general description the MAX4880 is an overvoltage-protection controller with an internal current-limited switch that can be con- figured as a low-cost battery charger. when the input voltage exceeds the overvoltage trip level (5.7v), or drops below the undervoltage-lockout level (4.2v), the MAX4880 turns off the external n-channel mosfet and asserts an undervoltage/overvoltage flag indicator ( flagv ) low to notify the processor. the MAX4880 internal current-limited switch limits the charge current flowing to the battery to 525ma. the switch opens when the battery voltage reaches its full- charged state (4.2v), and a flag ( bat_ok ) asserts to notify the processor. the MAX4880 includes a switch- control input (cb) to turn off the internal current-limited switch, regardless of the battery voltage. the MAX4880 also features a built-in startup delay that allows the adapter voltage to settle down before turning on the mosfet. other features include 15kv esd pro- tection for the input and a shutdown function ( en ) to turn off the external n-channel mosfet. the MAX4880 is available in a space-saving 10-pin tdfn package and is specified for operation over the extended -40? to +85? temperature range. applications cell phones digital still cameras pdas and palmtop devices mp3 players features ? overvoltage protection up to 28v ? preset 5.6v overvoltage trip level ? internal 525ma current-limited switch ? 1.2% accurate battery disconnect (4.2v) ? drives low-cost n-channel mosfet ? internal 50ms startup delay ? overvoltage/undervoltage-fault flagv indicator ? battery-voltage-trip bat_ok indicator ? undervoltage lockout ? thermal shutdown protection ? tiny 10-pin tdfn package MAX4880 overvoltage-protection controller with internal disconnect switch ________________________________________________________________ maxim integrated products 1 flagv gnd btb btb_sns MAX4880 bat_ok in gate bta en 3mm x 3mm tdfn top view cb 134 10 8 7 2 9 5 6 pin configuration ordering information ac-dc adapter 5.25v gate in flagv bat_ok btb_sns li+ btb bta cb en gnd dc-dc converter v io MAX4880 typical operating circuit 19-3776; rev 0; 7/05 for pricing, delivery, and ordering information, please contact maxim/dallas direct! at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part temp range pin- package top mark MAX4880etb -40? to +85? 10 tdfn-ep* apj * ep = exposed pad
MAX4880 overvoltage-protection controller with internal disconnect switch 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v in = 5v, t a = -40 c to +85 c, unless otherwise noted. typical values are at t a = +25 c.) (note 1) stresses beyond those listed under ?bsolute maximum ratings?may cause permanent damage to the device. these are stress rating s only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specificatio ns is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. (all voltages referenced to gnd.) in ............................................................................-0.3v to +30v gate ......................................................................-0.3v to +12v en , cb, flagv , bat_ok , bta, btb, btb_sns .....-0.3v to +6v continuous power dissipation (t a = +70?) 10-pin tdfn (derate 18.5mw/? above +70?) ...1481.5mw operating temperature range ...........................-40? to +85? junction temperature .................................................... +150? storage temperature range ............................-65? to +150? lead temperature (soldering, 10s) ................................+300? parameter symbol conditions min typ max units input voltage (in) input voltage range v in 1.2 28.0 v overvoltage trip level ovlo v in rising 5.5 5.6 5.7 v o ver vol tag e- tr i p - level h yster esi s 50 mv undervoltage-lockout threshold uvlo v in falling 4.2 4.35 4.5 v undervoltage-lockout hysteresis 50 mv supply current i in + i bta no load, v in = 5.4v, v en = 0 or 5.5v, v cb = 0 or v in 240 380 ? internal switch bta input range v bta 2.8 5.7 v bta undervoltage lockout bta uvlo falling edge 2.4 2.7 v bta-undervoltage-lockout hysteresis 50 mv btb-switch-disconnect trip level btb trip 4.10 4.20 v btb-switch-disconnect hysteresis 200 mv switch-forward current limit i fwd 450 525 600 ma t a = +25 c 600 switch-reverse current limit i rev 650 ma voltage drop (v bta ?v btb )i l = 400ma 110 mv btb off current i btb-off v en = 0 ( v c b = 0, or v in < v u v l o and v bta = 0) 1 a gate gate voltage v gate i gate sourcing 1? , v in = 5v 9 10 v gate pulldown current i pd v in > v ovlo , v gate = 5v 60 ma timing gate startup delay t start v in > v uvlo , v gate > 0.3v (figure 1) 20 50 80 ms flagv delay time t delay v gate = 0.3v,v flagv = 2.4v (figure 1) 20 50 80 ms gate turn-on time t gon v gat e = 0.3v to 8v , c gat e = 1500p f ( fi g ur e 1) 7ms gate turn-off time t goff v in increasing from 5v to 8v at 3v/?, v gate = 0.3v, c gate = 1500pf (figure 2) 620 s
MAX4880 overvoltage-protection controller with internal disconnect switch _______________________________________________________________________________________ 3 note 1: all devices are 100% tested at t a = +25 c. electrical limits over the full temperature range are guaranteed by design. electrical characteristics (continued) (v in = 5v, t a = -40 c to +85 c, unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter symbol conditions min typ max units flagv assertion delay t flagv v in increasing from 5v to 8v at 3v/?, v flagv = 0.4v (figure 2) 5.8 ? initial overvoltage fault delay t ovp v in increasing from 0 to 8v, i gate = 80% of i pd (figure 3) 100 ns disable time t dis v en = 2.4v, v gate = 0.3v (figure 4) 580 ns en , cb inputs input-high voltage v ih 1.4 v input-low voltage v il 0.5 v input leakage 1 a flagv , bat_ok outputs output voltage low v ol i sink = 1ma, flagv , bat_ok assert 0.4 v leakage current v bat_ok = v flagv = 5.5v 1 a thermal protection thermal shutdown +150 c thermal hysteresis 40 c typical operating characteristics (v in = 5v, t a = +25 c, otherwise noted.) i in + i bta current vs. input voltage input voltage (v) i in + i bta current ( a) MAX4880 toc01 0 5 10 15 20 25 30 0 50 100 150 200 250 300 350 400 v en = 0 v cb = 5v ovlo trip point uvlo trip point i in + i bta current vs. temperature temperature ( c) i in + i bta current ( a) MAX4880 toc02 -40 -15 10 35 60 85 0 50 100 150 200 250 300 350 400 gate voltage vs. input voltage input voltage (v) gate voltage (v) MAX4880 toc03 012345678 0 3 6 9 12 uvlo trip point ovlo trip point
MAX4880 overvoltage-protection controller with internal disconnect switch 4 _______________________________________________________________________________________ typical operating characteristics (continued) (v in = 5v, t a = +25 c, otherwise noted.) btb trip level vs. input voltage input voltage (v) btb trip level (v) MAX4880 toc04 5.0 5.1 5.2 5.3 5.4 5.5 5.6 5.7 4.00 4.04 4.08 4.12 4.16 4.20 btb trip level vs. temperature temperature ( c) btb trip level (v) MAX4880 toc05 -40 -15 10 35 60 85 4.00 4.04 4.08 4.12 4.16 4.20 btb off current vs. temperature temperature ( c) btb off current (na) MAX4880 toc06 -40 -15 10 35 60 85 0.1 1 10 100 1000 v en = 0v v cb = 0v v btb = 5.5v power-up response MAX4880 toc07 20ms/div 5v 0 10v 0 5v 0 5v 0 in gate bta flagv power-down response MAX4880 toc08 20ms/div 5v 0 10v 0 5v 0 5v 0 in gate bta flagv en vs. gate MAX4880 toc09 100 s/div 5v 0 10v 0 en gate overvoltage response MAX4880 toc10 400ns/div 8v 5v 10v 0 50ma 0 5v 0 in gate i gate flagv
MAX4880 overvoltage-protection controller with internal disconnect switch _______________________________________________________________________________________ 5 current limit vs. temperature temperature ( c) current limit (ma) MAX4880 toc11 -40 -15 10 35 60 85 0 100 200 300 400 500 600 700 800 v cb = 5v v bta = 5v v btb = 3.6v current limit vs. v btb v btb (v) current limit (ma) MAX4880 toc12 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0 100 200 300 400 500 600 700 800 v cb = 5v v bta = 5v pin description typical operating characteristics (continued) (v in = 5v, ta = +25 c, otherwise noted.) pin name function 1in input. in is the power input for the overvoltage (ovp) charge pump. bypass in to gnd with a 1? or larger capacitor to achieve 15kv esd protection. 2 en active-low enable input. driving en high turns off the external mosfet. pulling en low activates the overvoltage-protection circuitry and turns on the external mosfet. 3 gate gate-drive output. gate is the output of an on-chip ovp charge pump. when v uvlo < v in < v ovlo , gate is driven high to turn on the external n-channel mosfet. when v in (min) < v in < v uvlo or v in > v ovlo , gate is driven low to turn off the external n-channel mosfet. 4 bta input terminal for the internal-current-limited switch. connect bta to the source of the external n- channel mosfet. bta is the power input for the entire device (except the ovp charge pump). bypass bta to gnd with a 0.1? capacitor as close to the device as possible. 5cb control input for the internal-current-limited switch. drive cb high to leave the internal switch control for the internal logic. the internal switch turns on and off depending on the battery voltage level. the internal switch turns off when the battery voltage reaches the btb trip level (4.2v), and turns back on when the battery falls by 200mv. driving cb low turns off the internal switch regardless of the battery voltage. 6 gnd ground 7 btb output terminal for the internal-current-limited switch. when the btb voltage exceeds the trip level (4.2v), the internal switch opens. the switch closes only when the btb voltage drops 200mv below the trip level. 8 btb_sns battery-voltage-sensing input. btb_sns must be connected to btb for proper operation. bypass btb_sns to gnd with a 0.1? capacitor as close to the device as possible. 9 bat_ok active-low, open-drain, battery-voltage-limit flag output. bat_ok asserts low when the voltage on btb exceeds the btb trip level (4.2v). bat_ok is disabled when en goes high.
MAX4880 overvoltage-protection controller with internal disconnect switch 6 _______________________________________________________________________________________ pin description (continued) pin name function 10 flagv active-low, open-drain-fault flag output. flagv goes low when either an overvoltage or undervoltage fault occurs at in. flagv is disabled when en goes high. during startup, flagv has a delay of 50ms after v gate > 0.3v, before being initially driven high. ?p exposed pad. ep is internally connected to gnd. do not use ep as the only electrical ground connection. v in v gate 1.2v v uvlo 0.3v t start 2.4v t delay 8v t gon 5v v flagv figure 1. startup timing diagram v in v gate v ovlo 0.3v t goff 0.4v t flag 5v 8v v flagv figure 2. overvoltage fault timing diagram v in i gate v ovlo 80% t ovp 0v figure 3. power-up overvoltage timing diagram v gate 0.3v t dis 2.4v v en figure 4. disable timing diagram
detailed description the MAX4880 provides up to 28v overvoltage protection for low-voltage systems. when the input voltage at in exceeds the overvoltage trip level (ovlo), the MAX4880 turns off a low-cost, external n-channel mosfet to pre- vent damage to the protected components and issues an overvoltage fault flag. when the correct adapter is plugged in, the n-channel mosfet is turned on. the output of the mosfet is then connected to the internal current-limit switch that provides the charge-current path to the battery. when the battery reaches the trip voltage (4.2v), the internal switch turns off and bat_ok asserts low, indicating that the battery has reached its full charged state. the internal switch turns back on only when the battery volt- age drops by more than 200mv. in overvoltage lockout (ovlo) the MAX4880 has a 5.6v typical overvoltage threshold (ovlo). when v in is higher than v ovlo , gate goes low to turn off the external n-channel mosfet. an over- voltage flagv is asserted low to notify the processor of the fault condition. in undervoltage lockout (uvlo) the MAX4880 includes a fixed 4.35v typical undervolt- age-lockout level (uvlo). when v in is below the v uvlo (1.2v v in 4.35v), gate goes low to turn off the external n-channel mosfet. in addition, the driver for the internal switch (bta-btb) is also turned off; there- fore, this switch is open. this ensures the reverse cur- rent, drained from the battery, is less than 1 a when the adapter is not present. fault flag output ( flagv ) the flagv output signals the host system that there is a fault with the input voltage. flagv asserts low in response to either an overvoltage or an undervoltage fault. flagv stays low for 50ms after gate turns on, before deasserting high. flagv is an open-drain, active-low output. connect a pullup resistor from flagv to the logic i/o voltage of the host system or to any voltage source up to 6v. flagv is invalid when driving en high. battery-voltage-limit flag output ( bat_ok ) the MAX4880 includes a battery-voltage-limit flag out- put ( bat_ok ). bat_ok asserts low to indicate the volt- age on btb exceeds the btb trip level of 4.2v. bat_ok deasserts high when the voltage on btb falls by the btb hysteresis voltage of more than 200mv. bat_ok is an open-drain, active-low output. connect a pullup resistor from bat_ok to the logic i/o voltage of the host system, or to any voltage source up to 6v. bat_ok is invalid when driving en high. en input the MAX4880 features an active-low enable input ( en ). drive en low or connect to ground for normal opera- tion. drive en high to force the external n-channel mosfet off, disabling flagv and bat_ok . internal current limit (bta to btb) the internal switch from bta to btb has a preset cur- rent-limit of 525ma (typ). if the load current from bta to btb reaches this current limit, the switch operates in the continuous mode, limiting the load current to the preset value. the switch remains in the current-limit condition until the battery voltage on btb exceeds 4.2v, or until the control bit cb is driven low to open the switch. internal switch control input (cb) the cb input controls the internal switch. when cb is high, the on/off state of the internal switch depends on the battery voltage level. the internal switch turns off when the battery voltage reaches the btb trip level, MAX4880 overvoltage-protection controller with internal disconnect switch _______________________________________________________________________________________ 7 in ovlo uvlo 10v charge pump gate in bat_ok flagv en charge pump gnd 525ma limit i ref v ref bta uvlo bta btb btb_sns cb MAX4880 figure 5. functional diagram
MAX4880 and turns back on when the battery falls below the btb trip level minus btb hysteresis. drive cb low to turn off the internal switch, regardless of the battery voltage. this control bit can be used to provide additional top- off charge for the battery. when the cb pin is cycled, the internal battery switch is turned on and off. this effectively provides an average current that is lower than the full-charge current. gate driver an on-chip charge pump drives the gate voltage to approximately twice v in , allowing the use of a low-cost, n-channel mosfet ( figure 5). the actual gate output voltage tracks approximately 2 x v in, until v in exceeds the ovlo trip level, 5.6v (typ). the gate output volt- age, as a function of input voltage, is shown in the typical operating characteristics . applications information mosfet selection the MAX4880 is designed for use with an n-channel mosfet. mosfets with r ds(on) specified for a v gs of 4.5v are ideal. if the input supply is near the uvlo min- imum of 4.2v, consider using a mosfet specified for a lower v gs voltage. also, the v ds should be 30v for the mosfet to withstand the full 28v in range of the MAX4880. table 1 shows a selection of mosfets appropriate for use with the MAX4880. in bypass considerations bypass in to gnd with a 1? ceramic capacitor to achieve 15kv esd-protected input. when the power source has significant inductance due to long lead length, take care to prevent overshoots due to the lc overvoltage-protection controller with internal disconnect switch 8 _______________________________________________________________________________________ charge-current- limit resistor discharge resistance storage capacitor c s 150pf r c 50 to 100 r d 330 high- voltage dc source device under test figure 8. iec 61000-4-2 esd test model charge-current- limit resistor discharge resistance storage capacitor c s 100pf r c 1m r d 1.5k high- voltage dc source device under test figure 6. human-body esd test model i p 100% 90% 36.8% t rl time t dl current waveform peak-to-peak ringing (not drawn to scale) i r 10% 0 0 amperes figure 7. human-body-model current waveform t r = 0.7ns to 1ns 30ns 60ns t 100% 90% 10% i peak i figure 9. iec 61000-4-2 esd generator current
tank circuit and provide protection if necessary to pre- vent exceeding the 30v absolute maximum rating on in. the MAX4880 provides protection against voltage faults up to 28v, but this does not include negative volt- ages. if negative voltages are a concern, connect a schottky diode from in to gnd to clamp negative input voltages. exposed pad the MAX4880 provides an exposed pad on the bottom of the package. this pad is internally connected to gnd. for the best thermal conductivity and higher power dissipation, solder the exposed pad to the ground plane. do not use the ground-connected pad as the only electrical ground connection or ground return. use gnd (pin 6) as the primary electrical ground connection. esd test conditions esd performance depends on a number of conditions. the MAX4880 is specified for 15kv typical esd resis- tance on in when in is bypassed to ground with a 1? low-esr ceramic capacitor. contact maxim for a relia- bility report that documents test setup, methodology, and results. human body model figure 6 shows the human body model, and figure 7 shows the current waveform it generates when dis- charged into a low impedance. this model consists of a 100pf capacitor charged to the esd voltage of inter- est, which is then discharged into the device through a 1.5k resistor. iec 61000-4-2 since january 1996, all equipment manufactured and/or sold in the european community has been required to meet the stringent iec 61000-4-2 specification. the iec 61000-4-2 standard covers esd testing and perfor- mance of finished equipment; it does not specifically refer to integrated circuits. the MAX4880 helps users design equipment that meets level 3 of iec 61000-4-2, without additional esd-protection components. the main difference between tests done using the human body model and iec 61000-4-2 is higher peak current in iec 61000-4-2. because series resistance is lower in the iec 61000-4-2 esd test model ( figure 8), the esd-withstand voltage measured to this standard is generally lower than that measured using the human body model. figure 9 shows the current waveform for the ?kv iec 61000-4-2 level 4 esd contact- discharge test. the air-gap test involves approaching the device with a charger probe. the contact- discharge method connects the probe to the device before the probe is energized. chip information transistor count: 2391 process: bicmos MAX4880 overvoltage-protection controller with internal disconnect switch _______________________________________________________________________________________ 9 part configuration/ package v ds max (v) r on at 4.5v (m ) manufacturer si1426dh single/sc70-6 30 115 vishay siliconix www.vishay.com 402-563-6866 fdg315n single/sc70-6 30 160 fairchild semiconductor www.fairchildsemi.com 207-775-8100 table 1. mosfet suggestions
MAX4880 overvoltage-protection controller with internal disconnect switch maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. jackson package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. 10 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products. inc. 6, 8, &10l, dfn thin.eps l c l c pin 1 index area d e l e l a e e2 n g 1 2 21-0137 package outline, 6,8,10 & 14l, tdfn, exposed pad, 3x3x0.80 mm -drawing not to scale- k e [(n/2)-1] x e ref. pin 1 id 0.35x0.35 detail a b d2 a2 a1 common dimensions symbol min. max. a 0.70 0.80 d 2.90 3.10 e 2.90 3.10 a1 0.00 0.05 l 0.20 0.40 pkg. code n d2 e2 e jedec spec b [(n/2)-1] x e package variations 0.25 min. k a2 0.20 ref. 2.300.10 1.500.10 6 t633-1 0.95 bsc mo229 / weea 1.90 ref 0.400.05 1.95 ref 0.300.05 0.65 bsc 2.300.10 8 t833-1 2.00 ref 0.250.05 0.50 bsc 2.300.10 10 t1033-1 2.40 ref 0.200.05 - - - - 0.40 bsc 1.700.10 2.300.10 14 t1433-1 1.500.10 1.500.10 mo229 / weec mo229 / weed-3 0.40 bsc - - - - 0.200.05 2.40 ref t1433-2 14 2.300.10 1.700.10 t633-2 6 1.500.10 2.300.10 0.95 bsc mo229 / weea 0.400.05 1.90 ref t833-2 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref t833-3 8 1.500.10 2.300.10 0.65 bsc mo229 / weec 0.300.05 1.95 ref -drawing not to scale- g 2 2 21-0137 package outline, 6,8,10 & 14l, tdfn, exposed pad, 3x3x0.80 mm downbonds allowed no no no no yes no yes no
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