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general description the max44284 is a high-side, current-sense amplifier that operates with a 1.7v to 5.5v single supply and is optimized for very low power operation with only 21a of quiescent current. the max44284 offers precision accuracy specifications of 2v v os and gain error of 0.05%. the device features an input common-mode voltage range from -0.1v to +36v. this current-sense amplifier has a voltage output and is offered in four different gain versions. the max44284 is offered in small 6-bump, 0.4mm-pitch wlp (1.3mm x 0.9mm) and 6-pin sot23 packages and is specified for operation over the -40c to +125c automo - tive temperature range. applications smartphones and tablets notebook computers dc-dc current sensing in power management portable-/battery-powered systems medical pulse oximeters and infusion pumps base-stations beneits and features supports use of small current-sense resistors to improve power-supply conversion efficiency and measurement accuracy ? input bias current of 80na (max) ? very low 2v input offset voltage (max44284f/h) ? extremely low 50nv/c input offset tempco coefficient ? -0.1v to +36v wide input common-mode range ? low 0.05% gain error extends battery life ? low supply current of 21a ? 1.7v to 5.5v single supply ? shutdown input (independent of v dd ) four fixed gain options simplify design ? 50v/v C max44284f ? 100v/v C max44284h ? 200v/v C max44284w ? 500v/v C max44284e ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maximintegrated.com/max44284.related . r sense v batt = up to 36v rs+ rs- adc c v dd = 3.3v out v dd = 3.3v load max44284 i load max44284 36v, input common-mode, high-precision, low-power current-sense amplifier 19-6862; rev 4; 1/15 typical application circuit downloaded from: http:///
v dd to gnd ............................................................ -0.3v to +6v rs+, rs- to gnd .................................................. -0.3v to +40v rs+ to rs- .......................................................................... 40v out, shdn to gnd ................................. -0.3v to (v dd + 0.3v) continuous input current (any pin) .................................. 20ma continuous power dissipation (t a = +70c) wlp (derate 10.5mw/c above +70c) ...................... 840mw sot23 (derate 4.3mw/c above +70c) ................. 347.8mw operating temperature range ......................... -40c to +125c junction temperature ...................................................... +150c storage temperature range ............................ -65c to +150c lead temperature (soldering, 10s) ................................. +300c soldering temperature (reflow) ....................................... +260c wlp junction-to-ambient thermal resistance ( ja ) .......... 70c/w (note 1) (v dd = 3.3v, v cm = 12v, v sense = v fs /2, v fs = (v dd - v oh - v ol )/gain, v shdn = v dd , r l = 10k to gnd, t a = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 2) parameter symbol conditions min typ max units power supply supply voltage v dd guaranteed by psrr 1.7 5.5 v shutdown supply current i shdn 0.3 0.8 a supply current i dd t a = +25c, r l = 21 31.2 a -40c t a +125c, r l = 41.5 power-supply rejection ratio psrr 1.7v v dd 5.5v, v out = 1v 100 110 db shutdown voltage low v il 0.55 v shutdown voltage high v ih 1.3 v dc characteristics input common-mode voltage range v cm guaranteed by cmrr -0.1 +36 v common-mode rejection ratio (note 5) cmrr -0.1v v cm +36v, v cm = rs- 91.3 140 db +0.1v v cm +36v, v cm = rs- (note 7) 120 145 input bias current i rs+ , i rs- 2 80 na input offset current i os 2 50 na max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 2 note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maximintegrated.com/thermal-tutorial . absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. electrical characteristics package thermal characteristics downloaded from: http:///
(v dd = 3.3v, v cm = 12v, v sense = v fs /2, v fs = (v dd - v oh - v ol )/gain, v shdn = v dd , r l = 10k to gnd, t a = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 2) parameter symbol conditions min typ max units input offset voltage (note 3) v os max44284f (t a = +25c) 2 10 v max44284f (-40c t a +125c) 28 max44284h (t a = +25c) 2 12 max44284h (-40c t a +125c) 28 max44284w (t a = +25c) 10 20.5 max44284w (-40c t a +125c) 38 max44284e (t a = +25c) 15 26 max44284e (-40c t a +125c) 40 input offset voltage temperature drift tcv os 50 nvc gain g max44284f 50 v/v max44284h 100 max44284w 200 max44284e 500 gain error (note 4) ge max44284f (t a = +25c) 0.05 0.15 % max44284f (-40c t a +125c) 0.20 max44284h (t a = +25c) 0.05 0.15 max44284h (-40c t a +125c) 0.26 max44284w (t a = +25c) 0.05 0.15 max44284w (-40c t a +125c) 0.35 max44284e (t a = +25c) 0.05 0.16 max44284e (-40c t a +125c) 0.39 output voltage high v oh v oh = v dd - v out , r l = 10k w to gnd 25 35 mv i source = 100a 20 output voltage low v ol no load 0.3 1 mv i sink = 100a 20 input differential impedance 6 m w output impedance 200 m w max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 3 electrical characteristics (continued) downloaded from: http:///
(v dd = 3.3v, v cm = 12v, v sense = v fs /2, v fs = (v dd - v oh - v ol )/gain, v shdn = v dd , r l = 10k to gnd, t a = -40c to +125c, unless otherwise noted. typical values are at t a = +25c.) (note 2) note 2: all devices are 100% production tested at t a = +25c. all temperature limits are guaranteed by design. note 3: v os is calculated by applying two values of v sense (10% of full-scale range to 90% of full-scale range). note 4: gain error is calculated by applying two values of v sense (10% of full-scale range to 90% of full-scale range) and calculat - ing the error of the slope, vs. the ideal. note 5: cmrr measurement is done at v out = v dd /2 condition. note 6: psrr measurement is done at v out = 1v condition. note 7: parameter is guaranteed by design. parameter symbol conditions min typ max units ac characteristics small-signal bandwidth bw 3db max44284f 3 khz max44284h 1.8 max44284w 1 max44284e 0.4 input voltage-noise density e n f = 1khz 150 nv/ hz ac common-mode rejection ratio ac cmrr f = 10khz, 600mv p-p sinusoidal waveform 80 db settling time t s v out from 250mv to 2.5v, gain = 50, within 12-bit accuracy 1500 s v out from 250mv to 2.5v, gain = 100, within 12-bit accuracy 1500 v out from 250mv to 2.5v, gain = 200, within 12-bit accuracy 1800 v out from 250mv to 2.5v, gain = 500, within 12-bit accuracy 4000 capacitive load c l r iso = 0 w 500 pf r iso = 20 w 2200 max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 4 electrical characteristics (continued) downloaded from: http:///
(t a = +25c, unless otherwise noted.) 17 19 21 23 25 27 29 -50 -25 0 25 50 75 100 125 supply current (a) temperature ( c) supply current vs. temperature toc01a v dd = 5.5v v dd = 1.7v v dd = 3.3v gain = 50v/v 20 22 24 26 28 30 32 34 -50 -25 0 25 50 75 100 125 supply current (a) temperature ( c) supply current vs. temperature toc01b v dd = 5.5v v dd = 1.7v v dd = 3.3v gain = 100v/v 17 18 19 20 21 22 23 24 25 -50 -25 0 25 50 75 100 125 supply current (a) temperature ( c) supply current vs. temperature toc01c v dd = 5.5v v dd = 1.7v v dd = 3.3v gain = 200v/v 22 23 24 25 26 27 28 29 30 31 32 -50 -25 0 25 50 75 100 125 supply current (a) temperature ( c) supply current vs. temperature toc01d v dd = 5.5v v dd = 1.7v v dd = 3.3v gain = 500v/v 0 2 4 6 8 10 12 14 16 18 -0.08 -0.06 -0.04 -0.02 0 0.02 0.04 0.06 0.08 occurrence n (%) gain error (%) gain error histogram toc03 histogram all gain options supply current vs. common voltage v cm (v) supply current (a) 21 22 23 24 25 26 27 28 29 3020 -1 4 9 14 19 24 29 34 v dd = 3.3v max44284 toc02 t a = -40oc t a = +125oc t a = +85oc t a = +25oc 0 5 10 15 20 25 30 -6 -4 -2 0 2 4 6 occurrence n (%) input offset voltage ( v ) input offset voltage histogram toc04a histogram gain = 50v/v gain = 100v/v 0 2 4 6 8 10 12 14 16 -20-18-16-14-12-10 -8 -6 -4 -2 0 2 4 6 8 10 12 14 16 18 20 occurrence n (%) input offset voltage ( v ) input offset voltage histogram toc04b histogram gain = 200v/v max44284 36v, input common-mode, high-precision, low-power current-sense ampliier maxim integrated 5 www.maximintegrated.com typical operating characteristics downloaded from: http:///
(t a = +25c, unless otherwise noted.) 0 1 2 3 4 5 6 7 8 -60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60 occurrence n (%) input offset voltage drift (nv/ c) input offset voltage drift histogram toc05 histogram all gain options shutdown supply current vs. temperature max44284 toc06 supply current (a) 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0 temperature (c) 120 100 80 60 40 20 0 -20 -40 gain = 50v/v v dd = 5.5v v dd = 3.3v v dd = 1.7v v oh vs. i out max44284 toc07 i out (ma) v oh (mv) 9 8 6 7 2 3 4 5 1 100 200 300 400 500 600 700 800 900 0 0 10 v dd = 3.3v v ol vs. i sink max44284 toc08 i sink (ma) 8 6 4 2 0 10 v ol (mv) 100 200 300 400 500 600 700 800 900 1000 0 v dd = 3.3v 0 5 10 15 20 25 30 -50 -25 0 25 50 75 100 125 input offset voltage (v) temperature ( c) input offset voltage vs. temperature toc09 gain = 200 gain = 100v/v gain = 50vv gain = 50v/v gain error vs. input common-mode voltage max44284 toc10 v cm (v) gain error (%) 34.9 29.9 24.9 19.9 14.9 9.9 4.9 0.01 0.02 0.03 0.04 0.05 0 -0.1 max44284 36v, input common-mode, high-precision, low-power current-sense ampliier maxim integrated 6 www.maximintegrated.com typical operating characteristics (continued) downloaded from: http:///
(t a = +25c, unless otherwise noted.) gain error vs. supply voltage max44284 toc11 v dd (v) gain error (%) 5.1 4.7 4.0 4.4 2.5 2.8 3.2 3.6 2.1 0.005 0.010 0.015 0.020 0.025 0.030 0.035 0.040 0.045 0.050 0 1.7 5.5 -0.04 -0.02 0 0.02 0.04 0.06 0.08 -50 -25 0 25 50 75 100 125 gain error (%) temperature ( c) gain error vs. temperature toc12 gain = 100v/v gain = 200 v/v gain = 500v/v gain = 50v/v common-mode rejection ratio vs. temperature max44284 toc13 temperature (oc) cmrr (db) 100 75 25 50 0 -25 90 100 110 120 130 140 150 160 170 180 80 -50 125 v cm = 0 to 36v v cm = -0.1v to +36v power-supply rejection ratio vs. temperature max44284 toc14 temperature (oc) psrr (db) 100 75 25 50 0 -25 80 90 100 110 120 130 140 150 70 -50 125 -4 -2 0 2 4 6 8 10 12 -40 -25 -10 5 20 35 50 65 80 95 110 125 input bias current (na) temperature ( c) input bias current vs. temperature toc16 v cm = 12v for all gain options -1200 -1000 -800 -600 -400 -200 0 200 -1 3 7 11 15 19 23 27 31 35 input bias current (na) input common - mode voltage(v) input bias current vs. input common - mode voltage toc15 t a = +25 c t a = +85 c t a = - 40 c t a = +125 c for all gain options max44284 36v, input common-mode, high-precision, low-power current-sense ampliier maxim integrated 7 www.maximintegrated.com typical operating characteristics (continued) downloaded from: http:///
(t a = +25c, unless otherwise noted.) input-voltage noise vs. frequency max44284 toc18 frequency (hz) input voltage noise (nv hz) 10k 1k 100 10 1 10 100 1000 0 0.1 100k small-signal input step response (v dd = 3.3v, r l = open, g = 100v/v) max44284 toc20 600mv300mv v out 6mv3mv v in 400s/div 0.1hz to 10hz peak-to-peak noise max44284 toc19 v out 1v/div 1s/div gain vs. frequency max44284 toc17 frequency (hz) magnitude (db) 10k 1k 100 -10 0 10 20 30 40 50 60 70 80 -20 10 100k g = 100v/ v g = 50v/ v g = 200v/ v g = 500v/v 0.01 0.1 1 10 100 1000 10000 100 1000 10000 isolation resistance r iso ( w ) capacitive load (pf) stability vs. capacitive load and isolation resistor toc22 stable unstable large-signal input step response (v cc = 3.3v, r l = open) max44284 toc21 0.3v v out 30mv3mv 3v v in 400s/div max44284 36v, input common-mode, high-precision, low-power current-sense ampliier maxim integrated 8 www.maximintegrated.com typical operating characteristics (continued) downloaded from: http:///
max44284 sot23 top view gnd rs+ 1 v dd 23 rs- 6 shdn 5 out + 4 a1 a2 a3 b1 b2 b3 rs+ v dd out rs- gnd shdn + top view max44284 wlp pin bump name function sot23 wlp 1 a2 v dd power-supply voltage input. bypass v dd to gnd with 0.1f and 4.7f capacitors in parallel as close as possible to the device. 2 b2 gnd ground 3 a1 rs+ external sense resistor power-side connection 4 b1 rs- external sense resistor load-side connection 5 a3 out output voltage. v out is proportional to v sense = v rs+ - v rs- . 6 b3 shdn active-low shutdown input. connect to v dd for normal operation. max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 9 pin description pin conigurations downloaded from: http:///
detailed description the max44284 family features a single-supply; high- accuracy unidirectional, current-sense amplifier in various gain options and a -0.1v to 36v input common-mode range that is independent of supply voltage (v dd ). the max44284 is ideal for many battery-powered, handheld devices because it uses only maximum 31.2a quiescent supply current to extend battery life. the devices low input offset voltage, tight gain error, and low temperature drift characteristics allow the use of small-sense resistors for current measurements to improve power-supply con - version efficiency and accuracy of measurements. this feature allows monitoring of power-supply load current even if the rail is shorted to ground. high-side current monitoring does not interfere with the ground path of the load being measured, making the ic particularly useful in a wide range of high-reliability systems. because of its extended common-mode range below ground, this part can also be used as a low-side current sensing element. shutdown the max44284 features active-low logic shutdown input to reduce the supply current. drive shdn high for normal operation. drive shdn low to place the device in shut - down mode. in shutdown mode, the supply current drawn from the v dd is less than 1a (max). precision the max44284 uses capacitive-coupled instrumentation amplifier architecture that enables the part to achieve over the top common-mode voltage ranges, high power efficiency, high gain accuracy, and low-power design. low offset voltage and low gain error the max44284 utilizes capacitive-coupled chopper instrumentation amplifier (ccia) architecture to achieve a low-input offset voltage of less than 10a. these tech - niques also enable extremely low-input offset voltage drift over time and temperature to 50nv/c. the precision v os specification allows accurate current measurements with lower values of current-sense resistors, thus reducing power dissipation in battery-powered systems, as well as load regulation issues in low-voltage dc power supplies. working with error tolerances with very few internal blocks in this architecture is instrumental in achieving a gain error of less than 0.20% over the entire temperature range of -40c to +125c. applications information input differential signal range the max44284s input structure is optimized for sens - ing small differential signals as low as 3.4mv full scale (v fs ) for high efficiency with lowest power dissipation in the sense resistor, or 110mv full scale for high dynamic range. the input differential signal range is determined by the following equation for the max44248 family. ( ) dd sense range v v gain = the input differential voltage range is estimated for v dd from 1.7v to 5.5v for different gain values of the max44284 as shown in table 1 ideally, the maximum load current develops the full-scale sense voltage across the current-sense resistor. choose the gain needed to yield the maximum output voltage required for the application: out sense v gain v = choosing the sense resistor voltage loss a high r sense value causes the power-source voltage to drop due to ir loss. for minimal voltage loss, use the lowest r sense value. accuracy use the below linear equation to calculate total error: ( ) ( ) out sense os v gain ge v gain v = table 1. v sense input range part gain (v/v) v sense range (mv) with v dd (1.7v) v sense range (mv) with v dd (5.5v) max44284f 50 34 110 max44284h 100 17 55 max44284w 200 8.5 27.5 max44284e 500 3.4 11 max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 10 downloaded from: http:///
a high r sense value allows lower currents to be mea - sured more accurately because offsets are less significant when the sense voltage is larger. note that the toler - ance and temperature coefficient of the chosen resistors directly affect the precision of any measurement sys - tem. for best performance, select r sense to provide approximately maximum input differential sense voltage of 110mv (max44284f) or 55mv (max44284h) or 27.5mv (max44284w) or 11mv (max44284e) of sense voltage for the full-scale current in each application. sense resistors of 5m to 100m are available with 1% accuracy or better. eficiency and power dissipation at high current levels, the i 2 r losses in r sense can be significant. this should be taken into consideration when choosing the resistor value and its power dissipation (wattage) rating. the sense resistors value will drift if it is allowed to heat up excessively. the precision v os of the max44284 allows the use of small sense resistors to reduce power dissipation and reduce hot spots. kelvin connections because of the high currents that may flow through r sense based on the application, take care to eliminate solder and parasitic trace resistance from causing errors in the sense voltage. either use a four-terminal current- sense resistor or use kelvin (force and sense) pcb layout techniques. input filtering some applications of current-sense amplifiers need to measure currents accurately even in the presence of both differential and common-mode ripple, as well as a wide variety of input transient conditions. the max44284 allows two methods of filtering to help improve performance in the presence of input common- mode voltage and input differential voltage transients. figure 1 shows a differential input filter. the capacitor c in across rs+ and rs- along with the resistor r in helps filter against input differential voltages and prevents them from reaching the max44284. the corner frequency of this filter is determined by the choice of r in , c in . figure 2 shows a common-mode input filter. the choice of capaci - tance depends on corner frequency after r in is chosen. in case of mismatch or error in application design, an additional dc error is accumulated as offset voltage and increased gain error. ( ) ( ) os in offset in bias v r i dr i = + dr in is the resistance mismatch in r in at rs+ and rs-. if dr in is too small, its effect can be neglected. since i offset of the max44284 is smaller than 2na, and if we want to make sure v os is lesser than 1v range, choosing ( ) in os offset rv i < figure 1. differential input filtering figure 2. input common-mode filtering gnd c in r in r in load r sense c in out max44284 rs- rs+ gnd r in r in load r sense out max44284 rs- rs+ c in max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 11 downloaded from: http:///
for gain error, it depends on its input impedance and r in . in in r gainerror 2z ? = avoid additional gain error shift due to the effect of r in . for gain error, the max44284 is 0.15%. if the margin of additional effect of r in results in a gain error shift of less than 0.02%, then: in in 0.02% r 600 2z <= w so r in can be chosen 500?. output filtering the internal architecture of the max44284 suppresses the dc offset, 1/f noise, and accumulates at higher frequen - cies so that they can be filtered out. hence, minute ac disturbances can be observed at 10khz and 20khz. it is recommended to add an output filter after the max44284 to avoid noise and unwanted frequency disturbances at the output with 5khz -3db f c (see figure 3 ). (suggested values of c and r : 2.2nf and 1.8k, respec - tively.) bidirectional application battery-powered systems may require a precise bidirec - tional current-sense amplifier to accurately monitor the batterys charge and discharge currents. measurements of the two separate outputs with respect to gnd yield an accurate measure of the charge and discharge currents respectively ( figure 4 ). figure 3. filtering figure 4. bidirectional application rs- r rs+ r in r in c in2 r sense v batt out max44284 load c c in c in to wall-cubecharger rs+ out rs- rs+ out rs- r sense i load load c v dd = 3.3v v batt up to 36v max44284 max44284 adc adc max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 12 downloaded from: http:///
+denotes a lead(pb)-free/rohs-compliant package part gain (v/v) temp range pin-package top mark max44284fawt+ 50 -40c to +125c 6 wlp +cx max44284faut+ 50 -40c to +125c 6 sot23 +acsf max44284hawt+ 100 -40c to +125c 6 wlp +cy max44284haut+ 100 -40c to +125c 6 sot23 +acsg max44284wawt+ 200 -40c to +125c 6 wlp +cz max44284waut+ 200 -40c to +125c 6 sot23 +acsh MAX44284EAWT+ 500 -40c to +125c 6 wlp +da max44284eaut+ 500 -40c to +125c 6 sot23 +acsi package type package code outline no. land pattern no. 6 wlp w60a1+1 21-0656 refer to application note 1891 6 sot23 u6+1 21-0058 90-0175 max44284 36v, input common-mode, high-precision, low-power current-sense ampliier www.maximintegrated.com maxim integrated 13 ordering information package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different su ffix character, but the drawing pertains to the package regardless of rohs status. chip information process: bicmos downloaded from: http:///
revision number revision date description pages changed 0 12/13 initial release 1 5/14 updated typical operating characteristics and the ordering information 8, 13 2 6/14 corrected general description and updated electrical characteristics globals 1C4 3 9/14 released max44284e and updated the electrical characteristics 3, 13 4 1/15 revised beneits and features section 1 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. max44284 36v, input common-mode, high-precision, low-power current-sense ampliier ? 2015 maxim integrated products, inc. 14 revision history for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///

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