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general description the max4291/max4292/max4294 family of micropow- er operational amplifiers operates from a 1.8v to 5.5v single supply or ?.9v to ?.75v dual supplies and has rail-to-rail input/output capabilities. these amplifiers provide a 500khz gain-bandwidth product and 120db open-loop voltage gain while using only 100? of sup- ply current per amplifier. the combination of low input offset voltage (?00?) and high open-loop gain makes them ideal for low-power/low-voltage, high-precision portable applications. the max4291/max4292/max4294 have an input com- mon-mode range that extends to each supply rail, and their outputs swing to within 46mv of the rails with a 2k ? load. although the minimum operating voltage is speci- fied at 1.8v, these devices typically operate down to 1.5v. the combination of ultra-low-voltage operation, rail- to-rail inputs/output, and low-power consumption makes these devices ideal for any portable/two-cell battery-pow- ered system. the single max4291 is offered in an ultra-small 5-pin sc70 package. the dual max4292 is offered in a space-saving 8-bump, 1.5mm x 1.5mm footprint, ultra chip-scale package (ucsp). applications 2-cell battery-operated systems portable electronic equipment battery-powered instrumentation digital scales strain gauges sensor amplifiers cellular phones features ultra-low voltage operation?uaranteed down to 1.8v 100? supply current per amplifier 500khz gain-bandwidth product 120db open-loop voltage gain (r l = 100k ? ) 0.017% total harmonic distortion plus noise (thd + n) at 1khz rail-to-rail input common-mode range rail-to-rail output drives 2k ? load no phase reversal for overdriven inputs unity-gain stable for capacitive loads up to 100pf 200? input offset voltage (max4292/max4294) single in small 5-pin sc70 available in ultra-small packages: 5-pin sc70 (max4291) 8-bump ucsp (max4292) max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps ________________________________________________________________ maxim integrated products 1 19-1612; rev 3; 4/02 pin configurations rail-to-rail is a registered trademark of nippon motorola, ltd. ucsp is a trademark of maxim integrated products, inc. ordering information selector guide 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 amplifiers pin-package max4291 1 5-pin sc70/sot23 max4292 2 8-pin max/so/ucsp max4294 4 14-pin so/tssop top view (bumps on bottom) outa v cc outb ina- ina+ inb- inb+ v ee ucsp max4292 pin configurations continued at end of data sheet. *ucsp reliability is integrally linked to the user? assembly methods, circuit board material, and environment. refer to the ucsp reliability notice in the ucsp reliability section of this data sheet for more information. part temp range pin- package top mark max4291 exk-t -40 c to +85 c 5 sc70-5 aad max4291euk-t -40 c to +85 c 5 sot23-5 adml max4292 ebl-t* -40 c to +85 c 8 ucsp-8 aaj max4292eua -40 c to +85 c 8 max max4292esa -40 c to +85 c 8 so max4294 esd -40 c to +85 c 14 so max4294eud -40 c to +85 c 14 tssop
common-mode rejection ratio max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = 1.8v to 5.5v, v ee = v cm = 0, v out = v cc /2, r l = 100k ? connected to v cc /2, t a = +25 c , unless otherwise noted.) (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 to v ee) ....................................................6v all other pins ...................................(v cc + 0.3v) to (v ee - 0.3v) current into in_+, in_- ..................................................... 25ma output short-circuit duration.....................................continuous continuous power dissipation (t a = +70 c) 5-pin sc70 (derate 2.5mw/ c above +70 c) ................200mw 5-pin sot23 (derate 7.1mw/ c above +70 c)................ 571mw 8-bump ucsp ( derate 4.7mw/ c above +70 c) ........... 379mw 8-pin max (derate 4.10mw/ c above +70 c)..............330mw 8-pin so (derate 5.88mw/ c above +70 c) ..................471mw 14-pin so (derate 8.33mw/ c above +70 c) ................667mw 14-pin tssop (derate 6.3mw/ c above +70 c) ............500mw operating temperature range............................-40 c to +85 c junction temperature ......................................................+150 c storage temperature range .............................-65 c to +150 c lead temperature (soldering, 10s) .................................+300 c max4292/max4294 200 1200 v cc = 5.0v, 0 v cm 5.0v na 15 60 i b input bias current v cc = 1.8v inferred from psrr test inferred from cmrr test |v in+ - v in- | < 10mv v cc = 5.0v, 0 v cm 5.0v max4291 conditions a 100 210 i q v 1.8 5.5 v cc supply voltage range quiescent supply current (per amplifier) v 0v cc v cm input common-mode voltage range m ? 0.75 r in differential input resistance na 1 7 i os input offset current v 400 2500 v os input offset voltage units min typ max symbol parameter v cc = 5.0v 100 255 77 100 db psrr power-supply rejection ratio 50 80 db tested for 0 v cm 1.8v; v cc = 1.8v cmrr common-mode rejection ratio 57 80 60 90 db tested for 0 v cm 5.0v, v cc = 5.0v max4291 max4292/max4294 max4291 max4292/max4294 66 90
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps _______________________________________________________________________________________ 3 electrical characteristics (v cc = 1.8v to 5.5v, v ee = v cm = 0, v out = v cc /2, r l = 100k ? connected to v cc /2, t a = t min to t max , unless otherwise noted.) (note 1) electrical characteristics (continued) (v cc = 1.8v to 5.5v, v ee = v cm = 0, v out = v cc /2, r l = 100k ? connected to v cc /2, t a = +25 c , unless otherwise noted.) (note 1) channel-to-channel isolation gain-bandwidth product phase margin gain margin slew rate input voltage-noise density input current-noise density capacitive-load stability ch iso gbwp m gm sr e n i n specified at f = 10khz (max4292/max4294 only) f = 10khz f = 10khz a vcl = 1v/v, no sustained oscillations 83 500 65 12 0.2 70 0.05 100 pf pa/ hz nv/ hz v/s db degrees khz db ma 20 sourcing or sinking i out(sc) output short-circuit current output-voltage swing low v ol specified as |v ee - v ol | r l = 2k ? to v cc /2 r l = 100k ? to v cc /2 46 120 25 80 mv mv 15 40 220 r l = 2k ? to v cc /2 r l = 100k ? to v cc /2 specified as |v cc - v oh | v oh output-voltage swing high large-signal voltage gain a v v cc = 5.0v v cc = 1.8v r l = 100k ? , 0.02v v out v cc - 0.02v r l = 2k ? , 0.1v v out v cc - 0.1v r l = 100k ? , 0.02v v out v cc - 0.02v r l = 2k ? , 0.1v v out v cc - 0.1v 80 120 80 130 80 110 80 120 db units min typ max conditions symbol parameter 270 v cc = 5.0v parameter symbol min typ max units 2000 input offset voltage v os 3000 v quiescent supply current (per amplifier) supply-voltage range v cc 1.8 5.5 v i q 240 a conditions max4292/max4294 max4291 inferred from psrr test v cc = 1.8v
80 db ultra-small, 1.8v, power, rail-to-rail i/o op amps 4 _______________________________________________________________________________________ note 1: all devices are 100% tested at t a = +25 c. all temperature limits are guaranteed by design. electrical characteristics (continued) (v cc = 1.8v to 5.5v, v ee = v cm = 0, v out = v cc /2, r l = 100k ? connected to v cc /2, t a = t min to t max , unless otherwise noted.) (note 1) max4291/max4292/max4294 120 r l = 2k ? to v cc /2 r l = 100k ? to v cc /2 r l = 100k ? to v cc /2 80 80 80 v cc = 5.0v r l = 2k ? , 0.1v v out v cc - 0.1v r l = 100k ? , 0.02v v out v cc - 0.02v r l = 2k ? , 0.1v v out v cc - 0.1v r l = 100k ? , 0.02v v out v cc - 0.02v parameter symbol min typ max units large-signal voltage gain a v 80 db 50 input common-mode voltage range v cm 0v cc v output-voltage swing high v oh 20 mv output-voltage swing low v ol mv input bias current input offset voltage drift tcv os 1.2 v/ c i b 90 na input offset current i os 10 na conditions v cc = 1.8v inferred from cmrr test specified as |v cc - v oh | specified as |v ee - v ol | v cc = 5.0v, 0 v cm 5.0v v cc = 5.0v, 0 v cm 5.0v db cmrr common-mode rejection ratio tested for 0 v cm 1.8v, v cc = 1.8v 75 db psrr power-supply rejection ratio 53 tested for 0 v cm 5.0v, v cc = 5.0v 60 62 db max4291 max4292/max4294 max4291 max4292/max4294 40 r l = 2k ? to v cc /2
ultra-small, 1.8v, power, rail-to-rail i/o op amps max4291/max4292/max4294 _______________________________________________________________________________________ 5 1.0 1.2 1.1 1.5 1.4 1.3 1.6 1.7 1.9 1.8 2.0 -55 -25 -10 -40 52035 50 65 80 95 110 minimum operating voltage vs. temperature (psrr 80db) max4291 toc02 temperature ( c) minimum operating voltage (v) 125 -900 -600 -750 -300 -450 -150 0 -55 -25 -10 5 -40 20 50 35 65 80 95 110 125 input offset voltage vs. temperature max4291 toc03 temperature (?) input offset voltage ( v) v cc = 5.5v v cc = 1.8v v cc = 2.4v 0 10 5 20 15 30 25 35 -55 -25 -10 5 -40 20 35 50 65 80 95 110 125 input bias current vs. temperature max4291 toc04 temperature ( c) input bias current (na) v cc = 5.5v v cc = 1.8v -40 -30 -20 -10 0 10 20 30 40 -0.5 0.5 0 1.0 1.5 2.0 2.5 input bias current vs. common-mode voltage (v cc = 1.8v) max4291 toc05 common-mode voltage (v) input bias current (na) -40 -10 -20 -30 0 10 30 20 40 -0.5 0.5 1.5 2.5 3.5 4.5 5.5 input bias current vs. common-mode voltage (v cc = 5.5v) max4291 toc06 common-mode voltage (v) input bias current (na) 0 10 5 20 15 25 30 -55 5 35 -25 65 95 125 output voltage swing vs. temperature (r l = 100k ? to v cc /2) max4291-07 temperature ( c) output voltage swing (mv) v oh = v cc - v out v ol = v out - v ee v oh (v cc = 5.5v or 1.8v) v ol (v cc = 5.5v) v ol (v cc = 1.8v) 0 20 10 40 30 50 60 -55 5 35 -25 65 95 125 output voltage swing vs. temperature (r l = 2k ? to v cc /2) max4291-08 temperature ( c) output voltage swing (mv) v oh = v cc - v out v ol = v out - v ee v oh (v cc = 1.8v) v ol (v cc = 5.5v) v ol (v cc = 1.8v) v oh (v cc = 5.5v) -105 -90 -95 -100 -85 -80 -70 -75 -65 -55 -25 -10 -40 5 203550658095110125 common-mode rejection ratio vs. temperature max4291 toc09 temperature ( c) cmrr (db) v cc = 5.5v v cc = 1.8v 0 v cm v cc typical operating characteristics (v cc = 2.4v, v ee = v cm = 0, v out = v cc /2, no load, t a = +25 c, unless otherwise noted.) 60 80 70 110 100 90 120 130 150 140 160 -55 -25 -10 -40 52035 50 65 80 95 110 supply current per amplifier vs. temperature max4291 toc01 temperature ( c) supply current ( a) 125 v cc = 5.5v v cc = 1.8v
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = 2.4v, v ee = v cm = 0, v out = v cc /2, no load, t a = +25 c, unless otherwise noted.) 50 70 60 80 110 120 100 90 130 0 100 150 200 250 50 300 350 400 450 500 open-loop gain vs. output swing low (v cc = 1.8v, r l connected to v cc ) max4291 toc10 v ol (mv) gain (db) r l = 2k ? r l = 1k ? 50 70 60 90 80 110 100 120 0 200 100 300 400 50 250 150 350 450 500 open-loop gain vs. output swing high (v cc = 1.8v, r l connected to v ee ) max4291 toc11 v oh (mv) gain (db) r l = 2k ? r l = 1k ? 50 70 60 80 110 120 100 90 130 0 100 150 200 250 50 300 350 400 450 500 open-loop gain vs. output swing low (v cc = 5.5v, r l connected to v cc ) max4191 toc12 v ol (mv) gain (db) r l = 2k ? r l = 1k ? 50 70 60 80 110 120 100 90 130 0 100 150 200 250 50 300 350 400 450 500 open-loop gain vs. output swing high (v cc = 5.5v, r l connected to v ee ) max4191 toc13 v oh (mv) gain (db) r l = 2k ? r l = 1k ? 50 80 70 60 90 100 120 110 130 -55 -25 -10 -40 5 203550658095110125 open-loop gain vs. temperature max4291 toc14 temperature ( c) open-loop gain (db) r l = 2k ? to v cc r l = 2k ? to v ee r l = 1k ? to v cc r l = 1k ? to v ee v cc = 5.5v 60 -40 0.1 1 10 100 1000 gain and phase vs. frequency (c l = 100pf) -20 max4291 toc17 frequency (khz) gain (db) 0 20 40 30 10 -10 -30 50 a v = 1000v/v 180 144 108 72 36 0 -36 -72 -108 -144 -180 phase (degrees) 1 0.01 0.01 10 100 0.1 frequency (khz) thd + noise (%) 1 0.1 total harmonic distortion plus noise vs. frequency v cc = 5.5v v cc = 1.8v max4291 toc18 r l = 2k ? a v = 1v/v (noninverting configuration) 0 -90 0.01 0.1 1 10 100 1000 max4292/max4294 crosstalk vs. frequency -80 -70 max4291-15 frequency (khz) crosstalk (db) -50 -60 -20 -10 -30 -40 60 -40 0.1 1 10 100 1000 gain and phase vs. frequency (c l = 0) -20 max4291 toc16 frequency (khz) gain (db) 0 20 40 30 10 -10 -30 50 a v = 1000v/v 180 144 108 72 36 0 -36 -72 -108 -144 -180 phase (degrees)
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps _______________________________________________________________________________________ 7 0.01 0.1 10 1 100 0 2345 1 678910 load resistor vs. capacitive load max4291 toc19 capacitive load (nf) load resistor (k ? ) i out > 20ma v cc = 2.4v i out > 20ma v cc = 5.5v v cc = 5.5v v cc = 2.4v 10% overshoot a v = 1v/v (noninverting configuration) out in 0 100mv 0 100mv 1 s/div small-signal transient response (noninverting configuration) max4291 toc20 v cc = 2.5v v ee = -2.5v v cm = 0 out in 0 100mv 0 100mv 1 s/div small-signal transient response (inverting configuration) max4291 toc21 v cc = 2.5v v ee = -2.5v v cm = 0 out in -2v 2v -2v 2v 10 s/div large-signal transient response (noninverting configuration) max4291 toc22 v cc = 2.5v v ee = -2.5v v cm = 0 out in -2v 2v -2v 2v 10 s/div large-signal transient response (inverting configuration) max4291 toc23 v cc = 2.5v v ee = -2.5v v cm = 0 0 1000 500 2000 1500 2500 3000 01015 5 202530 supply current vs. sink current max4291/2/4-24 sink current (ma) supply current ( a) v cc = 5.5v v cc = 2.4v v cc = 1.8v 0 60 45 30 15 105 90 75 120 135 150 010 5152025 supply current vs. source current max4291/2/4-25 source current (ma) supply current ( a) v cc = 5.5v v cc = 1.8v v cc = 2.4v typical operating characteristics (continued) (v cc = 2.4v, v ee = v cm = 0, v out = v cc /2, no load, t a = +25 c, unless otherwise noted.)
detailed description rail-to-rail input stage the max4291/max4292/max4294 have rail-to-rail inputs and output stages that are specifically designed for low-voltage, single-supply operation in the smallest package possible. the input stage consists of separate npn and pnp differential stages, which operate togeth- er to provide a common-mode range extending to both supply rails. the crossover region of these two pairs occurs halfway between v cc and v ee . the input offset voltage is typically 200v (max4292/max4294). low operating supply voltage, low supply current, rail-to-rail common-mode input range, and rail-to-rail outputs make this family of operational amplifiers (op amps) an excellent choice for precision or general-purpose, low- voltage, battery-powered systems. since the input stage consists of npn and pnp pairs, the input bias current changes polarity as the common- mode voltage passes through the crossover region. match the effective impedance seen by each input to reduce the offset error caused by input bias currents flowing through external source impedances (figures 1a and 1b). the combination of high-source impedance plus input capacitance (amplifier input capacitance plus stray max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 8 _______________________________________________________________________________________ pin description r3 in r3 = r1 r2 r1 r2 max4291 max4292 max4294 r3 r3 = r1 r2 r1 r2 max4291 max4292 max4294 in figure 1a. minimizing offset error due to input bias current (noninverting) figure 1b. minimizing offset error due to input bias current (inverting) pin max4292 max4291 max/so ucsp max4294 name function 1 in+ noninverting input 2 4 c2 11 v ee negative supply. connect to ground for single-supply operation. 3 in- inverting input 4 out amplifier output 5 8 a2 4 v cc positive supply 1, 7 a1, a3 1, 7 outa, outb outputs for amplifiers a and b 2, 6 b1, b3 2, 6 ina-, inb- inverting inputs to amplifiers a and b 3, 5 c1, c3 3, 5 ina+, inb+ noninverting inputs to amplifiers a and b 8, 14 outc, outd outputs for amplifiers c and d 9, 13 inc-, ind- inverting inputs to amplifiers c and d 10, 12 inc+, ind+ noninverting inputs to amplifiers c and d
capacitance) creates a parasitic pole that produces an underdamped signal response. reducing input capaci- tance or placing a small capacitor across the feedback resistor improves response in this case. the max4291/max4292/max4294 family s inputs are protected from large differential input voltages by inter- nal 10.6k ? series resistors and back-to-back triple- diode stacks across the inputs (figure 2). for differential input voltages (much less than 1.8v), input resistance is typically 0.75m ? . for differential input voltages greater than 1.8v, input resistance is around 21.2k ? , and the input bias current can be approximat- ed by the following equation: in the region where the differential input voltage approaches 1.8v, the input resistance decreases expo- nentially from 0.75m ? to 21.2k ? as the diode block begins to conduct. conversely, the bias current increases with the same curve. in unity-gain configuration, high slew-rate input signals may capacitively couple to the output through the triple- diode stacks. rail-to-rail output stage the max4291/max4292/max4294 output stage can drive up to a 2k ? load and still swing to within 46mv of the rails. figure 3 shows the output-voltage swing of a max4291 configured as a unity-gain buffer, powered from a 2.5v supply. the output for this setup typically swings from (v ee + 25mv) to (v cc - 2mv) with a 100k ? load. applications information power-supply considerations the max4291/max4292/max4294 operate from a sin- gle 1.8v to 5.5v supply (or dual 0.9v to 2.75v sup- plies) and consume only 100a of supply current per amplifier. a high power-supply rejection ratio of 100db allows the amplifiers to be powered directly off a decaying battery voltage, simplifying design and extending battery life. the max4291/max4292/max4294 are ideally suited for use with most battery-powered systems. table 1 lists a i (v - 1.8v) 21.2k bias diff = ? max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps _______________________________________________________________________________________ 9 table 1. max4291 characteristics with typical battery systems 750 yes nickel-cadmium (2 cells) 1000 yes lithium-ion (1 cell) 1000 yes nickel-metal- hydride (2 cells) 2000 no alkaline (2 cells) battery type capacity, aa size (ma-h) 2.4 3.5 2.4 3.0 1.8 2.7 1.8 1.8 v end-of-life (v) v fresh (v) recharge- able 7500 10,000 10,000 20,000 max4291 operating time in normal mode (h) out 2.5v/div in 2.5v/div 0 0 20 s/div v cc = 2.5v, v ee = -2.5v figure 3. rail-to-rail input/output voltage range 10.6k ? 10.6k ? in- in+ figure 2. input protection circuit
max4291/max4292/max4294 variety of typical battery types showing voltage when fresh, voltage at end-of-life, capacity, and approximate operating time from a max4291 (assuming nominal conditions). although the amplifiers are fully guaranteed over tem- perature for operation down to a 1.8v single supply, even lower voltage operation is possible in practice. figures 4 and 5 show the offset voltage and supply cur- rent as a function of supply voltage and temperature. load-driving capability the max4291/max4292/max4294 are fully guaranteed over temperature and supply voltage range to drive a maximum resistive load of 2k ? to v cc /2, although heavier loads can be driven in many applications. the rail-to-rail output stage of the amplifier can be modeled as a current source when driving the load toward v cc , and as a current sink when driving the load toward v ee . the limit of this current source/sink varies with supply voltage, ambient temperature, and lot-to-lot variations of the units. figures 6a and 6b show the typical current source and sink capabilities of the max4291/max4292/max4294 family as a function of supply voltage and ambient tem- perature. the contours on the graph depict the output current value, based on driving the output voltage to within 50mv, 100mv, and 200mv of either power-sup- ply rail. for example, a max4291 running from a single 1.8v supply, operating at t a = +25 c can source 3.5ma to ultra-small, 1.8v, power, rail-to-rail i/o op amps 10 ______________________________________________________________________________________ supply voltage (v) -700 -600 -650 -550 -500 -450 0 3.0 2.5 2.0 1.0 1.5 0.5 3.5 4.0 4.5 5.0 5.5 max4291 offset voltage vs. supply voltage offset voltage ( v) t a = +25 c t a = -40 c t a = +85 c v cm = v cc / 2 figure 4. offset voltage vs. supply voltage 0 60 20 40 80 100 120 140 0 2.0 2.5 3.0 1.0 0.5 1.5 3.5 4.5 5.0 4.0 5.5 supply current per amplifier vs. supply voltage supply voltage (v) supply current ( a) t a = +85 c t a = -40 c t a = +25 c figure 5. supply current per amplifier vs. supply voltage 0 15 5 10 20 25 30 -55 5 20 35 -25 -40 -10 50 80 110 95 65 125 output source current vs. temperature temperature ( c) output source current (ma) v oh = v cc - v out v cc = 5.5v v oh = 200mv v cc = 5.5v v oh = 50mv v cc = 1.8v v oh = 100mv v cc = 1.8v v oh = 200mv v cc = 5.5v v oh = 100mv v cc = 1.8v v oh = 50mv figure 6a. output source current vs. temperature v ol = v out - v ee 0 10 2 4 6 8 12 14 16 18 -55 5 20 35 -25 -40 -10 50 80 110 95 65 125 output sink current vs. temperature temperature ( c) output sink current (ma) v cc = 1.8v v ol = 200mv v cc = 1.8v v ol = 50mv v cc = 5.5v v ol = 200mv v cc = 5.5v v ol = 100mv v cc = 1.8v v ol = 100mv v cc = 5.5v v ol = 50mv figure 6b. output sink current vs. temperature
within 100mv of v cc and is capable of driving a 485 ? load resistor to v ee : the same application can drive a 220k ? load resistor when terminated in v cc /2 (0.9v in this case). driving capacitive loads the max4291/max4292/max4294 are unity-gain stable for loads up to 100pf (see the load resistor vs. capacitive load graph in the typical operating characteristics ). applications that require greater capacitive-drive capability should use an isolation resistor between the output and the capacitive load (figure 7). note that this alternative results in a loss of gain accuracy because r iso forms a voltage divider with the load resistor. power-supply bypassing and layout the max4291/max4292/max4294 family operates from either a single 1.8v to 5.5v supply or dual 0.9v to 2.75v supplies. for single-supply operation, bypass the power supply with a 100nf capacitor to v ee (in this case gnd). for dual-supply operation, both the v cc and the v ee supplies should be bypassed to ground with separate 100nf capacitors. good pc board layout techniques optimize perfor- mance by decreasing the amount of stray capacitance at the op amp s inputs and output. to decrease stray capacitance, minimize trace lengths and widths by placing external components as close as possible to the op amp. surface-mount components are an excel- lent choice. using the max4291/max4292/max4294 as comparators although optimized for use as operational amplifiers, the max4291/max4292/max4294 can also be used as rail-to-rail i/o comparators. typical propagation delay depends on the input overdrive voltage, as shown in figure 8. external hysteresis can be used to minimize the risk of output oscillation. the positive feedback cir- cuit, shown in figure 9, causes the input threshold to change when the output voltage changes state. the two thresholds create a hysteresis band that can be calculated by the following equations: r (1.8v 0.1v) 3.5ma 485 to v lee = ? = ? max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps ______________________________________________________________________________________ 11 r iso c l r l max4291 max4292 max4294 a v = r l 1 r l + r iso out in figure 7a. using a resistor to isolate a capacitive load from the op amp out in 0 100mv 0 100mv 10 s/div v cc = 2.4v, r l = 2k ? to v ee, c l = 1000pf figure 7b. pulse response without isolating resistor out in 0 100mv 0 100mv 10 s/div v cc = 2.4v, r l = 2k ? to v ee , c l = 1000pf, r iso = 100 ? figure 7c. pulse response with isolating resistor (100 ? )
max4291/max4292/max4294 when the output of the comparator is low, the supply current increases. the output stage has biasing circuit- ry to monitor the output current. when the amplifier is used as a comparator, the output stage is overdriven and the current through the biasing circuitry increases to maximum. for the max4291, typical supply currents increase to 1.5ma with v cc = 1.8v and to 9ma when v cc = 5.0v (figure 10). using the max4291/max4292/max4294 as low-power current monitors the max4291/max4292/max4294 are ideal for appli- cations powered from a two-cell battery stack. figure 11 shows an application circuit in which the max4291 is used for monitoring the current of a two-cell battery stack. in this circuit, a current load is applied, and the voltage drop at the battery terminal is sensed. the voltage on the load side of the battery stack is equal to the voltage at the emitter of q1 due to the feedback loop containing the op amp. as the load cur- rent increases, the voltage drop across r1 and r2 increases. thus, r2 provides a fraction of the load cur- rent (set by the ratio of r1 and r2) that flows into the emitter of the pnp transistor. neglecting pnp base cur- rent, this current flows into r3, producing a ground-ref- erenced voltage proportional to the load current. to minimize errors, scale r1 to give a voltage drop that is large enough in comparison to the op amp s v os . calculate the output voltage of the application using the following equation: vi r1 r2 r3 out load = ? ? ? ? ? ? ? ? ? ? ? ? ? ? ultra-small, 1.8v, power, rail-to-rail i/o op amps 12 ______________________________________________________________________________________ 06090 20 30 10 40 50 80 70 100 propagation delay vs. input overdrive v od (mv) 10 100 1000 t pd ( s) t pd + , v cc = 5.5v t pd - , v cc = 5.5v t pd + , v cc = 1.8v t pd - , v cc = 1.8v figure 8. propagation delay vs. input overdrive r2 r1 v sig output input v oh v ol v ee = gnd v cc v out r hyst v ee = gnd max4291 max4292 max4294 hysteresis v lo v hi v ref figure 9. hysteresis comparator circuit 0 6 2 4 8 10 12 0 2.0 2.5 3.0 1.0 0.5 1.5 3.5 4.5 5.0 4.0 5.5 maximum supply current per amplifier vs. supply voltage supply voltage (v) maximum supply current (ma) comparator configuration v in + = (v in -) - 100mv figure 10. maximum supply current per amplifier vs. supply voltage v v v v 1 r1 r2 r1 r v v v r1 r v hyst hi lo hi hyst ref lo hi hyst cc =? =+ + ? ? ? ? ? ? =? ? ? ? ? ? ?
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps ______________________________________________________________________________________ 13 for a 1v output and a current load of 50ma, the choice of resistors can be r1 = 2 ? , r2 = 100k ? , and r3 = 1m ? . ucsp information layout issues design the layout for the ic to be as compact as possi- ble to minimize parasitics. the ucsp uses a bump pitch of 0.5mm (19.7mil) and bump diameter of 0.3 (~12mil). therefore, lay out the solder-pad spacing on 0.5mm (19.7mil) centers, using a pad size of 0.25mm (~10mil) and a solder mask opening of 0.33mm (13mil). round or square pads are permissible. connect multi- ple vias from the ground plane as close to the ground pins as possible. install capacitors as close as possible to the ic supply voltage pin. place the ground end of these capacitors near the ic gnd pins to provide a low-impedance return path for the signal current. prototype chip installation alignment keys on the pc board, around the area where the chip is located, will be helpful in the proto- type assembly process. it is better to align the chip on the board before any other components are placed, and then place the board on a hot plate or hot surface until the solder starts melting. remove the board from the hot plate without disturbing the position of the chip and let it cool down to room temperature before pro- cessing the board further. ucsp reliability the ucsp represents a unique packaging form factor that may not perform as well as a packaged product through traditional mechanical reliability tests. ucsp reliability is integrally linked to the user s assembly methods, circuit board material, and usage environ- ment. the user should closely review these areas when considering use of a ucsp. performance through operating-life test and moisture resistance remains uncompromised. the wafer-fabrica- tion process primarily determines the performance. mechanical stress performance is a greater considera- tion for ucsps. ucsps are attached through direct sol- der contact to the user s pc board, foregoing the inherent stress relief of a packaged product lead frame. solder-joint contact integrity must be considered. comprehensive reliability tests have been performed and are available upon request. in conclusion, the ucsp performs reliably through environmental stresses. marking information r1 i load r2 v cc v ee r3 v out q1 max4291 figure 11. current monitor for a 2-cell battery stack aaa aaa orientation product id code lot code
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 14 ______________________________________________________________________________________ v ee out in- 1 5 v cc in+ sc70/sot23 top view 2 3 4 v ee outb outa inb- inb+ v cc ina+ ina- max/so 1 2 8 7 3 4 6 5 max4292 max4291 outa outb outd outc v cc ina+ inb+ ind+ inc+ ina- inb- ind- inc- v ee 1 5 6 7 max4294 tssop/so 2 3 4 14 10 9 8 13 12 11 pin configurations (continued) chip information max4291 transistor count: 149 max4292 transistor count: 356 max4294 transistor count: 747 process: bicmos
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps ______________________________________________________________________________________ 15 sot5l.eps sc70, 5l.eps 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 .)
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 16 ______________________________________________________________________________________ 8lumaxd.eps package outline, 8l umax/usop 1 1 21-0036 j rev. document control no. approval proprietary information title: max 0.043 0.006 0.014 0.120 0.120 0.198 0.026 0.007 0.037 0.0207 bsc 0.0256 bsc a2 a1 c e b a l front view side view e h 0.60.1 0.60.1 ? 0.500.1 1 top view d 8 a2 0.030 bottom view 1 6 s b l h e d e c 0 0.010 0.116 0.116 0.188 0.016 0.005 8 4x s inches - a1 a min 0.002 0.95 0.75 0.5250 bsc 0.25 0.36 2.95 3.05 2.95 3.05 4.78 0.41 0.65 bsc 5.03 0.66 6 0 0.13 0.18 max min millimeters - 1.10 0.05 0.15 dim note: the max4292 does not have an exposed pad. tssop.eps note: the max4294 does not have an exposed pad. package information (continued) (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 .)
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps ______________________________________________________________________________________ 17 soicn.eps package information (continued) (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 .)
max4291/max4292/max4294 ultra-small, 1.8v, power, rail-to-rail i/o op amps 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. 18 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ? 2002 maxim integrated products printed usa is a registered trademark of maxim integrated products. 9lucsp, 3x3.eps package information (continued) (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 .)
e nglish ? ???? ? ??? ? ??? what's ne w p roducts solutions de sign ap p note s sup p ort buy comp any me mbe rs max4291 part number table notes: see the max4291 quickview data sheet for further information on this product family or download the max4291 full data sheet (pdf, 576kb). 1. other options and links for purchasing parts are listed at: http://www.maxim-ic.com/sales . 2. didn't find what you need? ask our applications engineers. expert assistance in finding parts, usually within one business day. 3. part number suffixes: t or t&r = tape and reel; + = rohs/lead-free; # = rohs/lead-exempt. more: see full data sheet or part naming c onventions . 4. * some packages have variations, listed on the drawing. "pkgc ode/variation" tells which variation the product uses. 5. part number free sample buy direct package: type pins size drawing code/var * temp rohs/lead-free? materials analysis max4291esa-t -40c to +85c rohs/lead-free: no max4291esa -40c to +85c rohs/lead-free: no MAX4291EXK+ sc -70;5 pin; dwg: 21-0076e (pdf) use pkgcode/variation: x5+1 * -40c to +85c rohs/lead-free: yes materials analysis MAX4291EXK sc -70;5 pin; dwg: 21-0076e (pdf) use pkgcode/variation: x5-1 * -40c to +85c rohs/lead-free: no materials analysis MAX4291EXK+t sc -70;5 pin; dwg: 21-0076e (pdf) use pkgcode/variation: x5+1 * -40c to +85c rohs/lead-free: yes materials analysis MAX4291EXK-t sc -70;5 pin; dwg: 21-0076e (pdf) use pkgcode/variation: x5-1 * -40c to +85c rohs/lead-free: no materials analysis max4291euk+ sot-23;5 pin; dwg: 21-0057f (pdf) use pkgcode/variation: u5+1 * -40c to +85c rohs/lead-free: yes materials analysis
max4291euk sot-23;5 pin; dwg: 21-0057f (pdf) use pkgcode/variation: u5-1 * -40c to +85c rohs/lead-free: no materials analysis max4291euk+t sot-23;5 pin; dwg: 21-0057f (pdf) use pkgcode/variation: u5+1 * -40c to +85c rohs/lead-free: yes materials analysis max4291euk-t sot-23;5 pin; dwg: 21-0057f (pdf) use pkgcode/variation: u5-1 * -40c to +85c rohs/lead-free: no materials analysis didn't find what you need? c ontac t us: send us an email c opyright 2 0 0 7 by m axim i ntegrated p roduc ts , dallas semic onduc tor ? legal n otic es ? p rivac y p olic y

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