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for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. general description the max6361?ax6364 supervisory circuits reduce the complexity and number of components required for power-supply monitoring and battery control functions in microprocessor (?) systems. the circuits significantly improve system reliability and accuracy compared to that obtainable with separate ics or discrete components. their functions include ? reset, backup battery switchover, and power failure warning. the max6361?ax6364 operate from supply voltages as low as +1.2v. the factory-preset reset threshold voltage ranges from 2.32v to 4.63v (see ordering information ). these devices provide a manual reset input (max6361), watchdog timer input (max6362), battery-on output (max6363), and an auxiliary adjustable reset input (max6364). in addition, each part type is offered in three reset output versions: an active-low open-drain reset, an active-low open-drain reset, and an active-high open- drain reset (see selector guide at end of data sheet). applications features low +1.2v operating supply voltage (v cc or v batt ) precision monitoring of +5.0v, +3.3v, +3.0v, and +2.5v power-supply voltages debounced manual reset input (max6361) watchdog timer with 1.6s timeout period (max6362) battery-on output indicator (max6363) auxiliary user-adjustable reset in (max6364) three available output structures push-pull reset , open-drain reset , open-drain reset reset/ reset valid down to 1.2v guaranteed (v cc or v batt ) power-supply transient immunity 150ms (min) reset timeout period small 6-pin sot23 package max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup ________________________________________________________________ maxim integrated products 1 19-1615; rev 4; 10/11 ordering information pin configurations note: these parts offer a choice of reset threshold voltages. from the table below, select the suffix corresponding to the desired threshold vol tage and insert it into the part number to complete it. when ordering from the factory, there is a 2500- piece minimum on the sot package (tape-and-reel only). devices are available in both leaded and lead-free packaging. specify lead-free by replacing "-t" with "+t" when ordering. gnd v cc mr 16 batt 5 out reset, reset max6361 top view 2 34 sot23-6 computers controllers intelligent instruments critical ?/? power monitoring fax machines industrial control pos equipment portable/battery-powered equipment selector guide appears at end of data sheet. typical operating circuit appears at end of data sheet. pin configurations continued at end of data sheet. 6 sot23 -40? to +85? max6364hut_ _-t 6 sot23 -40? to +85? max6364put_ _-t 6 sot23 -40? to +85? max6364 lut_ _-t 6 sot23 -40? to +85? 6 sot23 -40? to +85? max6363hut_ _-t max6363put_ _-t 6 sot23 -40? to +85? 6 sot23 -40? to +85? max6363 lut_ _-t 6 sot23 pin-package temp range -40? to +85? max6361hut_ _-t 6 sot23 -40? to +85? max6361put_ _-t max6361 lut_ _-t part 6 sot23 -40? to +85? max6362hut_ _-t 6 sot23 -40? to +85? max6362put_ _-t 6 sot23 -40? to +85? max6362 lut_ _-t suffix min 46 4.50 4.63 max typ 44 4.25 4.38 31 3.00 3.08 4.75 4.50 3.15 23 2.25 29 2.85 2.93 2.32 26 2.55 2.63 2.38 3.00 2.70 reset threshold ranges (v)
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +2.4v to +5.5v, v batt = 3v, t a = -40? to +85?, reset not asserted. typical values are at t a = +25?, unless otherwise noted.) (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. terminal voltages (with respect to gnd) v cc , batt, out.......................................................-0.3v to +6v reset (open drain), reset (open drain) ................-0.3v to +6v batt on, reset (push-pull), reset in, wdi.......................................................-0.3v to (v out + 0.3v) mr .............................................................-0.3v to (v cc + 0.3v) input current v cc peak ............................................................................1a v cc continuous ............................................................250ma batt peak ....................................................................250ma batt continuous ............................................................40ma gnd ................................................................................75ma output current out................................short-circuit protection for up to 10s reset, reset , batt on ..............................................20ma continuous power dissipation (t a = +70?) 6-pin sot23 (derate 8.70mw/? above +70?) .........696mw operating temperature range ...........................-40? to +85? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) lead(pb)-free...............................................................+260? packages containing lead(pb).....................................+240? parameter symbol conditions min typ max units v 0 5.5 no load (note 2) v cc , v batt operating voltage range, v cc or v batt supply current (excluding i out ) i cc no load, v cc > v th , wdi = v cc or gnd (max6362) v cc = 2.8v v cc = 3.6v v cc = 5.5v 10 30 11 35 15 50 ? ? 1 3 t a = +25? t a = -40? to +85? v batt = 2.8v, v cc = 0v i supply i supply in battery-backup mode (excluding i out ) batt standby current i batt 5.5v > v cc > (v batt + 0.2v) t a = +25? t a = -40? to +85? -0.1 0.02 -1.0 0.05 ? ? 2.75 3.0 4.6 v cc = 4.75v, i out 150ma v cc = 3.15v, i out 65ma v cc = 2.38v, i out 25ma r on v cc to out on-resistance v out in battery-backup mode battery-switchover threshold (v cc - v batt ) reset threshold v cc falling reset delay reset-active timeout period t rp v th v batt = 4.5v, i out 20ma v batt = 3.0v, i out 10ma v batt = 2.25v, i out 5ma v cc < v th max636_ut46 v cc falling at 10v/ms v batt - 0.2 v batt - 0.15 v batt - 0.15 20 -20 4.50 4.63 4.75 4.25 4.38 4.50 3.00 3.08 3.15 2.85 2.93 3.00 2.55 2.63 2.70 2.25 2.32 2.38 35 150 280 ms ? v mv v power-up power-down max636_ut23 max636_ut26 max636_ut29 max636_ut31 max636_ut44
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup _______________________________________________________________________________________ 3 electrical characteristics (continued) (v cc = +2.4v to +5.5v, v batt = 3v, t a = -40? to +85?, reset not asserted. typical values are at t a = +25?, unless otherwise noted.) (note 1) note 1: all devices are 100% production tested at t a = +25?. limits over temperature are guaranteed by design. note 2: v batt can be 0v anytime or v cc can go down to 0v if v batt is active (except at startup). parameter symbol min typ max units conditions output voltage v ol 0.4 v output short-circuit current 60 ma i sink = 3.2ma, v batt = 2.1v sink current, v cc = 5v reset output voltage v ol 0.3 v mr input voltage 0.7 v cc v pull-up resistance 20 k ? minimum pulse width 1 ? glitch immunity 100 ns mr to reset delay 120 ns reset not asserted v cc = 3.3v v cc = 3.3v reset output voltage v ol 0.3 v reset asserted, v batt = 0v input threshold 1.185 1.235 1.285 v reset in leakage current ?.01 ?5 na 1.5 ? overdrive voltage = 50mv, reset in falling reset in to reset delay 10 30 100 ? source current, v batt 2v v ih v il 0.3 v cc v oh 0.8 v cc reset not asserted (max636_l only) i source = 500?, v cc v th(max) 0.4 i sink = 100?, v cc 1.2v i sink = 1.6ma, v cc 2.1v reset , reset output leakage current i lk 1 ? max636_p, max636_h only i sink = 1.6ma, v cc v th(max) minimum wdi input pulse width t wdi 100 ns input voltage v il 0.3 v cc v watchdog timeout period t wd 1.00 1.60 2.25 s manual reset (max6361 only) batt on (max6363 only) reset in (max6364 only) watchdog input (max6362 only) v ih 0.7 v cc
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup 4 _______________________________________________________________________________________ typical operating characteristics (t a = +25?, unless otherwise noted.) 12 14 16 18 20 supply current vs. temperature (no load) max6361 toc01 temperature ( c) supply current ( a) -40 20 40 -20 0 60 80 v batt = 0v v cc = 5.0v 0 0.2 0.6 0.4 0.8 1.0 1.2 battery supply current (backup mode) vs. temperature max6361 toc02 temperature ( c) battery supply current ( a) -40 20 40 -20 0 60 80 v batt = 2.0v v cc = 0 v batt = 2.8v 0 1 4 3 2 5 6 7 battery to out on-resistance vs. temperature max6361 toc03 temperature ( c) batt to out on-resistance ( ? ) -40 20 40 -20 0 60 80 v batt = 5.0v i out = 25ma v cc = 0v v batt = 2.8v v batt = 2.0v 0 0.3 0.9 0.6 1.2 v cc to out on-resistance vs. temperature max6361 toc04 temperature (?) v out to out on-resistance ( ? ) -40 20 40 -20 0 60 80 v cc = 3.0v i out = 65ma v cc = 4.5v i out = 150ma v cc = 2.3v i out = 25ma 190 195 205 200 210 reset timeout period vs. temperature max6361 toc05 temperature ( c) reset timeout period (ms) -40 20 40 -20 0 60 80 0 30 15 75 60 45 135 120 105 90 v cc to reset propagation delay vs. temperature max6361 toc06 temperature ( c) propagation delay ( s) -40 20 40 -20 0 60 80 v cc falling 0.25v/ms 1v/ms 10v/ms 2.0 3.0 2.5 5.0 4.5 4.0 3.5 reset threshold vs. temperature max6361 toc07 temperature (?) threshold (v) -40 20 40 -20 0 60 80 max636_46 max636_26 1.2 1.4 1.3 1.6 1.5 1.9 1.8 1.7 2.0 -40 0 -20 20406080 max6362 watchdog timeout period vs. temperature max6361toc06a temperature ( c) watchdog timeout period (s) 1 100 10 1k 10k maximum transient duration vs. reset threshold overdrive max6361 toc08 reset threshold overdrive v th - v cc (mv) maximum transient duration ( s) 400 300 350 250 200 0 50 150 100 max636_46 max636_26 reset occurs above curve
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup _______________________________________________________________________________________ 5 1.234 1.235 1.236 max6364 reset in threshold vs. temperature max6361 toc10 temperature (?) threshold (v) -40 20 40 -20 0 60 80 typical operating characteristics (continued) (t a = +25?, unless otherwise noted.) 1.0 1.9 1.6 1.3 2.8 2.5 2.2 max6364 reset in to reset propagation delay vs. temperature max6361 toc11 temperature (?) propagation delay ( s) -40 20 40 -20 0 60 80 v od = 50mv pin description backup-battery input. when v cc falls below the reset threshold, batt switches to out if v batt is 20mv greater than v cc . when v cc rises 20mv above v batt , v cc switches to out. the 40mv hysteresis prevents repeated switching if v cc falls slowly. batt 6 supply voltage, 0 to 5.5v. reset is asserted when v cc drops below the reset threshold voltage (v th ). reset remains asserted until v cc rises above v th and for at least 150ms after v cc rises above v th . v cc 4 output. out sources from v cc when it is above the reset threshold (v th ), and from the greater of v cc or batt when v cc is below v th . out 5 ground gnd 2 pin active-low reset output. reset is continuously low when v cc is below the reset threshold (v th ), mr is low, or reset in is low. it asserts in pulses when the internal watchdog times out. reset remains low for the reset timeout period (t rp ) after v cc rises above the reset threshold, after the manual reset input goes from low to high, after reset in goes high, or after the watchdog triggers a reset event. the max636_l is an active-low push-pull output while the max636_p is an active-low open-drain output. reset active-high reset output. reset is continuously high when v cc is below the reset threshold (v th ), mr is low, or reset in is low. it asserts in pulses when the internal watchdog times out. reset remains high for the reset timeout period (t rp ) after v cc rises above the reset threshold, after the manual reset input goes from low to high, after reset in goes high, or after the watchdog triggers a reset event. the max636_h is an active-high open-drain output. reset 1 function name 0 3 2 1 4 5 6 7 8 9 10 01234 battery supply current vs. supply voltage max6361 toc09 v cc (v) battery supply current ( a) v batt = 2.8v v batt = 2.5v v th = 2.93v v batt = 2.3v max6361 manual-reset input. maintaining logic low on mr asserts a reset. reset output remains assert- ed for at least 150ms (t rp ) after mr transitions from low to high. leave unconnected or connected to v cc if not used. mr 3 max6364 reset input. when reset in falls below 1.235v, reset is asserted. reset output remains asserted as long as reset in is low and for at least 150ms (t rp ) after reset in goes high. max6363 battery-on output. batt on goes high in battery backup mode. max6362 watchdog input. if wdi remains high or low for longer than the watchdog timeout period (t wd ), the internal watchdog timer runs out and a reset pulse is triggered for the reset timeout period (t rp ) (figure 1). the internal watchdog clears whenever reset asserts or whenever wdi sees a rising or falling edge. reset in batt on wdi
max6361?ax6364 detailed description the typical operating circuit shows a typical connection for the max6361?ax6364 family. out powers the stat- ic random-access memory (sram). out is internally connected to v cc if v cc is greater than the reset thresh- old, or to the greater of v cc or v batt when v cc is less than the reset threshold. out can supply up to 150ma from v cc . when v cc is higher than v batt , the batt on (max6363) output is low. when v cc is lower than v batt , an internal mosfet connects the backup battery to out. the on-resistance of the mosfet is a function of backup-battery voltage and is shown in the battery to out on-resistance vs. temperature graph in the typical operating characteristics section. backup-battery switchover in a brownout or power failure, it may be necessary to preserve the contents of the ram. with a backup bat- tery installed at batt, the max6361?ax6364 auto- matically switch the ram to backup power when v cc falls. the max6363 has a batt on output that goes high when in battery-backup mode. these devices require two conditions before switching to battery- backup mode: 1) v cc must be below the reset threshold. 2) v cc must be below v batt . table 1 lists the status of the inputs and outputs in bat- tery-backup mode. the device will not power up if the only voltage source is on batt. out will only power up from v cc at startup. manual reset input (max6361 only) many ?-based products require manual reset capabili- ty, allowing the operator, a test technician, or external logic circuitry to initiate a reset. for the max6361, a logic low on mr asserts reset. reset remains asserted while mr is low, and for a minimum of 150ms (t rp ) after it returns high. mr has an internal 20k ? pull-up resistor to v cc . this input can be driven with ttl/cmos logic lev- els or with open-drain/collector outputs. connect a nor- mally open momentary switch from mr to gnd to create a manual reset function; external debounce circuitry is not required. if mr is driven from long cables or the device is used in a noisy environment, connect a 0.1? capacitor from mr to gnd to provide additional noise immunity. watchdog input (max6362 only) the watchdog monitors ? activity through the input wdi. if the ? becomes inactive, the reset output is asserted in pulses. to use the watchdog function, con- nect wdi to a bus line or ? i/o line. a change of state (high to low or low to high) within the watchdog timeout period (t wd ) with a 100ns minimum pulse width clears the watchdog timer. if wdi remains high or low for longer than the watchdog timeout period, the internal watchdog timer runs out and a reset pulse is triggered for the reset timeout period (t rp ). the internal watchdog timer clears whenever reset asserts or the wdi sees a rising or falling edge within the watchdog timeout period. if wdi remains in a high or low state for an extended period of time, a reset pulse asserts after every watchdog timeout period (t wd ) (figure 1). reset in (max6364 only) reset in is compared to an internal 1.235v reference. if the voltage at reset in is less than 1.235v, reset is asserted. the reset in comparator may be used as an undervoltage detector to signal a failing power sup- ply. it can also be used as a secondary power-supply reset monitor. to program the reset threshold (v rth ) of the secondary power supply, use the following equation (see typical operating circuit ): where v ref = 1.235v. to simplify the resistor selection, choose a value for r2 and calculate r1: since the input current at reset in is 25na (max), large values (up to 1m ? ) can be used for r2 with no signifi- cant loss in accuracy. for example, in the typical sot23, low-power ? supervisory circuits with battery backup 6 _______________________________________________________________________________________ table 1. input and output status in battery-backup mode pin status v cc disconnected from out out connected to batt batt connected to out. current drawn from the battery is less than 1? (at v batt = 2.8v, excluding i out ) when v cc = 0. reset/ reset asserted batt on high state mr , reset in, wdi inputs ignored vv r r rth ref =+ ? ? ? ? ? ? 1 2 1 rrvv rth ref 12 1 / = () ? []
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup _______________________________________________________________________________________ 7 operating circuit, the max6362 monitors two supply voltages. to monitor the secondary 5v logic or analog supply with a 4.60v nominal programmed reset thresh- old, choose r2 = 100k ? , and calculate r1 = 273k ? . reset output a ?? reset input starts the ? in a known state. the max6361?ax6364 ? supervisory circuits assert a reset to prevent code-execution errors during power- up, power-down, and brownout conditions. reset is guaranteed to be a logic low or high depending on the device chosen (see ordering information ). reset or reset asserts when v cc is below the reset threshold and for at least 150ms (t rp ) after v cc rises above the reset threshold. reset or reset also asserts when mr is low (max6361) and when reset in is less than 1.235v (max6364). the max6362 watchdog function will cause reset (or reset ) to assert in pulses follow- ing a watchdog timeout (figure 1). applications information operation without a backup power source the max6361?ax6364 were designed for battery- backed applications. if a backup battery is not used, connect v cc to out and connect batt to gnd. replacing the backup battery if batt is decoupled with a 0.1? capacitor to ground, the backup power source can be removed while v cc remains valid without danger of triggering a reset pulse. the device does not enter battery-backup mode when v cc stays above the reset threshold voltage. negative-going v cc transients these supervisors are relatively immune to short-dura- tion, negative-going v cc transients. resetting the ? when v cc experiences only small glitches is usually not desirable. the typical operating characteristics section shows a graph of maximum transient duration vs. reset threshold overdrive for which reset is not asserted. the graph was produced using negative-going v cc pulses, starting at v cc and ending below the reset threshold by the magnitude indicated (reset threshold overdrive). the graph shows the maximum pulse width that a negative-going v cc transient can typically have without triggering a reset pulse. as the amplitude of the transient increases (i.e., goes further below the reset threshold), the maximum allowable pulse width decreases. typically, a v cc transient that goes 100mv below the reset threshold and lasts for 30? will not trigger a reset pulse. a 0.1? bypass capacitor mounted close to the v cc pin provides additional transient immunity. reset wdi t rp t rp t wd t wd = watchdog timeout period t rp = reset timeout period t wd figure 1. max6362 watchdog timeout period and reset active time
max6361?ax6364 watchdog software considerations (max6362 only) to help the watchdog timer monitor software execution more closely, set and reset the watchdog input at dif- ferent points in the program, rather than ?ulsing?the watchdog input low-high-low. this technique avoids a ?tuck?loop, in which the watchdog timer would contin- ue to be reset within the loop, keeping the watchdog from timing out. figure 2 shows an example of a flow diagram where the i/o driving the wdi is set low at the beginning of the program, set high at the beginning of every subroutine or loop, then set low again when the program returns to the beginning. if the program should ?ang?in any subroutine, the problem would quickly be corrected, since the i/o is continually set low and the watchdog timer is allowed to time out, trigger- ing a reset. sot23, low-power ? supervisory circuits with battery backup 8 _______________________________________________________________________________________ start set wdi low return end subroutine or program loop set wdi high figure 2. watchdog flow diagram
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup _______________________________________________________________________________________ 9 aago aagu aagt aags aagr aagv aagg aagf aagw aagq aagn aagp aagh aagl aagi top mark aagj aagm aagk max6364put29* max6364hut29 max6364hut31 max6364hut44 max6364hut46* max6364hut26 max6364lut44 max6364lut46* max6364hut23 max6364put23 max6364put31 max6364put26 max6364lut31 max6364put46* max6364lut29* part max6364lut26 max6364put44 max6364 lut23 aafw aagc aagb aaga aafz aagd aafo aafn aage aafy aafv aafx aafp aaft aafq top mark aafr aafu aafs max6363put29* max6363hut29 max6363hut31 max6363hut44 max6363hut46* max6363hut26 max6363lut44 max6363lut46* max6363hut23 max6363put23 max6363put31 max6363put26 max6363lut31 max6363put46* max6363lut29* part max6363lut26 max6363put44 max6363 lut23 max6362put29* max6362hut29 max6362hut31 max6362hut44 max6362hut46* max6362hut26 max6362lut44 max6362lut46* max6362hut23 max6362put23 max6362put31 max6362put26 max6362lut31 max6362put46* max6362lut29* part max6362lut26 max6362put44 max6362 lut23 max6361hut29 max6361hut31 max6361hut44 max6361hut46* max6361hut26 max6361hut23 max6361put31 max6361put46* max6361put44 max6361put29* max6361lut44 max6361lut46* max6361put23 max6361put26 max6361lut31 max6361lut29* part max6361lut26 max6361 lut23 aafe aafk aafj aafi aafh aafl aaew aaev aafm aafg aafd aaff aaex aafb aaey top mark aaez aafc aafa aaes aaer aaeq aaep aaet aaeu aael aaej aaek aaem aaee aaed aaeo aaen aaef aaeg top mark aaeh aaei *sample stock generally held on standard versions only. contact factory for availability of nonstandard versions. device marking codes reset push- pull reset in reset open drain max6364put_ _ max6364hut_ _ reset open drain max6363 lut_ _ max6363put_ _ max6363hut_ _ max6364 lut_ _ max6361hut_ _ part batt on manual reset input mr max6361put_ _ max6361 lut_ _ max6362 lut_ _ max6362put_ _ max6362hut_ _ watchdog input wdi selector guide
max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup 10 ______________________________________________________________________________________ gnd v cc batt on 16 batt 5 out reset, reset max6363 top view 2 34 gnd v cc reset in 16 batt 5 out reset, reset max6364 2 34 sot23-6 sot23-6 gnd v cc wdi 16 batt 5 out reset, reset max6362 2 34 sot23-6 pin configurations (continued) typical operating circuit bus reset out gnd batt reset in v cc v cc v cc gnd p gnd sram 0.1 f r2 r1 0.1 f reset unregulated dc voltage 3.6v li+ battery 2.4v to 5.5v max6364 chip information process: bicmos package information for the latest package outline information and land patterns (footprints), go to www.maxim-ic.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. package type package code outline no. land pattern no. 6 sot23 u6-1 21-0058 90-0175
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. 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 guidanc e. 11 ____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. max6361?ax6364 sot23, low-power ? supervisory circuits with battery backup revision history revision number revision date description pages changed 0 1/00 initial release 3 11/05 added lead-free information. 1 4 10/11 updated electrical characteristics .2

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