general description the max1259 battery manager provides backup-battery switching for cmos ram, microprocessors, or other low- power logic ics. it automatically switches to the backup battery when the primary power supply is interrupted. low-loss switches guarantee an input-to-output differ - ential of only 200mv while supplying 250ma from the primary power supply or 15ma from the battery. battery discharge during shipping does not occur in the max1259, since the backup battery can be disconnected by strobing the rst input. a battery-fail output signal indicates when the backup bat - tery is below +2v, and a power-fail output signal indicates when the primary power supply is low. the max1259 monitors the backup battery, warns of impending power failures, and switches the memory to the battery when failures occur. the max1259 is pincompatible with the ds1259, but consumes three times less supply current. commercial, extended, and military temperature range devices are available. applications battery backup for cmos ram uninterruptible power supplies computers controllers features switches to backup battery if power fails consumes less than 100na of battery current power-fail output signals primary power-supply loss battery monitor indicates low battery battery can be disconnected to prevent discharge during shipping battery automatically reconnected when v cc is applied pin-compatible with the ds1259 supply current three times lower than ds1259 available in extended-industrial and military temperature ranges 19-4638; rev 3; 9/14 *contact factory for dice specifications.note: devices in pdip and so packages are available in both leadedpb) and lead(pb)-free packaging. specify lead-free by adding the + symbol at the end of the part number when ordering. lead-free not available for cerdip package. part temp range pin-package max1259c/d 0c to +70c dice* max1259cpe 0c to +70c 16 pdip max1259cwe 0c to +70c 16 wide so max1259epe -40c to +85c 16 pdip max1259ewe -40c to +85c 16 wide so max1259mje -55c to +125c 16 cerdip v cci v cco v batt reset logic gnd bat rst pf bf ref max1259 dip/so v cci v cco v cco v cci v n.c. bf n.c. n.c. max1259 12 3 4 1615 14 13 bat rst gnd gnd n.c. n.c. pf 56 7 8 1211 10 9 batt top view max1259 battery manager functional diagram pin coniguration ordering information downloaded from: http:///
voltage on any pin (with respect to gnd)............-0.3v to +7.0v operating temperature range c suffix................................................................0c to +70c e suffix.............................................................-40c to +85c m suffix..........................................................-55c to +125c storage temperature range .............................-55c to +125c lead temperature (soldering, 10s) .................................+300c (all grades, t a = t min to t max , unless otherwise noted.) (v cc = +4.5v to +5.5v, all grades, t a = t min to t max , unless otherwise noted.) (v cci < v batt , all grades, t a = t min to t max , unless otherwise noted.) parameter symbol conditions min typ max units primary power supply v cci (note 1) 5.0 5.5 v input high voltage (note 1) v ih max1259c 2.0 v cci + 0.3 v max1259e/m 2.4 v cci + 0.3 input low voltage v il (note 1) -0.3 +0.8 v battery voltage v batt pin 2 (note 2) 2.5 3.0 3.7 v battery output bat pin 5 (note 1) v batt - 0.1 v parameter symbol conditions min typ max units leakage current i lo -1.0 +1.0 a output current pf , bf i oh v oh = 2.4v (note 3) -1.0 ma i ol v ol = 0.4v 4.0 input supply current i cci (note 4) 2.00 3.33 ma v cco output current i cco v cco = v cci - 0.2v, pins 12, 13 250 ma power-fail trip point v tp pin 11 (notes 2, 5) 1.26 x v batt - 250mv 1.26 x v batt 1.26 x v batt + 250mv v battery-fail trip point v battf pin 3 ( bf detect) (note 6) 2.0 v parameter symbol conditions min typ max units v cco output current i cco2 v cco = v batt - 0.2v, pins 12, 13 (note 7) 15 ma battery leakage (note 8) i batt max1259c 100 na max1259e 150 max1259m 10 a bat output current i batout pin 5 (note 9) 100 a max1259 battery manager www.maximintegrated.com maxim integrated 2 absolute maximum ratings stresses beyond those listed under absolute maximum ratings may cause permanent damage to the device. these are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. exposure to absolute maximum rating conditions for extended periods may affect device reliability. recommended dc operating conditionsdc electrical characteristics dc electrical characteristics downloaded from: http:///
(all grades, t a = +25c, unless otherwise noted.) (note 10) (v cc = 4.0v to 5.5v, all grades, t a = +25c, unless otherwise noted.) note 1: all voltages referenced to ground. note 2: trip-point voltage for power-fail detect: v tp = 1.26 x v batt . for 5% operation: v batt = 3.7v max. note 3: 50pf load capacity. note 4: measured with pins 3, 11, 12, 13, and open. note 5: v tp is the point at which pf is driven low. note 6: v battf is the point at which bf is driven low. note 7: i cco2 may be limited by battery capacity. note 8: battery leakage is the internal energy consumed by the max1259. note 9: see the typical operating characteristics bat switch drop vs. battery voltage graph. note 10: guaranteed by design. not tested. parameter symbol conditions min typ max units input capacitance c in 5 10 pf output capacitance c out 5 10 pf parameter symbol conditions min typ max units v cci fall time t f 300 s v cci rise time t r 1 s power-down to pf low t pf 0 s pf high after power-up t rec 100 s rst pulse width rst pw 50 10 ns pin name function 1, 4, 9, 10, 14 n.c. no connection. make no connection to these pins. 2 v batt backup battery input 3 bf battery-fail output. bf is high for v cci at or above v tp and the backup battery greater than 2v. if the backup battery is below 2v or v cci falls below v tp , bf will be driven low. 5 bat battery output. during normal operation, the bat output supplies up to 1ma of continuous battery current. in shipping mode, the bat output is high impedance. 6 rst battery-disconnect input. the rst input is used to prevent battery discharge during shipping. pulsing the rst input disconnects the backup battery from the v cco and bat outputs. 7, 8 gnd ground 11 pf power-fail output. pf is high for v cci greater than 1.26 x v batt (v tp ), indicating a valid v cci voltage. 12, 13 v cco cmos ram is powered from v cco . the battery switchover circuit compares v cci to the v batt input, and connects v cco to whichever is higher. 15, 16 v cci +5v v cc input max1259 battery manager www.maximintegrated.com maxim integrated 3 capacitancepin description ac electrical characteristics downloaded from: http:///
(t a = +25c, unless otherwise noted.) 200150 100 50 0 100 50 150 200 250 switch voltage drop vs. load current i cco (ma) v cci - v cco (mv) v cc mode t a = +75c v cci = +4.5v v cci = +5.0v max1259toc02 0 200150 100 50 0 5 10 15 switch voltage drop vs. load current i cco2 (ma) v batt - v cco (mv) battery-backup mode t a = +25c v batt = +2.5v v batt = +3.0v max1259toc03 0 200150 100 50 0 5 10 15 switch voltage drop vs. load current i cco2 (ma) v batt - v cco (mv) battery-backup mode t a = +75c v batt = +2.5v v batt = +3.0v max1259toc04 0 3.0 3.63.4 3.2 4.03.8 4.84.6 4.4 4.2 5.0 2.4 2.6 2.8 3.0 3.2 3.4 3.6 3.8 power-fail trip point vs. battery voltage v batt (v) power-fail trip point (v) t a = +25c v cci rising v cci falling max1259toc05 1.6 1.81.7 2.01.9 2.22.1 2.3 0 40 20 60 80 10 50 30 70 90 100 battery-fail trip point vs. temperature temperature (c) battery-fail trip point (v) v cci = 5.0v v batt rising v batt falling max1259toc06 1.00.5 2.01.5 3.02.5 3.5 0 2 3 1 4 5 6 quiescent supply current vs. power supply v cci (v) i cci (ma) v batt = 3.0v, i cco = 0ma t a = +25c max1259toc07 0 200150 100 50 0 100 50 150 200 250 switch voltage drop vs. load current i cco (ma) v cci - v cco (mv) v cc mode t a = +25c v cci = +4.5v v cci = +5.0v max1259toc01 0 0.8 1.21.0 1.61.4 1.8 2.0 2.0 3.0 2.5 3.5 4.0 bat current vs. battery voltage v batt (v) i bat (ma) v batt - bat = 100mv t a = +75c t a = +25c max1259toc08 0 20 40 60 80 100 2.2 2.8 3.0 2.4 2.6 3.2 3.4 3.6 3.8 4.0 bat switch drop vs. battery voltage v batt (v) v batt - bat (mv) i bat = 100a i bat = 1ma max1259toc09 maxim integrated 4 www.maximintegrated.com max1259 battery manager typical operating characteristics downloaded from: http:///
detailed description battery switchover and v cco figure 2 shows a typical application for the max1259. cmos ram is powered from v cco . the battery switcho - ver circuit compares v cc to the v batt input, and con - nects v cco to whichever is higher. switchover occurs when v cc equals v batt as v cc falls, and when v cc is 60mv greater than v batt as v cc rises. this hysteresis prevents repeated, rapid switching if v cc falls very slowly or remains nearly equal to the battery voltage. low-loss switches guarantee an input-to-output differential of only 200mv, while supplying 250ma from the primary power supply or 15ma from the battery. note: with adequate filtering, the max1259 need only supply the average current drawn by the cmos ram. many ram data sheets specify a 75ma maximum sup - ply current, but this peak current spike lasts only 100ns. if the sum of the peak currents is greater than 250ma, a capacitor placed on the v cco output can supply the high instantaneous current, while v cco need only supply the average current, which is much less. the max1259 operates with battery voltages from 2.5v to 3.7v. high-value capacitorseither standard electrolytic or farad-sized, double-layer capacitorscan also be used for short-term memory backup (figure 3). figure 1. power-down/power-up conditions figure 2. typical application circuit figure 3. using a maxcap as a backup battery v cci +4.25v +3v pf battery current t f t pf t r t rec max1259 v cci v cc v batt v cco gnd pf 15, 16 7, 8 12, 13 11 2 p nmi address decode ram1 ram2 ram16 ce15 ce1 ce0 to ram 12, 13 15, 16 3k ? 6.2k ? 2n3904 2 v cc v batt v cci v cc0 0.22f maxcap gnd 7, 8 note: large value capacitors, such as a 0.22f maxcap, may be used for short-term memory backup. max1259 max1259 battery manager www.maximintegrated.com maxim integrated 5 downloaded from: http:///
to achieve rated performance, the v cc input should be connected to both v cci pins (pins 15 and 16). as well, the switched output should be connected to both v cco pins (pins 12 and 13).power fail the power-fail ( pf ) output is high for v cci greater than 1.26 x v batt (v tp ), indicating a valid v cci voltage. battery failif v cci is at or above the voltage trip threshold (vtp) and the backup battery is greater than 2v, the battery-fail ( bf ) output will be held high, indicating a charged battery. if the backup battery drops below 2v or v cci falls below v tp , bf will be driven low. bat output during normal operation, the bat output stays at the bat - tery voltage, regardless of the v cci level. this provides 1ma battery current. reset (digitally controlled battery disconnect) to prevent battery discharge during shipping, the backup battery can be disconnected from v cco to bat. this disconnect feature is activated by pulsing the reset (rst) input high for a minimum of 50ns with v cci greater than v tp (figure 4). when primary power is removed, the v cco and bat outputs will go high impedance. the next time primary power is applied with v cci greater than 1.26 x v batt (vtp) , normal operation resumes. note that when the max1259 is first powered up, v cci must be brought above 1.26 x v batt . this resets an internal flip- flop, ensuring that the part is in normal v cc mode and not in shipping mode. applications information if a protection diode is placed in series with the backup battery, pin 2 must be bypassed with at least a 0.01f capacitor to ground. figure 4. reset timing +5v v cci v cco rst 0v +5v+3v 0v +3v 0v v ih v il bat 50ns min high impedancehigh impedance max1259 battery manager www.maximintegrated.com maxim integrated 6 downloaded from: http:///
package type package code outline no. land pattern no. 16 pdip p16+2 21-0043 16 wide so w16+2 21-0042 90-0107 16 cerdip j16-3 21-0045 max1259 battery manager www.maximintegrated.com maxim integrated 7 package information for the latest package outline information and land patterns (footprints), go to www.maximintegrated.com/packages . note that a +, #, or - in the package code indicates rohs status only. package drawings may show a different suffix character, but the drawing pertains to the package regardless of rohs status. chip topography downloaded from: http:///
revision number revision date description pages changed 3 9/14 removed automotive reference from applications 1 maxim integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim integrated product. no circuit patent licenses are implied. maxim integrated reserves the right to change the circuitry and speciications without n otice at any time. the parametric values (min and max limits) shown in the electrical characteristics table are guaranteed. other parametric values quoted in this data sheet are provided for guidance. maxim integrated and the maxim integrated logo are trademarks of maxim integrated products, inc. ? 2014 maxim integrated products, inc. 8 max1259 battery manager revision history for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim integrateds website at www.maximintegrated.com. downloaded from: http:///
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