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????????????????????????????????????????????????????????????????? maxim integrated products 1 simplified applications circuit appears at end of data sheet. 19-4245; rev 0; 1/12 ordering information appears at end of data sheet. for related parts and recommended products to use with this part, refer to www.maxim-ic.com/MAX8971.related . general description the MAX8971 is a compact, high-frequency, high- efficiency switch-mode charger for a one-cell lithium-ion (li+) battery. it delivers up to 1.55a of current to the battery from inputs up to 7.5v and withstands transient inputs up to 22v. the 4mhz switch-mode charger is ideally suited for small portable devices, such as head - sets and ultra-portable media players. it minimizes component size and heat. battery-protection features include: low-voltage prequali - fication, charge fault timer, die temperature monitoring, and battery temperature monitoring. the battery temperature monitoring adjusts the charge current and termination voltage for safe use of secondary lithium-ion batteries. the ic accepts either a general dc input or usb. it has programmable automatic input-current limiting to pro - tect upstream charging sources such as usb. charge parameters are easily adjustable through an i 2 c interface. charge is terminated based on user-selectable minimum current level. a safety timer with reset control provides a safety backup for i 2 c interface. charge status is provided to the application processor through an inter - rupt pin. the ic is available in a space-saving, 20-bump, 2.18mm x 1.62mm wlp package. applications usb charging headsets and media players smartphones digital cameras gps, pdas benefits and features s switch-mode charger ? high-efficiency ? low heat ? fast charge time s small and simple s precise ? up to q 5% current regulation and 0.5% voltage regulation s safe ? jeita battery temperature monitor ? over / undervoltage protection, safety timers, temperature regulation ? usb friendly s flexible ? programmable voltage /current ? status / interrupts through i 2 c ? automatic input current limit s i 2 c interface ? input current limit (100ma to 1500ma) ? fast-charge / termination current (250ma to 1550ma) ? charge voltage (4.1v, 4.15v, 4.2v, 4.35v) ? safety timer ? termination enable s +22v absolute maximum input voltage rating s up to 7.5v maximum operating input voltage s 5v usb/safeout ldo for usb phy s 2.3a gsm rf test mode (factory testing) s charge current to voltage conversion (v ichg ) for baseband adc s reverse battery leakage protection s input /output overvoltage protection s interrupt status output MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger evaluation kit available for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxims website at www.maxim-ic.com.
????????????????????????????????????????????????????????????????? maxim integrated products 2 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table of contents absolute maximum ratings ...................................................................... 4 package thermal characteristics .................................................................. 4 electrical characteristics ........................................................................ 4 typical operating characteristics ................................................................. 9 typical operating characteristics ................................................................ 11 typical operating characteristics ................................................................ 12 typical operating characteristics ................................................................ 13 bump configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 bump description ............................................................................. 14 detailed description ........................................................................... 16 dc inputfast-hysteretic step-down regulator ........................................................................ 16 soft-start .................................................................................. 16 pvl and avl ............................................................................... 16 thermistor input (thm) ....................................................................... 16 thermal foldback ........................................................................... 17 charger states ............................................................................. 17 charger-disabled state .................................................................... 20 dead-battery state ........................................................................ 20 dead-battery + prequalification state ......................................................... 20 prequalification state ...................................................................... 20 fast-charge constant-current state .......................................................... 20 fast-charge constant voltage state .......................................................... 20 top- off state ............................................................................ 20 done state .............................................................................. 20 timer fault state ......................................................................... 21 overvoltage and protection .................................................................... 21 automatic input current limit protection ............................................................................. 21 v ichg charging current monitor ............................................................... 22 safeout ................................................................................. 22 jeita description ........................................................................... 22 maxim model gauge m3 support .............................................................. 22 factory-mode gsm test mode support .......................................................... 22 applications information ........................................................................ 23 inductor selection ........................................................................... 23 input capacitor selection ..................................................................... 23
????????????????????????????????????????????????????????????????? maxim integrated products 3 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table of contents (continued) list of tables list of figures output capacitor selection .................................................................... 23 charge current resistor selection .............................................................. 23 i 2 c registers ................................................................................ 26 charger interrupt requests .................................................................... 26 charger interrupt masks ...................................................................... 27 charger status ............................................................................. 28 details1 ................................................................................. 29 details2 ................................................................................. 30 usb suspend ............................................................................... 31 input voltage disable ........................................................................ 31 fast-charge current and timer control .......................................................... 31 input-current limit and charger restart threshold ................................................. 32 done current, timer, gsm test mode, and battery regulation voltage ................................. 35 temperature regulation ...................................................................... 36 charger protection .......................................................................... 36 simplified applications circuit ................................................................... 37 ordering information .......................................................................... 37 chip information .............................................................................. 37 package information ........................................................................... 38 revision history .............................................................................. 39 table 1. trip temperatures for different thermistors .................................................. 17 table 2. suggested inductors ................................................................... 23 table 3. charge current settings for 47m? and 68m? sense resistors .................................. 24 table 4. topoff current settings for 47m? and 68m? sense resistors ................................... 24 table 5. high-level i 2 c register map ............................................................. 24 table 6. chgcc[4:0] decoding .................................................................. 32 table 7. dcilmt[5:0] bit code .................................................................. 33 figure 1. typical application circuit ............................................................... 15 figure 2. li/li-poly charge profile ................................................................ 18 figure 3. functional state diagram ............................................................... 19 figure 4. jeita safety region ................................................................... 22 figure 5. MAX8971 with max17047 ............................................................... 22
????????????????????????????????????????????????????????????????? maxim integrated products 4 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger byp to pg_ ........................................................... -0.3v to +22v dc_ to byp ............................................................ -6v to +0.3v i2cin, v ichg , irqb, sda, scl to gnd ................. -0.3v to +6v bst to avl ............................................................ -0.3v to +16v bst to lx_ ............................................................... -0.3v to +6v pvl, sfo, bat, cs to pg_ ..................................... -0.3v to +6v avl, thm to gnd ................................................... -0.3v to +6v pg_ to gnd .......................................................... -0.3v to +0.3v dc_, lx_, cs, bat, byp continuous current ............. 1.6a rms continuous power dissipation (t a = +70 n c) wlp derate 21.7mw/ n c above +70 n c ..................... 1736mw operating temperature range. ......................... -40 n c to +85 n c junction temperature. .................................................... +150 n c storage temperature range ............................ -65 n c to +150 n c soldering temperature (reflow) ...................................... +260 n c absolute maximum ratings *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 recommended in the industry-standard specification, jedec 020a, paragraph 7.6, table 3 for ir / vpr and convection reflow. preheating is required. hand or wave soldering is not allowed. stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional opera - tion 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 (v dc = 5v, c byp = 1 f f, i fchg = 500ma, c avl = 4.7 f f, v thm = avl/2, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) wlp junction-to-ambient thermal resistance ( q ja ) .......... 46c/w junction-to-case thermal resistance ( q jc ) ................. 2c/w 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.maxim-ic.com/thermal-tutorial . package thermal characteristics (note 1) parameter conditions min typ max units dc input dc operating voltage range 4.0 v ovp v dc undervoltage lockout dc rising, 500mv hysteresis 3.6 3.8 4.0 v dc overvoltage threshold (v ovp )* dc rising, 250mv hysteresis 7.25 7.5 7.75 v dc ovp interrupt delay 16 ms dc to bat shutdown threshold when charging stops, v dc falling, 150mv hysteresis 0 50 100 mv dc supply current charger enabled, v dc = 5.5v 2 ma bst leakage current v bst = 5.5v, lx_ = pg_ t a = +25 c 0.01 10 f a t a = -40 c to +85 c 0.1 lx_ leakage current v lx_ = 0 or 5.5v t a = +25 c 0.01 10 t a = -40 c to +85 c 0.1 bat reverse leakage current v dc = 0v, v bat = 4.2v 1 5 f a input-current limit range 0.1 1.5 a
????????????????????????????????????????????????????????????????? maxim integrated products 5 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger electrical characteristics (continued) (v dc = 5v, c byp = 1 f f, i fchg = 500ma, c avl = 4.7 f f, v thm = avl/2, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) parameter conditions min typ max units input-current limit accuracy usb 100ma mode 90 95 100 ma usb 500ma mode 450 475 500 input limit programmed to 1.5a, i fchg = 1500ma 1350 1500 1650 adaptive input-current limit (aicl) (note 4) dc voltage where charge current is regulated 4.5 v dc voltage where charge current is set to 75ma 4.4 input limit switch v dc = 5.5v, i byp = 100ma 35 80 m i buck operation switching frequency v bat = 3.6v 4 mhz maximum duty cycle 99.5 % minimum on-time 55 ns maximum on-time 10 s minimum off-time 65 ns soft-start time 1.5 ms high-side resistance i lx = 100ma, v dc = 5.5v 120 250 m i low-side resistance i lx = 100ma, v dc = 5.5v 150 220 m i thermal regulation temperature (t reg ) i 2 c programmable 2-bits (90, 105, 120, and disable selections, 105 default) 105 c thermal regulation gain percentage decrease in i fchg above the thermal regulation temperature 5 %/ c battery charger precharge battery-prequalification lower threshold (v pqlth ) v bat rising, 130mv hysteresis 2.1 v dead-battery charge current (i dbat ) 0v v bat 2.1v 45 ma battery-prequalification upper threshold (v pquth ) ** v bat rising, 150mv hysteresis 2.5 v prequalification charge current (i pq ) percentage of fast-charge current programmed 10 % constant-current mode bat fast-charge current range (i fc ) 5 bitsC50ma steps, r cs = 47m i 250 1550 ma fast-charge current accuracy t a = +15 n c to +45 n c -5 +5 % jeita safety region (figure 6) -65 -50 -35 %
????????????????????????????????????????????????????????????????? maxim integrated products 6 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger electrical characteristics (continued) (v dc = 5v, c byp = 1 f f, i fchg = 500ma, c avl = 4.7 f f, v thm = avl/2, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) parameter conditions min typ max units constant voltage mode battery regulation voltage (v batreg ) i bat = 100ma, operating in voltage-regulation mode, i 2 c- programmable 4.1v, 4.15v, 4.2v, and 4.35v selection t a = +25 n c -0.5 +0.5 % t a = -40 n c to +85 n c -1 +1 jeita safety region, percentage of battery regulation voltage (note 6) 96 97 98 battery refresh threshold (below regulation point), 100mv and 150mv selection, default 150mv (note 5) 120 150 185 mv battery overvoltage protection v bat threshold over regulation voltage to turn off charger during charge (% of regulation voltage) (note 7) 102 103.5 105 % hysteresis (v bat falling) at 4.2v 1.4 charge-current termination threshold (i topoff ) programmable topoff current independent of jeita functionality, default 50ma, 200ma hysteresis 50 200 ma deglitch time 16 ms charge-current termination accuracy i topoff = 200ma -20 +20 % gsm test mode gsm test-mode output pulse current v bat capacitance 60 f f, peak current pulse frequency = 217hz, on-duty cycle 12.5% 2.3 a gsm test-mode minimum output v bat capacitance 60 f f, current pulse frequency = 217hz, on-duty cycle 12.5% (note 3) 3.7 v charger timer prequalification time (t pq ) v bat < v batpq_ut 45 mins fast-charge time (t fc ) default 5 hours, i 2 c programmable (4C10 hours and disabled selection) 5 hrs timer accuracy 20 % top-off time (t topoff ) i 2 c programmable 0 to 70 mintues, 10-minute steps, default 30 mintues 0 70 mins top-off timer accuracy 20 % timer-extend current threshold (note 3) percentage of fast-charge current below which the timer clock operates at half speed 50 %
????????????????????????????????????????????????????????????????? maxim integrated products 7 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger electrical characteristics (continued) (v dc = 5v, c byp = 1 f f, i fchg = 500ma, c avl = 4.7 f f, v thm = avl/2, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) parameter conditions min typ max units thermistor monitor thm threshold, cold, no charge (0 c) v thm/avl rising, 1% hysterisis (thermistor temperature falling) 71.06 74.56 78.06 % thm threshold, cold, current foldback (+15 c) v thm/avl rising, 1% hysterisis (thermistor temperature falling) 57.00 60.00 63.00 % thm threshold, hot, voltage foldback (+45 c) v thm/avl falling, 1% hysterisis (thermistor temperature rising) 32.68 34.68 36.68 % thm threshold, hot, no charge (+60 n c) v thm/avl falling, 1% hysterisis (thermistor temperature rising) 21.24 22.54 23.84 % thm input bias current v thm = v avl or 0v t a = +25 n c -0.2 0.01 +0.2 f a t a = +85 n c 0.01 v ichg v ichg output voltage i bat = 100ma 150 mv i bat = 1000ma 1260 1400 1540 mv i bat = 1500ma 2100 mv irqb output low-level output saturation voltage i irqb =10ma, sinking current 0.4 v high-level leakage current v irqb = 5v t a = +25 n c -1 0.01 +1 f a t a = +85 n c 0.1 f a safeout output regulated output i sfo = 30ma, v dc = 5.5v 4.75 5 5.25 v dropout voltage i sfo = 30ma 45 mv current limit 590 ma maximum output current 100 ma pok output threshold 2.7 v pvl/avl output pvl output voltage 5.5v < v dc < 7.5v, no load 5.05 v avl output voltage 5.5v < v dc < 7.5v, no load 5.05 v logic levels and timing characteristics (scl, sda) output low threshold i o = 3ma, sink current (sda) 0.4 v input low threshold v i2cin = 1.8v 0.4 v input high threshold v i2cin = 1.8v 1.4 v
????????????????????????????????????????????????????????????????? maxim integrated products 8 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger electrical characteristics (continued) (v dc = 5v, c byp = 1 f f, i fchg = 500ma, c avl = 4.7 f f, v thm = avl/2, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) (note 2) note 2: parameters are production tested at t a = +25 n c. limits over the operating temperature range are guaranteed through correlation using statistical quality control (sqc) methods. note 3: guaranteed by design, not production tested. note 4: voltage for 4.35v battery mode increases by 100mv. note 5: refresh voltage for 4.15v increases by 50mv. note 6: jeita decreases by 1% for 4.15v termination voltage. note 7: battery overvoltage increases by 1% for 4.15v termination voltage. * = contact factory for alternate thresholds (6.7v, 9.7v, and 14v available). ** = contact the factory for 3.0v. parameter conditions min typ max units input bias current v i2cin = 1.8v, t a = +25 c 1 a scl clock frequency 100 400 khz bus free time between start and stop (note 3) 1.3 s hold time repeated start condition (note 3) 0.6 s scl low period (note 3) 1.3 s scl high period (note 3) 0.6 s setup time repeated start condition (note 3) 0.6 s sda hold time (note 3) 0 s sda setup time (note 3) 100 ns maximum pulse width of spikes (must be suppressed by the input filter of both sda and scl signals) (note 3) 50 ns setup time for stop condition (note 3) 0.6 s thermal regulation and shutdown thermal shutdown temperature (note 3) +160 c thermal shutdown hysteresis (note 3) 15 c
????????????????????????????????????????????????????????????????? maxim integrated products 9 typical operating characteristics (v dc = 5v, c byp = 1 f f, c avl = 4.7 f f, v thm = 2.5v, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) dc quiescent current vs. dc supply voltage MAX8971 toc01 dc voltage (v) quiescent current (ma) 12 10 8 6 0.5 1.0 1.5 2.0 2.5 3.0 0 41 4 dc supply current vs. temperature temperature (c) dc supply current (ma) 80 70 60 50 40 30 20 10 0 -10 -20 -30 2.5 0 -40 90 MAX8971 toc02 0.5 1.0 1.5 2.0 battery leakage current vs. temperature temperature (c) battery leakage current (a) 80 70 60 50 40 30 20 10 0 -10 -20 -30 1.8 0 -40 90 MAX8971 toc03 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 medium load switching wavefroms MAX8971 toc06 i fchg = 500ma 200ns / div 20mv/div ac-coupled 2v/div 200ma /div 0 v bat v lx i lx fast-charge current vs. dc supply voltage MAX8971 toc04 dc voltage (v) fast-charge current (ma) 100 200 300 400 500 600 0 3.0 3.5 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 v dc , rising i fchg = 500ma v dc , falling heavy load switching wavefroms MAX8971 toc07 i fchg = 1.55a 400ns / div 20mv/div ac-coupled 2v/div 1a /div 0 v bat v lx i lx MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger
???????????????????????????????????????????????????????????????? maxim integrated products 10 typical operating characteristics (continued) (v dc = 5v, c byp = 1 f f, c avl = 4.7 f f, v thm = 2.5v, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) usb removal MAX8971 toc11 100ms / div 500ma /div 2v/div 5v/div 5v/div 0 0 0 v usb v bat i bat v lx usb insertion into 500ma default fast-charge current MAX8971 toc10 100ms / div 250ma /div 5v/div 5v/div 2v/div 0 0 0 v bat i bat v lx v usb with automatic usb 100ma mode charger enable soft-start time MAX8971 toc08 400s / div 500ma /div 500ma /div 2v/div 2v/div 0 0 0 i bat v bat i dc v dc battery insertion/removal (1a input current limit) MAX8971 toc12 10ms / div 500ma /div 2v/div 2v/div 5v/div 0 0 0 v dc v bat i bat v lx lg lp-ahkm (950mah) i lim = 1a i fchg = 500ma dc plug-in to 1a default fast-charge current MAX8971 toc10a 40ms / div 500ma /div 500ma /div 2v/div 2v/div 0 0 0 0 v bat i bat v dc i dc i fchg = 1.a with automatic usb 100ma mode avl/pvl voltage vs. dc supply voltage MAX8971 toc09 dc voltage (v) avl/pvl voltage (v) 4.4 4.5 4.6 4.7 4.8 4.9 5.0 5.1 5.2 4.3 v pvl v avl 4.0 4.5 5.0 5.5 6.0 6.5 7.0 7.5 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger
???????????????????????????????????????????????????????????????? maxim integrated products 11 typical operating characteristics (v dc = 5v, c byp = 1 f f, c avl = 4.7 f f, v thm = 2.5v, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) battery charger efficiency vs. battery voltage MAX8971 toc17 battery voltage (v) efficiency (%) 4.1 3.9 3.5 3.7 2.9 3.1 3.3 2.7 55 60 65 70 75 80 85 90 95 100 50 2.5 4.3 i bat = 1.25a i bat = 1.5a i bat = 0.5a v dc = 5v, preq = 2.5v, v bat = 4.2v fast charge to suspend MAX8971 toc15 400ms / div 200ma /div 5v/div 5v/div 5v/div 0 0 0 v sda v bat v lx i lx fast-charge current vs. temperature temperature (c) fast-charge current (ma) 80 70 60 50 40 30 20 10 0 -10 -20 -30 550 450 -40 90 MAX8971 toc13 460 470 480 490 500 510 520 530 540 battery charger efficiency vs. charge current MAX8971 toc18 charge current (ma) efficiency (%) 55 60 65 70 75 80 85 90 95 100 50 0 200 400 600 800 1000 1200 1400 v bat = 3v v bat = 3.6v v bat = 4.2v battery regulation voltage vs. temperature temperature (c) battery voltage (v) 80 70 60 50 40 30 20 10 0 -10 -20 -30 4.220 4.190 -40 90 MAX8971 toc16 4.195 4.200 4.205 4.210 4.215 fast-charge current vs. battery voltage MAX8971 toc14 battery voltage (v) fast-charge current (ma) 1.5 2.5 1.0 2.0 3.5 3.0 4.0 100 200 300 400 500 600 0 0.5 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger
???????????????????????????????????????????????????????????????? maxim integrated products 12 typical operating characteristics (v dc = 5v, c byp = 1 f f, c avl = 4.7 f f, v thm = 2.5v, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) automatic input current limit (2 i cable resistance) MAX8971 toc23 100ms / div 500ma /div 500ma /div 2v/div 2v/div 0 0 0 0 v bat i bat i dc v dc charge profile for 1500mah 4.2v battery with 70ma constant load charged at 0.6c MAX8971 toc21 time (minutes) battery voltage (v) 0.5 1.5 1.0 2.0 2.5 3.0 3.5 4.0 4.5 0 900 -100 03 06 09 0 120 150 180 0 100 200 300 500 600 700 800 400 battery charger efficiency vs. battery voltage MAX8971 toc19 battery voltage (v) efficiency (%) 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 10 20 30 40 50 60 70 80 90 100 0 1.0 i bat = 0.5a i chg = 500ma, preq = 2.5v i bat = 0.5a automatic input current limit (1i cable resistance) MAX8971 toc24 4ms / div 200ma /div 500ma /div 2v/div 2v/div 0 0 0 0 v bat i bat i dc v dc automatic input current limit MAX8971 toc22 10ms / div 500ma /div 500ma /div 2v/div 2v/div 0 0 0 v bat i bat i dc v dc charge profile for 1830mah 4.35v battery charged at 0.55c MAX8971 toc20 time (minutes) battery voltage (v) 0.5 1.5 1.0 2.0 2.5 3.0 3.5 4.0 4.5 0 1000 0 03 06 09 0 120 150 100 200 300 400 600 700 800 900 500 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger
???????????????????????????????????????????????????????????????? maxim integrated products 13 typical operating characteristics (v dc = 5v, c byp = 1 f f, c avl = 4.7 f f, v thm = 2.5v, t a = -40 n c to +85 n c, unless otherwise noted. typical values are at t a = +25 n c.) charge current vs. ambient temperature MAX8971 toc29 rising ambient temperature (c) charge current (ma) 100 200 300 400 600 500 700 0 40 45 50 55 60 65 100ki, = 4250 thermistor i fchg = 500ma, safety region 1 v ichg gain vs. charge current MAX8971 toc27 charge current (ma) v ichg gain (v/ v) 1500 1300 1100 900 700 500 300 1.3 1.4 1.5 1.6 1.7 1.8 1.2 100 sfo output voltage vs. input voltage MAX8971 toc25 input voltage (v) sfo output voltage (v) 7.0 6.5 6.0 5.5 4.80 4.85 4.90 4.95 5.00 5.05 5.10 4.75 5.0 7.5 i fso = 50ma i fso = 100ma i fchg = 500ma gsm test mode MAX8971 toc30 2ms /d iv v batt i batt v dc charge current vs. ambient temperature MAX8971 toc28 falling ambient temperature (c) charge current (ma) 25 20 15 10 5 100 200 300 400 500 600 0 03 0 100ki, = 4250 thermistor i fchg = 500ma, safety region 1 sfo output voltage vs. load current MAX8971 toc26 load current (ma) sfo voltage (v) 90 80 70 60 50 40 30 20 10 4.80 4.85 4.90 4.95 5.00 5.05 5.10 4.75 0 100 v dc = 7v v dc = 5v MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger
???????????????????????????????????????????????????????????????? maxim integrated products 14 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger bump description bump configuration pin name function a1, a2 pg1, pg2 power ground for step-down low-side fet a3 v ichg battery-charging current monitor output. this pin is an analog representation of the charger current at 1.4mv/ma. a4 cs current-sense input power pin a5 bat battery connection. connect to a single-cell li+ battery. b1, b2 lx1, lx2 buck inductor connection. connect the inductor between lx_ and cs. the lx1 and lx2 pins must be connected together externally. b3 irqb open-drain host processor interrupt pin b4 i2cin i 2 c interface supply b5 thm thermistor input. connect a negative temperature coefficient (ntc) thermistor from thm to gnd. connect a resistor equal to the thermistor +25 c resistance from thm to avl. charging is suspended when the thermistor is outside the hot and cold limits. connect thm to gnd to disable the thermistor temperature sensor. if the thermistor function is disable through i 2 c, connect thm to gnd. c1 byp connection point between reverse blocking mosfet and high-side switching mosfet. bypass to pg_ with a minimum 1 f f ceramic capacitor. c2 bst high-side fet driver supply. bypass bst to lx with a 0.1 f f ceramic capacitor. c3 gnd analog ground. gnd is the low-noise ground connection for the internal circuitry. MAX8971 top view (bump side down) a b c d wlp 1234 a1 pg1 pg2 v ichg cs bat thm i2cin irqb lx2 lx1 sda scl gnd bst byp a2 a3 a4 a5 b1 b2 b3 b4 b5 c1 c2 c3 c4 c5 d1 d2 d3 d4 d5 avl sfo pvl dc2 dc1 5 +
???????????????????????????????????????????????????????????????? maxim integrated products 15 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger bump description (continued) figure 1. typical application circuit pin name function c4 scl i 2 c interface clock. connect a 10k i resistor from scl to i2cin. c5 sda i 2 c interface data. connect a 10k i resistor from sda to i2cin. d1, d2 dc1, dc2 high-current charger input supply pin(s). bypass to pg_ with a 2.2 f f ceramic capacitor. dc is capable of delivering up to 1.5a to byp. dc supports both ac adapter and usb inputs. short dc1 and dc2 together externally. d3 pvl internal bias regulator high-current output bypass pin. supports internal noisy and high-current gate drive loads. bypass to pgnd with a minimum 1 f f ceramic capacitor. do not use pvl to power external loads. d4 sfo 5v regulated ldo output. bypass sfo to gnd with a 1 f f or larger ceramic capacitor. sfo can be used to supply low-voltage rated usb systems. d5 avl internal-bias-regulator quiet analog bypass pin. internal 10 i connection between pvl and avl forms a lowpass filter with external bypass capacitor to gnd. do not use avl to power external loads. avl bat+ bat- system load dc byp scl sda irqb i2cin v ichg gnd avl pvl sfo dc1, dc2 bst byp c1 2.2f 25v 0603 c7 4.7f 6.3v 0402 c3 1f 6.3v 0402 c4 4.7f 6.3v 0402 c5 2.2f 6.3v 0603 c2 1f 25v 0603 c6 0.1f 0402 r1, 47mi 0402 l1, 1h 2520 r tb 0402 r2, 100ki lx1, lx2 pg1, pg2 cs bat thm -0.3v to +22v tolerant 4.0v to 10v operational MAX8971 p
???????????????????????????????????????????????????????????????? maxim integrated products 16 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger detailed description the MAX8971 is a jeita-compliant li+ switching battery charger that safely charges a single li+ cell in accordance with jeita specifications. the ic accepts an input supply range from 4v to 7.5v, but disables charging if the supply voltage exceeds +7.5v, protecting against unqualified or faulty ac adapters. the step-down converter supplies up to 1.5a to the bat - tery. the ic includes charger features thermistor monitor, charger status and fault outputs. also included are interrupt signals to the processor. flexibility is maintained with adjustable charge current, input current limit, and a minimum battery voltage (when charging is scaled back to hold the battery voltage up) through an i 2 c interface. dc inputfast-hysteretic step-down regulator if a valid dc input is present, battery charging is supplied by the high-frequency step-down regulator from dc. the step-down regulation point is then controlled by three feedback signals: maximum step-down output current programmed by the input current limit, maxi - mum charger current programmed for the fast-charge current, and maximum die temperature. the feedback signal requiring the smallest current controls the average output current in the inductor. this scheme minimizes total power dissipation for battery charging, and allows the battery to absorb any load transients with minimum voltage disturbance. a proprietary hysteretic current pwm control scheme ensures fast switching and physically tiny external components. the feedback control signal that requires the smallest input current, controls the center of the peak and valley currents in the inductor. the ripple current is internally set to provide 4mhz operation. when the input voltage decreases near the output voltage, very high duty cycle occurs. due to minimum off-time, 4mhz operation is not achievable. the controller then provides minimum off-time, peak current regulation. similarly, when the input voltage is too high to allow 4mhz opera - tion due to the minimum off-time, the controller becomes a minimum on-time, valley current regulator. in this way, ripple current in the inductor is always as small as possible to reduce ripple voltage-on battery for a given capacitance. the ripple current is made to vary with input voltage and output voltage in a way that reduces frequency variation. however, the frequency still varies somewhat with operating conditions. soft-start to prevent input current transients, the rate of change of the input current (di/dt) and charge current is limited. when the input is valid the charge current ramps from 0ma to the fast-charge current value in 1.5ms. charge current also soft-starts when transitioning from the prequalification state to the fast-charge state. there is no di/dt limiting when transitioning from the done state to the fast-charge state. pvl and avl pvl is a 5v linear regulator that the ic uses to power the gate drivers for its step-down charger. pvl also charges the bst capacitor. the pvl linear regulator is on when dc is greater than ~2.5v, otherwise it is off. bypass pvl with a 1 f f ceramic capacitor to pg. powering external loads from pvl is not recommended. as shown in figure 1, avl is a filtered output from the pvl linear regulator that the ic uses to power its internal analog circuits. the filter consists of an internal 10 i resistor, and the avl external bypass capacitor (4.7 f f). this filter creates a 100khz lowpass fil - ter that cleans the 4mhz switching noise from the analog portion of the ic. connect a 4.7 f f ceramic capacitor from avl to gnd. powering external loads with avl is not recommended. thermistor input (thm) the thm input connects to an external negative temperature coefficient (ntc) thermistor to monitor battery or system temperature. charging is suspended when the thermistor temperature is out of range. the charge timers are suspended and hold their state, but no fault is indicated. when the thermistor comes back into range, charging resumes and the charge timer continues from where it left. since the thermistor monitoring circuit employs an external bias resistor from thm to avl, the thermistor is not limited only to 10k i (at +25 n c). any resistance thermistor can be used as long as the value is equivalent to the thermistors +25 n c resistance. for example, with a
???????????????????????????????????????????????????????????????? maxim integrated products 17 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger 10k i at r tb resistor, the charger enters a temperature suspend state when the thermistor resistance falls below 3.97k i (too hot) or rises above 28.7k i (too cold). this corresponds to the 0 n c to +50 n c range when using a 10k i ntc thermistor with a beta of 3500. the general relation of thermistor resistance to temperature is defined by the following equation: r t = r 25 x e{ a ((1/(t+273)) x (1/298))} where: r t = the resistance in i of the thermistor at tempera - ture t in celsius r 25 = the resistance in i of the thermistor at +25 n c a = the material constant of the thermistor, which typi - cally ranges from 3000k to 5000k t = the temperature of the thermistor in n c some designs might prefer other thermistor temperature limits. threshold adjustment can be accommodated by changing r tb , connecting a resistor in series and/or in parallel with the thermistor, or using a thermistor with different a . for example, a +45 n c hot threshold and 0 n c cold threshold can be realized by using a thermistor with a a to 4250, and connecting 120k i in parallel. since the thermistor resistance near 0 n c is much higher than it is near +50 n c, a large parallel resistance lowers the cold threshold, while only slightly lowering the hot threshold. conversely, a small series resistance raises the cold threshold, while only slightly raising the hot threshold. raising r tb, lowers both the hot and cold threshold, while lowering r tb raises both thresholds. note that since avl is active whenever valid input power is connected at dc, thermistor bias current flows at all times. using a 10k i thermistor and a 10k i pullup to avl, results in an additional 250 f a load. this load can be reduced to 25 f a by instead using a 100k i thermistor and 100k i pullup resistor. thermal foldback thermal foldback maximizes the battery charge current while regulating the ic's junction temperature. when the die temperature exceeds t reg , a thermal limiting circuit reduces the battery charge-current target until the charge current reaches 10% of the fast-charge current setting. the charger maintains 10% of the fast-charge current until the die temperature reaches t shdn . please note that the ic is rated for a maximum ambient tem - perature of +85 n c. furthermore, although the maximum die temperature of the MAX8971 is +150 n c, it is common industry practice to design systems in such a way that the die temperature never exceeds +125 n c. limiting the maximum die temperature to +125 n c extends long-term reliability. charger states the ic utilizes several charging states to safely and quickly charge batteries as shown in figure 3. figure 2 shows an exaggerated view of a li+/li-poly battery progressing through the following charge states when the die and battery are close to room temperature: dead battery ? prequalification ? fast charge ? top-off ? done. table 1. trip temperatures for different thermistors thermistor temperature r thm at t a =+25 c 10,000 10,000 10,000 47,000 47,000 100,000 100,000 thermistor beta ( ai ) 3380 3940 3940 4050 4050 4250 4250 rtb ( i ) 10,000 10,000 10,000 47,000 47,000 100,000 100,000 rtp ( i ) open open 301,000 open 1,200,000 open 1,800,000 rts ( i ) short short 499 short 2,400 short 6,800 resistance at t1_n15 ( i ) 61,788 61,788 77,248 290,410 380,716 617,913 934,027 resistance at t1_0( i ) 29,308 29,308 31,971 137,750 153,211 293,090 343,283
???????????????????????????????????????????????????????????????? maxim integrated products 18 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger figure 2. li/li-poly charge profile dead battery battery voltage battery charge current 0 i pq i dbat i pq + i dbat i fchg v batreg v plth v plth v dbat dead battery + prequalification prequalification fast-charge (constant current) fast-charge (constant voltage) top-off time time done
???????????????????????????????????????????????????????????????? maxim integrated products 19 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger figure 3. functional state diagram no pwr charger disabled prequal check chg_dtls[3:0 ] i bat = i preq fast chg check chg_dtls[3:0 ] i bat = i fc v bat > v dbat v bat < v dbat v bat > v pquth soft-start set timer = 0 v bat < v pquth timer fault i rbq = low check chgint, chgstat, and detail s register i bat = 0 timer > tpreq topoff i rbq = low check chgint, chgstat, and details register done i rbq = low check chg_dtls[3:0 ] i bat = 0 v bat < v restr set timer = 0 v in too high i rbq = low i bat = 0 any charging state dead bat, prequal, fast charge or topoff battery cold i rbq = low, i bat = 0, if v bat > v dbat battery hot i rbq = low, i bat = 0, if v bat > v dbat v dc > v ovlo timer = suspend v dc < v ovlo timer = resume thermistor > t1 timer = resume thermistor < t1 timer = suspend thermistor > t4 timer = suspend thermistor < t4 timer = resume timer > t topoff i bat > i topoff + 200ma set timer = 0 i bat < i topoff v dc > v uvlo and v dc > v bat and t j < t shdn dead bat i rbq = low check chgint, chgstat, and details register i bat = i dbat v bat > v pqlth v bat < v pqlth set timer = 0 deadbat+ prequal check chg_dtls[3:0 ] i bat = i bat + i preq battery cool i bat = 50%, *ifchg if v bat > v dbat battery warm i rbq = low, v bat_term = v bat 125mf, if v bat > v dbat timer > tfchg
???????????????????????????????????????????????????????????????? maxim integrated products 20 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger charger-disabled state when dc is low or the input voltage is out of range, the ic disables the charger. to exit this state, the input voltage must be within its valid range. dead-battery state when a deeply discharged battery is inserted with a voltage of less than v pqlth , the ic disables the switch - ing charger and linearly charges with i dbat . once v bat increases beyond v pqlth , the ic clears the prequalifica - tion timer, and transitions to the dead battery + prequali - fication state. this state prevents the ic from dissipating excessive power in the event of a shorted battery. the dead-battery linear charge remains on, except when in the charger disabled state, timer fault state, thermal shutdown and v bat > v dbat . dead-battery + prequalification state the dead battery + prequalification state occurs when the battery voltage is greater than v pqlth, and less than v dbat . in this state, both the linear dead-battery charger and the switching charger are on, delivering current to the battery. the total battery current is i dbat + i pq . if the ic remains in this state for longer than t pq , the ic transitions to the timer fault state. a normal battery typically stays in this state for several minutes or less. when the battery voltage rises above v dbat the ic transitions to the prequalification states. the dead-battery linear charger remains on except when in the charger disabled state, timer fault state, thermal shutdown and v bat > v dbat . prequalification state the prequalification state occurs when the battery voltage is greater than v dbat and less than v pquth . in this state, the linear dead-battery charger is turned off. only the switching charger is on and delivering current to the battery. the total battery current is i pq . if the ic remains in this state for longer than t pq , then the ic transitions to the timer fault state. a normal battery typically stays in the prequalification state for several minutes or less. when the battery voltage rises above v pquth , the ic transitions to the fast-charge constant- current state. fast-charge constant-current state the fast-charge constant-current state occurs when the battery voltage is greater than v pquth and less than v batreg . in this state, the switching charger is on and delivering current to the battery. the total battery current is i fc . if the ic remains in this state and the fast-charge constant voltage state for longer than t fc , then the ic transitions to the timer fault state. when the battery voltage rises to v batreg , the ic transitions to the fast-charge constant voltage state. the fast-charge constant-current is set to 50% of programmed value when 0 n c < thm <+15 n c, and 100% of programmed value when +15 n c < thm <+60 n c. the MAX8971 dissipates the most power in the fast- charge constant-current state. this power dissipation causes the internal die temperature to rise. if the die temperature exceeds t reg , i fc is reduced. if there is low input-voltage headroom (v in - v bat ), then i fc decreases due to the impedance from in to bat. fast-charge constant voltage state the fast-charge constant voltage state occurs when the battery voltage is at the v batreg , and the charge cur - rent is greater than i topoff . in this state, the switching charge is on and delivering current to the battery. the ic maintains v batreg and monitors the charge current to detect when the battery consumes less than the topoff current. when the charge current decreases below the topoff threshold, the ic transitions to the top-off state. if the ic remains in the fast-charge constant-current state for longer than t fc , then it transitions to the timer fault state. top-off state the top-off state occurs when the battery voltage is at v batreg and the battery current decreases below topoff current. in this state, the switching char - ger is on and delivers current to the battery. the ic maintains v batreg for a specified time. when this time expires, the ic transitions to the done state. if the charging current increases to i topoff + 200ma before this time expires, then the charge reenters the fast-charge constant voltage state. done state the ic enters its done state after the charge has been in the top-off state for t topoff . in this state, the switching charger is off and no current is delivered to the battery. if the system load presented to the battery is low << 10 f a, then a typical system can remain in the done state for many days. if left in the done state long enough, the bat - tery voltage decays below the restart threshold and the ic transitions back into the fast-charge state. there is no soft-start (di/dt limiting) during the done-to-fast-charge state transition.
???????????????????????????????????????????????????????????????? maxim integrated products 21 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger timer fault state the timer fault state occurs when either the prequalifica - tion or fast-charge timers expire. in this state, the charger is off. the charger can exit this timer fault state by cycling input power. overvoltage and protection the ic provides for a +22v absolute maximum positive input voltage, and a -0.3v absolute maximum negative input voltage. excursions to the absolute maximum volt - age levels should be on a transient basis only, but can be withstood by the ic indefinitely. situations that typically require extended input voltage ratings include, but are not limited to the following: u inductive kick u charge source failure u power surge u improperly wired wall adapter u improperly set universal wall adapter u wall adapter with the correct plug, but wrong voltage u home-built computer with usb wiring harness con - nected backwards (negative voltage) u usb connector failure u excessive ripple voltage on a switch-mode wall charger u usb-powered hub that is powered by a wall charger (typically through a barrel connector) that has any of the aforementioned issues u unregulated charger automatic input current limit protection the ic includes an input-current-limiting feature. the amplifiers required for sensing the currents and associ - ated logic circuitry for making decisions and changing the battery-charger current are fully integrated in the ics. this not only helps in reducing cost, but also improves the speed of system response. the ic works by monitoring the current being drawn from the ac adapter and comparing it to the pro - grammed current limit. the current limit should be set based on the current-handling capability of the ac adapter. generally, this limit is chosen to optimally fulfill the system-power requirements while achieving a satisfactory charging time for the batteries. if the ac-adapter current exceeds its output capability, the charger responds by cutting back on the charger current, thereby keeping the current drawn from the ac adapter within its capability. with such a battery charger, the ac adapter doesnt need to be oversized to meet maximum system and battery-charging requirements simultaneously, thereby reducing ac adapter cost. the input current limit has two control inputs, one based on voltage and one based on current. the voltage input monitors the input voltage, and when it drops below the desired input (4.5v), it generates a flag (aicl) to decre - ment the fast-charge current. when the voltage comparator initially trips at 4.5v, fast- charge current decrements at a slow rate, allowing the charger output to settle until the voltage on dc returns above this voltage threshold. once the dc voltage resolves itself, the current delivery of the adapter is maxi - mized. in the event of a limited input current source, an example being a 500ma adaptor plugged into a 1a input current limit setting, a second voltage comparator set at 4.4v triggers and throttles the fast-charge current to a minimum of 75ma. once the dc voltage corrects itself to above 4.5v, the fast-charge level is checked every 16ms to allow the system to recover if the available input power increases. the current-limit input monitors the current through the input fet and generates a flag (dc_i) to decrement the fast-charge current when the input limit is exceeded. the fast-charge current is slowly decremented until the input- limit condition is cleared. at this point, the fast-charge current is maintained for 16ms and is then sampled again.
???????????????????????????????????????????????????????????????? maxim integrated products 22 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger figure 4. jeita safety region v ichg charging current monitor v ichg is a buffered output that can be interpreted to the charge current (v ichg = 1400mv/i fchg). see the typical operating characteristics section for the v ichg curve. safeout safeout is a linear regulator that provides an output voltage of 5v and can be used to supply low-voltage rated usb systems. the sfo linear regulator turns on when v in > 2.5v. jeita description the ic jeita-compliant switching li+ battery charger safely charges a single li+ cell in accordance with jeita specifications. the ic monitors the battery temperature while charging, and automatically adjusts the fast-charge current and/or charge termination voltage as the battery temperature varies. in safety region 1, the ic automatically reduces the fast-charging current for t bat < +10 n c, and reduces the charge termination voltage from 4.200v ( q 25mv) to 4.075v ( q 25mv) for t bat > +45 n c. the fast-charge current is reduced to 50% of the nominal fast-charge current with options for 25% and 75%. jeita never specifically states one or the other. when battery charge current is reduced by 50%, the timer is doubled. in safety region 2, the ic automatically reduces the charge termination voltage from 4.200v ( q 25mv) to 4.075v ( q 25mv) for t bat < +10 n c and for t bat > +45 n c. the fast-charge current is not changed in safety region 2. maxim model gauge m3 support figure 5 illustrates how the ic can easily integrate with maxims model gauge m3 max17047 chip. the user just needs to add a schottky diode between v batt and v tt on the max17047. factory-mode gsm test mode support the ic supports gsm pulse programming scheme. when dc is inserted with no battery operation, the ic soft-starts and cycles through dead-battery, prequalification, and fast charge, settling at constant voltage-mode operation, and regulating to the termination voltage (4.2v default). at this time, when b4 of register 0x08 is sent, the part can now support gsm pulse. see the typical operating characteristics section. figure 5. MAX8971 with max17047 t1 c 0.5c 0c 10c 25c 45c temperature fast-charge current charge termination voltage 60c 85c 0c 10c 25c 45c temperature 60c 85c t2 t1 t2 4.0v 4.075v 4.2v 4.1v q25mv q25mv safety region 1 safety region 2 r t (battery) r td thrm batt dc byp lx pgnd v ichg sda scl avl thm pvl agnd i2cin sfo ain batt v tt v ss MAX8971 max17047
???????????????????????????????????????????????????????????????? maxim integrated products 23 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger the battery node should have enough capacitance to hold the battery voltage to some minimum acceptable system value (v sys ) during the done to fast-charge state transition time of 100us (t done2fc) . c bat i load x t done2fc /(v batreg - v sys ) for example, if the maximum system load without a bat - tery is 400ma (i load ), and the minimum acceptable sys - tem voltage is 3.4v (v sys ), then the battery node should have at least 40f. c bat 400ma x 100s/(4.2v - 3.4v) = 40f. applications information inductor selection the charger operates with a switching frequency of 4mhz and uses a 1 f h or 2.2 f h inductor. this operating frequency allows the use of physically small inductors while maintaining high efficiency. the inductors dc current rating only needs to match the maximum load of the application because the ic features zero current overshoot during startup and load transients. for optimum transient response and high effi - ciency, choose an inductor with dc series resistance in the 40m i to 120m i range. see table 2 for suggested inductors and manufacturers. input capacitor selection the input capacitor reduces the current peaks drawn from the input power source and reduces switching noise in the ic. the impedance of the input capacitor at the switching frequency should be kept very low. ceramic capacitors with x5r or x7r temperature characteristics are highly recommended due to their small size, low esr, and small temperature coefficients. a 4.7ff capacitor is recommended. for optimum noise immunity and low input ripple, the input capacitor value can be increased. note that some ceramic dielectrics exhibit large capaci - tance and esr variation with temperature and dc bias. ceramic capacitors with z5u or y5v temperature char - acteristics should be avoided. output capacitor selection for the charger, the output capacitor keeps the output voltage ripple small and ensures regulation loop stabil - ity. the output capacitor must have low impedance at the switching frequency. ceramic capacitors with x5r or x7r temperature characteristics are highly recommend - ed due to their small size, low esr, and small tempera - ture coefficients. a 4.7 f f capacitor is recommended. for optimum load-transient performance and very low output ripple, increase the output capacitor value. charge current resistor selection both the top-off current range and fast-charge cur - rent range depends on the sensing resistor (r sns ). the default resistor recommended is a 47m i , 0.125w resistor. select a 0.125w,47m i 2% sense resistor, e.g., panasonic erj2bwgr047. this is a standard value. p rsns = i charge 2 x r sns p rsns = 1.5 2 x 0.047 p rsns = 0.105w the charge current step (i charge ) is calculated using equation below: i charge_step = v( chgcc<> )/r sns table 3 below shows the charge current settings for two sensing resistors. i charge_current_step = v( topoff<> )/r sns table 2. suggested inductors manufacturer series inductance (h) esr ( i ) current rating (ma) dimensions fdk mipsa2520d1r0 1.0 0.08 1500 2.5mm x 2.0mm x 1.2mm = 6mm 3 murata lqm2hpn_g0 1.0 0.05 1600 2.5mm x 2.0mm x 0.6mm = 3mm 3 coilcraft epl2014 1.0 0.059 1600 2.0mm x 2.0mm x 1.4mm = 5.6mm 3 tdk mlp2520s 1.0 0.06 1500 2.0mm x 2.5mm x 1.0mm = 5mm 3 toko mipf2520 2.2 0.05 1500 2.5mm x 2.0mm x 1.0mm = 5mm 3 toko dfe252012c 1 0.06 2500 2.5 x 2.0 x 1.2 = 6mm 3 murata lqm32pn1r0mg0 1 0.06 1800 3.2 x 2.5 x 0.9 = 7.2mm3
???????????????????????????????????????????????????????????????? maxim integrated products 24 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table 3. charge current settings for 47m ? and 68m ? sense resistors table 4. topoff current settings for 47m ? and 68m ? sense resistors table 5. high-level i 2 c register map bit vi reg (mv) i charge (ma) r sns = 47m i i charge (ma) r sns = 68m i v (chgcc<11110>) 70.5 1500 1037 v (chgcc<10100>) 47 1000 691 v (chgcc<01010>) 23.5 500 345 bit v( topoff ) i( topoff ) (ma) r sns = 47m i i( topoff ) (ma) r sns = 68m i v (topoff<>) 9.4 200 138.2 v (topoff<>) 4.7 100 69.1 v (topoff<>) 2.35 50 34.5 register name register address r/w reset condition b7 b6 b5 b4 b3 b2 b1 b0 chgint 0x0f r vstby or rising edge of sfo_pok aicl_i topoff dc_ ovp dc_ uvp chg_i bat_i thm_i powerup chgint?msk 0x01 r/w vstby or rising edge of sfo_pok aicl_m topoff_ m dc_ ovp_m dc_ uvp_m chg_m bat_m thm_m chg?stat 0x02 r vstby or rising edge of sfo_pok dcv_ok dci_ok dcovp_ ok dcuvp_ ok chg_ok bat_ ok thm_ ok details1 0x03 r vstby or rising edge of sfo_pok dc_v dc_i dc_ovp dc_uvp rsvd thm_d[2:0] details2 0x04 r vstby or rising edge of sfo_pok rsvd rsvd bat_dt[1:0] chg_d[2:0]
???????????????????????????????????????????????????????????????? maxim integrated products 25 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table 5. high-level i 2 c register map (continued) register name register address r/w reset condition b7 b6 b5 b4 b3 b2 b1 b0 chgcntl1 0x05 r/w vstby or rising edge of sfo_pok rsvd rsvd rsvd rsvd rsvd rsvd dcmon_ dis usb_ sus fchgcrnt 0x06 r/w vstby or rising edge of sfo_pok fchgt[2:0] chgcc[3:0] dccrnt 0x07 r/w vstby or rising edge of sfo_pok rsvd chgr strt dcilmt[5:0] topoff 0x08 r/w vstby or rising edge of sfo_pok topofft[2:0] ifst2p8 toffs[1:0] chgcv[1:0] tempreg 0x09 r/w vstby or rising edge of sfo_pok rtemp[1:0] thm cnfg rsvd rsvd thmres safe reg protcmd 0x0a r/w vstby or rising edge of sfo_pok rsvd rsvd rsvd rsvd c_prot[1:0] rsvd rsvd
???????????????????????????????????????????????????????????????? maxim integrated products 26 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger i 2 c registers charger interrupt requests register name i 2 c slave address register address reset value access type special features reset condition chgint 0x6a 0x0f 0x01 r cleared upon read vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name aicl_i topoff dc_ovp dc_uvp chg_i bat_i thm_i powerup bit name bit description default b7 aicl_i dc interrupt 0 = the dc status has not changed since the last time this bit was read. 1 = the dc status has changed since the last time this bit was read. 0 b6 topoff topoff interrrupt 0 = the charger topoff status has not changed since the last time this bit was read. 1 = the charger has entered topoff. 0 b5 dc_ovp dc overvoltage interrupt 0 = the dc status has not changed since the last time this bit was read. 1 = the dc status has changed since the last time this bit was read. 0 b4 dc_uvp dc undervoltage interrupt 0 = the dc status has not changed since the last time this bit was read. 1 = the dc status has changed since the last time this bit was read. 0 b3 chg_i charge current interrupt 0 = the charger status has not changed since the last time this bit was read. 1 = the charger status has changed since the last time this bit was read. 0 b2 bat_i battery interrupt 0 = the battery status has not changed since the last time this bit was read. 1 = the battery status has changed since the last time this bit was read. 0 b1 thm_i thermistor interrupt 0 = the thm status has not changed since the last time this bit was read. 1 = the thm status has changed since the last time this bit was read. 0 b0 powerup power-up ok interrupt 0 = the i 2 c registers have not been reset since the last time this bit was read. 1 = the i 2 c registers have been reset since the last time this bit was read. 1
???????????????????????????????????????????????????????????????? maxim integrated products 27 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger charger interrupt masks register name i 2 c slave address register address reset value access type special features reset condition chgint_mask 0x6a 0x01 0x00 r/w n/a vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name aicl_m topoff_m dc_ ovp_m dc_ uvp_m chg_m bat_m thm_m bit name bit description default b7 aicl_m dc interrupt mask 0 = unmask 1 = mask 0 b6 topoff_m topoff interrupt mask 0 = unmask 1 = mask 0 b5 dc_ovp_m dc overvoltage interrupt mask 0 = unmask 1 = mask 0 b4 dc_uvp_m dc undervoltage interrupt mask 0 = unmask 1 = mask 0 b3 chg_m charger-current interrupt mask 0 = unmask 1 = mask 0 b2 bat_m battery interrupt mask 0 = unmask 1 = mask 0 b1 thm_m thermistor interrupt mask 0 = unmask 1 = mask 0
???????????????????????????????????????????????????????????????? maxim integrated products 28 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger charger status register name i 2 c slave address register address reset value access type special features reset condition chg_stat 0x6a 0x02 r n/a vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name dcv_ok dci_ok dcovp_ ok dcuvp_ ok chg_ok bat_ok thm_ok bit name bit description b7 dcv_ok single-bit dc input status indicator. see dc_dtls[1:0] for more information. 1 = the dc input is invalid. dc_v = 1. 0 = the dc input is valid. dc_dtls[1:0]=dc_v=0. b6 dci_ok 1 = the dc input is invalid. dc_i = 1. 0 = the dc input is valid. dc_dtls[1:0] =dci=0. b5 dcovp_ok 1 = the dc input is invalid. dc_ovp = 1. 0 = the dc input is valid. dc_dtls[1:0] =dc_ovp=0. b4 dcuvp_ok 1 = the dc uvp is invalid. 0 = the dc input is valid. dc_dtls[1:0] =dc_uvp=0. b3 chg_ok single-bit charger status indicator. see chg_dtls[3:0] for more information. 1 = the charger has suspended charging. chg_dtls[3:0 ] = 0b0101 or 0b0110 or 0b0111 or 0b1000. 0 = the charger is okay. chg_dtls[3:0] 0b0101 or 0b0110 or 0b0111 or 0b1000. b2 bat_ok single-bit battery status indicator. see bat_dtls[1:0] for more information. 1 = the battery has an issue and the charger has been suspended. bat_dtls[1:0]=0b01 or 0b11. 0 = the battery is okay. bat_dtls[1:0]=0b10 or 0b00. b1 thm_ok single-bit thermistor status indicator. see the thm_dtls[2:0] for more information. 1 = the thermistor temperature is outside of the allowable range for charging. thm_dtls[2:0] 0b100 or 0b101. 0 = the thermistor temperature is inside of the allowable range for charging. thm_dtls[2:0] = 0b100 or 0b101.
???????????????????????????????????????????????????????????????? maxim integrated products 29 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger details1 register name i 2 c slave address register address access type special features reset condition details1 0x6a 0x03 r n/a vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name dc_v dc_i dc_ovp dc_uvp rsvd thm_d[2:0] bit name description default dc_v dc details 0b0= v dc is in aicl mode. 3v < v dc < 4.5 0b1= v dc is valid. v dc > 4.5 valid dc_i dc details 0b0 = i dc is valid. idc < input current limit 0b1 = i dc is invalid. idc > input current limit valid dc_ovp dc details 0b0 = v dc is valid. v dc < v dcovlo 0b1 = v dc is invalid. v dc > v dcovlo valid dc_uvp dc details 0b0 = v dc is valid. v dc > v dcuvlo 0b1 = v dc is invalid. v dc < v dcuvlo valid rsvd reserved thm _d[2:0] thermistor details 0b001 = low temperature and charging suspended (cold, < 0 c) 0b010 = low temperature charging (cool, > 0 c and < 10 c) 0b011 = standard temperature charging (normal, > 10 c and < 45 c) 0b100 = high temperature charging (warm, > 45 c and < 60 c) 0b101 = high temperature and charging suspended (> 60 c) valid
???????????????????????????????????????????????????????????????? maxim integrated products 30 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger details2 register name i 2 c slave address register address access type special features reset condition details2 0x6a 0x04 r n/a vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name bat_d[1:0] chg_d[3:0] name description default bat_d[1:0] battery details 0b00 = v bat < 2.1v. this condition is also reported in the chg_dtls[3:0] as 0b0000 0b01 = the battery is taking longer than expected to charge. this could be due to high system currents, an old battery, a damaged battery or something else. charging has suspended and the charger is in its timer fault mode. this condition is also reported in the chg_dtls[3:0] as 0b0110. 0b10 = the battery is ok. 0b11=the battery voltage is greater than the battery overvoltage flag threshold (batov), batov is set to a percentage above the v batreg target as programmed by chgcv. note that this flag is only generated when there is a valid dc input. n/a chg_d[3:0] charger details 0b0000 = charger is in dead-battery region. 0b0001 = charger is in prequalification mode. 0b0010 = charger is in fast-charge constant-current mode. 0b0011 = charger is in fast-charge constant voltage mode. 0b0100 = charger is in top-off mode. 0b0101 = charger is in done mode. 0b0110 = charger is in timer fault mode. 0b0111 = charger is in temperature suspend mode, see thm_dtls[2:0]. 0b1000 = charger is off, dc is invalid and/or charger is disabled. 0b1001 = charger is in prequalification, fast-charge or top-off modes and is operating with its thermal loop active (i.e., the junction temperature is greater than the value set by regtemp[1:0]. n/a
???????????????????????????????????????????????????????????????? maxim integrated products 31 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger usb suspend input voltage disable fast-charge current and timer control register name i 2 c slave address register address access type special features reset condition chgcntl1 0x6a 0x05 r/w n/a vstby invalid or rising edge of sfo_pok bits b7 b6 b5 b4 b3 b2 b1 b0 name dcmon_dis usb_sus bits b7 b6 b5 b4 b3 b2 b1 b0 name fchgt[2:0] chgcc[4:0] bit name bit description default 0 0 0 0 0 0 dcmon_dis dcmon_dis, disabled the monitoring of input voltage by the input power limiter 0 usb_sus usb suspend, low-quiescent current standby mode 0 bit name description default b4Cb0 chgcc[4:0] fast-charge current selection when the charger is enabled, the charge current limit is set by these bits. these bits range from 250ma to 1.55a in 50ma steps. see table 6 for a complete listing of codes for chgcc[4:0] 500ma b7, b6, b5 fchgt[2:0] fast-charge timer duration (t fc ) 0x00 = 0b000 = disable 0x01 = 0b001 = 4hrs 0x02 = 0b010 = 5hrs 0x03 = 0b011 = 6hrs 0x04 = 0b100 = 7hrs 0x05 = 0b101 = 8hrs 0x06 = 0b110 = 9hrs 0x07 = 0b111 = 10hrs 0b010 register name i 2 c slave address register address access type special features reset condition fchgcrnt 0x6a 0x06 r/w protected with cprot[1:0] vstby invalid or rising edge of sfo_pok
???????????????????????????????????????????????????????????????? maxim integrated products 32 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table 6. chgcc[4:0] decoding input-current limit and charger restart threshold chgcc[4:0] charge current with 47m ? sense (ma) 0 0 0 0 0 250 0 0 0 0 1 250 0 0 0 1 0 250 0 0 0 1 1 250 0 0 1 0 0 250 0 0 1 0 1 250 0 0 1 1 0 300 0 0 1 1 1 350 0 1 0 0 0 400 0 1 0 0 1 450 0 1 0 1 0 500 0 1 0 1 1 550 0 1 1 0 0 600 0 1 1 0 1 650 0 1 1 1 0 700 0 1 1 1 1 750 chgcc[4:0] charge current with 47m ? sense (ma) 1 0 0 0 0 800 1 0 0 0 1 850 1 0 0 1 0 900 1 0 0 1 1 950 1 0 1 0 0 1000 1 0 1 0 1 1050 1 0 1 1 0 1100 1 0 1 1 1 1150 1 1 0 0 0 1200 1 1 0 0 1 1250 1 1 0 1 0 1300 1 1 0 1 1 1350 1 1 1 0 0 1400 1 1 1 0 1 1450 1 1 1 1 0 1500 1 1 1 1 1 1550 bits b7 b6 b5 b4 b3 b2 b1 b0 name chgrstrt dcilmt[5:0] name description default chgrstrt fast-charge restart threshold 0b0 = -150mv 0b1 = -100mv 0b0 dcilmt[5:0] input-current limit selection when the dc-dc converter is on, the v dc input current limit is set by this register. the bits set 100ma, to 1.5a in 25ma steps. see table 7 for a complete listing of the codes for dcilmt[5:0]. 500ma register name i 2 c slave address register address access type special features reset condition dccrnt 0x6a 0x07 r/w protected with cprot[1:0] vstby invalid or rising edge of sfo_pok
???????????????????????????????????????????????????????????????? maxim integrated products 33 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table 7. dcilmt[5:0] bit code dcilmt[5:0] target input limit (ma) 0 0 0 0 0 0 100 0 0 0 0 0 1 100 0 0 0 0 1 0 100 0 0 0 0 1 1 100 0 0 0 1 0 0 100 0 0 0 1 0 1 100 0 0 0 1 1 0 100 0 0 0 1 1 1 100 0 0 1 0 0 0 100 0 0 1 0 0 1 100 0 0 1 0 1 0 250 0 0 1 0 1 1 275 0 0 1 1 0 0 300 0 0 1 1 0 1 325 0 0 1 1 1 0 350 0 0 1 1 1 1 375 0 1 0 0 0 0 400 0 1 0 0 0 1 425 0 1 0 0 1 0 450 0 1 0 0 1 1 475 0 1 0 1 0 0 500 0 1 0 1 0 1 525 0 1 0 1 1 0 550 0 1 0 1 1 1 575 0 1 1 0 0 0 600 0 1 1 0 0 1 625 0 1 1 0 1 0 650 0 1 1 0 1 1 675 0 1 1 1 0 0 700 0 1 1 1 0 1 725 0 1 1 1 1 0 750 0 1 1 1 1 1 775 1 0 0 0 0 0 800 1 0 0 0 0 1 825 1 0 0 0 1 0 850 1 0 0 0 1 1 875 1 0 0 1 0 0 900 1 0 0 1 0 1 925 1 0 0 1 1 0 950 1 0 0 1 1 1 975 1 0 1 0 0 0 1000
???????????????????????????????????????????????????????????????? maxim integrated products 34 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger table 7. dcilmt[5:0] bit code (continued) note: dcilim threshold is 95% of target. dcilmt[5:0] target input limit (ma) 1 0 1 0 0 1 1025 1 0 1 0 1 0 1050 1 0 1 0 1 1 1075 1 0 1 1 0 0 1100 1 0 1 1 0 1 1125 1 0 1 1 1 0 1150 1 0 1 1 1 1 1175 1 1 0 0 0 0 1200 1 1 0 0 0 1 1225 1 1 0 0 1 0 1250 1 1 0 0 1 1 1275 1 1 0 1 0 0 1300 1 1 0 1 0 1 1325 1 1 0 1 1 0 1350 1 1 0 1 1 1 1375 1 1 1 0 0 0 1400 1 1 1 0 0 1 1425 1 1 1 0 1 0 1450 1 1 1 0 1 1 1475 1 1 1 1 0 0 1500 1 1 1 1 1 1 disable
???????????????????????????????????????????????????????????????? maxim integrated products 35 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger done current, timer, gsm test mode, and battery regulation voltage bits b7 b6 b5 b4 b3 b2 b1 b0 name tofft[2:0] ifst2p8 toffs[1:0] chgcv[1:0] name description default tofft[2:0] topoff timer setting 0x00 = 0b000 = 0min 0x01 = 0b001 = 10min 0x02 = 0b010 = 20min 0x03 = 0b011 = 30min 0x04 = 0b100 = 40min 0x05 = 0b101 = 50min 0x06 = 0b110 = 60min 0x07 = 0b111 = 70min 0b011 ifst2p8 scales maximum fast-charge current to 2.8a this is used as a pulsed customer test mode and the part cannot run 2.8a continuously. 0b0 toffs[1:0] topoff current threshold topoff timer starts when ichg reaches this current setting. 0x0 = 0b00 = 50ma 0x1 = 0b01 = 100ma 0x2 = 0b10 = 150ma 0x3 = 0b11 = 200ma 0b00 chgcv[1:0] charge termination voltage setting 0x00 = 0b00 = 4.2v 0x01 = 0b01 = 4.10v 0x02 = 0b10 = 4.35v 0x03 = 0b11 = 4.15v 0b00 register name i 2 c slave address register address access type special features reset condition topoff 0x6a 0x08 r/w protected with cprot[1:0] vstby invalid or rising edge of sfo_pok
???????????????????????????????????????????????????????????????? maxim integrated products 36 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger temperature regulation charger protection bits b7 b6 b5 b4 b3 b2 b1 b0 name regtemp[1:0] thm_cnfg thmres[1:0] safetyreg bits b7 b6 b5 b4 b3 b2 b1 b0 name cprot[1:0] name bit description default regtemp[1:0] die-temperature thermal regulation loop setpoint 0x0 = 0b00 = 105 c 0x1 = 0b01 = 90 c 0x2 = 0b10 =120 c 0x3 = 0b11 = disabled 0b00 thm_cnfg thermistor monitor configuration 0b0 = the thermistor is continuously monitored. 0b1 = the thermistor is not being monitored. 0b1 reserved reserved na reserved reserved na safetyreg jeita safety region selection 0 = safety region 1 1 = safety region 2 0b0 register name i 2 c slave address register address access type special features reset condition tempreg 0x6a 0x09 r/w protected with cprot[1:0] vstby invalid or rising edge of sfo_pok register name i 2 c slave address register address access type special features reset condition protcmd 0x6a 0x0a r/w n/a vstby invalid or rising edge of sfo_pok name description default cprot[1:0] charger-setting protection bits writing 11 to these bits unlocks the settings for the above registers. writing any value besides 11 locks these registers. 0b00 = locked 0b01 = locked 0b10 = locked 0b11 = unlocked 0b00
???????????????????????????????????????????????????????????????? maxim integrated products 37 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger chip information process: bicmos ordering information + denotes a lead(pb)-free/rohs-compliant package. simplified applications circuit avl bat+ bat+ system load dc scl sda irqb i2cin v ichg gnd avl pvl sfo dc1, dc2 bst byp lx1, lx2 pg1, pg2 cs bat thm -0.3v to +22v tolerant 4.0v to 10v operational MAX8971 p part temp range pin-package MAX8971ewp+ -40 n c to +85 n c 20-bump wlp (0.4mm pitch)
???????????????????????????????????????????????????????????????? maxim integrated products 38 MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger package information for the latest package outline information and land patterns (footprints), go to www.m axim-ic .com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. e d aaaa pin 1 indicator marking a3 a2 a1 a see note 7 0.05 s s e d1 e1 sd b se b a side view -drawing not to scale- 1 a top view bottom view a 1 21-0544 b 0.64 0.19 0.45 0.025 0.27 1.20 1.60 0.40 w201a2+1 2.33 2.36 1.92 1.95 w201b2+1 2.16 2.19 1.63 1.60 5 3 4 2 d b c w201c2+1 2.01 2.04 1.61 1.64 2.08 1.74 1.71 2.11 w201d2+1 0.05 m s ab title document control no. rev. 1 1 approval package outline 20 bumps, wlp pkg. 0.4mm pitch common dimensions a a2 a1 a3 b e1 d1 e sd se 0.05 0.03 0.03 basic basic 0.20 basic 0.00 basic basic ref basic min max max min e d pkg. code depopulated bumps none notes: 1. terminal pitch is defined by terminal center to center value. 2. outer dimension is defined by center lines between scribe lines. 3. all dimensions in millimeter. 4. marking shown is for package orientation reference only. 5. tolerance is 0.02 unless specified otherwise. 6. all dimensions apply to pbfree (+) package codes only. 7. front - side finish can be either black or clear. none none none package type package code outline no. land pattern no. 20 wlp w201b2-1 21-0544 refer to application note 1891
maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice 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 products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 39 ? 2012 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 1/12 initial release MAX8971 industry's smallest 1.55a 1-cell li+ dc-dc charger

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