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general description the max1666 provides complete protection against over- voltage, undervoltage, overcharge current, overdischarge current, and cell mismatch for 2-cell to 4-cell lithium-ion (li+) battery packs. the voltage of each cell in the battery pack is checked and compared to the programmable threshold and to the other cells in the pack. the max1666 protects the battery pack in an overcurrent condition by disconnecting the pack from the load at a pro- grammable limit. on-chip power mosfet drivers control external p-channel mosfets to disconnect the cells from external terminals when faults occur. the max1666 employs a unique timing scheme that allows three modes of operation for optimal performance and battery power conservation. the max1666 can oper- ate in a stand-alone configuration or in conjunction with a microcontroller. it is available in four versions: the s ver- sion monitors two li+ cells, the a and v versions monitor three cells, and the x version monitors four cells. when the charge path is disabled by the charge control pin, the MAX1666A reduces current consumption compared to the max1666s/v/x. applications 2/3/4-cell lithium-ion battery pack features ? overvoltage protection programmable limits from +4.0v to +4.4v accurate to ?.5% ? undervoltage protection programmable limits from +2.0v to +3.0v accurate to ?.5% ? cell mismatch protection programmable limits from 0 to 500mv accurate to ?0% ? overcharge current protection ? overdischarge current protection ? low 30? (typ) operating supply current ? low 1? (max) standby current ? +28v (max) input voltage ? available in small 16-pin qsop (max1666s) and 20-pin qsop (MAX1666A/v/x) packages MAX1666A/s/v/x advanced lithium-ion battery-pack protector ________________________________________________________________ maxim integrated products 1 top view 20 19 18 17 16 15 14 13 1 2 3 4 5 6 7 8 uvo v cc ref ova cgo tko dso src uva mma wrn pkf b1p b2p b3p b3p 12 11 9 10 cgi dsi pkn gnd MAX1666A/v 20 19 18 17 16 15 14 13 1 2 3 4 5 6 7 8 uvo v cc ref ova cgo tko dso src uva mma wrn pkf b1p b2p b3p b4p 12 11 9 10 cgi dsi pkn gnd max1666x 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 src v cc ref ova uva mma pkf cgi dsi max1666s dso tko bip cgo b2p gnd pkn qsop qsop qsop 19-1465; rev 2; 12/03 part max1666seee MAX1666Aeep max1666xeep -40? to +85? -40? to +85? -40? to +85? temp range pin-package 16 qsop 20 qsop 20 qsop pin configurations ordering information selector guide typical operating circuits appear at end of data sheet. number of li+ cells part max1666s 2 3 4 max1666x MAX1666A/v 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. max1666veep -40? to +85? 20 qsop
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v src = 16v, each cell voltage v cell = 3.6v, 330k ? load at ref, t a = 0? to +85? , unless otherwise noted. typical values are at t a = +25?.) 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. src, dso , tko , cgo , uvo, pkf , wrn to gnd ...-0.3v to +28v v cc , ref, ova, uva, mma to gnd ........................-0.3v to +6v b4p to b3p ...............................................................-0.3v to +6v b3p to b2p ...............................................................-0.3v to +6v b2p to b1p ...............................................................-0.3v to +6v b1p to gnd ..............................................................-0.3v to +6v pkn to gnd...........................................................................?v v cc , cgi , dsi to pkn...............................................-0.3v to +6v continuous power dissipation (t a = +70?) 16-pin qsop (derate 8.3mw/? above +70?)...........667mw 20-pin qsop (derate 9.1mw/? above +70?)...........727mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? parameter symbol conditions min typ max units charge-mode detection threshold v src - v b_p 1v v src - v b_p = 1v, v cgi = v dsi = gnd 2 10 MAX1666A only, v src - v b3p = 1v, v cgi = 3v, v dsi = gnd 25 src supply current MAX1666A only, v src - v b3p = 1v, v dsi = 3v, v cgi = gnd 25 ? supply current i sup no faults, long-time average current from the top battery terminal b_p 30 45 ? shutdown supply current i shdn 1a v cc output voltage v cc r load 665 ? , 2v < v cell < 4.4v 3.09 3.25 3.41 v v cc undervoltage-lockout threshold 2.7 2.85 3.0 v reference output voltage v ref pulse on 1.221 v ova = gnd 3.980 4.000 4.020 v ova = v ref / 2 4.2 overvoltage threshold cell voltage rising ova = ref 4.378 4.400 4.422 v overvoltage-threshold hysteresis 200 mv uva = gnd 1.950 2.000 2.050 v uva = v ref / 2 2.500 undervoltage threshold cell voltage falling uva = ref 2.925 3.000 3.075 v undervoltage-threshold hysteresis 100 mv
MAX1666A/s/v/x advanced lithium-ion battery-pack protector _______________________________________________________________________________________ 3 electrical characteristics (continued) (v src = 16v, each cell voltage v cell = 3.6v, 330k ? load at ref, t a = 0? to +85? , unless otherwise noted. typical values are at t a = +25?.) parameter symbol conditions min typ max units wrn early-warning threshold above undervoltage threshold, cell voltage falling 100 mv wrn early-warning-threshold hysteresis 200 mv ova, uva, mma input current ova, uva, mma = ref 0.1 20 na mma = gnd 0 v mma = v ref / 2 250 cell mismatch threshold all cells > 2v mma = ref 450 500 550 mv pkn to gnd overdischarge- current threshold 270 300 330 mv pkn to gnd overcharge-current threshold -220 -200 -180 mv overcurrent fault-timer delay t p-delay 330 550 770 ms overdischarge/overcharge- current fault-blanking time t i-delay 1.6 2.4 3.2 ms dso , cgo , uvo output sink current no faults, v dso = v cgo = v uvo = 1v to 27v 20 30 40 ? dso , cgo output source current v dso = v src - 4v and v cgo = v src - 4v, fault condition 210 ma dso , cgo , uvo leakage current v dso = v cgo = v uvo = 27v, fault condition 0.2 ? tko pulldown resistance, max1666s/v/x 100 200 k ? tko sink current, MAX1666A only v tko = 16v 1 2.5 ma tko leakage current, MAX1666A only v tko = 16v, v cgi = 3v 1 ? minimum b3p voltage for tko low, MAX1666A only v src = v b3p + 1v, i tko = 0.5ma 2.4 3.6 v tko source current tko = gnd 1 8 ma dsi , cgi input high voltage referenced to pkn 2 v dsi , cgi input low voltage referenced to pkn 0.45 v dsi , cgi input current v dsi , v cgi = 5v 1 a wrn sink current fault condition, v wrn = 0.4v 2 4 ma pkf sink current fault condition, v pkf = 0.4v 4 8 ma pkf , wrn leakage current v pkf = v wrn = 27v 0.2 ? undervoltage, overvoltage, or mismatch fault, to dso , cgo , tko transition delay t f-delay fault persistent for four consecutive sample periods 180 320 460 ms
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 4 _______________________________________________________________________________________ electrical characteristics (v src = 16v, each cell voltage v cell = 3.6v, 330k ? load at ref, t a = -40? to +85? , unless otherwise noted.) (note 1) parameter symbol conditions min typ max units charge-mode detection threshold v src - v b_p 1v v src - v b_p = 1v, v cgi = v dsi = gnd 10 MAX1666A only, v src - v b3p = 1v, v cgi = 3v, v dsi = gnd 5 src supply current MAX1666A only, v src - v b3p = 1v, v dsi = 3v, v cgi = gnd 5 ? supply current i sup no faults, long-time average current from the top battery terminal b_p 45 ? shutdown supply current i shdn 1a v cc output voltage v cc r load 665 ? , 2v < v cell < 4.4v 3.09 3.41 v v cc undervoltage-lockout threshold 2.7 3.0 v ova = gnd 3.975 4.025 overvoltage threshold ova = ref 4.373 4.427 v uva = gnd 1.950 2.050 undervoltage threshold uva = ref 2.925 3.075 v ova, uva, mma leakage ova, uva, mma = ref 20 na cell mismatch threshold all cells > 2v, mma = ref 450 550 mv pkn to gnd overdischarge- current threshold 270 330 mv pkn to gnd overcharge-current threshold -220 -180 mv overcurrent fault-timer delay t p-delay 330 770 ms overdischarge/overcharge- current fault-blanking time t i-delay 1.6 3.2 ms dso , cgo , uvo output sink current no faults; v dso , v cgo , v uvo = 1v to 27v 20 40 ? dso , cgo output source current v dso = v src - 4v and v cgo = v src - 4v, fault condition 2ma dso , cgo , uvo leakage current v dso = v cgo = v uvo = 27v, fault condition 0.2 ?
MAX1666A/s/v/x advanced lithium-ion battery-pack protector _______________________________________________________________________________________ 5 note 1: specifications to -40? are guaranteed by design, not production tested. electrical characteristics (v src = 16v, each cell voltage v cell = 3.6v, 330k ? load at ref, t a = -40? to +85? , unless otherwise noted.) (note 1) parameter symbol conditions min typ max units tko pulldown resistance, max1666s/v/x 100 k ? tko sink current, MAX1666A only v tko = 16v 1 ma minimum b3p voltage for tko low v src = v b3p + 1v, i tko = 0.5ma 3.6 v tko source current tko = gnd 1 ma dsi , cgi input high voltage referenced to pkn 2 v dsi , cgi input low voltage referenced to pkn 0.45 v dsi , cgi input current v dsi = v cgi = 5v 1 a wrn sink current fault condition, v wrn = 0.4v 2 ma pkf sink current fault condition, v pkf = 0.4v 4 ma pkf , wrn leakage current v pkf = v wrn = 27v 0.2 ? undervoltage, overvoltage, or mismatch fault, to dso , cgo , tko transition delay t f-delay fault persistent for four consecutive sample periods 180 460 ms
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 6 _______________________________________________________________________________________ t ypical operating characteristics (t a = +25?, unless otherwise noted.) 700 720 710 740 730 760 750 770 -40 0 20 -20 40 6 080100 shutdown supply current vs. temperature max1666toc01 temperature (?) supply current (na) v cell = 3.6v 25 27 31 29 33 35 -40 0 20 -20 40 60 80 100 supply current vs. temperature max1666toc02 temperature (?) supply current ( a) v cell = 3.6v 3.0000 3.0005 3.0010 3.0015 undervoltage threshold vs. temperature max1666toc03 temperature (?) undervoltage threshold (v) -40 20 40 -20 0 60 80 100 uva = ref 4.385 4.390 4.395 4.400 overvoltage threshold vs. temperature max1666toc04 temperature (?) undervoltage threshold (v) -40 20 40 -20 0 60 80 100 ova = ref 295 297 296 299 298 301 300 302 -40 0 20 -20 40 6 080 100 overdischarge threshold vs. temperature max1666toc07 temperature (?) overdischarge threshold (mv) 495 497 496 499 498 500 501 -40 20 40 -20 0 60 80 100 mismatch voltage threshold vs. temperature max1666toc05 temperature (?) mismatch voltage threshold (mv) mma = ref 199 200 201 202 203 overcharge threshold vs. temperature max1666toc06 temperature (?) overcharge threshold (mv) -40 20 40 -20 0 60 80 100 1ms/div overdischarge protection pkn (0.5v/div) dso (10v/div) max1666toc08 t i-delay 100ms/div overdischarge recovery time (0.5v/div) (10v/div) pkn dso max1666toc09 t p
MAX1666A/s/v/x advanced lithium-ion battery-pack protector _______________________________________________________________________________________ 7 100ms/div overcharge (0.5v/div) (10v/div) pkn cgo max1666toc10 t p-delay t ypical operating characteristics (continued) (t a = +25?, unless otherwise noted.) 100ms/div overvoltage fault 4.1v (1v/div) 4.5v 12 3 4 12 3 4 ref b1p max1666toc11 (10v/div) cgo t f-delay t f-delay v cell2 = v cell3 = v cell4 = 4.15v, overvoltage threshold = 4.4v 100ms/div undervoltage fault 3.4v 2.9v (10v/div) (1v/div) (10v/div) ref b1p dso max1666toc12 wrn t f-delay t f-delay v cell2 = v cell3 = v cell4 = 3.35v, undervoltage threshold = 3.0v, uva = ref 1234 12 3 4 100ms/div cell mismatch fault 3.4v 2.9v 3 2 141234 (10v/div) (1v/div) (10v/div) ref b1p dso max1666toc13 pkf t f-delay t f-delay v cell2 = v cell3 = v cell4 = 3.6v, cell mismatch threshold = 0.5v, mma = ref 100ms/div undervoltage fault without charge source (v src < v b4p + 1v) v cell2 = v cell3 = v cell4 = 3.35v, undervoltage threshold = 3.0v, uva = ref 3.4v 2.9v (1v/div) (10v/div) (2v/div) ref b1p v cc dso max1666toc14
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 8 _______________________________________________________________________________________ pin description pin mma uvo v cc ref ova uva 12 16 15 14 13 15 15 mismatch adjust input. set the mismatch threshold by a resistor- divider from ref to gnd. 20 20 undervoltage fault output 19 19 3.3v linear regulator output. bypass with a 0.47? min capacitor to gnd. 18 18 reference voltage output. minimize pc board stray capacitance on this node. 17 17 overvoltage adjust input. set the overvoltage threshold with a resistor-divider from ref to gnd. 16 16 undervoltage adjust input. set the undervoltage threshold with a resistor-divider from ref to gnd. wrn pkf name src dso tko b2p b3p b4p cgo cgi dsi pkn gnd b1p 11 max1666s 1 2 3 5 4 10 9 8 7 6 14 14 undervoltage/overvoltage warning output 13 13 pack fail output. pkf goes low when any cell voltage exceeds the mismatch threshold or when a shorted cell is detected. function max1666x MAX1666A/v 1 1 charge source input. provides current for gate drivers dso , tko , cgo , and uvo. 2 2 discharge driver output. drives external p-channel mosfet to con- trol discharge. 3 3 trickle-charge driver output. drives external p-channel mosfet to control trickle-charge current. MAX1666A requires an external pullup resistor of 470k ? 7 7 cell 2 positive input. power supply input for max1666s. 6 5, 6 cell 3 positive input. power supply input for MAX1666A/v. 5 cell 4 positive input. power supply input for max1666x. 4 4 fast-charge driver output. drives external p-channel mosfet to control fast charge. 12 12 charge control input 11 11 discharge control input 10 10 battery pack negative terminal. connect to bottom of current-sense resistor. ground reference for logic inputs dsi and cgi . 9 9 ground 8 8 cell 1 positive input
MAX1666A/s/v/x advanced lithium-ion battery-pack protector _______________________________________________________________________________________ 9 bias b4p cqi_fault 550ms timer set/reset warning ov-fault uv-fault cm-fault pkf wrn v cc dqi_fault tko src src shutdown charge dqi_hi cqi_hi ov_fault uv_fault cm_fault uv_fault warning uv_fault cgi ov_fault cm_fault ov_fault cm_fault uv_fault q d rb 30 a cgo b4p b3p b2p bip gnd cmp_p cmp_n latch_cm latch_uv latch_ov latch_wrn cmp ova uva mma gnd gnd pkn src b4p 200mv 300mv 30 a n n n 1v ref 1.221v ck cqi_fault cgi 3.3v linear reg. threshold voltage selector cell voltage selector state machine 50khz osc osc "1" cm_fault uv_fault q d rb 30 a n n n n gnd dso ck dqy_fault dsi "1" reg early warning reg over- voltage reg under- voltage reg cell mismatch uvo gnd gnd max1666 figure 1. functional diagram
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 10 ______________________________________________________________________________________ yes yes no no standby 80ms sample 2.5ms check v ref latch uvw = ? v ref > 1.1v v cell < undervoltage warning threshold yes no v cell < undervoltage threshold latch uvf = ? yes no v cell > overvoltage threshold latch ovf = ? yes yes no cell mismatch latch mmf = ? no uvf = ?? and v src < v b4p + 1v go to table 2 yes yes no v cc > 2.85v v src < v b4p + 1v v src > v b4p + 1v shutdown battery connected charge current monitor overcharge cgo = h over- discharge dso = h (discharge current r cs ) 300mv (>2.4ms) (charge current r cs ) 200mv (>2.4ms) 550ms delay reset ds0 = l reset cgo = l figure 2. cell fault monitor
MAX1666A/s/v/x advanced lithium-ion battery-pack protector ______________________________________________________________________________________ 11 detailed description the max1666 battery-pack protectors supervise the charging and discharging processes of li+ battery cells. designed for 2-, 3-, and 4-cell applications, these devices monitor the voltage across each cell to provide protection against undervoltage, overvoltage, and over- current damage. control pins cgo , tko , and dso allow control of external mosfet gates. this allows fast charging, trick- le charging, and discharging processes (see the typical operating circuits ). the voltage of each cell is measured individually. also, each cell is measured dif- ferentially between every other cell of the pack. the max1666 contains a state machine, a voltage reg- ulator, an oscillator, and other logic functions to selec- tively drive cgo , uvo, tko , dso , wrn , and pkf (figure 1). modes of operation shutdown mode the max1666 goes into shutdown mode when a bat- tery pack is first connected. the quiescent current is less than 1?. all circuitry is inactive except the com- parator monitoring v src and the top-cell voltage. the max1666 remains in shutdown mode as long as v src is less than the top-cell voltage. when src is connect- ed to an external charger and v src is 1v above the top-cell voltage, the device goes into standby mode. the max1666 returns to shutdown mode under two conditions: the battery is disconnected and then re- connected, or the device detects an undervoltage fault and no charge source. normal mode the standby state activates the bias circuitry, overcurrent comparator, and timer. the standby state lasts 80ms, then the max1666 goes into the sample state for 2.5ms. within the 2.5ms, the max1666 checks for overvoltage, undervoltage, and mismatch between cells sequential- ly, and it stores the results in internal latches. the max1666 drives the outputs according to the faults (if any) detected by reading the latches (figure 2) at the end of the sample state. then the max1666 returns to the standby state. overvoltage protection the max1666 provides overvoltage protection to avoid overcharging of any cell. when any cell is at overvolt- age, cgo and tko go high, turning off the external mosfets and stopping the charging process (see the typical operating circuits ). wrn goes low. overvoltage is set when any cell voltage exceeds the overvoltage threshold. overvoltage threshold is linearly adjustable through an external 1% resistor-divider (figure 3) from ref. determine the overvoltage threshold (v ovt ) required. v ovt must be between 4v and 4.4v. set r total = r1 + r2 = 1m ? . calculate r1 and r2 as follows: r2 = [(v ovt - 4v) / (4.4v- 4v)] r total r1 = r total - r2 mode time (ms) typical quiescent current (?) condition 80 24 only bias circuitry, overcurrent comparator, and timer are active. normal 2.5 250 all circuitry active. shutdown 0.7 all circuitry inactive. device enters shutdown when it detects an undervolt- age fault and v src < v top-cell + 1v (no charge source). table 1. operating modes r1 r3 ref ova r5 r2 r4 r6 uva mma gnd max1666 figure 3. using an external resistor-divider to adjust overvoltage threshold state standby sample
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 12 ______________________________________________________________________________________ maximum mismatch of 1% external resistor-dividers is ?%. the external adjusted overvoltage-threshold accu- racy includes the internal overvoltage-threshold accuracy (?.5%) and the error due to the external resistor-divider multiplied by maximum adjustment: the total external adjusted overvoltage-threshold (v ovt ) accuracy is ?.7%. undervoltage protection the max1666 provides undervoltage protection to avoid overdischarging the cells. when any cell is under voltage, uvo, dso , and cgo go high, turning off the external charging and discharging mosfets. tko remains low to keep the trickle-charge current on. undervoltage threshold is linearly adjustable through an external resistor-divider (figure 3) from ref. determine the undervoltage threshold (v uvt ) required. v uvt must be between 2v and 3v. set r total = r3 + r4 = 1m ? . calculate r3 and r4 as follows: r4 = [(v uvt - 2v) / (3v - 2v)] r total r3 = r total - r4 maximum mismatch of 1% external resistor-dividers is ?.0%, and the error due to the external resistor-divider multiplied by maximum adjustment is ?% (3v - 2v) / 3v = ?.7%. the total external adjusted undervoltage- threshold (v uvt ) accuracy including the internal under- voltage-threshold accuracy (?.5%) is ?.2%. undervoltage warning when any cell drops to 100mv above the undervoltage threshold, wrn goes low. wrn returns high when all cells are 300mv above the undervoltage threshold. cell-mismatch protection the max1666 disables charging or discharging when mismatch occurs. when any two cells are mismatched, tko , cgo , uvo, and dso go high, turning off the external mosfets. pkf goes low. pkf has a strong pulldown current (>4ma), and can be used to control an external thermal fuse. the cell-mismatch threshold is linearly adjustable through an external resistor-divider (figure 3) from ref. determine the cell-mismatch threshold (v cmt ) required. v cmt has to be between 0 and 500mv. set r total = r5 + r6 = 1m ? . calculate r5 and r6: r6 = (vcmt / 500mv) rtotal r5 = rtotal - r6 maximum mismatch of a 1% external resistor-divider is ?%. the total external adjusted cell-mismatch thresh- old accuracy, including the internal cell-mismatch threshold accuracy (?0%), is ?2%. cell voltage sampling the max1666 does not introduce cell mismatch. when the battery cells are matched, the max1666 draws close to zero current from the intermediate cells. figure 4 shows a simplified diagram of the voltage sampling scheme: b4p: i 4 = 3i cb + v 4 / r = 4v 4 / r = bat4 current b3p: i 3 = i 3p + i 4 = bat3 current i 3p + i cb = v3 / r ? i 3p = v 3 / r - v 4 / r i 3 = i 4 + (v 3 - v 4 ) / r = (3v 4 + v 3 ) / r b2p: i 2 = i 2p + i 3 = bat2 current i 2p + i cb = v 2 / r ? i 2p = v 2 / r - v 4 / r i 2 = i 3 + v 2 / r - v 4 / r = i 4 + (v3 - v 4 ) / r + (v 2 - v 4 ) / r = (2v 4 + v 3 + v 2 ) / r b1p: i 1 = i 1p + i 2 = bat1 current i 1p + i cb = v 1 / r ? i 1p = v 1 / r - v 4 / r i 1 = i 2 + v 1 / r - v 4 / r = i 4 + (v 3 - v 4 ) / r + (v 2 - v 4 ) / r + (v 1 - v 4 ) / r = (v 4 + v 3 + v 2 + v 1 ) / r when v 1 = v 2 = v 3 = v 4 , i 1p = i 2p = i 3p = 0, and i 1 = i 2 = i 3 = i 4 = 4v 4 / r ? = 2 44 40 44 02 % . . . .% vv v + v4 - b3p b2p b1p b4p + v3 - i 3 i 4 i 3p i 2p i 1p i 2 i 1 + v2 - + v2 - + v1 - rr r r + v1 - i cb = v4 r i cb = v4 r i cb = v4 r v1 r v2 r + v3 - v3 r + v4 - v4 r figure 4. cell voltage sampling
MAX1666A/s/v/x advanced lithium-ion battery-pack protector ______________________________________________________________________________________ 13 table 2. truth table control inputs control outputs notes uvw uvf ovf mmf cgi dsi occ odc dso cgo tko wrn pkf uvo 0000000 0 lllhhl normal operation 0000000 1 psllhhl overdischarge current fault 0000001 0 lpslhhl overcharge current fault 0000010 0 hllhhl disable dischar g e p ath 0000011 0 hpslhhl disable discharge path, overcharge current fault 0000100 0 l hhhhl disable charge path 0000100 1 ps hhhhl disable charge path, overdischarge current fault 0000110 0 hhhhhl disable charge and discharge path 0001000 0 hhhhlh mismatch fault 0001010 0 hhhhlh mismatch fault, disable discharge path 0001100 0 hhhhlh mismatch fault, disable charge path 0001110 0 hhhhlh mismatch fault, disable charge and discharge path 0010000 0 lhhlhl overvoltage fault 0010000 1 pshhlhl overvoltage fault, overdischarge current fault 0010010 0 hhhlhl overvoltage fault, disable discharge path 0010100 0 lhhlhl overvoltage fault, disable charge path 0010100 1 pshhlhl overvoltage fault, disable charge path, overdischarge current fault 0010110 0 hhhlhl overvoltage fault, disable charge and discharge path 0011000 0 hhhllh overvoltage fault, mismatch fault 0011010 0 hhhllh overvoltage fault, mismatch fault, disable discharge path 0011100 0 hhhllh overvoltage fault, mismatch fault, disable charge path 0011110 0 hhhllh overvoltage fault, mismatch fault, disable charge and discharge path 1100000 0 hhllhh undervoltage fault 1100010 0 hhllhh undervoltage fault, disable discharge path 1100100 0 hhhlhh undervoltage fault, disable charge path 1100110 0 hhhlhh undervoltage fault, disable charge and discharge path 1101000 0 hhhllh undervoltage fault, mismatch fault 1101010 0 hhhllh undervoltage fault, mismatch fault, disable discharge path 1101100 0 hhhllh undervoltage fault, mismatch fault, disable charge path 1101110 0 hhhllh undervoltage fault, mismatch fault, disable charge and discharge path 1111000 0 hhhllh undervoltage fault, overvoltage fault, mismatch fault 1111010 0 hhhllh undervoltage fault, overvoltage fault, mismatch fault, disable discharge path 1111100 0 hhhllh undervoltage fault, overvoltage fault, mismatch fault, disable charge path 1111110 0 hhhllh undervoltage fault, overvoltage fault, mismatch fault, disable charge and discharge path 1000000 0 llllhl undervoltage fault early warning 1000000 1 pslllhl undervoltage fault early warning, overdischarge current fault 1000001 0 lpsllhl undervoltage fault early warning, overcharge current fault 1000010 0 hlllhl undervoltage fault early warning, disable discharge path 1000011 0 hpsllhl undervoltage fault early warning, disable discharge path, overcharge current fault 1000100 0 lhhlhl undervoltage fault early warning, disable charge path 1000100 1 pshhlhl undervoltage fault early warning, disable charge path, overdischarge current fault 1000110 0 hhhlhl undervoltage fault early warning, disable charge and discharge path 1001000 0 hhhllh undervoltage fault early warning, mismatch fault 1001010 0 hhhllh undervoltage fault early warning, mismatch fault, disable discharge path 1001100 0 hhhllh undervoltage fault early warning, mismatch fault, disable charge path 1001110 0 hhhllh undervoltage fault early warning, mismatch fault, disable charge and discharge path 1011000 0 hhhllh undervoltage fault early warning, overvoltage fault, mismatch fault 1011010 0 hhhllh undervoltage fault early warning, overvoltage fault, mismatch fault, disable discharge path 1011100 0 hhhllh undervoltage fault early warning, overvoltage fault, mismatch fault, disable charge path 1011110 0 hhhllh undervoltage fault early warning, overvoltage fault, mismatch fault, disable charge and discharge path ps: overcurrent fault pulse sampling. (output goes high for 500ms then resets low to monitor charge/discharge current. output g oes high again if fault persists.) uvw: undervoltage fault early warning uvf: undervolta g e fault ovf: overvoltage fault mmf: mismatch fault occ: overcharge current fault odc: overdischarge current fault cgi : charge control input dsi : discharge control input
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 14 ______________________________________________________________________________________ overcharge/overdischarge current protection the max1666 checks for overcharge or overdischarge current in standby and sample states. the thresholds are factory preset to 200mv and 300mv, respectively. a charge current makes pkn go below gnd. a dis- charge current makes pkn go above gnd. when pkn exceeds the threshold, a fault is acknowledged. cgo goes high when the overcharge threshold is exceeded. dso goes high when the overdischarge threshold is exceeded. an internal 550ms timer starts. at the end of 550ms, dso or cgo goes low while the max1666 rechecks for an overcharge/overdischarge fault. a per- sistent fault causes dso and cgo to return high and restarts the 550ms timer again. truth table the max1666 has a total of eight signal inputs and six outputs. table 2 lists all the possible states. applications information choosing an external mosfet the external p-channel mosfets act as a gated switch to enable or disable the charging/discharging process. cgo controls the mosfet for normal charging of the battery. tko controls the mosfet for trickle charge of the cells. dso controls the discharging mosfet. use dif- ferent mosfets to optimize each function depending on the maximum charge and discharge rates. table 3 lists some suitable mosfets in a small 8-pin so package. layout considerations and bypassing as with all pc board designs, a careful layout is suggest- ed. minimize lead lengths to reduce losses in the traces. p-channel mosfets maximum drain current (a) irf7406 4.7 irf7404 5.3 si4431 4.5 si4947 (dual) 2.5 ea table 3. mosfet selection
MAX1666A/s/v/x advanced lithium-ion battery-pack protector ______________________________________________________________________________________ 15 dsi cgi wrn pkf uvo v cc ref 17 18 20 13 14 12 11 19 0.47 f 16 15 10 9 8 7 6 5 3 4 2 1 ova 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% +3.3v 5ma 0.05 ? uva mma pkn gnd r sense b1p b2p b3p b4p cgo dso src p pack+ overdischarge protection pack- trickle charge overcharge protection 470k ? 470k ? max1666x tko p p 270 ? t ypical operating circuits
MAX1666A/s/v/x advanced lithium-ion battery-pack protector 16 ______________________________________________________________________________________ t ypical operating circuits (continued) dsi cgi wrn pkf uvo v cc v cc ref 17 18 100k ? 100k ? 220k ? 20 13 14 11 12 19 1 f 16 15 10 9 8 7 6 5 3 4 2 1 ova 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% 499k ? 1% +3.3v 5ma 0.05 ? uva mma pkn gnd gnd pack controller r sense b1p b2p out1 out2 in1 in2 in3 b3p b4p cgo dso src p pack+ overdischarge protection pack- trickle charge overcharge protection 470k ? 470k ? max1666x tko p p 270 ? ___________________chip information transistor count: 4835
MAX1666A/s/v/x advanced lithium-ion battery-pack protector maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circu it patent licenses are implied. maxim reserves the right to change the circuitry and specifications without notice at any time. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 17 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. qsop.eps ________________________________________________________package information

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