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MP2611 2a, 1-cell li-ion battery switching charger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 1 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. the future of analog ic technology description the MP2611 is a monolithic switching charger with built-in power mosfets for a single-cell li-ion battery pack. it achieves up to a 2a- charge current that can be programmed through an accurate sense resistor over the whole input range. it can operate from separate inputs for usb or ac adapter: for usb input, the input current limit can be programmed to 500ma and 900ma through the usbm pin to cover both usb2.0 and usb3.0 standards. the MP2611 regulates the charge current and battery voltage using two control loops to realize highly accurate constant-current charge and constant-voltage charge. a 100% duty cycle can be achieved when battery voltage is close to the input voltage due to the high-side p-channel mosfet. battery charge temperature and charging status are always monitored for each condition. two status-monitor output pins indicate the battery charging status and input status. the MP2611 also features internal reverse-blocking protection. the MP2611 is available in a 3mm x 4mm qfn14 package. features ? 4.5v-to-6v operating input voltage ? up to 100% duty operation. ? up to 2a programmable charge current ? 0.5% battery voltage accuracy ? separate inputs for usb and ac adapter ? fully-integrated power switches ? programmable input current limit for the usb port ? no external reverse blocking diode required ? charging operation indicators ? programmable safety timer ? thermal shutdown ? cycle-by-cycle over current protection ? battery temperature monitor and protection applications ? smartphones ? portable hand-held solutions ? portable media players all mps parts are lead-free and adhere to the rohs directive. for mps green status, please visit mps website under products, quality assurance page. ?mps? and ?the future of analog ic technology? are registered trademarks of monolithic power systems, inc. typical application c1 rs1 stat1 stat2 ntc tmr batt csp sw MP2611 usbm ac adapter input usb port acin r3 usbin c2 vref33 r1 r2 c3 r ntc agnd l 1-cell battery en off on pgnd c4 c tmr 1 2 3 4 5 6 7 8 9 10 11 12 13 14 r ilim 22uf 22uf 1.5k 1.5k 1uf 0.1uf 22uf 50m 2.2uh
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 2 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. ordering information part number* package top marking MP2611gl qfn14 (3x4mm) 2611 * for tape & reel, add suffix ?z (eg. MP2611gl?z); package reference 14 13 12 11 10 9 8 1 2 3 4 5 6 7 top view exposed pad on backside absolute maxi mum ratings (1) acin ........................................................... 7.5v usbin ......................................................... 7.5v sw ..................................... -0.3v to (v in + 0.3v) csp, batt .......................................-0.3v to 6v all the other pins ..............................-0.3v to 6v continuous power dissipation (t a =25c) (2) ............................................................. 2.6w junction temperature ...............................150c lead temperature ....................................260c storage temperature................. -65c to 150c recommended operating conditions (3) acin ..................................................4.5v to 6v usbin ................................................4.5v to 6v operating junction temp. (t j )..-40c to +125c thermal resistance (4) ja jc qfn14 (3mm x 4mm) ............. 48 ...... 10... 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.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 3 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. electrical characteristics v in (5) = 5v, t a = 25c, unless otherwise noted. parameters symbol condition min typ max units ac input acin operating range v acin 4.5 5 6 v acin under voltage lockout (uvlo) rising threshold v uvlo 3.55 3.75 3.95 v acin under voltage lockout (uvlo) threshold hysteresis 200 mv switching frequency f s 1.5 mhz constant charger current i cc rs1=50m ? 1.8 2 2.2 a high-side pfet on resistance r h_ds(on) 130 m ? low-side nmos on resistance r l_ds(on) 200 m ? high-side pfet peak current limit 3 3.5 a dead time 10 ns en =0v, no load 2.0 ma supply current i in en =4v 20 a usb input usbin operating range v usbin 4.5 5 6 v usbin under voltage lockout (uvlo) rising threshold v uvlo 3.55 3.75 3.95 v usbin under voltage lockout (uvlo) threshold hysteresis 200 mv r ilim =82.5k ? , v usbin = 5v, v batt =4v 450 500 ma usb input current limit i usb_lim r ilim =45.3k ? , v usbin = 5v, v batt =4v 810 900 ma high-side pfet on resistance 110 m ? en =0v, no load 2.0 ma usb supply current en =4v, no load 30 a battery charger terminal battery voltage v batt_full v in =5v 4.179 4.2 4.221 v battery over-voltage threshold v bovp v in =5v 4.26 4.34 4.42 v recharge threshold at v batt v rechg 4.0 v recharge hysteresis 100 mv trickle-charge threshold v tc 3 v trickle-charger hysteresis 300 mv trickle-charge current i tc 10 15 %i cc termination charge current i bf 5 10 15 %i cc maximum current-sense voltage (csp to batt) 100 mv stat1/stat2 open-drain sink current v drain =0.3v 9 ma
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 4 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. electrical characteristics (continued) v in (5) = 5v, t a = 25c, unless otherwise noted. parameters symbol condition min typ max units vin min head-room (reverse blocking) v in -v batt 200 mv csp, batt current i csp ,i batt charging disabled 1 a protection trickle-charge time c tmr =0.1f 30 min total charge time c tmr =0.1f 180 min ntc high temp. rising threshold v th_high r ntc =ncp18xh103,50c 30 32 34 %v ref33 ntc low temp. falling threshold v th_low r ntc =ncp18xh103, 0c 72 74 76 %v ref33 thermal shutdown (6) t shtdwn 150 c en logic en input low voltage 0.8 v en input high voltage 1.2 v en =4v 4 en input current en =0v 0.2 a vref33 output voltage v vref33 3.23 3.3 3.37 v vref33 load regulation ? v vref33 i load =0 to 20ma 0.2 v notes: 5) v in represents v acin or v usbin which depends on the input mode. the following is the same. 6) guaranteed by design..
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 5 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical characteristics v in =5v, c1=c2=22f, c4=22f, c tmr =0.1f, l=1.5h, rs1=50m ? , r ilim =40.2k ? , battery simulator, unless otherwise noted. quiescent current (ma) charge current accuracy vs. temperature ac/usb mode usb current limit accuracy vs. temperature usb mode, i usb_lim =500ma quiescent current vs. temperature v en =0v, ac/usb mode shutdown current vs. temperature v en =4v (disabled), ac/usb mode vref accuracy vs. temperature ac/usb mode batt voltage accuracy vs. temperature ac/usb mode -1.6 -1.4 -1.2 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 -40-25 -10 5 20 35 50 65 80 95110125 -1.0 -0.8 -0.6 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 -40-25 -10 5 20 35 50 65 80 95110 125 -1.50 -1.25 -1.00 -0.75 -0.50 -0.25 0.00 0.25 0.50 0.75 1.00 1.25 1.50 -40-25-10 5 20 35 50 65 80 95110125 -1.20 -1.00 -0.80 -0.60 -0.40 -0.20 0.00 0.20 0.40 0.60 0.80 1.00 1.20 -40-25-10 5 20 35 50 65 80 95110125 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 -40-25-10 5 20 35 50 65 80 95110 125 4 5 6 7 8 9 10 -40-25-10 5 20 35 50 65 80 95110125
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 6 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical performanc e characteristics v in =5v, c1=c2=22f, c4=22f, c tmr =0.1f, l=1.5h, rs1=50m ? , r ilim =40.2k ? , battery simulator, unless otherwise noted. input voltage(v) input voltage(v) battery votlage (v) battery reverse current ac/usb mode, v in =pgnd/float shutdown current v en =4v (disabled), ac/usb mode charge current accuracy vs. v in ac mode usbm input current limit accuracy usb mode charge full voltage accuracy vs. v in ac/usb mode usbm input current limit vs. 1000/r ilim usb mode case temperature vs. battery voltage rs1=50m, ac mode vref33 regulation accuracy rs1=50m, ac mode input voltage (v) i usb_lim set point (ma) usb input current limit (ma) input voltage(v) battery voltage (v) input voltage(v) breakdown voltage ac/usb mode 0 500 1000 1500 2000 2500 3000 3500 4000 0123456789 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 1.5 2 2.5 3 3.5 4 4.5 0 5 10 15 20 25 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5 6 6.5 -0.100 -0.075 -0.050 -0.025 0.000 0.025 0.050 0.075 0.100 4.5 4.9 5.3 5.7 6.1 6.5 -0.30 -0.20 -0.10 0.00 0.10 0.20 0.30 4.5 4.9 5.3 5.7 6.1 6.5 -5 0 5 10 15 20 25 30 0 200 400 600 800 1000 -0.50 -0.45 -0.40 -0.35 -0.30 -0.25 -0.20 -0.15 -0.10 -0.05 0.00 0.05 0.10 0.15 0.20 4.5 5.0 5.5 6.0 6.5 battery float v batt =3.7v 0 100 200 300 400 500 600 700 800 900 1000 0 5 10 15 20 25 0 20 40 60 80 100 3.0 3.2 3.4 3.6 3.8 4.0 4.2
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 7 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical performanc e characteristics (continued) v in =5v, c1=c2=22f, c4=22f, c tmr =0.1f, l=1.5h, rs1=50m ? , r ilim =40.2k ? , battery simulator, unless otherwise noted. frequency (khz) battery voltage (v) frequency (khz) battery voltage(v) charge current (a) battery voltage (v) usb mode charge curve usb mode charge curve frequency vs. battery voltage usb mode ac mode efficiency in tc/cc charge frequency vs. battery voltage ac mode usb mode efficiency ac mode efficiency in cv charge battery voltage(v) battery voltage (v) battery voltage (v) charge current (ma) charge current(a) battery voltage(v) ac mode charge curve charge current (a) 0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.8 2.0 2.2 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 v acin =4.5v v acin =5v 0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 v usbin =5v v usbin =5.5v v usbin =4.5v 0 0.5 1 1.5 2 2.5 3 1.6 1.9 2.2 2.5 2.8 3.1 3.4 3.7 4.0 4.3 i usb_lim =2a i usb_lim =1.5a i usb_lim =1a i usb_lim =0.5a 0 200 400 600 800 1000 1200 1400 1600 1800 1 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 v acin =4.5v v acin =6v v acin =5v 0 200 400 600 800 1000 1200 1400 1600 1800 1 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 v usbin >5v v usbin =4.5v 50 55 60 65 70 75 80 85 90 95 100 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 v acin =6v v acin =4.5v v acin =5v 50 55 60 65 70 75 80 85 90 95 100 400 800 1200 1600 2000 v acin =6v v acin =5v v acin =4.5v 50 55 60 65 70 75 80 85 90 95 100 1.0 1.4 1.8 2.2 2.6 3.0 3.4 3.8 4.2 v usbin =5.5v v usbin =5v v usbin =4.5v stat2 2v/div. stat1 2v/div. v ref33 2v/div. v en 200mv/div. vref startup waveform v batt =3.7v, en on
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 8 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical performanc e characteristics (continued) v in =5v, c1=c2=22f, c4=22f, c tmr =0.1f, l=1.5h, rs1=50m ? , r ilim =40.2k ? , battery simulator, unless otherwise noted. v in 2v/div. v batt 1v/div. v batt 1v/div. v sw 2v/div. v sw 2v/div. i l 500ma/div. i l 1a/div. batt float waveform usb/ac mode v acin 1v/div. v batt 1v/div. v sw 2v/div. i l 1a/div. v acin 1v/div. v batt 1v/div. v sw 2v/div. i l 1a/div. v acin 1v/div. v batt 1v/div. v sw 2v/div. i l 500ma/div. v acin 2v/div. v batt 500mv/div. v sw 2v/div. i l 500ma/div. v in 2v/div. v batt 1v/div. v sw 2v/div. i l 500ma/div. v acin 1v/div. v batt 1v/div. v sw 2v/div. i l 200ma/div. v in 2v/div. v batt 1v/div. v sw 2v/div. i l 1a/div. v acin 1v/div. low input voltage charge state ac mode, v acin =4.5v, v batt =3.8v low input voltage charge state ac mode, v acin =4.5v, v batt =4v low input voltage charge state ac mode, v acin =4.5v, v batt =4.02v low input voltage charge state ac mode, v acin =4.5v, v batt =4.18v tc charge steady state ac/usb mode, v batt =1.5v cc charge steady state ac mode, v acin =5v, v batt =3.8v cc charge steady state usb mode, v usbin =5v, v batt =3.8v cv charge steady state ac / usb mode, v batt =4.2v
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 9 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical performanc e characteristics (continued) v in =5v, c1=c2=22f, c4=22f, c tmr =0.1f, l=1.5h, rs1=50m ? , r ilim =40.2k ? , battery simulator, unless otherwise noted. power on ac mode, v batt =3.8v v tmr 1v/div. stat1 2v/div. i chg 1a/div. stat2 2v/div. v batt 2v/div. v sw 5v/div. i l 1a/div. v in 2v/div. v batt 1v/div. v usbin 1v/div. i chg 1a/div. v acin 1v/div. v batt 1v/div. v sw 5v/div. i chg 1a/div. v acin 2v/div. v batt 2v/div. v sw 2v/div. i chg 1a/div. v acin 2v/div. v batt 1v/div. v usbin 1v/div. i chg 1a/div. v acin 1v/div. v batt 1v/div. v sw 5v/div. i chg 1a/div. v en 2v/div. v batt 1v/div. v sw 5v/div. i chg 1a/div. v en 2v/div. v batt 1v/div. v sw 5v/div. i chg 1a/div. v ntc 2v/div. power off ac mode, v batt =3.8v en on ac mode, v batt= 3.8v en off ac mode, v batt =3.8v ac adapter insertion v acin =6v, v usbin =4.5v, v batt =4.1v ac adapter removal v acin =6v, v usbin =4.5v, v batt =4.1v ntc control v batt =3.7v timer out ctmr=150pf, v batt =3.7v short-circuit protection
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 10 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. pin functions package pin # name description 1 acin ac adapter power input. bypass acin to pgnd with at least a 4.7 f ceramic capacitor when the pin is not applied for powering. 2 pgnd power ground. voltage reference for the regulated output voltage: take extra care with its layout. place this node should be placed out side of the switching diode (sw-pin) to the input ground path to prevent switching current spikes from inducing voltage noise into the part. 3 sw switch output. connect to the switched side of the external inductor. 4 usbin usb power input. bypass usbin to pgnd with at least a 4.7 f ceramic capacitor when the pin is not applied for powering. 5 agnd analog ground. 6 vref33 internal linear regulator referenc e output. powered from acin or usbin. 7 usbm usb input current-limit set. connect a resist or from this pin to agnd to program the usb mode input current limit. 8 batt positive battery terminal. 9 csp battery current sense positive input. connect resistor rs1 between csp and batt to sense the charge current. 10 en on/off control input. 11 stat1 12 stat2 charging status indicator: 1. charging; 2. end of charge; 3. charging suspended; 4. fault; 5. invalid input supply. 13 ntc thermistor input. connect a resistor from th is pin to the vref33 and the thermistor from this pin to agnd. 14 tmr internal safety timer control. connect a c apacitor from this node to agnd to set the timer. and the timer can be disabled by connecting this pin to agnd.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 11 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. block diagram figure 1: functional block diagram
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 12 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. operation the MP2611 is a monolithic switching charger with built-in power mosfets for a single-cell li- ion battery pack. it achieves up to a 2a charge current that can be programmed through an accurate sense resistor over the whole input range. it can operate with separate inputs for usb and ac adapter: for usb mode, the input current limit can be programmed to 500ma and 900ma via the usbm-pin for both usb2.0 and usb3.0. charge cycle (trickle charge ? cc charge ? cv charge) the MP2611 regulates the charge current (i chg ) and battery voltage (v batt ) using two control loops to realize highly-accurate constant current (cc) charge and constant voltage (cv) charge. the device uses the resistor rs1 to sense the battery charge current and amplifies the signal using the internal amplifier a3 (figure 1). the charge starts in trickle-charge mode (tc, 10% of the constant current i cc ) until the battery voltage reaches 3v. if the charger stays in the trickle- charge mode until it triggers a time-out condition, the charging terminates. otherwise, the charger operates in constant-current charging mode. the compi voltage, regulated by the amplifier gmi, determines the duty cycle. when the battery voltage rises to the constant- voltage mode threshold, the amplifier gmv regulates the comp-pin and the duty cycle. consequently, the charger operates in constant- voltage mode. figure 2: li-ion battery charge profile acin and usbin detection there are two separate battery charger inputs; acin for the ac adapter, and usbin for the usb port. acin is used as the battery-charger primary power supply. as soon as the acin voltage exceeds acin uvlo (3.75v), q1 turns on and q2 turns off. the adapter charges the battery with up to 2a constant charge current through the step-down dc/dc converter implemented by q1 and q3. the charge current can be set by rs1. if the acin input is absent or less than 3.75v, the usbin can act as the power supply for the battery charger: q1 turns off and q2 turns on. usb supply mode uses the input current limit loop so that the threshold can be programmed by connecting a resistor r ilim from the usbm-pin to agnd. when acin and usbin are both absent, q1 and q2 are completely off and the reverse blocking function blocks the battery reverse-leakage current to the input port. note that if acin and usbin are both present, the device selects the ac adapter as the power supply of the charger. however, avoid this practice. dc/dc converter the MP2611 integrates both the high-side switch and the synchronous low-side switch, which provides high efficiency and eliminates the external schottky diode. during normal operation, the high-side switch turns on for a period of time to ramp-up the inductor current at each rising edge of the internal oscillator, and switches off when the peak inductor current rises above the comp voltage. once the high-side switch turns off, the synchronous switch turns on immediately and stays on until the next cycle starts (see figure 1). the device allows the high-side switch to remain on for more than one switching cycle and increases the duty cycle while the input voltage drops close to the output voltage. when the duty cycle reaches 100%, the high-side switch is held on continuously to deliver current to the output.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 13 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. charge-full termination and auto-recharge when the charge current drops below the termination threshold (i bf ) during the cv charge phase, the charger ceases charging and the stat1 -pin becomes an open drain. the timer will also be reset and turned off. if the battery voltage falls below 4.0v, auto-recharge begins and the timer restarts a new charge cycle . charger status indication stat1 and stat2 are two open-drain nmos outputs that must connect to the vref33 output or some other bias power supply through pull-up resistors. their output logic level combinations indicate three status of the charger: table 1: charging status indicator stat2 stat1 charger status low low charging low high end of charge; faults (thermal shutdown; time-out; ntc fault) high high input power absent; v in -v batt <0.2v; en disabled safety timer operation the MP2611 adopts an internal timer to terminate charging if the timer times out. an external capacitor on the tmr-pin programs the timer duration. the trickle mode charge time is: tmr trickle_tmr c t30(minutes) 0.1 f = the total charge time is: tmr total_tmr c t =3 (hours) 0.1 f where c tmr is the capacitor connected from tmr-pin to gnd. the timer can be disabled by pulling tmr to gnd. if a timer-out event occurs, the charging will be terminated and the stat1 will become an open drain to indicate the fault. the charger can exit the timer-out fault state and initiates a new charge cycle when one of the following conditions occurs: (a) the battery voltage falls below the auto- recharge threshold v rechg ; (b) a power-on-reset (por) event occurs; (c) en is toggled. negative thermal coefficient (ntc) thermistor the MP2611 has a built-in ntc window comparator that allows it to sense the battery temperature via the thermistor packed internally in the battery. it ensures a safe battery operating environment. connect an appropriately-valued resistor from vref33 to the ntc-pin and connect the thermistor from the ntc-pin to agnd. the resistor divider with a dividing ratio depends on the battery temperature determins the voltage on the ntc-pin. once the voltage at the ntc-pin is out of the ntc window, the MP2611 stops charging. the charger restarts if the voltage re-enters the ntc window range. short circuit protection the MP2611 has an internal comparator to check for battery short circuit. once v batt falls below 2v, the device detects a battery-short status and the cycle-by-cycle peak current limit falls to about 2a to limit the current spike during the battery-short transition. furthermore, the switching frequency also folds back to minimize the power loss. thermal shutdown protection to prevent the chip from overheating during charging, the MP2611 monitors the junction temperature, t j , of the die. once t j reaches the thermal shutdown threshold (t shtdwn ) of 150c, the charger converter turns off. charging restarts when t j falls below 130c.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 14 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. battery charge timing diagram figure 3: battery charge timing diagram note: 7) the stat1 and stat2 are pulled up to vref33 with an 1k ? resistor respectively.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 15 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. operation flow chart figure 4: normal charging operation and fault protection flow chart
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 16 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. application information setting the charge current in ac mode in ac mode, rs1 sets the charge current (i chg ) of the MP2611 (see typical application). the equation to determine the programmable cc- charge is as follows: (a) ) rs1(m 100mv i cc = (1) assume i cc =2a, thus: rs1=50m ? . for either ac mode or usb mode, the trickle charge current is given by the following equation: (a) ) rs1(m 10mv 10%i i cc tc = = (2) setting the usb input current limit in usb supply mode, connect a resistor from the usbm pin to agnd to program the input current limit for different usb ports. the relationship between the input current limit and setting resistor is as following: (ma) ) (k r 37000 i ilim usb_lim = (3) where r ilim is greater than 18.5k ? so that i usb_lim is in the range of 0a to 2a. if using a resistor smaller than 18.5k ? , the MP2611 suppresses i usb_lim to a value less than 2a. for most applications, use a 45.3k ? r ilim (i usb_lim =900ma) for usb3.0 mode, and use a 82.5k ? r ilim (i usb_lim =500ma) for usb2.0 mode. note that in usb mode, the MP2611 doesn?t monitor the charge current through rs1 during cc charge phase, but regulates the input current constant at the limitation value i usb_lim . thus the cc charge current varies with different input and battery voltages. figure 5 shows the charge current vs. battery voltage curve when v usbin =5.5v. the maximum cc charge value can be calculated as: (a) v i v i tc usb_lim usbin cc_max ? ? = (4) where v tc is trickle charge threshold (3v) and =83%, thus i cc_max = 2.28a. figure 5: i chg variation with v usbin =5.5v for certain battery packs, the cc charge current should never go too high so set the i usb_lim based on the i cc_max . selecting the inductor inductor selection trades off between cost, size, and efficiency. a lower inductance value corresponds with smaller size, but results in higher ripple currents, higher magnetic hysteretic losses, and higher output capacitances. however, a higher inductance value benefits from lower ripple current and smaller output filter capacitors, but results in higher inductor dc resistance (dcr) loss. from a practical standpoint, the inductor ripple current does not exceed 15% of the maximum charge current under worst cases. for a MP2611 with a typical 5v input voltage, the maximum inductor current ripple occurs at the corner point between trickle charge and cc charge (v batt =3v). estimate the required inductance as: s in batt l_max batt in f v v i v - v l ? = (5) where v in , v batt , and f s are the typical input voltage, the cc charge threshold, and the switching frequency, respectively. l_max i is the maximum inductor ripple current ,which is usually 15% of the cc charge current.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 17 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. cc l_max 15%i = i (6) for i cc =2a, v in =5v, v batt =3v and f s =1.5mhz, the calculated inductance is 2.66h. the maximum inductor peak current must exceed 2.3a. to optimize efficiency, chose an inductor with a dc resistance less than 50m ? . choose the inductor 7447745022 from wurth corporation with ratings at l=2.2h/3.5a /36m ? . ntc function figure 6 shows that an internal resistor divider sets the low temperature threshold and high temperature threshold at 74%vref33 and 32%vref33, respectively. for a given ntc thermistor, select appropriate r t1 and r t2 to set the ntc window. the thermistor (ncp18xh103) noted above has the following electrical characteristic: at 0c, r ntc_cold = 27.445k ? ; at 50c, r ntc_hot = 4.1601k ? . the following equations are derived assuming that the ntc window is between 0c and 50c: 74% vref33 v //r r r //r r th_low ntc_cold t2 t1 ntc_cold t2 = = + (7) 32% vref33 v //r r r //r r th_high ntc_hot t2 t1 ntc_hot t2 = = + (8) according to equation (7) and equation (8), \r t1 = 8.7k ? and r t2 = 252.3k ? . simplified for applications, r t1 =8.7k ? and r t2 = no connect approximates the values. figure 6: ntc function block selecting the input capacitor the input capacitors c1/c2 from the typical application circuit absorbs the maximum ripple current from the buck converter, which is given by: in_max tc in_max tc cc_max rms_max v ) v (v v i i ? = (9) for i cc_max =2a, v tc =3v, v in_max =6v, the maximum ripple current is 1a. select the input capacitors so that the temperature rise due to the ripple current does not exceed 10c. use ceramic capacitors with x5r or x7r dielectrics because of their low esr and small temperature coefficients. for most applications, use a 22f capacitor. selecting the output capacitor the output capacitor?c4 from the typical application circuit?is in parallel with the battery. c4 absorbs the high-frequency switching ripple current and smoothes the output voltage. its impedance must be much less than that of the battery to ensure it absorbs the ripple current. use a ceramic capacitor because it has lower esr and smaller size that allows us to ignore the esr of the output capacitor. thus, the output voltage ripple is given by: l f 8c v v 1- v v r 2 s o in o o o o = = (10) in order to guarantee the 0.5% battery voltage accuracy, the maximum output voltage ripple must not exceed 0.5% (e.g. 0.1%). the maximum output voltage ripple occurs at the minimum battery voltage of the cc charge and the maximum input voltage. for v in_max =6v, v cc_min =v tc =3v, l=1.5h, f s =1.5mhz, % 1 . 0 = o_max r , the output capacitor can be calculated as: tc in_max o 2 so_max v 1- v c= =18.5 f 8f l r (11) we can then choose a 22f ceramic capacitor.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 18 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. pcb layout guide pcb layout is important to meet specified noise, efficiency and stability requirements. the following design considerations can improve circuit performance: 1) route the power stage adjacent to their grounds. aim to minimize the high-side switching node (sw, inductor), trace lengths in the high-current paths and the current- sense resistor trace. keep the switching node short and away from the feedback network. 2) the exposed thermal pad on the backside of the MP2611 package must be soldered to the pgnd plane. there must be sufficient thermal vias underneath the ic connected to the ground plane on the other layers. 3) connect the charge current sense resistor to csp (pin 9), batt (pin 8) with a kelvin contact. minimize the length and area of this circuit loop. 4) place the input capacitor as close as possible to the acin/usbin and pgnd pins. place the output inductor close to the ic as and connect the output capacitor between the inductor and pgnd of the ic. this minimizes the current path loop area from the sw pin through the lc filter and back to the pgnd pin. 5) connect agnd and pgnd at a single point.
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 19 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. typical application circuits power-path management power-path applications require powering the system while simultaneously charging the battery. traditional designs adopt the simplest battery-fed topology that connects the system to the battery directly. an obvious drawback is that it cannot operate the system with a drained battery. figure 7 shows an improved battery-fed topology. the additional circuit between the current sense resistor and the battery works like a variable resistor. while the battery voltage is less than the preset threshold (less than v tc of 3v), the mosfet q1 turns off. the 5 ? resistor, r p , is then in series with the battery to raise the system voltage to 1v (i tc =0.2a assumed). as a result, the system can also operate at low battery voltage. while the battery voltage is high enough, q1 turns on to short though the r p resistor to reduce power loss. figure 7: improved battery-fed power-path management structure the power-path auto-selection topology shown in figure 8 adopts external switches to decouple the system supply and battery charging process. thus the adapter directly powers the system independent of the battery?s state as long as the adapter is plugged in. if the adapter is absent, the battery supplements the system. replace m1 and m2 with a power diode each, to reduce the costs. however, the efficiency may decline due to the forward voltage drop of the diode. even usbin is not used, a least 4.7 f capacitor is necessary connecting the pin to gnd. figure 8: power-path auto-selection structure
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 20 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. single input port application for some portable devices, only one input port that covers both ac adapter and usb port is adopted. the charger is then required to identify the input source (ac adapter or usb port) via an external logic signal from mode-pin. mode-pin pulled high indicates an ac adapter is connected, low indicates an usb port source. figure 9 shows a single input port application circuit. the mosfet m1 is used to alter the input source. high-level voltage at mode-pin turns on the m1 and the charger is then switched from usb input mode to ac input mode. the capacitor c5 and r5 are necessary to realize the soft-start of voltage at acin, increase the value if the recommended value in figure 9 does not work. figure 9: single input port application circuit ?1 figure 10 shows another single input port application circuit. for the ac adapter input, the high-level signal at mode-pin turns on the m1 to connect the parallel resistor r4 at usbm-pin. due to the increased input current limitation, charge current is enlarged. please refer to the usb input current setting and choose the appropriate resistor based on the actual battery specification. r8 and c5 are necessary for soft tuning on and off of m1 to avoid unexpected usbm reference caused by noise. in addition, a least 4.7 f ceramic capacitor connected between acin-pin to pgnd is necessary to avoid noise interference. c2 rs1 stat1 stat2 ntc tmr batt csp sw MP2611 usbm input port acin r3 usbin vref33 r1 r2 c3 r ntc agnd l 1-cell battery en off on pgnd c4 c tmr 1 2 3 4 5 6 7 8 9 10 11 12 13 14 r ilim r7 m1 mode ac usb 200k 2n7002 22uf 1.5k 1.5k 1uf 0.1uf 22uf 50m 2.2uh r4 c1 4.7uf r8 c5 20 1uf figure 10: single input port application circuit ?2
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power MP2611 rev. 1.12 www.monolithicpower.com 21 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. input ovp application for MP2611, the maximum rating of input voltage is only 7.5v. in order to prevent an unmatched adapter from being connected to damage this part, the input over-voltage protection (ovp) is required. figure 11 shows the application circuit for the input ovp, where the ovp threshold can be programmed via the resistor divider consist of r4 and r5. for the given parameters below, the ovp threshold is 6.2v and maximum input rating is extended to 18v (limited by the tlvh431). figure 11: ac input mode with input ovp
MP2611 ? 2a, 1-cell switching char ger for usb and adapter power notice: the information in this document is subject to change wi thout notice. please contact m ps for current specifications. users should warrant and guarantee that third party intellectual property rights ar e not infringed upon when integrating mps products into any application. mps will not assume any legal responsibility for any said applications. MP2611 rev. 1.12 www.monolithicpower.com 22 12/7/2012 mps proprietary information. patent protec ted. unauthorized photocopy and duplication prohibited. ? 2012 mps. all rights reserved. package information qfn 14 (3mm x 4mm) side view top view 1 14 8 7 bottom view 2.90 3.10 1.60 1.80 3.90 4.10 3.20 3.40 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 3.30 0.70 pin 1 id option b r0.20 typ. pin 1 id option a 0.30x45 o typ. detail a 0.30 0.50 pin 1 id index area

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