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1 lmv321a/lmv358a / lmv324a 8 0 a , 1 .0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 features ? upgrade to lmv321/lmv358/lmv324 family ? stable 1. 0 mhz g bwp with low i q of only 8 0 a typical per amplifier ? 0. 7 v/s slew rate ? excellent emirr performance : 80db(1ghz) ? offset voltage tolerance : 4 00 v max . ? offset voltage temperature drift: 1 uv/ c ? input bias current: 1p a typical ? high output current: 50ma (1.0v drop) ? cmrr/psrr: 95 db/ 90 db ? beyond the rails input common - mode range ? outputs swing to within 6 mv max of each rail ? no phase reversal for overdriven inputs ? no crossover distortion ? drives 2k resistive loads ? single +2.1 v to +6.0 v supply voltage ran ge ? C 40c to 125c operati on range ? esd rating : robust 8kv C hbm , 2kv C cdm ? green, popular type package applications ? active filters , asic input or output amplifier ? sensor interface ? smoke/gas/ environment sensors ? portable instrument s and mobile device ? audio output ? pcmcia cards ? battery or solar powered systems ? medical equipment ? piezo electrical transducer amplifier pin configuration (top view) description lmv321 a /358 a /324 a are cmos single , dual , and quad op - amps with low offset , stable high frequency response , low power, low supply voltage, and rail - to - rail inputs and outputs. they incorporate 3peak ? s proprietary and patented design techniques to achieve best in - class performance among all micro - power cmos amplifiers. the lmv321 a /358 a /324 a are unity gain stable with a ny c apacitive l oad with a constant 1. 0 mhz gain - bandwidth product, 0. 7 v/s s lew rate while consuming only 8 0 a of supply current per amplifier . analog trim and calibration routine reduces input offset voltage t olerance to below 4 00 v . adaptive biasing and dynamic compensation enables the lmv321 a /358 a /324 a to achieve ?thd+ noise ? for 1khz and 10khz 2v pp signal at - 105db and - 90db, respectively. beyond the rails input and rail - to - rail output characteristics allow the full power - supply voltage to be used for signal range . this combination of features makes the lmv321 a /358 a /324 a superior among rail - to - rail input /output cmos op amps in its power class . t he lmv321 a /358 a /324 a are ideal choices for battery - powered applications because they minimize errors due to power supply voltage variations over the li fetime of the battery and maintain high cmrr even for a rail - to - rail input op - amp. the lmv321 a /358 a /324 a can be used as cost - effective plug - in replacements for many commercially available op amps to reduce power and improve input/output range and performance. 3peak and the 3peak logo are registered trademarks of 3peak incorporated . all other trademarks are the property of their respective owners. 3 p e a k l m v 3 2 1 a 5 - p i n s o t 2 3 / s c 7 0 ( - t a n d - c s u f f i x e s ) 4 5 3 2 1 + i n - v s - i n o u t + v s 1 4 1 3 1 2 1 1 1 0 9 8 6 5 7 3 2 1 4 o u t a - v s + i n a - i n a + v s d a c b o u t d + i n d - i n d o u t b + i n b - i n b o u t c + i n c - i n c l m v 3 2 4 a 1 4 - p i n s o i c / t s s o p ( - s a n d - t s u f f i x e s ) 8 6 5 7 3 2 1 4 o u t a - v s + i n a - i n a + v s + i n b - i n b o u t b a b l m v 3 5 8 a 8 - p i n s o i c / m s o p ( - s a n d - v s u f f i x e s )
2 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps order information model name order number package transport media, quantity marking information lmv321a lmv321a - t r 5 - pin sot23 tape and reel, 3,000 321 lmv321a - c r 5 - pin s c70 tape and reel, 3,000 321 lmv358a lmv358a - s r 8 - pin so p tape and reel, 4,000 lmv358a lmv358a - v r 8 - pin msop tape and reel, 3,000 lmv358a lmv324a lmv324a - s r 14 - pin so p tape and reel, 2,5 00 lmv324a lmv324a - t r 14 - pin tssop tape and reel, 3,000 lmv324a absolute maximum ratings note 1 supply voltage: v + C v C note 2 ...................... .. ..... . 7 .0 v input voltage . ........................ . ... v C C 0. 3 to v + + 0. 3 input current: +in, C in note 3 .... . . ... ............ .... . 2 0ma output short - circuit duration note 4 .. ..... .... . . in finite current at supply pins .. ............. 6 0 ma operating temperature range..... . . . C 40c to 12 5c maximum junction temperature................... 150c storage temperature range....... . .. C 65c to 150c lead temperature (soldering, 10 sec) ..... .... 260c note 1 : stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. exposure to any absolute maximum rating condition for extended periods may affect device reliability and lifetime. note 2 : the op amp supplies must be established simultaneously , with, or before, the application of any input signals. note 3 : the inputs are protected by esd protection diodes to each power supply. if the input extends more than 500mv beyond the power supply, the input current should be limited to less than 10ma. note 4 : a heat sink may be required to keep the junction temperature below the absolute maximu m. this depends on the power supply voltage and how many amplifiers are shorted. thermal resistance varies with the amount of pc board metal connected to the package. the specified values are for short traces connected to the leads. esd, electrostatic discharge protection symbol parameter condition minimum level unit hbm human body model esd mil - std - 883h method 3015.8 8 kv cdm charged device model esd jedec - eia/jesd22 - c101e 2 kv thermal r e sistance package type ja j c unit 5 - pin sot23 250 81 c /w 5 - pin sc70 395 165 c /w 8 - pin so p 158 43 c /w 8 - pin msop 210 45 c /w 14 - pin so p 120 36 c /w 14 - pin tssop 180 35 c /w
3 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 electrical characteristics the specifications are at t a = 27 c. v s = + 2. 1 v to + 6.0 v, or 1. 05 v to 3.0 v , r l = 2 k , c l = 10 0pf . unless otherwise noted. symbol parameter conditions min typ max units v os input offset voltage v cm = v ss +0.1v 0 . 6 1 1. 4 m v v os tc input offset voltage drift - 40 c to 125 c 1 v/ c i b input bias current t a = 27 c 1 10 p a t a = 85 c 25 pa i os input offset current 0.001 p a v n input voltage noise f = 0.1hz to 10hz 7 v pp e n input voltage noise density f = 1khz 27 nv/hz i n input current noise f = 1khz 2 fa /hz c in input capacitance differential common mode 8 7 pf cmrr common mode rejection ratio v cm = 0 v to 2.5 v 85 95 db v cm common - mode input voltage range v C - 0. 3 v + + 0. 3 v psrr power supply rejection ratio v cm = 0 v , v s = 3 v to 5v 7 7 90 db a v ol open - loop large signal gain r load = 10 k 98 1 20 db v ol , v oh output swing from supply rail r load = 10 k 3 6 mv r out closed - loop output impedance g = 1, f =1khz, i o ut = 0 0.002 r o open - loop output impedance f = 1khz, i o ut = 0 125 i sc output short - circuit current sink or source current 10 0 120 m a i o output current sink or source current , output 1v drop 5 0 m a v dd supply voltage 2. 1 6.0 v i q quiescent current per amplifier v s = 5v 80 12 0 a pm phase margin r load = 1 k, c load = 6 0pf 65 gm gain margin r load = 1 k, c load = 6 0pf 15 db gbw p gain - bandwidth product f = 1khz 1 .0 m hz sr slew rate av = 1, vout = 1.5v to 3.5v, c load = 60pf, r load = 1k 0. 7 v/s fpbw full power bandwidth note 1 58.6 khz t s settling time, 0.1% settling time, 0.01% a v = C 1, 1v step 3.7 4. 9 s thd+ n total harmonic distortion and noise f = 1khz, av =1, r l = 2k, v out = 1vp - p 0.0 03 % x talk channel separation f = 1 k hz, r l = 2 k 110 db note 1 : full power bandwidth is calculated from the slew rate fpbw = sr/ ? v p - p
4 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps typical performance characteristics v s = 2.75 v, v cm = 0v, r l = open, unless otherwise specified. offset voltage production distribution unity gain bandwidth vs. temperature open - loop gain and phase input voltage noise spectral density input bias current vs. temperature input bias current vs. input common mode voltage 0 500 1000 1500 2000 2500 3000 3500 4000 600 650 700 750 800 850 900 950 1000 1050 1100 1150 1200 1250 1300 population offset voltage(uv) number = 20000 pcs 0.0 0.3 0.5 0.8 1.0 1.3 1.5 1.8 2.0 -50 0 50 100 150 gbw(mhz) temperature( ) -150 -100 -50 0 50 100 150 200 -60 -40 -20 0 20 40 60 80 100 120 140 0.1 10 1k 100k 10m 1000m phase ( ) gain(db) frequency (hz) phase gain 1 10 100 1000 1 10 100 1k 10k 100k 1m noise(nv/hz) frequency(hz) -10 0 10 20 30 40 50 -40 -20 0 20 40 60 80 100 120 input bias current(pa) temperature( ) -25 -20 -15 -10 -5 0 0 1 2 3 4 5 input bias current(pa) common mode voltage(v)
5 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 typical performance characteristics v s = 2.75 v, v cm = 0v, r l = open, unless otherwise specified. (continued) common mode rejection ratio cmrr vs. frequency quiescent current vs. temperature short circuit current vs. temperature power - supply rejection ratio quiescent current vs. supply voltage 0 20 40 60 80 100 120 140 0 1 2 3 4 5 cmrr(db) common - mode voltage(v) 0 20 40 60 80 100 120 140 160 1 10 100 1k 10k 100k 1m cmrr(db) frequency(hz) 0 20 40 60 80 100 120 -50 0 50 100 150 supply current(a) temperature( ) v cm = 0v v cm = 2.5v v cm = 5.0v 0 20 40 60 80 100 120 140 -50 0 50 100 150 current(ma) temperature( ) i sink i source -20 0 20 40 60 80 100 120 0.1 10 1k 100k psrr(db) frequency(hz) psrr+ psrr - 0 20 40 60 80 100 120 1.5 2 2.5 3 3.5 4 4.5 5 supply current (ua) supply voltage (v)
6 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps typical performance characteristics v s = 2.75 v, v cm = 0v, r l = open, unless otherwise specified. (continued) p srr vs. temperature cmrr vs. temperature emirr in+ vs. frequency large - scale step response negative over - voltage recovery positive over - voltage recovery 0 20 40 60 80 100 120 -50 0 50 100 150 psrr( - db) temperature( ) 0 20 40 60 80 100 120 140 -50 0 50 100 150 cmrr( - db) temperature( ) 0 10 20 30 40 50 60 70 80 90 1 10 100 1000 emirr in+ (db) frequency (mhz) time (50 s/div) 2v/div 2v/div gain = 1 r l = 10k time (50 s/div) 1v/div 2v/div gain = +10 v = 2.5v time (50 s/div) 1v/div 2v/div gain = +10 v = 2.5v
7 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 typical performance characteristics v s = 2.75 v, v cm = 0v, r l = open, unless otherwise specified. (continued) 0.1 hz to 10 hz i nput voltage noise o ffset v oltage vs c ommon - m ode v oltage positive o utput s wing vs . l oad c urrent negative o utput s wing vs . l oad c urrent offset voltage vs . temperature -1500 -1000 -500 0 500 1000 1500 0 1 2 3 4 5 offset voltage change(v) common - mode voltage(v) 0 20 40 60 80 100 120 0 1 2 3 4 5 iout(ma) vout dropout (v) 25 - 40 125 -140 -120 -100 -80 -60 -40 -20 0 0 1 2 3 4 5 iout(ma) vout dropout (v) 25 - 40 125 0 10 20 30 40 50 60 70 80 -50 0 50 100 150 offset voltage change(v) temperature( ) time (1s/div) 5 v/div
8 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps pin functions - in: inverting input of the amplifier. +in: non - inverting input of amplifier. out: amplifier output. the voltage range extends to within mv of each supply rail. v+ or +v s : positive power supply. typically the voltage is from 2. 1 v to 6.0 v. split supplies are possible as long as the voltage between v+ and v C is between 2. 1 v and 6.0 v. a bypass capacitor of 0.1f as close to the part as possible should be used between power supply pins or between supply pins and ground. v - or - v s : negative power supply. it is normally tied to ground. it can also be tied to a voltage other than ground as long as t he voltage between v + and v C is from 2. 1 v to 6.0 v. if it is not connected to ground, bypass it with a capacitor of 0.1f as close to the part as possible. operation the lmv321 a /358 a /324 a input signal range extends beyond the negative and positive power supplies. the output can even extend all the way to the negative supply. the input stage is comprised of two cmos differential amplifiers, a pmos stage and nmos stage that are active over different ranges of common mode inpu t voltage. the class - ab control buffer and output bias stage uses a proprietary compensation technique to take full advantage of the process technology to drive very high capacitive loads. this is evident from the transient over shoot measurement plots in the typical performance characteristics. applications information low supply voltage and low power consumption the lmv321 a /358 a /324 a of operational amplifiers can operate w ith power supply voltages from 2.1v to 6.0 v. each amplifier draws only 8 0 a quiescent current . the low supply voltage capability and low supply current are ideal for portable applications demanding h igh c apacitive l oad d riving c apability and w ide b andwidth . the lmv321 a /358 a /324 a is optimized for wide bandwidth low power applications. they have a n industry leading high gbw p to power ratio and are unity gain stable for any capacitive load . when the load capacitance increases, the increased capacitance at the output pushed the non - d ominant pole to lower frequency in the open loop frequency response, lowering the phase and gain margin. higher gain configurations tend to have better capacitive drive capability than lower gain configurations due to lower closed loop bandwidth and hence higher phase margin. low input referred noise the lmv321 a /358 a /324 a provides a low input referred noise density of 27 nv/ hz at 1khz. the voltage noise will grow slowly with the frequency in wideband range , and the input voltage noise is typically 7 v p - p at the frequency of 0.1hz to 10hz. low input offset voltage the lmv321 a /358 a /324 a has a low offset voltage tolerance of 400 v maximum which is essential for precision applications. the offset voltage is trimmed with a proprietary trim algorithm to ensure low offset voltage for precision signal processing requirement . low input bias current the lmv321 a /358 a /324 a is a cmos opa family and features very low input bias current in pa range. t he low input bias current allows the amplifiers to be used in applications with high resistance sources. care must be taken to minimize pcb surface leakage. see below section on pcb surface leakage for more details. pcb surface leakage
9 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 in applications where low input bias current is crit ical, printed circuit board (pcb) surface leakage effects need to be considered. surface leakage is caused by humidity, dust or other contamination on the board. under low humidity conditions, a typical resistance between nearby traces is 10 12 . a 5v diffe rence would cause 5pa of current to flow, which is greater than the lmv321 a /358 a /324 a opa? s input bias current at +27 c (1pa, typical). it is recommended to use multi - layer pcb layout and rout e the opa?s - in and +in signal under the pcb surface. the effective way to reduce surface leakage is to use a guard ring around sensitive pins (or traces). the guard ring is biased at the same voltage as the sensitive pin. an example of this type of layout is shown in figure 1 for inverting gain application . 1. f or non - i nverting gain and unity - gain buffer: a) connect the non - inverting pin (v in +) to the input with a wire that does not touch the pcb surface. b) connect the guard ring to the inverting input pin (v in C ). this biases the guard ring to the common mode input voltage. 2. for inverting gain and trans - impedance gain amplifiers (convert current to voltage, such as photo detectors): a) connect the guard ring to the non - inverting input pin (v in +). this biases the guard ring to the same reference voltage as the op - amp (e.g., v dd /2 or ground). b) connect the inverting pin (v in C ) to the input with a wire that does not touch the pcb surfac e. figure 1 ground sensing and rail to rail output the lmv321 a /358 a /324 a has excellent output drive capability, delivering over 10 0 ma of output drive current. the output stage is a rail - to - rail topology that is capable of swinging to within 5 mv of either rail. since the inputs can go 100mv beyond either rail, the op - amp can easily perform ? t rue g round s ensing?. the maximum output current is a function of total supply voltage. as the supply voltage to the amplifier increases, the output current capability also increases. attention must be paid to keep the junction temp erature of the ic below 150c when the output is in continuous short - circuit. the output of the amplifier has reverse - biased esd diodes connected to each supply. the output should not be forced more than 0.5v beyond either supply, otherwise current will fl ow through these diodes. esd the lmv321 a /358 a /324 a has reverse - biased esd protection diodes on all inputs and output. input and out pins cannot be biased more than 200mv beyond either supply rail. feedback components and s uppression of r inging care should be taken to ensure that the pole formed by the feedback resistors and the parasitic capacitance at the inverting input does not degrade stability. for example, in a gain of +2 configuration with gain and feedback resistors of 10k, a poorly designed circui t board layout with parasitic capacitance of 5pf (part +pc board) at the amplifier?s inverting input will cause the amplifier to ring due to a pole formed at 3.2mhz. an additional capacitor of 5pf across the feedba ck resistor as shown in figure 2 will eliminate any ringing . careful layout is extremely important because low power signal conditioning applications demand high - impedance circuits. the layout should also minimize stray capacitance at the opa?s inputs. however some stray capacitance may be una voidable and it may be necessary to add a 2pf to 10pf capacitor acros s the feedback resistor. select the smallest capacitor value that ensures stability. v i n + v i n - + v s g u a r d r i n g
10 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps figure 2 driving large capacitive load the lmv321 a /358 a /324 a of opa is designed to drive large capacitive loads. refer to typical performance characteristics for phase margin vs. load capacitance. as always, larger load capacitance decreases overall phase margi n in a feedback system where internal frequency compensation is utilized. as the load capacitance increases, the feedback loop?s phase margin decreases, and the closed - loop bandwidth is reduced. this produces gain peaking in the frequency response, with o vershoot and ringing in output step response. the unity - gain buffer (g = +1v/v) is the most sensitive to large capacitive loads. when driving large capacitive loads with the lmv321 a /358 a /324 a (e.g., > 2 00 pf when g = +1v/v), a small series resistor at the output (r iso in figure 3 ) improves the feedback loop?s phase margin and stability by making the output load resistive at higher frequencies. figure 3 power supply layout a nd bypass the lmv321 a /358 a /324 a opa ?s power supply pin (v dd for single - supply) should have a local bypass capacitor (i.e., 0.01 f to 0.1 f) within 2mm for good high frequency performance. it can also use a bulk capacitor (i.e., 1f or larger) within 100mm to provide large, slow currents. this bulk capacito r can be shared with other analog parts. ground layout improves performance by decreasing the amount of stray cap acitance and noise at the opa ?s inputs and outputs. to decrease stray capacitance, minimize pc board lengths and resistor leads, and place external components as close to the op amps? pins as possible. proper board l ayout to ensure optimum performance at the pcb level, care must be taken in the design of the board layout. to avoid leakage currents, the surface of the board should be kept clean and free of moisture. coating the surface creates a barrier to moisture accumulation and helps reduce parasitic resistance on the board. keeping supply traces short and properly bypassing the power supplies minimizes power supply disturbances due to output current variation, such as when driving an ac signal into a heavy load. bypass capacitors should be connected as closely as possible to the device supply pins. stray capacitances are a concern at the outputs and the inputs of the amplifier. it is recommended that signal traces be kept at least 5mm from supply lines to minimize coupling. a variation in temperature across the pcb can cause a mismatch in the seebeck voltages at solder join ts and other points where dissi milar m etals are in contact, resulting in thermal voltage errors. to minimize these thermocouple effects, orient resistors so heat sources warm both ends equally. input signal paths should contain matching numbers 1 0 k 5 p f 1 0 k c p a r v i n v o u t v i n v o u t c l o a d r i s o
11 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 and types of components, where possible to match the number and type of thermocouple junctions. for example, dummy components such as zero value resistors can be used to match real resistors in the opposite input path. matching components should be located in close proximity and should be oriented in the same manner. ensure leads are of equal length so that thermal conduction is in equilibrium. keep heat sources on the pcb as far away from amplifier input circuitry as is practical. the use of a ground plane is highly recommended. a ground plane reduces emi noise and also helps to maintain a constant temperature across the circuit board. instrumentation amplifier the lmv321 a /358 a /324 a opa is well suited for conditioning sensor signals in battery - powered applications. figure 4 shows a two op - amp instrument ation amplifier, using the lmv321 a /358 a /324 a opa. the circuit works well for applications requiring rejection of common mode noise at higher gains. the reference voltage (v ref ) is supplied by a low - impedance source. in single voltage supply applications, v ref is typically v dd /2. figure 4 gain - of - 100 amplifier circuit figure 5 shows a gain - of - 100 amplifier circuit using two lmv321 a /358 a /324 a opa s . it draws 74ua total current from supply rail, and has a - 3db frequency at 100 k hz. figure 6 shows the small signal frequency response of the circuit. figure 5 : 100 k hz, 74a gain - of - 100 amplifier v r e f v o u t r g r 2 r 2 r 1 r 1 v 2 v 1 11 12 2 2 =( )(1 ) out ref g rr v v v v rr ? ? ? ? v o u t v i n 9 0 . 9 k 9 0 . 9 k 1 0 k 1 0 k - 0 . 9 v + 0 . 9 v
12 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps figure 6 : frequency response of 100 k hz, 74ua gain - of - 100 amplifier buffered c hemical s ensor (ph) probe the lmv321 a /358 a /324 a opa has input bias current in the pa range. this is ideal in buffering high impedance chemical sensors such as ph probe. as an example, the circuit in figure 7 eliminates expansive low - leakage cables that that is required to connect ph probe to metering ics such as adc, afe and/or mcu. a l mv321 a /358 a /324 a opa and a lithium battery are housed in the probe assembly. a conventional low - cost coaxial cable can be used to carry opa?s output signal to subsequent ics for ph reading. figure 7 : buffer ph probe two - pole micro - p ower sallen - key low - pass filter figure 8 shows a micro - power two - pole sallen - key low - pass f ilter with 400hz cut - off frequency. for best results, the filter?s cut - off frequency should be 8 to 10 times lower than the opa?s crossover fr equency. additi onal opa?s phase margin shift can be avoided if the opa?s bandwidth - to - signal ratio is greater than 8. the design equations for the 2 - pole sallen - key low - pass filter are given below with component values selected to set a 400hz low - pass filter cutoff frequ ency: r 1 1 0 m r 2 1 0 m c o a x b a t t e r y 3 v ( d u r a c e l l d l 1 6 2 0 ) a l l c o m p o n e n t s c o n t a j n e d w i t h i n t h e p h p r o b e g e n e r a l p u r p o s e c o m b i n a t i o n p h p r o b e ( c o r n i n g 4 7 6 5 4 0 ) p h p r o b e t o a d c / a f e / m c u
13 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 figure 8 portable gas sensor amplifier gas sensors are used in many different industrial and medical applications. gas sensors generate a current that is proportional to the percentage of a particular gas concentration sensed in an air sample. this output current flows through a load resistor and the resultant voltage drop is amplified. depending on the sensed gas and sensitivity of the sensor, the output current can be in the range of t ens of microamperes to a few mi l li - amperes. gas sensor datasheets often specify a recommended load resistor value or a range of load resistors from which to choose. there are two main applications for oxygen sensors C applications which sense ox ygen when it is abundantly present (that is, in air or near an oxygen tank) and those which detect traces of oxygen in parts - per - million concentration. in medical applications, oxygen sensors are used when air quality or oxygen delivered to a patient needs to be monitored. in fresh air, the concentration of oxygen is 20.9% and air samples containing less than 18% oxygen are considered dangerous. in industrial applications, oxygen sensors are used to detect the absence of oxygen; for example, vacuum - packagin g of food products . the circuit in figure 9 illustrates a typical implementation used to amplify the output of an oxygen detector . with the components shown in the figure, th e circuit consumes less than 100 a of supply current ensuring that small form - factor single - or button - cell batteries (exhibiting low mah charge ratings) could last beyond the operating life of the oxygen sensor. the precision specifications of these amplifiers, such as their low offset voltage, low tc - v os , low input bias current, high cmrr, and high psrr are other factors which make these amplifiers excellent choices for this application. figure 9 r 1 1 m r 2 1 m c 1 4 0 0 p f c 2 4 0 0 p f r 3 2 m r 4 2 m v i n v o u t 12 12 -3db 3 4 3 4 r = r = r = 1m c = c = c = 400pf q = filter peaking factor = 1 f = 1/(2 ) = 400 r = r /(2-1/q) ; with q = 1, r =r rc hz ? ? 1 0 0 k 1 % 1 0 0 1 % v o u t 1 0 0 k 1 % 1 0 m 1 % o x y g e n s e n s o r c i t y t e c h n o l o g y 4 o x 2 2 o i 2 1 in air ( 21% o ) 0.7 out dd vv i ua ? ?
14 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps revision history the revision history provided is for informational purposes only and is believed to be accurate, but not warranted. please go to web to make sure you have the latest revision. revision change rev . a initial release
15 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 package outline dimensions sc70 - 5 /sot - 353 sot23 - 5 symbol dimensions in millimeters dimensions in inches min max min max a 1.050 1.250 0.041 0.049 a1 0.000 0.100 0.000 0.004 a2 1.050 1.150 0.041 0.045 b 0.300 0.400 0.012 0.016 c 0.100 0.200 0.004 0.008 d 2.820 3.020 0.111 0.119 e 1.500 1.700 0.059 0.067 e1 2.650 2.950 0.104 0.116 e 0.950typ 0.037typ e1 1.800 2.000 0.071 0.079 l 0.700ref 0.028ref l1 0.300 0.460 0.012 0.024 0 8 0 8 symbol dimensions in millimeters dimensions in inches min max min max a 0.900 1.100 0.035 0.043 a1 0.000 0.100 0.000 0.004 a2 0.900 1.000 0.035 0.039 b 0.150 0.350 0.006 0.014 c 0.080 0.150 0.003 0.006 d 2.000 2.200 0.079 0.087 e 1.150 1.350 0.045 0.053 e1 2.150 2.450 0.085 0.096 e 0.650typ 0.026typ e1 1.200 1.400 0.047 0.055 l 0.525ref 0.021ref l1 0.260 0.460 0.010 0.018 0 8 0 8
16 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps package outline dimensions so p - 8 symbol dimensions in millimeters dimensions in inches min max min max a1 0.100 0.250 0.004 0.010 a2 1.350 1.550 0.053 0.061 b 0.330 0.510 0.013 0.020 c 0.190 0.250 0.007 0.010 d 4.780 5.000 0.188 0.197 e 3.800 4.000 0.150 0.157 e1 5.800 6.300 0.228 0.248 e 1.270 typ 0.050 typ l1 0.400 1.270 0.016 0.050 0 8 0 8 d e 1 b e a 1 a 2 e l 1 c
17 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 package outline dimensions msop - 8 symbol dimensions in millimeters dimensions in inches min max min max a 0.800 1.200 0.031 0.047 a1 0.000 0.200 0.000 0.008 a2 0.760 0.970 0.030 0.038 b 0.30 typ 0.012 typ c 0.15 typ 0.006 typ d 2.900 3.100 0.114 0.122 e 0.65 typ 0.026 e 2.900 3.100 0.114 0.122 e1 4.700 5.100 0.185 0.201 l1 0.410 0.650 0.016 0.026 0 6 0 6 e 1 e e a 1 a 2 a d l 1 l 2 l r r 1 b
18 r ev. a .0 2 www.3 peakic .com .cn lmv321a / lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps package outline dimensions tssop - 14 symbol dimensions in millimeters min typ max a - - 1.20 a1 0.05 - 0.15 a2 0.90 1.00 1.05 b 0.20 - 0.28 c 0.10 - 0.19 d 4.86 4.96 5.06 e 6.20 6.40 6.60 e1 4.30 4.40 4.50 e 0.65 bsc l 0.45 0.60 0.75 l1 1.00 ref l2 0.25 bsc r 0.09 - - 0 - 8 e e e 1 a 1 a 2 a d l 1 l 2 l r r 1 c
19 lmv321a/lmv358a / lmv324a 8 0 a , 1. 0 mhz, micro - power rail - to - rail i/o op amps www.3 peakic .com .cn r ev. a .0 2 package outline dimensions so p - 14 symbol dimensions in millimeters min typ max a 1.35 1.60 1.75 a1 0.10 0.15 0.25 a2 1.25 1.45 1.65 b 0.36 0.49 d 8.53 8.63 8.73 e 5.80 6.00 6.20 e1 3.80 3.90 4.00 e 1.27 bsc l 0.45 0.60 0.80 l1 1.04 ref l2 0.25 bsc 0 8 e b e 1 e d a 1 a a 2 l 1 l l 2

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