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general description the max6365?ax6368 supervisory circuits simplifypower-supply monitoring, battery-backup control func- tions, and memory write protection in microprocessor (?) systems. the circuits significantly improve the size, accuracy, and reliability of modern systems with an ultra- small integrated solution. these devices perform four basic system functions: 1) provide a ? reset output during v cc supply power- up, power-down, and brownout conditions. 2) internally control v cc to backup-battery switching to maintain data or low-power operation for cmosram, cmos ?s, real-time clocks, and other digital logic when the main supply fails. 3) provide memory write protection through internal chip-enable gating during supply or processor faults. 4) include one of the following options: a manual reset input (max6365), a watchdog timer function(max6366), a battery-on output (max6367), or an auxiliary user-adjustable reset input ( max6368). the max6365?ax6368 operate from v cc supply volt- ages as low as 1.2v. the factory preset reset thresholdvoltages range from 2.32v to 4.63v (see the ordering information ). in addition, each part is offered in three reset output versions: push-pull active low, open-drainactive low, or open-drain active high (see the selector guide ). the max6365?ax6368 are available in minia- ture 8-pin sot23 packages. applications critical ?/? power portable/battery- monitoring powered equipment fax machines set-top boxes industrial control pos equipment computers/controllers 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 ? on-board gating of chip-enable signals, 1.5ns propagation delay ? debounced manual reset input (max6365) ? watchdog timer, 1.6s timeout (max6366) ? battery-on output indicator (max6367) ? auxiliary user-adjustable reset in (max6368) ? low 10 a quiescent supply current ? 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 ? miniature 8-pin sot23 package max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ _____________ maxim integrated products 1 out v cc mr 12 8 7 ce out batt ce in gnd reset, reset sot23 top view 3 4 6 5 max6365 pin configurations 19-1658; rev 5; 10/11 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. ordering information * these parts offer a choice of reset threshold voltages. from the reset threshold ranges table, insert the desired threshold volt- age code in the blank to complete the part number. sot parts come in tape and reel only and must be ordered in 2500-piece increments. see device marking codes for a complete parts list, including sot top marks and standard threshold versions. see selector guide for a listing of device features. devices are available in both leaded and lead(pb)-free packaging. specify lead-free by replacing ?t?with ?t?when ordering. - denotes a package containing lead(pb). t = tape and reel. /v denotes an automotive qualified part. pin configurations continued at end of data sheet. typical operating circuit appears at end of data sheet. part* temp range pin-package m a x6 3 6 5 lk a_ _-t -40? to +85? 8 sot23 max6365pka_ _-t -40? to +85 c 8 sot23 max6365hka_ _-t -40? to +85? 8 sot23 m a x6 3 6 6 lk a_ _-t -40? to +85? 8 sot23 m a x 6 36 6p k a_ _-t -40? to +85? 8 sot23 m a x 6 36 6h k a_ _-t -40? to +85? 8 sot23 m a x6 3 6 7 lk a_ _-t -40? to +85? 8 sot23 m a x 6 36 7p k a_ _-t -40? to +85? 8 sot23 m a x 6 36 7p k a_ _/v-t -40? to +85? 8 sot23 m a x 6 36 7h k a_ _-t -40? to +85? 8 sot23 m a x6 3 6 8 lk a_ _-t -40? to +85? 8 sot23 m a x 6 36 8p k a_ _-t -40? to +85? 8 sot23 m a x 6 36 8h k a_ _-t -40? to +85? 8 sot23 downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 2 __________________________________________________ _____________________________________ absolute maximum ratings electrical characteristics (v cc = +2.4v to +5.5v, v batt = +3.0v, ce in = v cc , reset not asserted, t a = -40? to +85?. 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 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. 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, ce in, ce out ...........................-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 protected for up to 10s reset, reset , batt on, ce out...............................20ma continuous power dissipation (t a = +70?) 8-pin sot23 (derate 8.75mw/? above +70?)........700mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? junction temperature .....................................................+150? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) lead (pb)-free packages..............................................+260? packages containing lead (pb).....................................+240? parameter symbol conditions min typ max units operating voltage range(note 2) v cc , v batt no load 0 5.5 v v cc = 2.8v 10 30 v cc = 3.6v 12 35 supply current(excluding i out ) i cc no load, v cc > v th v cc = 5.5v 15 50 ? t a = +25 c1 supply current in battery- backup mode (excluding i out ) i back v batt = 2.8v, v cc = 0v t a = -40 c to +85 c3 ? t a = +25 c -0.10 +0.02 batt standby current i batt 5.5v > v cc > (v batt + 0.2v) t a = -40 c to +85 c -1.00 +0.05 ? v cc = 4.75v, i out = 150ma 3.1 v cc = 3.15v, i out = 65ma 3.7 v cc to out on-resistance r on v cc = 2.38v, i out = 25ma 4.6 ? v batt = 4.5v, i out = 20ma v batt - 0.2 v batt = 3.0v, i out = 10ma v batt - 0.15 output voltage in battery-backup mode v out v batt = 2.25v, i out = 5ma v batt - 0.15 v power-up 20 battery-switchover threshold (v cc - v batt ) v sw v cc < v th power-down -20 mv max636 _ _ka46 4.50 4.63 4.75 max636 _ _ka44 4.25 4.38 4.50 max636 _ _ka31 3.00 3.08 3.15 max636 _ _ka29 2.85 2.93 3.00 max636 _ _ka26 2.55 2.63 2.70 reset threshold v th max636 _ _ka23 2.25 2.32 2.38 v v cc falling reset delay t rd v cc falling at 10v /ms 20 ? downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ ____________________________________ 3 electrical characteristics (continued) (v cc = +2.4v to +5.5v, v batt = +3.0v, ce in = v cc , reset not asserted, t a = -40? to +85?. typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units reset active timeout period t rp 150 280 ms i sink = 1.6ma, v cc > 2.1v 0.3 v ol reset asserted,v batt = 0v i sink = 100?, v cc > 1.2v 0.4 reset output voltage v oh reset not asserted(max636_l only) i source = 500?, v cc > v th(max) 0.8 ? v cc v v ol reset not asserted i sink = 1.6ma, v cc > v th (max) 0.3 i source = 1ma, v cc > 1.8v 0.7 ? v cc reset output voltage v oh reset not asserted,v batt = 0v (max636_h only)(note 3) i source = 200?, v cc > 1.2v 0.8 ? v cc v re s e t outp ut leakag e c ur r ent i lkg max636_p and max636_h only 1 ? manual reset (max6365 only) v il 0.3 ? v cc mr input voltage v ih 0.7 ? v cc v pullup resistance 20 k ? minimum pulse width 1 s glitch immunity v cc = 3.3v 100 ns mr to reset delay v cc = 3.3v 120 ns watchdog (max6366 only) watchdog timeout period t wd 1.00 1.65 2.25 s minimum wdi input pulse width t wdi 100 ns v il 0.3 ? v cc wdi input voltage v ih 0.7 ? v cc v wdi input current -1.0 1.0 ? batt on (max6367 only) output voltage v ol i sink = 3.2ma, v batt = 2.1v 0.4 v sink current, v cc = 5v 60 ma output short-circuit current source current, v batt > 2v 10 30 100 ? downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 4 _______________________________________________________________________________________ typical operating characteristics (t a = +25?, unless otherwise noted.) 8 10 9 1211 1514 13 16 -40 0 -20 20 40 60 80 supply current vs. temperature (no load) max6365/8-01 temperature ( c) supply current ( a) v cc = 5.0v v batt = 0v 0 0.2 0.60.4 0.8 1.0 1.2 battery supply current (backup mode) vs. temperature max6365/8-02 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 21 43 76 5 8 -40 0 -20 20 40 60 80 batt-to-out on-resistance vs. temperature max6365/8-03 temperature ( c) batt-to-out on-resistance ( ? ) v batt = 5.0v v batt = 2.0v v batt = 2.8v i out = 25ma v cc = 0v electrical characteristics (continued)(v cc = +2.4v to +5.5v, v batt = +3.0v, ce in = v cc , reset not asserted, t a = -40? to +85?. typical values are at t a = +25?, unless otherwise noted.) (note 1) parameter symbol conditions min typ max units reset in (max6368 only) reset in threshold v rth 1.185 1.235 1.285 v reset in leakage current 0.01 25 na reset in to reset delay v od = 50mv, reset in falling 1.5 ? chip-enable gating ce in leakage current reset asserted 1 ? ce in to ce out resistance reset not asserted (note 4) 20 100 ? ce out short-circuit current reset asserted, v ce out = 0v 0.75 2.0 ma v cc = 4.75v 1.5 7 ce in to ce out propagation delay 50 ? source, c load = 6365 50pf v cc = 3.15v 2 9 ns v cc = 5v, v cc > v batt , i source = 100? 0.8 ? v cc ce out output voltage high v cc = 0v, v batt > 2.2v, i source = 1? v batt - 0.1 v reset-to- ce out delay 12 ? 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). note 3: reset is pulled up to out. specifications apply for out = v cc or out = batt. note 4: the chip-enable resistance is tested with v cc = v th(max) and v ce in = v cc /2. downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating _______________________________________________________________________________________ 5 typical operating characteristics (continued) (t a = +25?, unless otherwise noted.) 0 0.40.2 0.80.6 1.21.0 1.4 -40 0 20 -20 40 60 80 v cc to out on-resistance vs. temperature max6365/8-04 temperature (?) v cc to out on-resistance ( ? ) v cc = 3.0v i out = 65ma v cc = 4.5v i out = 150ma v cc = 2.3v i out = 25ma 190 195 205200 210 reset timeout period vs. temperature max6365/8-05 temperature ( c) reset timeout period (ms) -40 20 40 -20 0 60 80 0 3015 7560 45 135120 105 90 max6365/8-06 temperature (?) propagation delay ( s) -40 20 40 -20 0 60 80 v cc to reset propagation delay vs. temperature v cc falling 0.25v/ms 1v/ms 10v/ms 2.0 3.02.5 5.04.5 4.0 3.5 reset threshold vs. temperature max6365/8-07 temperature ( c) threshold (v) -40 20 40 -20 0 60 80 max636_ 46 (v th = 4.63v) max636_ 26 (v th = 2.63v) 11 0 0 10 1000 10,000 maximum transient duration vs. reset threshold overdrive max6365/8-08 reset threshold overdrive v th - v cc (mv) maximum transient duration ( s) 400300 350250 200 0 50 150100 max636_ 26(v th = 2.63v) max636_ 46(v th = 4.63v) reset occursabove curve 0 32 1 54 98 7 6 10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 battery supply current vs. supply voltage max6365/8-09 v cc (v) battery supply current ( a) v th = 2.93v v batt = 2.8v v batt = 2.5v v batt = 2.3v downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 6 __________________________________________________ _____________________________________ 1.234 1.235 1.236 max6368 reset in threshold vs. temperature max6365/8 -10 temperature ( c) v rth (v) -40 20 40 -20 0 60 80 1.0 1.91.6 1.3 2.82.5 2.2 max6368 reset in to reset propagation delay vs. temperature max6365/8-11 temperature ( c) propagation delay ( s) -40 20 40 -20 0 60 80 v od = 50mv 0 1 32 4 5 max6365/8-12 c load (pf) propagation delay (ns) 0 100 50 150 200 chip-enable propagation delay vs. ce out load capacitance v ce in = 0v to v cc driver sourceimpedance = 50 ? v cc = 3v v cc = 5v 0 5 1510 20 25 -40 0 -20 20 40 60 80 max6365/8-13 temperature ( c) ce in to ce out on-resistance ( ? ) ce in to ce out on-resistance vs. temperature v cc = 3.0v v cc = 5.0v v ce in = v cc /2 v batt = 0v 1.0 1.31.2 1.1 1.51.4 1.91.8 1.7 1.6 2.0 -40 -20 0 20 40 60 80 max6365/8-14 temperature ( c) watchdog timeout period (s) max6366 watchdog timeout period vs. temperature v cc = 5.0v v batt = 0v typical operating characteristics (continued) (t a = +25?, unless otherwise noted.) downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ ____________________________________ 7 pin description pin name function reset acti ve- h i g h reset outp ut. re s e t asser ts hi g h conti nuousl y w hen v c c i s b el ow the r eset thr eshol d ( v th ) , m r i s l ow , or re s e t in i s l ow . it asser ts i n p ul ses w hen the inter nal w atchd og ti m es out. re s e t r em ai ns asser ted for the r eset ti m eout p er i od ( t rp ) after v c c r i ses ab ove the r eset thr eshol d , after the m anual r eset i np ut g oes fr om l ow to hi g h, after re s e t in g oes hi g h, or after the w atchd og tr i g g ers a r eset event. re s e t i s an op en- d r ai n acti ve- hi g h r eset outp ut. 1 reset active-low reset output. reset asserts low continuously when v c c is below the reset threshold (v th ), the manual reset input is low, or reset in is low. it asserts low in pulses when the internal watchdog times out. reset remains asserted low for the reset timeout period (t rp ) after v c c rises above the reset threshold, after the manual reset input goes from low to high, after resetin 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. 2 ce in chip-enable input. the input to chip-enable gating circuitry. connect to gnd or out if not used. 3 gnd ground mr max6365 manual-reset input. maintaining logic low on mr asserts a reset. reset output remains asserted as long as mr is low and for the reset timeout period (t rp ) after mr transitions from low to high. leave unconnected, or connect to v cc if not used. mr has an internal 20k pullup to v cc . wdi max6366 watchdog input. if wdi remains high or low for longer than the watchdog timeout period (t w d ), the internal watchdog timer runs out and a reset pulse is triggered for the reset timeout period (t rp ). the internal watchdog clears whenever reset asserts or whenever wdi sees a rising or falling edge (figure 2). batt on max6367 battery-on output. batt on goes high when in battery-backup mode. 4 reset in max6368 reset input. when reset in falls below 1.235v, reset asserts. reset output remains asserted as long as reset in is low and for at least t rp after reset in goes high. 5v cc supply voltage, 1.2v to 5.5v. reset asserts when v c c drops below the reset threshold voltage (v th ). reset remains asserted until v c c rises above v th and for at least t rp after v c c rises above v th . 6 out output. out sources from v c c when not in reset and from the greater of v cc or batt when v c c is below the reset threshold. 7 batt backup-battery input. when v c c falls below the reset threshold, out switches to batt if v batt is 20mv greater than v c c . when v c c rises 20mv above v batt , out switches to v c c . the 40mv hysteresis prevents repeated switching if v cc falls slowly. 8 ce out chip-enable output. ce out goes low only when ce in is low and reset is not asserted. if ce in is low when reset is asserted, ce out will stay low for 12? (typ) or until ce in goes high, whichever occurs first. downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 8 __________________________________________________ _____________________________________ max6365max6366 max6367 max6368 chip-enable output control v cc batt ce in 20k mr (max6365 only) wdi (max6366 only) reset in (max6368 only) reset generator watchdog transition detector watchdog timer 1.235v gnd 1.235v reset(reset) ce out out batt on (max6367 only) detailed description the typical operating circuit shows a typical connec- tion for the max6365?ax6368. out powers the staticrandom-access memory (sram). if v cc is greater than the reset threshold (v th ), or if v cc is lower than v th but higher than v batt , v cc is connected to out. if v cc is lower than v th and v cc is less than v batt , batt is connected to out. out supplies up to 150mafrom v cc . in battery-backup mode, an internal mosfet connects the backup battery to out. the on-resistanceof the mosfet is a function of backup-battery voltage and is shown in the batt-to-out on-resistance vs. temperature graph in the typical operating char- acteristics . chip-enable signal gating the max6365?ax6368 provide internal gating of ce signals to prevent erroneous data from being written to cmos ram in the event of a power failure. during nor-mal operation, the ce gate is enabled and passes all ce transitions. when reset asserts, this path becomes disabled, preventing erroneous data from corruptingthe cmos ram. all of these devices use a series trans- mission gate from ce in to ce out. the 2ns propaga- tion delay from ce in to ce out allows the devices to be used with most ?s and high-speed dsps.during normal operation, ce in is connected to ce out through a low on-resistance transmission gate.this is valid when reset is not asserted. if ce in is high when reset is asserted, ce out remains high regard- less of any subsequent transitions on ce in during the reset event. if ce in is low when reset is asserted, ce out is held low for 12? to allow completion of the read/write oper-ation (figure 1). after the 12? delay expires, the ce functional diagram downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ ____________________________________ 9 out goes high and stays high regardless of any sub-sequent transitions on ce in during the reset event. when ce out is disconnected from ce in, ce out is actively pulled up to out.the propagation delay through the chip-enable circuit- ry depends on both the source impedance of the drive to ce in and the capacitive loading at ce out. the chip-enable propagation delay is production testedfrom the 50% point of ce in to the 50% point of ce out, using a 50 ? driver and 50pf load capacitance. minimize the capacitive load at ce out to minimize propagation delay, and use a low-output-impedancedriver. backup-battery switchover in a brownout or power failure, it may be necessary topreserve the contents of the ram. with a backup bat- tery installed at batt, the max6365?ax6368 auto- matically switch the ram to backup power when v cc falls. the max6367 has a batt on output that goeshigh 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 devices do not power up if the only voltage source is on batt. out only powers up from v cc at startup. manual reset input (max6365 only) many ?-based products require manual reset capabili-ty, allowing the user or external logic circuitry to initiate a reset. for the max6365, a logic low on mr asserts reset. reset remains asserted while mr is low and for a mini- mum of 150ms (t rp ) after it returns high. mr has an inter- nal 20k ? pullup resistor to v cc . this input can be driven with ttl/cmos logic levels or with open-drain/collectoroutputs. connect a normally open momentary switch from mr to gnd to create a manual reset function; exter- nal debounce circuitry is not required. if mr is driven from long cables or the device is used in a noisy environ-ment, connect a 0.1? capacitor from mr to gnd to pro- vide additional noise immunity. figure 1. reset and chip-enable timing v cc or batt reset threshold v th reset ce in ce out reset * t rd t rd t rp t rp if ce in goes high before reset asserts, ce out goes high without delay as ce in goes high. reset-to-ce out delay (12 s) * pin status v cc disconnected from out out connected to batt batt connected to out. current drawn fromthe battery is less than 1 a (at v batt = 2.8v, excluding i out ) when v cc = 0v. reset/ reset asserted batt on high state mr , reset in, ce in, wdi inputs ignored ce out connected to out table 1. input and output status in battery-backup mode downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 10 _________________________________________________ _____________________________________ watchdog input (max6366 only) the watchdog monitors ? activity through the watch-dog input (wdi). if the ? becomes inactive, reset asserts. to use the watchdog function, connect wdi to a bus line or ? i/o line. a change of state (high to low, low to high, or a minimum 100ns pulse) resets the watchdog timer. 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 triggeredfor the reset timeout period (t rp ). the internal watchdog timer clears whenever reset asserts or whenever wdisees a rising or falling edge. if wdi remains in either a high or low state, a reset pulse asserts periodically after every t wd (figure 2). batt on indicator (max6367 only) batt on is a push-pull output that drives high when inbattery-backup mode. batt on typically sinks 3.2ma at 0.1v saturation voltage. in battery-backup mode, this terminal sources approximately 10? from out. use batt on to indicate battery-switchover status or to supply base drive to an external pass transistor for higher current applications (figure 3). reset in comparator (max6368 only) reset in is compared to an internal 1.235v reference.if the voltage at reset in is less than 1.235v, reset asserts. use the reset in comparator as an undervolt- age detector to signal a failing power supply or as a secondary power-supply reset monitor. to program the reset threshold (v rth ) of the secondary power supply, use the following (see typical operating circuit ): v rth = v ref (r1 / r2 + 1) where v ref = 1.235v. to simplify the resistor selection, choose a value for r2 and calculate r1: r1 = r2 [(v rth / v ref ) - 1] since the input current at reset in is 25na (max),large values (up to 1m ? ) can be used for r2 with no significant loss in accuracy. for example, in the typical operating circuit , the max6368 monitors two supply voltages. to monitor the secondary 5v logic or analogsupply 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. themax6365?ax6368 ? 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 logic high, depending on the device chosen (see the 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 (max6365) and when reset in is less than 1.235v (max6368). the max6366 watch-dog function will cause reset (or reset ) to assert in pulses following a watchdog timeout (figure 2). applications information operation without a backup power source the max6365?ax6368 provide battery-backup func-tions. if a backup power source is not used, connect batt to gnd and out to v cc . figure 2. max6366 watchdog timeout period and reset active time reset wdi t rp t rp t wd t wd = watchdog timeout period t rp = reset timeout period t wd downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ ___________________________________ 11 watchdog software considerations one way to help the watchdog timer monitor the soft-ware execution more closely is to set and reset the watchdog at different points in the program rather than pulsing the watchdog input periodically. figure 4 shows a flow diagram in which the i/o driving the watchdog is set low in the beginning of the program, set high at the beginning of every subroutine or loop, and set low again when the program returns to the beginning. if the program should hang in any subrou- tine, the problem would be quickly corrected. replacing the backup battery when v cc is above v th , the backup power source can be removed 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 has a maximum transient duration vs. reset thresholdoverdrive graph 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 neg- ative-going v cc transient can typically have without triggering a reset pulse. as the amplitude of the tran-sient 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 trig-ger a reset pulse. a 0.1? bypass capacitor mounted close to the v cc pin provides additional transient immunity. batt batt on out cmos ram 0.1 f gnd reset ce in ce reset ce out max6367 v cc a0?15 p +2.4v to +5.5v address decode figure 3. max6367 batt on driving an external pass transistor figure 4. watchdog flow diagram start set wdi low return end subroutine or program loop set wdi high downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 12 _________________________________________________ _____________________________________ reset threshold ranges (v) suffix min typ max 46 4.50 4.63 4.75 44 4.25 4.38 4.50 31 3.00 3.08 3.15 29 2.85 2.93 3.00 26 2.55 2.63 2.70 23 2.25 2.32 2.38 part top mark part top mark part top mark max6365lka23 aaam max6366pka23 aabk max6367hka23 aaci max6365lka26 aaal max6366pka26 aabj max6367hka26 aach max6365lka29* aaak max6366pka29* aabi max6367hka29 aacg max6365lka31 aaaj max6366pka31 aabh max6367hka31 aacf max6365lka44 aaai max6366pka44 aabg max6367hka44 aace max6365lka46* aaah max6366pka46* aabf max6367hka46* aacd max6365pka23 aaas max6366hka23 aabq max6368lka23 aaco max6365pka26 aaar max6366hka26 aabp max6368lka26 aacn max6365pka29* aaaq max6366hka29 aabo max6368lka29* aacm max6365pka31 aaap max6366hka31 aabn max6368lka31 aacl max6365pka44 aaao max6366hka44 aabm max6368lka44 aack max6365pka46* aaan max6366hka46* aabl max6368lka46* aacj max6365hka23 aaay max6367lka23 aabw max6368pka23 aacu max6365hka26 aaax max6367lka26 aabv max6368pka26 aact max6365hka29 aaaw max6367lka29* aabu max6368pka29* aacs max6365hka31 aaav max6367lka31 aabt max6368pka31 aacr max6365hka44 aaau max6367lka44 aabs max6368pka44 aacq max6365hka46* aaat max6367lka46* aabr max6368pka46* aacp max6366lka23 aabe max6367pka23 aacc max6368hka23 aada max6366lka26 aabd MAX6367PKA26 aacb max6368hka26 aacz max6366lka29* aabc max6367pka29* aaca max6368hka29 aacy max6366lka31 aabb max6367pka31 aabz max6368hka31 aacx max6366lka44 aaba max6367pka44 aaby max6368hka44 aacw max6366lka46* aaaz max6367pka46* aabx max6368hka46* aacv reset threshold ranges device marking codes * these standard versions are available in small quantities through maxim distribution. sample stock is generally held on standard versions only. contact factory for availability of nonstandard versions. downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating ___________________________________________________ ___________________________________ 13 pin configurations (continued) out v cc wdi 12 8 7 ce out batt ce in gnd reset, reset sot23 top view 3 4 6 5 max6366 out v cc batt on 12 8 7 ce out batt ce in gnd reset, reset sot23 3 4 6 5 max6367 out v cc reset in 12 8 7 ce out batt ce in gnd reset, reset sot23 3 4 6 5 max6368 selector guide part manual reset input watch- dog input batt on reset in reset push- pull reset open-drain reset open-drain chip- enable gating max6365lka__ max6365pka__ max6365hka__ max6366lka__ max6366pka__ max6366hka__ max6367lka__ max6367pka__ max6367hka__ max6368lka__ max6368pka__ max6368hka__ downloaded from: http:///
max6365?ax6368 sot23, low-power ? supervisory circuits with battery backup and chip-enable gating 14 _________________________________________________ _____________________________________ ce in *reset in applies to max6368 only. batt reseti/o out r1r2 cmos ram reset wdi** ce out 0.1 f 0.1 f gnd max6366max6368 v cc address decode real-time clock a0?15 p +2.4v to +5.5v secondary dc voltage reset in* **wdi applies to max6366 only. ce typical operating circuit chip information process: cmos package type package code outline no. land pattern no. 8 sot23 k8sn-1 21-0078 90-0176 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. downloaded from: http:///
sot23, low-power ? supervisory circuits with battery backup and chip-enable gating max6365?ax6368 maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a maxim product. no circuit 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 guidance. 15 ____________________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. revision history revision number revision date description pages changed 4 5/09 added automotive part number to ordering information table 1 5 10/11 updated the electrical characteristics .2 downloaded from: http:///

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