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general description the max4249?ax4257 low-noise, low-distortion oper- ational amplifiers offer rail-to-rail outputs and single- supply operation down to 2.4v. they draw 400? of quiescent supply current per amplifier while featuring ultra-low distortion (0.0002% thd), as well as low input voltage-noise density (7.9nv/ hz ) and low input current-noise density (0.5fa/ hz ). these features make the devices an ideal choice for portable/battery-pow- ered applications that require low distortion and/or low noise. for additional power conservation, the max4249/ max4251/max4253/max4256 offer a low-power shut- down mode that reduces supply current to 0.5? and puts the amplifiers?outputs into a high-impedance state. the max4249-max4257? outputs swing rail-to- rail and their input common-mode voltage range includes ground. the max4250?ax4254 are unity- gain stable with a gain-bandwidth product of 3mhz. the max4249/max4255/max4256/max4257 are inter- nally compensated for gains of 10v/v or greater with a gain-bandwidth product of 22mhz. the single max4250/max4255 are available in space-saving 5-pin sot23 packages. the max4252 is available in an 8-pin ultra chip-scale package (ucsp) and the max4253 is available in a 10-pin ucsp. applications wireless communications devices pa control portable/battery-powered equipment medical instrumentation adc buffers digital scales/strain gauges features available in space-saving ucsp, sot23, and ?ax packages low distortion: 0.0002% thd (1k ? load) 400? quiescent supply current per amplifier single-supply operation from 2.4v to 5.5v input common-mode voltage range includes ground outputs swing within 8mv of rails with a 10k ? load 3mhz gbw product, unity-gain stable (max4250?ax4254) 22mhz gbw product, stable with a v 10v/v (max4249/max4255/max4256/max4257) excellent dc characteristics v os = 70? i bias = 1pa large-signal voltage gain = 116db low-power shutdown mode: reduces supply current to 0.5? places outputs in a high-impedance state 400pf capacitive-load handling capability max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps ________________________________________________________________ maxim integrated products 1 19-1295; rev 4; 1/02 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 continued at end of data sheet. selector guide appears at end of data sheet. rail-to-rail is a registered trademark of nippon motorola, ltd. ucsp is a trademark of maxim integrated products, inc. a b c 12 3 outa v dd outb ina- inb- inb+ v ss ina+ max4252 outa v dd outb ina- inb- ina+ inb+ v ss shdna shdnb max4253 c1 b1 a1 a2 a3 a4 b4 c2 c3 c4 top view (bumps on bottom) ucsp ucsp pin configurations continued at end of data sheet. pin configurations ordering information part temp range pin- package top mark max4249 esd -40 c to +85 c 14 so max4249eub -40 c to +85 c 10 max max4250 euk-t -40 c to +85 c 5 sot23-5 acci
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v dd = 5v, v ss = 0, v cm = 0, v out = v dd /2, r l tied to v dd /2, shdn = v dd , t a = -40 c to +85 c, unless otherwise noted. typical values are at t a = +25 c.) (notes 2, 3) 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. power-supply voltage (v dd to v ss ) ......................+6.0v to -0.3v analog input voltage (in_+, in_-)....(v dd + 0.3v) to (v ss - 0.3v) shdn input voltage ......................................6.0v to (v ss - 0.3v) output short-circuit duration to either supply ..........continuous continuous power dissipation (t a = +70 c) 5-pin sot23 (derate 7.1mw/ c above +70 c)...........571mw 8-pin max (derate 4.5mw/ c above +70 c) ............362mw 8-pin so (derate 5.88mw/ c above +70 c)...............471mw 8-pin ucsp (derate 4.7mw/ c above +70 c) ............379mw 10-pin ucsp (derate 6.1mw/ c above +70 c) ...........484mw 10-pin max (derate 5.6mw/ c above +70 c) ...........444mw 14-pin so (derate 8.33mw/ c above +70 c)..............667mw 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 bump temperature (soldering) (note 1) infrared (15s) ................................................................+220 c vapor phase (60s) ........................................................+215 c parameter symbol conditions min typ max units supply voltage range v dd (note 4) 2.4 5.5 v v dd = 3v 400 v dd = 5v 420 575 normal mode v dd = 5v, ucsp only 420 655 quiescent supply current per amplifier i q shutdown mode ( shdn = v ss ) (note 2) 0.5 1.5 a input offset voltage (note 5) v os 0.07 0.75 mv input offset voltage tempco tcv os 0.3 v/ c input bias current i b (note 6) 1 100 pa input offset current i os (note 6) 1 100 pa differential input resistance r in 1000 g ? input common-mode voltage range v cm guaranteed by cmrr test -0.2 v dd - 1.1 v common-mode rejection ratio cmrr v ss - 0.2v v cm v dd - 1.1v 70 115 db power-supply rejection ratio psrr v dd = 2.4 to 5.5v 75 100 db r l = 10k ? to v dd /2; v out = 25mv to v dd - 4.97v 80 116 large-signal voltage gain a v r l = 1k ? to v dd /2; v out = 150v to v dd - 4.75v 80 112 db v dd - v oh 825 output voltage swing v out |v in+ - v in- | 10mv r l = 10k ? to v dd /2 v ol - v ss 720 mv note 1: this device is constructed using a unique set of packaging techniques that impose a limit on the thermal profile the device can be exposed to during board-level solder attach and rework. this limit permits only the use of the solder profiles rec- ommended in the industry-standard specification, jedec 020a, paragrah 7.6, table 3 for ir/vpr and convection reflow. preheating is required. hand or wave soldering is not allowed.
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps _______________________________________________________________________________________ 3 electrical characteristics (continued) (v dd = 5v, v ss = 0, v cm = 0, v out = v dd /2, r l tied to v dd /2, shdn = v dd , t a = -40 c to +85 c, unless otherwise noted. typical values are at t a = +25 c.) (notes 2, 3) parameter symbol conditions min typ max units v dd - v oh 77 200 output voltage swing v out |v in+ - v in- | 10mv, r l = 1k ? to v dd /2 v ol - v ss 47 100 mv output short-circuit current i sc 68 ma output leakage current i leak shutdown mode ( shdn = v ss ), v out = v ss to v dd (note 2) 0.001 1.0 a shdn logic low v il (note 2) 0.2 x v d d v shdn logic high v ih (note 2) 0.8 x v dd v shdn input current i il /i ih shdn = v ss = v dd (note 2) 0.5 1.5 a input capacitance 11 pf max4250 max4254 3 gain-bandwidth product gbw max4249/max4255/max4256/max4257 22 mhz max4250 max4254 0.3 slew rate sr max4249/max4255/max4256/max4257 2.1 v/s peak-to-peak input-noise voltage e n p-p f = 0.1hz to 10hz 760 nv p-p f = 10hz 2.7 f = 1khz 8.9 input voltage-noise density e n f = 30khz 7.9 nv/ hz input current-noise density i n f = 1khz 0.5 fa/ hz f = 1khz 0.0004 max4250 max4254 a v = 1v/v, v out = 2v p-p , r l = 1k ? to gnd (note 7) f = 20khz 0.006 f = 1khz 0.0012 total harmonic distortion plus noise thd + n max4249/max4255/ max4256/max4257 a v = 1v/v, v out = 2v p-p , r l = 1k ? to gnd (note 7) f = 20khz 0.007 % capacitive-load stability no sustained oscillations 400 pf max4250 max4254, a v = 1v/v 10 gain margin gm max4249/max4255/max4256/max4257, a v = 10v/v 12.5 db max4250 max4254, a v = 1v/v 74 phase margin m max4249/max4255/max4256/max4257, a v = 10v/v 68 degrees
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 4 _______________________________________________________________________________________ electrical characteristics (continued) (v dd = 5v, v ss = 0, v cm = 0, v out = v dd /2, r l tied to v dd /2, shdn = v dd , t a = -40 c to +85 c, unless otherwise noted. typical values are at t a = +25 c.) (notes 2, 3) parameter symbol conditions min typ max units max4250 max4254 6.7 settling time to 0.01%, v out = 2v step max4249/max4255/ max4256/max4257 1.6 s max4251/max4253 0.8 delay time to shutdown t sh i vdd = 5% of normal operation max4249/max4256 1.2 s max4251/max4253 8 delay time to enable t en v out = 2.5v, v out settles to 0.1% max4249/max4256 3.5 s power-up delay time t pu v dd = 0 to 5v step, v out stable to 0.1% 6s note 2: shdn is available on the max4249/max4251/max4253/max4256 only. note 3: all device specifications are 100% tested at t a = +25 c. limits over temperature are guaranteed by design. note 4: guaranteed by the psrr test. note 5: offset voltage prior to reflow on the ucsp. note 6: guaranteed by design. note 7: lowpass-filter bandwidth is 22khz for f = 1khz and 80khz for f = 20khz. noise floor of test equipment = 10nv/ hz .
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps _______________________________________________________________________________________ 5 0 10 5 20 15 25 30 35 40 -95 -55 -35 -75 -13 7 28 49 69 90 110 131 152 172 192 max4251/max4256 input offset voltage distribution max4249-57 toc01 v os ( v) number of units 400 units v cm = 0 t a = +25 c -250 -100 -150 -200 -50 0 50 100 150 200 250 -40 0 -20 20 40 60 80 offset voltage vs. temperature max4249-57 toc02 temperature ( c) v cm = 0 v os ( v) -50 0 100 50 150 200 -0.5 1.5 0.5 2.5 3.5 4.5 max4249-57 toc03 input common-mode voltage (v) input offset voltage ( v) v dd = 3v v dd = 5v input offset voltage vs. input common-mode voltage 0 0.3 0.2 0.1 0.4 0.5 0.6 04 3 12 5678910 output voltage vs. output load current max4249-57 toc04 output load current (ma) output voltage (v) v dd = 3v or 5v v diff = 10mv v dd - v oh v ol 0 0.03 0.02 0.01 0.04 0.05 0.06 0.07 0.08 0.09 0.10 -40 0 -20 20 60 40 80 output voltage swing (v oh ) vs. temperature max4249-57 toc05 temperature ( c) r l = 1k ? r l = 10k ? r l = 100k ? v dd - v oh (v) 0 0.02 0.01 0.03 0.04 0.05 0.06 -40 0 -20 20 60 40 80 output voltage swing (v ol ) vs. temperature max4249 -57toc06 temperature ( c) v ol (v) r l = 10k ? r l = 1k ? r l = 100k ? 50 70 60 100 90 80 130 120 110 140 0 100 50 150 200 250 large-signal voltage gain vs. output voltage swing max4249-57 toc07 v out swing from either supply (mv) v dd = 3v r l referenced to gnd r l = 2k ? r l = 20k ? r l = 200k ? a v (db) 60 70 80 90 100 110 120 130 140 0 50 100 150 200 250 large-signal voltage gain vs. output voltage swing max4249-57 toc08 v out swing from either supply (mv) v dd = 3v r l referenced to gnd r l = 2k ? r l = 20k ? r l = 200k ? a v (db) 50 70 60 100 90 80 130 120 110 140 0 100 50 150 200 250 max4249-57 toc09 large-signal voltage gain vs. output voltage swing v out swing from either supply (mv) v dd = 5v r l referenced to gnd r l = 2k ? r l = 20k ? r l = 200k ? a v (db) typical operating characteristics (v dd = 5v, v ss = 0, v cm = v out = v dd /2, input noise floor of test equipment =10nv/ hz for all distortion measurements, t a = +25 c, unless otherwise noted.)
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 6 _______________________________________________________________________________________ 50 80 70 60 90 100 110 120 130 140 150 0 100 50 150 200 250 max4249-57 toc10 v dd = 5v r l referenced to gnd large-signal voltage gain vs. output voltage swing v out swing from either supply (mv) r l = 2k ? r l = 20k ? r l = 200k ? a v (db) 100 110 105 115 120 125 -40 0 -20 20 60 40 80 large-signal voltage gain vs. temperature max4249-57 toc11 temperature ( c) r l referenced to v dd /2 v dd = 5v a v (db) r l = 1k ? v out = 150mv to 4.75mv r l = 100k ? v out = 10mv to 4.99mv r l = 10k ? v out = 20mv to 4.975mv 0.373 0.374 0.375 0.376 340 380 360 400 420 440 460 -40 0 -20 20 60 40 80 supply current and shutdown supply current vs. temperature max4249-57 toc12 temperature ( c) shutdown supply current ( a) per amplifier shdn = v dd supply current ( a) shdn = v ss 320 340 360 380 400 420 440 0 0.1 0.2 0.3 0.4 0.5 0.6 1.8 2.8 2.3 3.3 3.8 4.3 4.8 5.3 5.5 supply current and shutdown supply current vs. supply voltage max4249-57 toc13 supply voltage (v) supply current ( a) shutdown supply current ( a) per amplifier shdn = v dd shdn = v ss 2000 100 0.001 0.1 1 0.01 5 supply current vs. output voltage max4249-57 toc14 output voltage (v) supply current ( a) 1000 400 v dd = 5v v dd = 3v 40 60 80 120 100 180 160 140 1.8 2.3 2.8 3.3 3.8 4.3 4.8 5.3 input offset voltage vs. supply voltage max4249-57 toc15 supply voltage (v) v os ( v) v cm = 0 v out = v dd /2 r l referenced to gnd r l = 10k ? r l = 1k ? r l = 100k ? 60 -40 100 10k 100k 1m 1k 10m max4250?ax4254 gain and phase vs. frequency -20 -10 0 -30 max4249-57 toc16 frequency (hz) gain (db) phase (degrees) 10 20 30 40 50 180 -180 -108 -72 -36 -144 0 36 72 108 144 gain phase v dd = 3v, 5v r l = 50k ? c l = 20pf a v = 1000 60 -40 100 10k 100k 1m 1k 10m max4249/max4255/max4256/max4257 gain and phase vs. frequency -20 -10 0 -30 max4249-57 toc17 frequency (hz) gain (db) phase (degrees) 10 20 30 40 50 180 -180 -108 -72 -36 -144 0 36 72 108 144 gain phase v dd = 3v, 5v r l = 50k ? c l = 20pf a v = 1000 0 -100 -110 1 1k 10k 100k 1m 10 100 10m max4250 max4254 power-supply rejection ratio vs. frequency -80 -70 -60 -90 max4249-57 toc18 frequency (hz) psrr (db) -50 -40 -30 -20 -10 psrr+ psrr- v dd = 3v, 5v typical operating characteristics (continued) (v dd = 5v, v ss = 0, v cm = v out = v dd /2, input noise floor of test equipment =10nv/ hz for all distortion measurements, t a = +25 c, unless otherwise noted.)
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps _______________________________________________________________________________________ 7 1000 0.1 1k 10k 100k 1m 10m output impedance vs. frequency max4249-57 toc19 frequency (hz) output impedance ( ? ) 1 10 100 a v = 1 (max4250?ax4254) a v = 10 (max4249/max4255/ max4256/max4257) 30 0 10 100 1k 10k 100k input voltage-n0ise density vs. frequency max4249-57 toc20 frequency (hz) vn-equivalent input noise-voltage (nv/ hz) 5 10 15 20 25 200nv/div 1s/div 0.1hz to 10hz p-p noise max4249-57 toc21 v dd = 3v or 5v v p-p noise = 760nv p-p -160 -140 -120 -100 -80 -60 -40 -20 0 max4250 max4254 fft of distortion and noise frequency (hz) amplitude (dbc) 10 5k 10k 15k 20k max4249-57 toc22 r l = 1k ? f o = 1khz a v = 1 f o hd2 hd3 hd4 hd5 v out = 2v p-p -140 -120 -100 -80 -60 -40 -20 0 20 10 5k 10k 15k 20k max4249/max4255/max4256/max4257 fft of distortion and noise max4249-57 toc23 frequency (hz) amplitude (dbc) v out = 4v p-p f o = 1khz hd2 hd3 v in 10k ? 100k ? 11k ? f o v o 0.001 0.01 0.1 1 10 02 1 345 max4250 max4254 total harmonic distortion plus noise vs. output voltage (v dd = 5v) max4249-57 toc24 output voltage (v p-p ) thd + n (%) v in r l = 1k ? 100k ? 11k ? a v = 10 f o = 3khz filter bw = 30khz v o r l r l = 10k ? r l = 100k ? 0.001 0.01 0.1 1 10 02 13 max4249-57 toc25 output voltage (v p-p ) thd + n (%) 100k ? 11k ? max4250 max4254 total harmonic distortion plus noise vs. output voltage swing (v dd = 3v) v out v in r l r l = 1k ? r l = 10k ? r l = 100k ? a v = 10 f o = 3khz filter bw = 30khz 0.001 0.01 0.1 1 034 12 5 max4249-57 toc26 output voltage (v p-p ) thd + n (%) f o = 20khz, filter bw = 80khz 100k ? 11k ? max4249/max4255/max4256/max4257 total harmonic distortion plus noise vs. output voltage swing v out v in r l a v = 10 f o = 3khz, filter bw = 30khz 0.0001 0.01 0.001 0.1 1 10 1k 100 10k max4250 max4254 total harmonic distortion plus noise vs. frequency max4249-57 toc27 frequency (hz) thd + n (%) r2 r1 r1 = 560 ?, r2 = 53k ? v in v out r l a v = 100 a v = 10 r1 = 5.6k ?, r2 = 53k ? filter bw = 22khz r l = 10k ? to gnd v o = 2v p-p a v = 1 typical operating characteristics (continued) (v dd = 5v, v ss = 0, v cm = v out = v dd /2, input noise floor of test equipment =10nv/ hz for all distortion measurements, t a = +25 c, unless otherwise noted.)
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 8 _______________________________________________________________________________________ 0.0001 0.001 0.01 0.1 10 1k 100 10k max4250 max4254 total harmonic distortion plus noise vs. frequency max4249-57 toc28 frequency (hz) thd + n (%) filter bw = 80khz a v = 1 r l = 1k ? v out = 2v p-p r l to v dd /2 r l to gnd r l to v dd v out 200mv/div 1.5v 0.5v 2 s/div max4250 max4254 large-signal pulse response max4249-57 toc29 v dd = 3v r l = 10k ? c l = 100pf v in = 1v pulse 0.6v 0.5v max4249-57 toc30 max4250 max4254 small-signal pulse response v out 20mv/div v dd = 3v r l = 10k ? c l = 100pf v in = 100v pulse 2 s/div 2v 1v max4249/max4255/max4256/max4257 large-signal pulse response max4249-57 toc31 v out 200mv/div v dd = 3v r l = 10k ? c l = 100pf v in = 100mv pulse a v = 10 2 s/div 1.6v 1.5v max4249/max4255/max4256/max4257 small-signal pulse response max4249-57 toc32 v out 50mv/div v dd = 3v r l = 10k ? c l = 100pf v in = 10mv pulse a v = 10 2 s/div 140 130 0 channel separation vs. frequency max4249-57 toc33 frequency (hz) channel separation (db) 100 110 120 90 80 70 1k 100k 1m 10k 10m typical operating characteristics (continued) (v dd = 5v, v ss = 0, v cm = v out = v dd /2, input noise floor of test equipment =10nv/ hz for all distortion measurements, t a = +25 c, unless otherwise noted.)
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps _______________________________________________________________________________________ 9 detailed description the max4249 max4257 single-supply operational amplifiers feature ultra-low noise and distortion while consuming very little power. their low distortion and low noise make them ideal for use as preamplifiers in wide dynamic-range applications, such as 16-bit analog-to- digital converters (see typical operating circuit ). their high-input impedance and low noise are also useful for signal conditioning of high-impedance sources, such as piezoelectric transducers. these devices have true rail-to-rail ouput operation, drive loads as low as 1k ? while maintining dc accura- cy, and can drive capactive loads up to 400pf without oscillation. the input common-mode voltage range extends from v dd - 1.1v to 200mv beyond the negative rail. the push-pull output stage maintains excellent dc characteristics, while delivering up to 5ma of current. the max4250 4254 are unity-gain stable, whereas, the max4249/max4255/max4256/max4257 have a higher slew rate and are stable for gains 10v/v. the max4249/max4251/max4253/max4256 feature a low- power shutdown mode, which reduces the supply cur- rent to 0.5a and disables the outputs. pin description pin/bump m a x4 2 5 0 / m a x4 2 5 5 m a x4 2 5 1 / m a x4 2 5 6 m a x4 2 5 2 / m a x4 2 5 7 m a x4 2 5 2 m a x4 2 4 9 / m a x4 2 5 3 m a x4 2 5 4 5-pin sot23 8-pin so/max 8-pin so/max 8-pin ucsp 10-pin ucsp 10-pin max 1 4 - pin so 14-pin so name function 1 6 1, 7 a1, a3 a1, c1 1, 9 1, 13 1, 7, 8, 14 out, outa, outb, outc, outd amplifier output 244c2b44411 v ss negative supply. connect to ground for single- supply operation 3 3 3, 5 c1, c3 a3, c3 3, 5 3, 11 3, 5, 10, 12 in + , in a+ , in b+ , in c + , in d + noninverting amplifier input 4 2 2, 6 b1, b3 a2, c2 2, 6 2, 12 2, 6, 9, 13 in-, ina-, inb-, inc-, ind- inverting amplifier input 5 7 8 a2 b1 8 14 4 v dd positive supply 8 a4, c4 5, 9 shdn , shdna , shdnb shutdown input, connect to v dd or leave unconnected for normal operation (amplifier(s) enabled). 1, 5 5, 7, 8, 10 n.c. no connection. not internally connected. b2 b2, b3 not populated with solder sphere
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 10 ______________________________________________________________________________________ low distortion many factors can affect the noise and distortion that the device contributes to the input signal. the following guidelines offer valuable information on the impact of design choices on total harmonic distortion (thd). choosing proper feedback and gain resistor values for a particular application can be a very important factor in reducing thd. in general, the smaller the closed- loop gain, the smaller the thd generated, especially when driving heavy resistive loads. large-value feed- back resistors can significantly improve distortion. the thd of the part normally increases at approximately 20db per decade, as a function of frequency. operating the device near or above the full-power bandwidth significantly degrades distortion. referencing the load to either supply also improves the part s distortion performance, because only one of the mosfets of the push-pull output stage drives the out- put. referencing the load to midsupply increases the part s distortion for a given load and feedback setting. (see the total harmonic distortion vs. frequency graph in the typical operating characteristics .) for gains 10v/v, the decompensated devices max4249/max4255/max4256/max4257 deliver the best distortion performance, since they have a higher slew rate and provide a higher amount of loop gain for a given closed-loop gain setting. capacitive loads below 400pf, do not significantly affect distortion results. distortion performance remains relatively con- stant over supply voltages. low noise the amplifier s input-referred, noise-voltage density is dominated by flicker noise at lower frequencies, and by thermal noise at higher frequencies. because the ther- mal noise contribution is affected by the parallel combi- nation of the feedback resistive network (r f || r g , figure 1), these resistors should be reduced in cases where the system bandwidth is large and thermal noise is dominant. this noise contribution factor decreases, however, with increasing gain settings. for example, the input noise-voltage density of the cir- cuit with r f = 100k ? , r g = 11k ? (a v = 10v/v) is e n = 15nv/ hz , e n can be reduced to 9nv/ hz by choosing r f = 10k ? , r g = 1.1k ? (a v = 10v/v), at the expense of greater current consumption and potentially higher distortion. for a gain of 100v/v with r f = 100k ? , r g = 1.1k ? , the e n is low (9nv/ hz ). c z r f v out v in r g 0 100mv a v = 2v/v r f = r g = 10k ? v in = 50mv/div v out = 100mv/div 2 s/div 0 100mv a v = 2 r f = r g = 100k ? c z = 11pf 50mv/div 100mv/div v in v out 2 s/div figure 1. adding feed-forward compensation figure 2a. pulse response with no feed-forward compensation figure 2b. pulse response with 10pf feed-forward compensation
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps ______________________________________________________________________________________ 11 using a feed-forward compensation capacitor, c z the amplifier s input capacitance is 11pf. if the resis- tance seen by the inverting input is large (feedback network), this can introduce a pole within the amplifier s bandwidth, resulting in reduced phase margin. compensate the reduced phase margin by introducing a feed-forward capacitor (c z ) between the inverting input and the output (figure 1). this effectively cancels the pole from the inverting input of the amplifier. choose the value of c z as follows: c z = 11 x (r f / r g ) [pf] in the unity-gain stable max4250 max4254, the use of a proper c z is most important for a v = 2v/v, and a v = -1v/v. in the decompensated max4249/max4255 /max4256/max4257, c z is most important for a v = 10v/v. figures 2a and 2b show transient response both with and without c z . using a slightly smaller c z than suggested by the for- mula above achieves a higher bandwidth at the expense of reduced phase and gain margin. as a gen- eral guideline, consider using c z for cases where r g || r f is greater than 20k ? (max4250 max4254) or greater than 5k ? (max4249/max4255/max4256/ max4257). applications information the max4249 max4257 combine good driving capa- bility with ground-sensing input and rail-to-rail output operation. with their low distortion, low noise and low- power consumption, these devices are ideal for use in portable instrumentation systems and other low-power, noise-sensitive applications. ground-sensing and rail-to-rail outputs the common-mode input range of these devices extends below ground, and offers excellent common- mode rejection. these devices are guaranteed not to undergo phase reversal when the input is overdriven (figure 3). figure 4 showcases the true rail-to-rail output operation of the amplifier, configured with a v = 10v/v. the output swings to within 8mv of the supplies with a 10k ? load, making the devices ideal in low-supply-voltage applica- tions. output loading and stability even with their low quiescent current of 400a, these amplifiers can drive 1k ? loads while maintaining excel- lent dc accuracy. stability while driving heavy capaci- tive loads is another key feature. v out v in r iso c l max4250 max4251 max4252 max4253 max4254 4.25v 4.45v -200mv 0 0 v out v in a v = 1 v dd = 5v r l = 10k ? 20 s/div 0 5v v dd = 5v r l = 10k ? a v = 10 f = 1khz 200 s/div v out 1v/div figure 3. overdriven input showing no phase reversal figure 4. rail-to-rail output operation figure 5. capacitive-load driving circuit
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 12 ______________________________________________________________________________________ these devices maintain stability while driving loads up to 400pf. to drive higher capacitive loads, place a small isolation resistor in series between the output of the amplifier and the capacitive load (figure 5). this resistor improves the amplifier s phase margin by isolat- ing the capacitor from the op amp s output. reference figure 6 to select a resistance value that will ensure a load capacitance that limits peaking to <2db (25%). for example, if the capacitive load is 1000pf, the corre- sponding isolation resistor is 150 ? . figure 7 shows that peaking occurs without the isolation resistor. figure 8 shows the unity-gain bandwidth vs. capacitive load for the max4250 max4254. power supplies and layout the max4249 max4257 operate from a single 2.4v to 5.5v power supply or from dual supplies of 1.20v to 2.75v. for single-supply operation, bypass the power supply with a 0.1f ceramic capacitor placed close to the v dd pin. if operating from dual supplies, bypass each supply to ground. good layout improves performance by decreasing the amount of stray capacitance and noise at the op amp s inputs and output. to decrease stray capacitance, min- imize pc board trace lengths and resistor leads, and place external components close to the op amp s pins. ucsp package consideration for general ucsp package information and pc layout considerations, please refer to the maxim application note (wafer-level ultra-chip-board-scale-package). ucsp reliability the ucsp represents a unique packaging form factor that may not perform equally to 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 oper- ating life test and moisture resistance remains uncom- promised as it is primarily determined by the wafer-fabrication process. mechanical stress perfor- mance is a greater consideration for a ucsp. ucsps are attached through direct solder contact to the user s pc board, foregoing the inherent stress relief of a pack- aged product lead frame. solder-joint contact integrity must be considered. table 1 shows the testing done to characterize the ucsp reliability performance. in con- clusion, the ucsp is capable of performing reliably through environmental stresses as indicated by the results in the table. additional usage data and recom- mendations are detailed in the ucsp application note, which can be found on maxim s website at www.maxim-ic.com. 160 140 0 10 10,000 60 20 40 120 100 80 capacitive loading (pf) 1000 100 shaded area indicates stable operation with no need for isolation resistor. note: using an isolation resistor reduces peaking. r iso ( ? ) 4.5 3.5 4.0 0 10 10,000 2.0 3.0 2.5 1.0 0.5 1.5 capacitive load (pf) unity-gain bandwidth (mhz) 1000 100 v dd = 3v shaded area indicates stable operation with no need for isolation resistor. note: r iso chosen for peaking < 2db. 25 20 0 10 10,000 15 5 10 capacitive load (pf) peaking (db) 1000 100 max4250 max4254 (a v = 1) max4249/max4255 max4257 (a v = 10) r iso = 0 shaded area indicates stable operation with no need for isolation resistor. figure 6. isolation resistance vs. capacitive loading to minimize peaking (<2db) figure 7. peaking vs. capacitive load figure 8. max4250-4254 unity-gain bandwidth vs. capacitive load
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps ______________________________________________________________________________________ 13 typical operating circuit max195 (16-bit adc) serial interface dout sclk shdn shdn ain v in ref -5v 2 50k ? 5v 3 4 6 7 8 5k ? v dd v ss 4.096v cs max4256 test conditions duration no. of failures per sample size temperature cycle -35 c to +85 c, -40 c to +100 c 150 cycles, 900 cycles 0/10, 0/200 operating life t a = +70 c 240h 0/10 moisture resistance -20 c to +60 c, 90% rh 240h 0/10 low-temperature storage -20 c 240h 0/10 low-temperature operational -10 c 24h 0/10 solderability 8h steam age 0/15 esd 2000v, human body model 0/5 high-temperature operating life t j = +150 c 168h 0/45 table 1. reliability test data
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 14 ______________________________________________________________________________________ selector guide part g a in b a n d wid t h ( m h z) minimum stable gain (v/v) no. of amplifiers per package shutdown mode pin-package max4249 22 10 2 yes 10-pin max, 14-pin so max4250 3 1 1 5-pin sot23 max4251 3 1 1 yes 8-pin max/so max4252 3 1 2 8-pin max/so, 8-pin ucsp max4253 3 1 2 yes 10-pin max, 14-pin so, 10-pin ucsp max4254 3 1 4 14-pin so max4255 22 10 1 5-pin sot23 max4256 22 10 1 yes 8-pin max/so max4257 22 10 2 8-pin max/so part temp range pin- package top mark max4251 esa -40 c to +85 c 8 so max4251eua -40 c to +85 c 8max max4252 ebl-t* -40 c to +85 c 8 ucsp-8 aao max4252esa -40 c to +85 c 8 so max4252eua -40 c to +85 c 8 max max4253 ebc-t* -40 c to +85 c 10 ucsp-10 aak max4253eub -40 c to +85 c 10 max max4253esd -40 c to +85 c 14 so max4254 esd -40 c to +85 c 14 so max4255 euk-t -40 c to +85 c 5 sot23-5 accj max4256 esa -40 c to +85 c 8 so max4256eua -40 c to +85 c 8 max max4257 esa -40 c to +85 c 8 so max4257eua -40 c to +85 c 8 max ordering information (continued) *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. chip information max4250/max4251/max4255/max4256 transistor count: 170 max4249/max4252/max4253/max4257 transistor count: 340 max4254 transistor count: 680
v ss in- in+ 15 v dd out max4250 max4255 sot23 top view 2 34 out n.c. v ss 1 2 8 7 shdn v dd in- in+ n.c. max/so 3 4 6 5 max4251 max4256 inb- inb+ v ss 1 2 8 7 v dd outb ina- ina+ outa max/so 3 4 6 5 max4252 max4257 1 2 3 4 5 10 9 8 7 6 v dd outb inb- inb+ v ss ina+ ina- outa max4249 max4253 max shdnb shdna 14 13 12 11 10 9 8 1 2 3 4 5 6 7 v dd outb inb- inb+ v ss ina+ ina- outa max4249 max4253 n.c. shdnb n.c. n.c. shdna n.c. so 14 13 12 11 10 9 8 1 2 3 4 5 6 7 outd ind- ind+ v ss v dd ina+ ina- outa max4254 inc+ inc- outc outb inb- inb+ so pin configurations (continued) max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps ______________________________________________________________________________________ 15
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 16 ______________________________________________________________________________________ package information sot5l.eps 8lumaxd.eps
package information (continued) 10lumax.eps 9lucsp, 3x3.eps max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps ______________________________________________________________________________________ 17
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps 18 ______________________________________________________________________________________ soicn.eps package information (continued)
max4249?ax4257 ucsp, single-supply, low-noise, low-distortion, rail-to-rail op amps package information (continued) 12l, uspc.eps 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 _____________________ 19 ? 2002 maxim integrated products printed usa is a registered trademark of maxim integrated products.

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