mp26028 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 1 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. the future of analog ic technology description the mp26028 is a linear, high-performance single cell li-ion battery charger. by integrating high voltage input protection into the charger ic, the mp26028 can tolerate an input surge up to 20v. the device features constant current (cc) and constant voltage (cv) charging modes with programmable charge currents (85ma to 1a), programmable battery full threshold, thermal protection, reverse current blocking, and trickle charge. the device also provides ac adapter power good and charge status indications to the system. mp26028 is available in a 10-pin 3mm x 3mm qfn package. features ? input surge up to 20v ? adapter or usb input ? programmable charge current: 85ma to 1a ? proprietary constant voltage auto recharge ? proprietary over-voltage protection ? 0.75% v batt accuracy ? <1a battery reverse current ? 90a standby current from v in ? over current protection ? ac adapter power good indicator ? charge status indicator ? programmable soft-start ? programmable charge termination current threshold ? tiny 10-pin qfn (3mm x 3mm) package applications ? cell phones ? mp3 players ? smart phones ? pdas ? digital cameras for mps green status, please visit m ps website under quality assurance. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application mp26028 batt iset ibf ss gnd 10 9 8 7 6 in chg acok en v bias 1 2 3 4 5 c in 1uf 430 r1 500k 430 r2 100k c ss 0.1uf c out 1uf - 22uf to system i batt v batt + _ r bf 20k r chg 2.3k 3.5v - 20v off on
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 2 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. ordering information part number* package top marking free air temperature (t a ) MP26028EQ qfn10 (3mm x 3mm) w9yw -20 ? c to +85 ? c * for tape & reel, add suffix ?z (e.g. MP26028EQ?z). for rohs compliant packaging, add suffix ?lf (e.g. MP26028EQ?lf?z) package reference top view in chg acok en v bias 1 2 3 4 5 batt iset ibf ss gnd 10 9 8 7 6 exposed pad on backside connect to gnd pin absolute maxi mum ratings (1) in to gnd .....................................-0.3v to +20v all other pins to gnd ..................-0.3v to +6.5v continuous power dissipation (t a = +25c) (2) ??????????????????....2.9w junction temperature ...............................140 ? c lead temperature ....................................260 ? c storage temperature............... -65c to +150 ? c recommended operating conditions (3) nominal supply voltage v in ............3.5v to 6.5v maximum junction temp. (t j ) ................+125c thermal resistance (4) ja jc qfn10 (3mm x 3mm) .............50 ...... 12 ... ? c/w notes: 1) exceeding these ratings may damage the device. 2) the maximum allowable power dissipation is a function of the maximum junction temperature t j (max), the junction-to- ambient thermal resistance ja , and the ambient temperature t a . the maximum allowable continuous power dissipation at any ambient temperature is calculated by p d (max) = (t j (max)-t a )/ ja . exceeding the maximum allowable powe r dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. internal thermal shutdown circuitry protects the device from permanent damage. 3) the device is not guaranteed to function outside of its operating conditions. 4) measured on jesd51-7, 4-layer pcb.
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 3 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. electrical characteristics v in = 5v, v en = 0v, t a = +25 ? c, unless otherwise noted. parameter symbol condition min typ max units en = high 40 supply current i supply en = low, i chg = 0a 500 over input voltage protection ovp v in rise 6.8 7.0 7.2 v ovp hysteresis 400 mv maximum input voltage dc leakage < 500a 20 v t a = +25c, i batt = 0 4.179 4.20 4.221 v battery voltage regulation v batt t a = -5c to +75c, i batt = 0 4.158 4.20 4.242 v battery over-voltage protection i batt_ovp v batt = 4.25v 0 a constant current regulation i chg v in = 5v, v batt = 3.8v r chg = 3.3k ? 450 515 580 ma constant current variation v in = 5v, v batt = 3.8v, t j = 0c to +120c, r chg = 1.6k ? to 8.0k ? 87 100 113 %i chg (5) trickle current v in = 5v, v batt = 2.3v 5 10 15 %i chg (5) trickle threshold voltage 2.45 2.6 2.75 v trickle voltage hysteresis 100 mv battery full programming range i bf refer to operation section for programming i bf 10 50 %i chg (5) ibf accuracy 75 125 %i bf (6) ss pin voltage c ss = 0.1uf, v batt = 3.6v 1.19 1.23 1.27 v input acok up range 6.8 7.0 7.2 v input acok low range 1.8 2.5 3.2 v en trip threshold high 2.4 v en trip threshold low 0.4 v chg , acok sink current pin voltage = 0.4v 8 ma battery reverse current to batt pin en = low and input = floating or 0v 1 a switch-on resistance r on v batt = 3.8v, i batt = 300ma, r chg = 1.7k ? 0.35 ? soft thermal shutdown threshold 105 120 135 c soft thermal shutdown hysteresis 10 c soft-start time from trickle to 90% of full current, c ss = 0.1f 10 20 35 ms notes: 5) i chg is the target preprogrammed charge current (die temperature below 110c). 6) i bf is the target preprogrammed battery full current threshold.
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 4 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. pin functions pin # name description 1 in input supply pin. in receives the ac adapter or usb supply voltage. 2 chg open-drain charge status indicator. this pin is low during charging. 3 acok open-drain input acok indicator. this pin is low if the voltage at the in pin is between 2.5v and 6.5v. 4 en charger ic enable. an input ?low? signal at th is pin or if the pin is floating will enable the ic. 5 v bias bias voltage for internal circuitry. to generate the bias voltage, connect a 500k ? resistor (r1) from this pin to the in pin and a 100k ? resistor (r2) from this pin to ground . shown in typical application circuit on front page 6 exposed pad gnd ground. connect exposed pad to the gnd pin 7 ss soft-start timer. connect this pin to an ex ternal capacitor to program the soft-start startup time using the equation: sec m 20 f 1 . 0 c t ss ss ? ? ? . 8 ibf charge status threshold program. connect this pin to an external resistor to program the charge termination current or battery full charge current. 9 iset constant charge current program. connect this pin to an external resistor to program the charging current in cc mode. 10 batt charger output.
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 5 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics v in = 5v, c in = 10f, c out = 4.7f, t a = +25 ? c, unless otherwise noted. 4.5 4.3 4.1 3.9 3.7 3.5 battery voltage (v) 4.5 4.8 5.1 5.4 5.8 6.0 input voltage (v) battery voltage vs input voltage i chg =0.43a 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 4.5 4.0 3.5 3.0 2.5 2.0 1.5 1.0 0.5 0 charge current (a) battery voltage (a) 0 40 80 120 160 200 charge time (minutes) battery charge curve v batt i batt 1100 900 700 500 300 100 charge current (ma) 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 battery voltage (v) charge currents vs battery voltage 1.0a 0.5a 0.2a 1.2 1.0 0.8 0.6 0.4 0.2 0 charge current (a) 0.0 1.0 2.0 3.0 4.0 battery voltage (v) charge current vs battery voltage v in 5v/div. v batt 2v/div. i batt 0.5a/div. v en 5v/div. v in 5v/div. v batt 2v/div. i batt 0.5a/div. v en 5v/div. 2ms/div.
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 6 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. typical performanc e characteristics (continued) v in = 5v, c in = 10f, c out = 4.7f, t a = +25 ? c, unless otherwise noted. v in =0v v bat =4.1v v bat =4.1v v bat =4v 1200 1000 800 600 400 200 0 charge current (ma) 4.3 4.4 4.5 4.6 4.8 4.7 4.9 5.0 input voltage (v) charge current vs input voltage 0.6 0.5 0.4 0.3 0.2 0.1 0 2.5 2.9 3.3 3.7 4.1 4.5 battery voltage (v) 740 720 700 680 660 640 620 600 charge current (ma) -50 -25 0 +25 +50 +75 -50 -25 0 +25 +50 +75 temperature ( c) 4.30 4.26 4.22 4.18 4.14 4.10 battery voltage (v) temperature ( c) reverse current vs battery voltage 16 14 12 10 8 6 4 2 0 0 200 400 600 800 1000 charge current (ma) charge current vs r chg resistance charge current vs temperature v batt = 3.8v battery voltage vs temperature i chg = 15ma
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 7 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. block diagram battery charge control 7 9 8 5 1 10 2 3 6 4 ss iset ibf v bias r2 c ss r chg r bf r1 in batt chg acok gnd en v in c in c out v batt + _ off on i batt figure 1?functional block diagram operation input voltage range the mp26028 has built-in input voltage surge protection up to +20v. the charger ic will be automatically disabled when the input voltage is lower than 2.5v or higher than 6.5v. the open- drain pin acok is used to indicate an input power good condition (i.e. 2.5v cc-> cv) figure 2 below shows the typical charging profile for the mp26028. figure 3 shows the typical charging procedure. for a fully depleted battery with a terminal voltage lower than 2.6v, the mp26028 will start with the trickle charge (preconditioning) at 10% of the programmed full charge current. after the battery voltage reaches 2.6v, the charger begins charging at the constant current of the programmed value (i chg ). this is referred to as constant current (cc) mode. once the battery voltage reaches 4.2v, the charger will operate in the constant voltage (cv) mode until the battery is fully charged. the charge current drops during cv mode, and the battery full indication is set when the charge current in the cv mode is reduced to the programmed full battery current (i bf ).
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 8 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. 2.6v 4.2v v batt 10% of i chg i bf trickle charging cc charging charging complete cv charging i chg i batt figure 2?typical charging profile trickle charging charge start charge end soft-start time cc mode cv mode 10% of i chg (i bf ) 90% of i chg i chg 2.6v 4.2v v batt v batt i batt i batt chg figure 3?typical charging procedure battery over-voltage protection and automatic recharge at any time when v batt is 50mv higher than the trimmed charge target, the mp26028 reduces its charge current to 0a. this ensures the safety of the battery. also, the cv control loop always monitors the battery voltage such that it will automatically recharge the battery when it is depleted below the target level. programming of charge current and battery full current the charge current (i chg ) is set by a resistor (r chg ) connecting from the iset pin to gnd. see table 1 and figure 4. the relationship of the charge current and the programming resistance is established by: chr chg r k 7 . 1 i ? ? (a) table 1?r pgm and i chg relationship r chg (k ? ) i chg (ma) 2.32 700 2.74 600 3.3 500 4.12 400 5.6 300 charge current vs 1/r pgm resistance 1000 900 800 700 600 500 400 300 200 charge current (ma) 0 0.2 0.1 0.3 0.4 0.6 0.7 0.5 figure 4?charge current vs 1/r pgm resistance the recommended resistance for programming the charge current is 2.3k ? mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 9 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. charge status indicator (chg) the mp26028 has an integrated charge status pin that remains low while the battery is charging. once the charge current has reduced to the battery full charge current threshold (i bf ), the chg pin will become high impedance. the acok and chg can be used to drive leds ( figure 1) or to interface with the system. when interfacing with the system, glitches may occur on the power supply input (in) when the ac-power adapter is plugged in and out. it is desirable to blank the glitches so that the system can properly operate with ac power adaptor. a simple solution is to add the rc filter (c5 and c6)on the pin acok / chg as shown in figure 5. the size of c5 and c6 depends on the width of the glitch and the rise time of the interface. thermal protection the mp26028 has proprietary thermal protection to prevent the ic from overheating. when in thermal protection mode, the charge current becomes a saw-tooth waveform instead of a dc current. the average current of the saw-tooth waveform will be lower than the programmed dc charge current to prevent the ic from overheating. the frequency and amplitude of the saw-tooth current waveform can be altered by changing the capacitance value connected to the ss pin. operating in thermal protection mode will slow down the charging process. lowering the input voltage and enhancing thermal dissipation to the environment can effectively prevent the ic from going into thermal protection mode. figure 5?filtered charge status & input power good interface
mp26028 ? 1a linear li-ion battery charger with trickle charge mp26028 rev.1.01 www.monolithicpower.com 10 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. application flow chart of operation power-on reset (por) feature can be applied to the mp26028 to ensure that the device starts operating in a known state. the flow chart in figure 5 describes the conditions and operation modes of the mp26028. cvc and ccc stand for ?constant voltage charge? and ?constant current charge?, respectively. por no yes yes charge mode ? v bat >2.6v? v bat >4.15v v bat <2.6v yes 2.6v130 c ? short circuit? v bat >4.15v? i chg <10% of ? v bat >4.2v? charge off yes yes yes yes no no no no r chg set up no no no charging set up? v bat detected? yes v chg led on trickle charge no v chg led off c.v.c c.c.c soft start soft-off t j <120 c ? yes i chg v in_uvlo mp26028 ? 1a linear li-ion battery charger with trickle charge notice: the information in this document is subject to change wi thout notice. users should warra nt and guarantee that third party intellectual property rights are not infringed upon w hen integrating mps products into any application. mps will not assume any legal responsibility for any said applications. mp26028 rev. 1.01 www.monolithicpower.com 11 10/28/2011 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2011 mps. all rights reserved. package information qfn10 (3mm x 3mm) side view top view 1 10 6 5 bottom view 2.90 3.10 1.45 1.75 2.90 3.10 2.25 2.55 0.50 bsc 0.18 0.30 0.80 1.00 0.00 0.05 0.20 ref pin 1 id marking 1.70 0.50 0.25 recommended land pattern 2.90 note: 1) all dimensions are in millimeters. 2) exposed paddle size does not include mold flash. 3) lead coplanarity shall be 0.10 millimeter max. 4) drawing conforms to jedec mo-229, variation veed-5. 5) drawing is not to scale. pin 1 id see detail a 2.50 0.70 pin 1 id option b r0.20 typ. pin 1 id option a r0.20 typ. detail a 0.30 0.50 pin 1 id index area
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