90 110 -60 -20 0 -40 20 40 60 80 100 short-circuit output current vs. temperature mazx976 toc2 temperature (?) output current (ma) v cc = 5.5v, sourcing v cc = 2.7v, sourcing v cc = 5.5v, sinking v cc = 2.7v, sinking 1.6 0 0.1 1 10 100 output low voltage vs. output sink current 0.4 0.8 0.6 0.2 1.0 1.2 1.4 max976 toc03 output current (ma) output low voltage (v) v cc = 5.5v v cc = 2.7v 6 0 0.1 1 10 100 output high voltage vs. output source current 2 3 1 4 5 max976 toc04 output current (ma) output high voltage (v) v cc = 5.5v v cc = 2.7v 17 19 18 21 20 22 24 23 25 26 27 -60 -20 0 -40 20406080100 propagation delay vs. temperature mazx976 toc5 temperature (?) propagation delay (ns) v cc = 5.5v v cc = 2.7v v od = 50mv c load = 15pf 40 10 10 100 1000 propagation delay vs. capacitive load max976 toc06 capacitive load (pf) propagation delay (ns) 15 25 20 30 35 v od = 50mv
v in+ 50mv/div 10ns/div propagation delay (t pd+, v cc = 5v) v out 2v/div max976 toc13 v od = 50mv c load = 15pf 10mhz response input 50mv/div 20ns/div output 2v/div v os v cc gnd max976 toc15 v in+ 50mv/div 10ns/div propagation delay (t pd-, v cc = 5v) v out 2v/div max976 toc14 v od = 50mv c load = 15pf max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators 4 _______________________________________________________________________________________ ______________________________typical operating characteristics (continued) (v cc = +5v, v cm = 0v, t a = +25?, unless otherwise noted.) 90 80 0 1 10 100 propagation delay vs. input overdrive max976 toc07 input overdrive (mv) propagation delay (ns) 10 30 20 50 40 70 60 c load = 15pf 100 -1 2345 01 6 input bias current vs. input common-mode voltage 0.01 max976 toc10 input common-mode voltage (v) input bias current (na) 0.1 1 10 v cc = 2.7v v cc = 5.5v -2.0 -1.0 -1.5 0 -0.5 0.5 1.0 1.5 2.0 -60 -20 0 -40 20 40 60 80 100 trip points and offset voltage vs. temperature max976 toc08 temperature ( c) trip points/offset voltage (mv) v trip+ v trip- v os 40 50 60 70 80 90 100 -60 -20 -40 0 20 40 60 80 100 input bias current vs. temperature max976 toc09 temperature (?) input bias current (na) v cc = 2.7v v cc = 5.5v v in+ 50mv/div 10ns/div propagation delay (t pd+, v cc = 3v) v out 1v/div max976 toc11 v od = 50mv c load = 15pf v in+ 50mv/div 10ns/div propagation delay (t pd-, v cc = 3v) v out 1v/div max976 toc12 c load = 15pf v od = 50mv
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators _______________________________________________________________________________________ 5 max978 3 3 max976 in_+ 2 4 in_- comparator inverting input 2, 4, 6, 8 2, 4 4 2 gnd 6 1 out_ comparator output 10, 11, 14, 15 6, 7 name ground 9, 13 5 comparator noninverting input 1, 3, 5, 7 1, 3 7 6 v cc supply voltage, +2.7v to +5.5v 12, 16 8 1, 5 n.c. 8 5 shdn shutdown input. drive low for shutdown mode. drive high or con- nect to v cc for normal operation. no connection. not internally connected. function max998 pin sot23-6 so so/max so/qsop ______________________________________________________________pin description __________________ detailed description the max976/max978/max998 dual/quad/single com- parators operate from a single +2.7v to +5.5v supply. they achieve a 20ns propagation delay while consum- ing only 225? of supply current per comparator. the max998 features a low-power shutdown mode that places the output in a high-impedance state and reduces supply current to 1na. activate shutdown mode by driving shdn low. the max976/max978/max998 comparator inputs have a common-mode voltage range of -0.2v to (v cc - 1.2v). either input can be driven to the absolute maximum ratings limit without false output inversion, as long as the other input is within the common-mode voltage range. their push/pull output structure is capable of rail-to-rail operation without external pull-up circuitry, making these devices ideal for interfacing with cmos/ttl logic. all inputs and outputs can tolerate a continuous short-circuit fault condition to either supply. the comparator? internal hysteresis ensures clean out- put switching, even with slow-moving input signals. ______________________________typical operating characteristics (continued) (v cc = +5v, v cm = 0v, t a = +25?, unless otherwise noted.) shdn 2v/div 200ns/div shutdown delay time v out 2v/div max976 toc16 v in+ > v in- shdn 2v/div 5 s/div wake-up from shutdown v out 2v/div max976 toc17 v in+ > v in-
hysteresis high-speed comparators can oscillate in the linear operating region because of noise or undesired para- sitic feedback. this tends to occur when the voltage on one input is equal to or very close to the voltage on the other input. the max976/max978/max998 have inter- nal hysteresis to counter parasitic effects and noise. the hysteresis in a comparator creates two trip points: one for the rising input voltage and one for the falling input voltage (figure 1). the difference between the trip points is the hysteresis. when the comparator input voltages are equal, the hysteresis effectively causes one comparator input voltage to move quickly past the other, taking the input out of the region where oscilla- tion occurs. figure 1 illustrates the case where in- has a fixed volt- age applied and in+ is varied. if the inputs were reversed, the figure would be the same, except with an inverted output. input-stage circuitry the max976/max978/max998 input common-mode voltage range is from -0.2v to (v cc - 1.2v). the voltage range for each comparator input extends to both v cc and gnd. the output remains in the correct logic state while one or both of the inputs are within the common- mode range. if both input levels are out of the common- mode range, input-stage current saturation occurs, and the output becomes unpredictable. shutdown mode the max998 features a low-power shutdown mode, which is activated by forcing shdn low. shutdown mode reduces the supply current to 1na (typical), dis- ables the comparator, and places the output in a high- impedance state. drive shdn high to enable the comparator. do not leave shdn unconnected. since it is a high-impedance input, leaving shdn unconnected could result in indeterminate logic levels, adversely affecting comparator operation. likewise, do not three- state shdn . due to the output leakage currents of three-state devices and the small internal current for shdn , three-stating this pin could also result in indeter- minate logic levels. the maximum input voltage for shdn is 6v, referred to gnd, and is not limited by v cc . this allows the use of 5v logic to drive shdn while v cc operates at a lower voltage, such as 3v. the logic threshold limits for shdn are proportional to v cc (see electrical characteristics ). _____________ applications information circuit layout and bypassing the max976/max978/max998 have a high-gain band- width and require careful board layout. we recommend the following design guidelines: 1) use a printed circuit board with an unbroken, low- inductance ground plane. surface-mount compo- nents are recommended. 2) place a decoupling capacitor (a 0.1? ceramic capacitor is a good choice) between v cc and ground as close to the pins as possible. 3) keep lead lengths short on the inputs and outputs to avoid unwanted parasitic feedback around the comparators. 4) solder the devices directly to the printed circuit board instead of using a socket. 5) minimize input impedance. 6) for slowly varying inputs, use a small capacitor (~1000pf) across the inputs to improve stability. additional hysteresis generate additional hysteresis with three resistors using positive feedback, as shown in figure 2. this positive feedback method slows the hysteresis response time. calculate resistor values as follows: 1) select r3. the leakage current of in+ is typically 75na, so the current through r3 should be at least 1.0? to minimize errors caused by leakage current. the current through r3 at the trip point is (v ref - v out ) / r3. consider the two possible output states when solving for r3. the two formulas are: r3 = v ref / 1.0? or r3 = (v cc - v ref ) / 1.0? use the smaller of the two resulting resistor values. for example, if v ref = 1.2v and v cc = 5.0v, the two resistor values are 1.2m and 3.8m . choose a standard value for r3 of 1.2m . max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators 6 _______________________________________________________________________________________ v ol v oh v in- = 0 v os = v trip+ + v trip- 2 comparator output v trip+ v in+ v hyst v trip- figure 1. input and output waveforms, noninverting input varied
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators _______________________________________________________________________________________ 7 2) choose the hysteresis band required (v hb ). for this example, choose 100mv. 3) calculate r1. r1 = r3 x (v hb / v cc ). plugging in the values for this example, r1 = 1.2m x (100mv / 5.0v) = 24k 4) choose the trip point for v in rising. this is the threshold voltage at which the comparator switches from low to high as v in rises above the trip point. in this example, choose 3.0v. 5) calculate r2 as follows: choose a standard value for r2 of 16k . 6) verify the trip voltage and hysteresis as follows: ir receiver the typical operating circuit shows an application using the max998 as an infrared receiver. the infrared photo- diode creates a current relative to the amount of infrared light present. this current creates a voltage across r d . when this voltage level crosses the voltage applied by the voltage divider to the inverting input, the output transitions. window comparator the max976 is ideal for making a window detector (undervoltage/overvoltage detector). the schematic shown in figure 3 uses a max6120 reference and com- ponent values selected for a 2.0v undervoltage thresh- old and a 2.5v overvoltage threshold. choose different thresholds by changing the values of r1, r2, and r3. outa provides an active-low undervoltage indication, and outb gives an active-low overvoltage indication. anding the two outputs provides an active-high, power-good signal. the design procedure is as follows: 1) select r1. the leakage current into inb- is normally 75na, so the current through r1 should exceed 1.0? for the thresholds to be accurate. r1 values in the 50k to 100k range are typical. 2) choose the overvoltage threshold (v oth ) when v in is rising, and calculate r2 and r3 with the following formula: r sum = r2 + r3 = r1 x [v oth / (v ref + v h ) - 1] where v h = 1/2v hyst . 3) choose the undervoltage threshold (v uth ) when v in is falling, and calculate r2 with the following formula: r2 = (r1 + r sum ) x [(v ref - v h ) / v uth ] - r1 where v h = 1/2v hyst . 4) calculate r3 with the following formula: r3 = (r sum ) - r2 5) verify the resistor values. the equations are as follows: v oth = (v ref + v h ) x (r1 + r2 + r3) / r1 v uth = (v ref - v h ) x (r1 + r2 + r3) / (r1 + r2) v rising: v = v x r1 x 1 r1 v falling in thr ref in : ++ ? ? ? ? ? ? =? ? ? ? ? ? ? =? 1 2 1 3 1 3 rr vv rxv r hysteresis v v thf thr cc thr thf r2 = 1 v v x r1 1 r1 1 r3 r2 = 1 3.0v 1.2 x 24k 1 24k 1 1.2m 16.2k thr ref ? ? ? ? ? ? ?? ? ? ? ? ? ? ?? = ? v cc max976 max978 max998 out 0.1 f r3 r1 r2 v ref gnd v in v cc figure 2. additional hysteresis 3 1 3 4 r3 82.1k 1% v cc v in r2 24.9k 1% r1 100k 1% 2 6 overvoltage undervoltage power good 1/2 max976 max6120 1 2 v cc 8 7 5 0.1 f 1/2 max976 figure 3. window comparator
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators 8 _______________________________________________________________________________________ ______________________________________________pin configurations (continued) max976 top view + - + - 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 ina+ v cc outa outb gnd v cc outc outd gnd so/qsop ina- inb+ inc- inb- inc+ ind+ ind- max978 + - + - + - + - out n.c. gnd 1 2 8 7 shdn v cc in- in+ n.c. so 3 4 6 5 max998 - + outb gnd inb- 1 2 8 7 v cc outa ina- inb+ ina+ so/ max 3 4 6 5 ___________________chip information process: cmos
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators _______________________________________________________________________________________ 9 6lsot.eps package outline, sot 6l body 21-0058 2 1 i package information for the latest package outline information and land patterns, go to www.maxim-ic.com/packages . package type package code document no. 8 so s8-2 21-0041 16 so s16m-3 21-0041 16 qsop e16m-1 21-0055 6 sot23 u6-2 21-0058 8 ?ax u8-1 21-0036
max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators 10 ______________________________________________________________________________________ package outline, sot 6l body 21-0058 2 2 i package information (continued) for the latest package outline information and land patterns, go to www.maxim-ic.com/packages .
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 ____________________ 11 2009 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. max976/max978/max998 single/dual/quad, sot23, single-supply, high-speed, low-power comparators revision history revision number revision date description pages changed 0 10/97 initial release 1 1/98 adding specs for max998 2 1/07 adding input current ratings to abs max 3 3/09 update chip information, package info, correct unit measurement in toc 8, style changes 1, 3, 4, 8

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