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general description the max4069?ax4072 low-cost, bidirectional, high- side, current-sense amplifiers are ideal for monitoring battery charge and discharge currents in notebooks, cell phones, and other portable equipment. they fea- ture up to 24v input common-mode voltage range, low 100? supply current (which drops to only 10? in shutdown), and a total output error of less than 1.5%. the wide 1.35v to 24v input common-mode range is independent of the supply voltage, ensuring that the current-sense feedback remains accurate even when connected to a battery pack in deep discharge. to achieve maximum flexibility, an external current-sense resistor is used along with a gain select pin to choose either 50v/v or 100v/v. a single output pin continuously monitors the transition from charge to discharge and avoids the need for a separate polarity output. the max4070 contains an internal 2.5v reference. the charging current is represented by an output voltage from 2.5v to v cc , while discharge current is given from 2.5v to gnd. the max4071 is similar, but with a refer- ence voltage of 1.5v. the max4069 has an adjustable reference voltage, set by two external resistors. the max4072 has an input for an external reference. the max4069/max4071/max4072 operate from a 2.7v to 24v single supply. the max4070 operates from a 3.6v to 24v single supply. all devices are specified over the automotive operating temperature range, -40 c to +125 c. the max4070/max4071/max4072 are available in 8-pin ?ax and 8-pin qfn packages. the max4069 is available in a 10-pin ?ax package. applications notebook fuel gauging smart-battery packs/chargers motor control power-management systems cell-phone battery-current monitoring features bidirectional, compact, current-sense solution total output error less than 1.5% selectable gain of 50v/v or 100v/v wide 1.35v to 24v common-mode range independent of supply voltage 2.7v to 24v single-supply operation internal precision reference adjustable (max4069) 2.50v (max4070) 1.50v (max4071) low 100a supply current 10a supply current in shutdown available in space-saving packages 8-pin qfn (max4070/max4071/max4072) 8-pin max (max4070/max4071max4072) 10-pin max (max4069) max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference ________________________________________________________________ maxim integrated products 1 ordering information max4070 v batt = 1.35v to 24v v cc = 3.6v to 24v from battery charger r sense load to adc 2.5v v cc gsel gnd rs- rs+ refout out shdn typical operating circuit 19-2423; rev 0; 4/02 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. part temp range pin- package top mark max4069 aub -40 c to +125 c 10 max max4070 aua -40 c to +125 c 8 max max4070aga* -40 c to +125 c 8 qfn abn max4071 aua -40 c to +125 c 8 max MAX4071AGA* -40 c to +125 c 8 qfn abo max4072 aua -40 c to +125 c 8 max max4072aga* -40 c to +125 c 8 qfn abp pin configurations appear at end of data sheet. selector guide part reference supply voltage range (v) common- mode range (v) max4069 adjustable 2.7 to 24 1.35 to 24 max4070 2.5v 3.6 to 24 1.35 to 24 max4071 1.5v 2.7 to 24 1.35 to 24 max4072 external 2.7 to 24 1.35 to 24 * future product?ontact factory for availability.
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v rs + = v rs - = v cc = 2.7v to 24v, v sense = v rs + - v rs - = 0, i refout = 0, v shdn = v cc , v gsel = gnd, v refin = 2.5v (max4072), t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c and at v cc = v rs + = 12v.) (notes 1, 2) 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. v cc , rs+, rs- to gnd ...........................................-0.3v to +26v out to gnd ....................-0.3v to lesser of (v cc + 0.3v) or 15v differential input voltage (v rs + - v rs - ) .............................. 0.3v gsel, shdn , refout, refin and adj to gnd.....................................-0.3v to (v cc + 0.3v) out short-circuit duration to gnd or to lesser of (v cc or 15v) ...................................continuous refout short circuit to v cc or gnd........................continuous current into any pin .......................................................... 20ma continuous power dissipation (t a = +70 c) 8-pin max (derate 4.5 mw/ c above +70 c) ............362mw 8-pin qfn (derate 4.7mw/ c above +70 c) ...............379mw 10-pin max (derate 5.6 mw/ c above +70 c) .......444.4mw operating temperature range .........................-40 c to +125 c junction temperature ......................................................+150 c storage temperature range .............................-65 c to +150 c lead temperature (soldering, 10s) .................................+300 c parameter symbol conditions min typ max units max4069/max4071/max4072 (note 4) 2.7 24 operating voltage range (note 3) v cc max4070 3.6 24 v t a = +25 c 0.08 0.25 t a = -40 c to +85 c 0.8 input-referred offset voltage (note 5) v os v cc = v rs+ = v rs- = 12v t a = t min to t max 1 mv common-mode input range cmvr guaranteed by cmrr test 1.35 24 v common-mode rejection ratio cmrr 1.35v v rs+ = v rs- 24v, v cc = 12v 100 120 db supply current i cc v cc = v rs+ = v rs- = 24v, r l = open, t a = t min to t max 100 250 a v cc = v rs+ = v rs- = 5.5v, shdn = gnd, t a = +25 c 9 shutdown supply current i cc shdn v cc = v rs+ = v rs- = 24v, shdn = gnd 10 30 a leakage current v rs+ = v rs- = 24v, v cc = 0 0.1 0.5 a input bias current i rs+ , i rs- v cc = v rs+ = v rs- = 24v 0 2.4 5 a gain = 50v/v 75 recommended full-scale sense voltage (note 6) v sense gain = 100v/v 50 mv
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference _______________________________________________________________________________________ 3 electrical characteristics (continued) (v rs + = v rs - = v cc = 2.7v to 24v, v sense = v rs + - v rs - = 0, i refout = 0, v shdn = v cc , v gsel = gnd, v refin = 2.5v (max4072), t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c and at v cc = v rs + = 12v.) (notes 1, 2) parameter symbol conditions min typ max units t a = +25 c 0.25 1.0 t a = - 40 c to + 85 c 1.5 v sense = 75mv, v cc = v rs+ = 12v, gain = 50 t a = t min to t max 2.0 t a = +25 c 0.25 1.0 t a = - 40 c to + 85 c 1.5 v sense = 50mv, v cc = v rs+ = 12v, gain = 100 t a = t min to t max 2.5 t a = +25 c 0.4 1.0 t a = - 40 c to + 85 c 2.0 max4069/max4070/ max4072: v sense = -35mv, v cc = v rs+ = 12v, gain = 50 t a = t min to t max 3.0 t a = +25 c 0.8 2.0 t a = - 40 c to + 85 c 4.0 max4069/max4070/ max4072: v sense = -17.5mv, v cc = v rs+ = 12v, gain = 100 t a = t min to t max 6 t a = +25 c 1.0 2.5 t a = - 40 c to + 85 c 4.0 max4071: v sense = -15mv, v cc = v rs+ = 12v, gain = 50 t a = t min to t max 6.0 t a = +25 c 2.0 5 t a = - 40 c to + 85 c 10 max4071: v sense = -7.5mv, v cc = v rs+ = 12v, gain = 100 t a = t min to t max 15 total out voltage error (note 7) v sense = 3mv, v c c = 12v , v rs + = 12v t a = +25 c 3 %
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 4 _______________________________________________________________________________________ electrical characteristics (continued) (v rs + = v rs - = v cc = 2.7v to 24v, v sense = v rs + - v rs - = 0, i refout = 0, v shdn = v cc , v gsel = gnd, v refin = 2.5v (max4072), t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c and at v cc = v rs + = 12v.) (notes 1, 2) parameter symbol conditions min typ max units max4071, v cc = 2.7v 65 150 i out = 10a, v sense =100mv, v rs+ = v cc max4069/max4070/ max4072, v cc = 3.6v 65 150 max4071, v cc = 2.7v 90 250 out voltage high v cc - v oh i out = 500a, v sense = 100mv, v rs+ = v cc max4069/max4070/ max4072, v cc = 3.6v 90 250 mv max4071, v cc = 2.7v 520 i out = -10a, v sense = -100mv, v rs+ = v cc max4069/max4070/ max4072, v cc = 3.6v 520 max4071, v cc = 2.7v 100 250 out voltage low v ol i out = -500a, v sense = -100mv, v rs+ = v cc max4069/max4070/ max4072, v cc = 3.6v 100 250 mv gain = 50v/v 100 -3db bandwidth bw v sense = 50mv, v cc = 12v, c l = 100pf gain = 100v/v 40 khz gsel = gnd 50 gain a v gsel = v cc 100 v/v capacitive-load stability 100 pf power-supply rejection ratio psrr v cc = 2.7v to 24v (max4069/max4071/max4072), v cc = 3.6v to 24v (max4070) 100 120 db logic low voltage (gsel, shdn )v il v cc = 3.6v or 24v 0.6 v logic high voltage (gsel, shdn )v ih v cc = 3.6v or 24v 2 v gain-select input current i gsel gsel = v cc = 24v or gnd 0.01 1 a shdn = v cc = 24v 3 12 shutdown input current i shdn shdn = gnd, v cc = 24v 0.01 1 a
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference _______________________________________________________________________________________ 5 electrical characteristics (continued) (v rs + = v rs - = v cc = 2.7v to 24v, v sense = v rs + - v rs - = 0, i refout = 0, v shdn = v cc , v gsel = gnd, v refin = 2.5v (max4072), t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c and at v cc = v rs + = 12v.) (notes 1, 2) parameter symbol conditions min typ max units refout (max4069/max4070/max4071) t a = +25 c 2.44 2.49 2.54 max4069, v cc = 12v (note 2) t a = t min to t max 2.39 2.59 t a = +25 c 2.45 2.5 2.55 max4070, v cc = 12v t a = t min to t max 2.40 2.60 t a = +25 c 1.47 1.5 1.53 reference output voltage v ref max4071, v cc = 12v t a = t min to t max 1.44 1.56 v -40 c t a +85 c15 reference output voltage temperature coefficient tcv ref v cc = 12v t a = t min to t max 20 ppm/ c i refout = 0 to 500a 2 load regulation ? v refout / ? i ref i refout = 0 to -100a 4 mv/ma line regulation ? v ref/ ? v cc 2.7v v cc 24v 20 v/v ref capacitive-load stability 500 pf reference adjust voltage threshold v adj max4069, v cc = 12v 1.230 v reference output voltage range max4069, range adjustable with r1 and r2, v cc = 12v v adj to +4 v reference adjust input current i adj max4069, v cc = 12v, v adj = 1.23v 100 na refin (max4072 only) input-voltage range v cc = 12v 1 4 v input current refin = 2.5v, v cc = 12v -60 +20 a note 1: all devices are 100% tested at t a = +25 c. limits over temperature are guaranteed by design. note 2: r1 = 215k ? , r2 = 210k ? for the max4069 only (see functional diagram ). this sets refout to 2.49v nominal. note 3: guaranteed by the psrr test. note 4: the refout voltage for the max4069 should be set such that it does not exceed v cc - 1.1v. similarly, the maximum refin voltage for the max4072 should also be less than v cc - 1.1v. note 5: input-referred offset voltage is defined as the voltage difference between out and refout, divided by the selected gain of either 50 or 100, when v sense = v rs+ - v rs- = 0. note 6: the negative full-scale sense voltage is limited by the voltage range of out from v refout to gnd. note 7: total out voltage error is the sum of offset voltage and gain errors. the output voltage is measured relative to the reference (refout or refin).
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 6 _______________________________________________________________________________________ typical operating characteristics (v cc = v rs+ = 12v, v sense = 50mv for gain of 100v/v and 75mv for gain of 50v/v, t a = +25 c, unless otherwise noted.) max4069 refout vs. temperature max4069-72 toc09 temperature ( c) refout (v) 100 75 25 50 0 -25 1.205 1.210 1.215 1.220 1.225 1.230 1.235 1.240 1.245 1.250 1.200 -50 125 refout connected to adj supply current vs. temperature max4069-72 toc08 temperature ( c) supply current ( a) 100 75 50 25 0 -25 60 80 100 120 140 160 180 40 -50 125 a v = 50v/v v cc = 24v v cc = 12v supply current vs. supply voltage max4069-72 toc07 supply voltage (v) supply current ( a) 22 20 4 6 8 12 14 16 10 18 70 80 90 100 110 120 130 140 60 224 a v = 100v/v max4071 max4070 max4069 max4072 total error vs. temperature max4069-72 toc06 temperature ( c) total error (%) 100 75 50 25 0 -25 -1.0 -0.5 0 0.5 1.0 1.5 -1.5 -50 125 v sense = 50mv a v = 100v/v v cc = 24v v cc = 12v total error vs. supply voltage (v sense = 3mv) max4069-72 toc05 supply voltage (v) total error (%) 18 14 610 -1.5 -1.0 -0.5 0 0.5 1.0 1.5 2.0 -2.0 222 a v = 100v/v a v = 50v/v total error vs. supply voltage max4069-72 toc04 supply voltage (v) total error (%) 22 20 16 18 8 10 12 14 6 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4 0.5 -0.5 424 v sense = 75mv a v = 50v/v v sense = 50mv a v = 100v/v (v out - v ref ) vs. v sense max4069-72 toc03 v sense (v) (v out - v ref ) (v) 225 200 150 175 50 75 100 125 25 1 2 3 4 5 6 7 8 9 10 11 12 0 0250 a v = 100v/v a v = 50v/v input offset voltage vs. temperature max4069-72 toc02 temperature ( c) input offset voltage ( v) 100 75 25 50 0 -25 -125 -100 -75 0 25 50 75 100 125 150 -150 -50 125 -50 -25 a v = 100v/v input offset voltage distribution max4069-72 toc01 v os ( v) percentage of units (%) 160 120 80 40 0 -40 -80 -120 5 10 15 20 25 0 -160 200 -200 30 35
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference _______________________________________________________________________________________ 7 typical operating characteristics (continued) (v cc = v rs+ = 12v, v sense = 50mv for gain of 100v/v and 75mv for gain of 50v/v, t a = +25 c, unless otherwise noted.) 0 -140 0.01 1 10 0.1 100 psrr and cmrr vs. frequency max4069-72 toc18 frequency (hz) psrr and cmrr (db) -100 -80 -60 -40 -20 -120 cmrr psrr small-signal gain vs. frequency max4069-72 toc17 frequency (khz) gain (db) 100 10 1 -15 -10 -5 0 5 -20 0.1 1000 a v = 50v/v a v = 100v/v v ol vs. temperature max4069-72 toc16 temperature ( c) v ol (mv) 100 75 25 50 0 -25 25 50 75 100 125 150 175 200 225 250 0 -50 125 i l = 500 a i l = 10 a v oh vs. temperature max4069-72 toc15 temperature ( c) v oh (mv) 100 75 25 50 0 -25 20 40 60 80 100 120 140 160 180 200 0 -50 125 v oh = v cc - v out i l = 500 a i l = 10 a max4071 refout vs. supply voltage max4069-72 toc14 supply voltage (v) refout (v) 18 14 10 6 1.496 1.497 1.498 1.499 1.500 1.501 1.502 1.495 222 max4070 refout vs. supply voltage max4069-72 toc13 supply voltage (v) refout (v) 22 20 16 18 6 8 10 12 14 4 2.491 2.492 2.493 2.494 2.495 2.496 2.497 2.498 2.499 2.500 2.490 224 max4069 refout vs. supply voltage max4069-72 toc12 supply voltage (v) refout (v) 22 20 16 18 6 8 10 12 14 4 1.217 1.219 1.221 1.223 1.225 1.227 1.229 1.231 1.233 1.235 1.215 224 max4071 refout vs. temperature max4069-72 toc11 temperature ( c) refout (v) 100 75 25 50 0 -25 1.480 1.485 1.490 1.495 1.500 1.505 1.510 1.515 1.520 1.525 1.475 -50 125 max4070 refout vs. temperature max4069-72 toc10 temperature ( c) refout (v) 100 75 50 25 0 -25 2.465 2.480 2.495 2.510 2.525 2.540 2.450 -50 125
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 8 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = v rs+ = 12v, v sense = 50mv for gain of 100v/v and 75mv for gain of 50v/v, t a = +25 c, unless otherwise noted.) exiting shutdown max4069-72 toc24 100 s/div v refout 2v/div v out 2v/div v shdn 5v/div startup delay max4069-72 toc23 20 s/div v refout 5v/div v out 5v/div v cc 10v/div large-signal transient response max4069-72 toc22 100 s/div output 2v/div input 20mv/div gain = 100 ref large-signal transient response max4069-72 toc21 100 s/div output 2v/div input 50mv/div gain = 50 ref small-signal transient response max4069-72 toc20 100 s/div output 500mv/div ref input 5mv/div gain = 100 small-signal transient response max4069-72 toc19 100 s/div output 200mv/div ref input 5mv/div gain = 50
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference _______________________________________________________________________________________ 9 max4069 rs+ rs- gsel shdn 2.7v to 24v v cc out to adc r1 r2 shutdown gain select r sense load from battery charger refout oa adj gnd v ref 1.23v csa functional diagram pin description pin max4069 max4070/ max4071 max4072 name function 111 shdn shutdown input. drive shdn low to select shutdown mode. connect shdn to v cc for normal operation. 2 2 2 rs- negative connection to the external sense resistor 3 3 3 rs+ positive connection to the external sense resistor 4 n.c. no connection. not internally connected. 5 4 4 gnd ground 6 adj adjustable output voltage feedback input. connect a resistor-divider between refout, adj, and gnd (max4069 only, see functional diagram ). 75 refout reference output voltage (max4069/max4070/max4071) 8 6 6 out voltage output. the difference voltage, v out - v ref , is proportional to the voltage difference between rs+ and rs- and indicates the correct polarity. 977v cc supply voltage input. bypass v cc to gnd with a 0.1f capacitor. 10 8 8 gsel gain-setting input. connect gsel low to select gain = 50v/v, or connect gsel high to select gain = 100v/v. 5 refin reference input voltage (max4072)
max4069?ax4072 detailed description the max4069 max4072 bidirectional, high-side, cur- rent-sense amplifiers are ideal for portable equipment. the wide 1.35v to 24v input common-mode voltage range is independent of the supply voltage, ensuring that the current-sense feedback remains accurate even when connected to a battery pack in deep discharge. the max4069/max4071/max4072 operate from a 2.7v to 24v single supply. because the max4070 has a 2.5v internal reference, it operates from 3.6v to 24v. all devices have a low 100a supply current that reduces to only 10a (typ) in shutdown mode. to achieve maxi- mum flexibility, an external current-sense resistor is used along with a gain select pin (gsel) to choose either 50v/v or 100v/v. drive gsel low to select gain of 50v/v or drive gsel high to choose gain of 100v/v (see functional diagram ). the max4069 has an adjustable reference voltage set by two external resis- tors between refout and adj, and gnd pins. the max4070 contains an internal 2.5v reference. the max4071 is similar to the max4070 but with a fixed internal reference voltage of 1.5v. the max4072 has a reference input pin to allow use of external references. charging current is represented by an output voltage from the reference voltage to v cc , while discharge cur- rent is given from the reference voltage to gnd. the direction of v sense is totally arbitrary. the input stage of the max4069 max4072 is shown in figure 1. its unique topology allows for monitoring bidi- rectional currents through the sense resistor (r sense ). if, for instance, current flows from rs+ to rs-, the max4069 max4072 match for the voltage drop over the external sense resistor (r sense ) by increasing the cur- rent through the internal q1 and rg1. at the same time, the current through q2 and rg2 decreases, however, internal circuitry not shown in figure 1 prevents q2 from turning off completely. likewise, if current flows from rs- to rs+, the current through q2 and rg2 increases and the current through q1 decreases. in this way, the volt- ages at the input terminals of the internal amplifier a1 are kept constant and an accurate measurement of the sense voltage is achieved. in the following amplifier stages of the max4069 max4072, the output signal of amplifier a2 is level-shifted towards the reference voltage (v ref ), resulting in a voltage at the output pin (out) that swings above the v ref voltage for positive-sense voltages and below v ref for negative-sense voltages. applications information bidirectional, current-sense amplifier systems such as laptop computers and other devices that have internal charge circuitry require a precise bidi- rectional, current-sense amplifier to accurately monitor the battery s current regardless of polarity. figure 2 shows the max4069 max4072 used as a bidirectional current monitor. in figure 2, the direction of v sense is assigned to charge and discharge, assuming charge is greater than discharge. the practical choice of direction is based on dynamic range at out, given that the range of ref to v cc is usually greater than from ref to ground. this is useful for implementing either smart bat- tery packs or fuel gauges. high-current measurement the max4069 max4072 can achieve high-current measurements by using low-value sense resistors, which can be paralleled to further increase the current- sense limit. adjusting v ref (max4069) the max4069 has an output reference voltage that can be set to a desired voltage by a two-resistor divider between refout, adj, and gnd. if refout and adj are connected together, the minimum output reference voltage is obtained, 1.23v (typ). the maximum voltage for refout is 4v (that requires v cc 5.1v). the rec- ommended range for the external resistors is: r1 + r2 should be > 20k ? and < 500k ? . bidirectional, high-side, current-sense amplifiers with reference 10 ______________________________________________________________________________________ max4069?ax4072 r sense rs- rs+ rg2 rg1 a1 a2 q1 q2 i out out figure 1. detailed input stage
external reference (max4072) the max4072 contains refin pin for external refer- ence voltage. the allowable voltage range on refin is 1v (min) to 4v (max) with v cc 5.1v. reference output (max4069/max4060/max4071) the refout of the max4069/max4070/max4071 can sink 100a and source 500a. keep the total capaci- tance on refout under 500pf to maintain stability. recommended component values 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: v out = v sense x a v where v sense is the full-scale sense voltage, 75mv for gain of 50v/v, or 50mv for gain of 100v/v. a v is the gain of the device. in applications monitoring high current, ensure that r sense is able to dissipate its own i 2 r loss. if the resistor s power dissipation is exceeded, its value may drift or it may fail altogether, causing a differential volt- age across the terminals in excess of the absolute max- imum ratings. use resistors specified for current- sensing applications. the max4069 max4072 sense a wide variety of cur- rents with different sense-resistor values. table 1 lists common resistor values for typical operation of these devices. listed output voltage is with respect to ref. sense resistor, r sense choose r sense based on the following criteria: voltage loss: a high r sense value causes the power- source voltage to degrade through ir loss. for minimal voltage loss, use the lowest r sense value. accuracy: a high r sense value allows lower currents to be measured more accurately. this is because off- sets become less significant when the sense voltage is larger. for best performance, select r sense to provide approximately 75mv (gain of 50v/v) or 50mv (gain of 100v/v) of sense voltage for the full-scale current in each application. efficiency and power dissipation: at high-current lev- els, the i 2 r losses in r sense can be significant. take this into consideration when choosing the resistor value and its power dissipation (wattage) rating. also, the sense resistor s value might drift if it is allowed to heat up excessively. inductance: keep inductance low if i sense has a large high-frequency component. wire-wound resistors have the highest inductance, while metal film is somewhat better. low-inductance metal-film resistors are also available. instead of being spiral-wrapped round a max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference ______________________________________________________________________________________ 11 max4070 i discharge r sense i charge load to adc 2.5v v cc gsel gnd rs- rs+ refout out shdn 2 cells -25mv 25mv 50mv 0 discharge current charge current -2.5v 5v 2.5v a v = 100 v out - v ref v sense figure 2. bidirectional current monitor i 2 r is a registered trademark of instruments for research and industry, inc.
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 12 ______________________________________________________________________________________ core, as in metal-film or wire-wound resistors, they are a straight band of metal and are available in values under 1 ? . peak current: the maximum current through r sense must be limited to: i peak = 0.3v / (r sense + r trace ) where r trace is the total stray resistance from rs+ and rs- to r sense . to prevent forwarding the back-to- back diodes between the differential input, the absolute maximum of the differential input voltage is 0.3v. dynamic range considerations although the max4069 max4072 have fully symmetri- cal, bidirectional, v sense input capability, the output- voltage range is usually higher from ref to v cc and lower from ref to gnd (unless the supply voltage is at the lowest end of the operating range). therefore, the user must consider the dynamic range of current moni- tored in both directions and choose the supply voltage and the reference voltage (refout or refin) to make sure the output swing above and below ref is ade- quate to handle the swings without clipping or running out of headroom. shutdown mode when shdn is low, the max4069 max4072 are shut down and consume only 10a. in shutdown mode, out is high impedance and turns off. connect shdn to v cc for normal operation. power-supply bypassing and grounding the max4069 max4072 do not require special bypassing and respond quickly to transient changes in line current. you can place a large capacitor at the rs- terminal (or load side) to decouple the load and, thereby, reduce the current transients. these capaci- tors are not required for operation or stability and their use does not degrade performance. the max4069 max4072 have been designed as a high- side current monitor to ease the task of grounding any battery charger, thermistor, etc., that may be a part of the battery pack. grounding these devices requires no special precautions; follow the same cautionary steps that apply to the system as a whole. high-current sys- tems can experience large voltage drops across a ground plane, and this drop may add to or subtract from v out. using differential measurement between v out and ref prevents this problem. for highest current-mea- surement accuracy, use a single-point star ground. full-scale current (a) current-sense resistor (m ? ) gain (v/v) v sense (mv) full-scale output voltage with respect to ref (v) 0.075 50 75 3.75 0.05 1000 100 50 5.0 0.75 50 75 3.75 0.5 100 100 50 5.0 3.75 50 75 3.75 2.5 20 100 50 5.0 7.5 50 75 3.75 5.0 10 100 50 5.0 15.0 50 75 3.75 10.0 5 100 50 5.0 table 1. recommended component values
layout in order to dissipate sense-resistor heat from large sense currents, solder the rs+ and the rs- pins to large copper traces. keep the part away from other heat-generating devices. for accurate measurement of v sense , the kelvin method is recommended. the current into rs+ and rs- is only a few microamps; therefore, a short distance from rs+ and rs- pins does not cause significant errors. it is recommended to keep the value of r sense reasonably higher than the values of the trace s resistance. max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference ______________________________________________________________________________________ 13 1 2 3 4 5 10 9 8 7 6 gsel v cc out refout n.c. rs+ rs- max4069 max top view adj gnd shdn out refout (refin) (refin) for max4072 only gnd 1 2 8 7 gsel v cc rs- rs+ qfn/ max 3 4 6 5 max4070 max4071 max4072 shdn pin configurations chip information transistor count: 338 process: bicmos
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 14 ______________________________________________________________________________________ 6l, 8l qfn(dual).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 .)
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference ______________________________________________________________________________________ 15 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 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 .)
max4069?ax4072 bidirectional, high-side, current-sense amplifiers with reference 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 ____________________ 16 ? 2002 maxim integrated products printed usa is a registered trademark of maxim integrated products. 10lumax.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 .)

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