general description the max6314 low-power cmos microprocessor (?) supervisory circuit is designed to monitor power supplies in ? and digital systems. the max6314? reset output is bidirectional, allowing it to be directly connected to ?s with bidirectional reset inputs, such as the 68hc11. it provides excellent circuit reliability and low cost by eliminating external components and adjustments. the max6314 also provides a debounced manual reset input. this device performs a single function: it asserts a reset signal whenever the v cc supply voltage falls below a preset threshold or whenever manual reset is asserted. reset remains asserted for an internally programmed interval (reset timeout period) after v cc has risen above the reset threshold or manual reset is deasserted. the max6314 comes with factory-trimmed reset threshold voltages in 100mv increments from 2.5v to 5v. preset timeout periods of 1ms, 20ms, 140ms, and 1120ms (minimum) are also available. the device comes in a sot143 package. for a ? supervisor with an open-drain reset pin, see the max6315 data sheet. ________________________applications computers controllers intelligent instruments critical ? and ? power monitoring portable/battery-powered equipment features ? small sot143 package ? reset output simplifies interface to bidirectional reset i/os ? precision factory-set v cc reset thresholds: 100mv increments from 2.5v to 5v ? ?.8% reset threshold accuracy at t a = +25? ? ?.5% reset threshold accuracy over temp. ? four reset timeout periods available: 1ms, 20ms, 140ms, or 1120ms (minimum) ? immune to short v cc transients ? 5? supply current ? pin-compatible with max811 max6314 68hc11/bidirectional-compatible p reset circuit ________________________________________________________________ maxim integrated products 1 1 2 4 3 v cc mr reset gnd max6314 sot143 top view pin configuration max6314 v cc v cc gnd reset p reset mr laser- trimmed resistors v cc 4.7k? 68hc11** **or other c/p with bidirectional reset i/o pin. reset circuitry t ypical operating circuit 19-1090; rev 2; 12/05 ordering information continued at end of data sheet. *p 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. ordering information part ? nominal v th (v) min t rp (ms) top mark ?? max6314us50d1-t 5.00 1 aa_ _ max6314us49d1-t 4.90 1 ab_ _ max6314us48d1-t 4.80 1 ac_ _ max6314us47d1-t 4.70 1 ad_ _ max6314us46d1-t 4.63 1 ae_ _ max6314us45d1-t 4.50 1 af_ _ ? the max6314 is available in a sot143 package, -40? to +85? temperature range. ?? the first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code. devices are available in both leaded and lead-free packaging. specify lead-free by replacing ?t?with ?t?when ordering.
v max6314 68hc11/bidirectional-compatible p reset circuit 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = +2.5v to +5.5v, t a = -40? 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 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. note 1: the max6314 monitors v cc through an internal, factory-trimmed voltage divider that programs the nominal reset threshold. factory-trimmed reset thresholds are available in 100mv increments from 2.5v to 5v (see ordering and marking information ). note 2: this is the minimum time reset must be held low by an external pull-down source to set the active pull-up flip-flop. note 3: measured from reset v ol to (0.8 x v cc ), r load = . v cc ........................................................................-0.3v to +6.0v all other pins..............................................-0.3v to (v cc + 0.3v) input current (v cc ) .............................................................20ma output current (reset) ......................................................20ma rate of rise (v cc ) ...........................................................100v/? continuous power dissipation (t a = +70?) sot143 (derate 4mw/? above +70?) .......................320mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +160? lead temperature (soldering, 10sec) .............................+300? t a = +25? v cc = 5.5v, no load t a = 0? to +70? v th > 4.0v v cc = falling at 1mv/? max6314us_ _d1-t v cc > 4.25v, i sink = 3.2ma conditions v 0.4 v ol reset output voltage k? 32 63 100 mr pullup resistance v th - 1.8% v th v th + 1.8% v th reset threshold (note 1) ? 512 i cc v 1.0 5.5 v cc operating voltage range v cc supply current ns 500 mr to reset delay ns 100 mr glitch rejection ? 1 mr minimum input pulse v 0.8 v il mr input threshold ppm/? 60 ? v th /? reset threshold tempco ? 35 v cc to reset delay ms 1 1.4 2 t rp reset timeout period units min typ max symbol parameter v il v ih v ih v cc = 3.6v, no load t a = -40? to +85? v th < 4.0v max6314us_ _d3-t max6314us_ _d2-t max6314us_ _d4-t v cc > 1.2v, i sink = 0.5ma v cc > 2.5v, i sink = 1.2ma v cc > 1.0v, i sink = 80? 410 v th - 2.5% v th + 2.5% 1120 1570 2240 140 200 280 20 28 40 0.3 x v cc 2.4 0.7 x v cc 0.3 0.3 0.3 v ns 400 t s transition flip-flop setup time (note 2) v cc = 5v v cc = 5v ma 20 reset active pullup current v 0.4 0.9 active pullup enable threshold v cc = 3v ns 333 k? 4.2 4.7 5.2 reset pullup resistance 333 666 v cc = 5v 666 t r reset output rise time (note 3) c load = 120pf c load = 250pf c load = 200pf c load = 400pf manual reset input reset internal pullup
max6314 68hc11/bidirectional-compatible p reset circuit _______________________________________________________________________________________ 3 __________________________________________typical operating characteristics (t a = +25?, unless otherwise noted.) 4.7k? pull-up 2v/div max6314 pull-up 2v/div input 5v/div 200ns/div pullup characteristics max6314-01 100pf 4.7k? +5v 74hc05 74hc05 v cc gnd mr 100pf +5v reset max6314 6 0 -50 -30 30 90 supply current vs. temperature 2 1 5 max6314-02 temperature (?) supply current (a) -10 10 50 3 4 70 v cc = 5v v cc = 3v v cc = 1v 6 0 0 1 35 supply current vs. supply voltage 2 1 5 max6314-03 supply voltage (v) supply current ( a) 2 3 4 4 t a = -40? t a = +25? t a = +85? 50 0 -50 -30 10 90 power-down reset delay vs. temperature 10 40 max6314-04 temperature (?) power-down reset delay ( s) -10 20 30 30 50 70 v cc falling at 1mv/ s v th = 4.63v v th = 3.00v 1.04 0.96 -50 -30 10 90 normalized reset timeout period vs. temperature (v cc rising) 0.97 0.98 1.02 1.00 1.03 max6314-05 temperature (?) normalized reset timeout period -10 0.99 1.01 30 50 70 1.006 0.994 -50 -30 10 90 normalized reset threshold vs. temperature (v cc falling) 0.996 0.998 1.004 1.000 max6314-06 temperature (?) normalized reset threshold -10 1.002 30 50 70 100 0 10 100 1000 maximum transient duration vs. reset comparator overdrive 20 max6314-07 reset comp. overdrive, v th - v cc (mv) maximum transient duration ( s) 40 60 80 t a = +25? reset occurs above curve v th = 4.63v v th = 3.00v 600 0 -50 -30 10 90 reset pullup time vs. temperature 100 200 500 300 max6314-08 temperature ( c) reset pull-up-time (ns) -10 400 30 50 70 c l = 390pf c l = 100pf
figure 1. functional diagram max6314 68hc11/bidirectional-compatible p reset circuit 4 _______________________________________________________________________________________ ______________________________________________________________pin description supply voltage and reset threshold monitor input v cc 4 manual reset input. a logic low on mr asserts reset. reset remains asserted as long as mr is low, and for the reset timeout period (t rp ) after the reset conditions are terminated. connect to v cc if not used. mr 3 pin active-low complementary output. in addition to the normal n-channel pulldown, reset has a p-channel pullup transistor in parallel with a 4.7k ? resistor to facilitate connection to ?s with bidirectional resets. see the reset output section. reset 2 ground gnd 1 function name v cc max6314 laser- trimmed resistors vref v cc 63k? mr reset generator 2s one-shot transition flip-flop rq s ff v cc 4.7k? reset active pullup enable comparator 0.5v gnd
max6314 68hc11/bidirectional-compatible p reset circuit _______________________________________________________________________________________ 5 detailed description the max6314 has a reset output consisting of a 4.7k ? pull-up resistor in parallel with a p-channel transistor and an n-channel pull down (figure 1), allowing this ic to directly interface with microprocessors (?s) that have bidirectional reset pins (see the reset output section). reset output a ?? reset input starts the ? in a known state. the max6314 asserts reset to prevent code-execution errors during power-up, power-down, or brownout conditions. reset is guaranteed to be a logic low for v cc > 1v (see the electrical characteristics table). once v cc exceeds the reset threshold, the internal timer keeps reset asserted for the reset timeout period (t rp ); after this interval reset goes high. if a brownout condition occurs (monitored voltage dips below its pro- grammed reset threshold), reset goes low. any time v cc dips below the reset threshold, the internal timer resets to zero and reset goes low. the internal timer starts when v cc returns above the reset threshold, and reset remains low for the reset timeout period. the max6314? reset output is designed to interface with ?s that have bidirectional reset pins, such as the motorola 68hc11. like an open-drain output, the max6314 allows the ? or other devices to pull reset low and assert a reset condition. however, unlike a standard open-drain output, it includes the commonly specified 4.7k ? pullup resistor with a p-channel active pullup in parallel. this configuration allows the max6314 to solve a prob- lem associated with ?s that have bidirectional reset pins in systems where several devices connect to reset . these ?s can often determine if a reset was asserted by an external device (i.e., the supervisor ic) or by the ? itself (due to a watchdog fault, clock error, or other source), and then jump to a vector appropriate for the source of the reset. however, if the ? does assert reset, it does not retain the information, but must determine the cause after the reset has occurred. the following procedure describes how this is done with the motorola 68hc11. in all cases of reset, the ? pulls reset low for about four e-clock cycles. it then releases reset , waits for two e-clock cycles, then checks reset ? state. if reset is still low, the ? con- cludes that the source of the reset was external and, when reset eventually reaches the high state, jumps to the normal reset vector. in this case, stored state information is erased and processing begins from scratch. if, on the other hand, reset is high after the two e-clock cycle delay, the processor knows that it caused the reset itself and can jump to a different vec- tor and use stored state information to determine what caused the reset. the problem occurs with faster ?s; two e-clock cycles is only 500ns at 4mhz. when there are several devices on the reset line, the input capacitance and stray capacitance can prevent reset from reaching the logic-high state (0.8 x v cc ) in the allowed time if only a passive pullup resistor is used. in this case, all resets will be interpreted as external. the ? is guaranteed to sink only 1.6ma, so the rise time cannot be much reduced by decreasing the recommended 4.7k ? pullup resistance. the max6314 solves this problem by including a pullup transistor in parallel with the recommended 4.7k ? resis- tor (figure 1). the pullup resistor holds the output high until reset is forced low by the ? reset i/o, or by the max6314 itself. once reset goes below 0.5v, a com- parator sets the transition edge flip-flop, indicating that the next transition for reset will be low to high. as soon as reset is released, the 4.7k ? resistor pulls reset up toward v cc . when reset rises above 0.5v, the active p-channel pullup turns on for the 2 s duration of the one-shot. the parallel combination of the 4.7k ? pullup and the p-channel transistor on- resistance quickly charges stray capacitance on the reset line, allowing reset to transition low to high with- in the required two e-clock period, even with several devices on the reset line (figure 2). once the one-shot times out, the p-channel transistor turns off. this process occurs regardless of whether the reset was caused by v cc dipping below the reset threshold, mr being asserted, or the ? or other device asserting reset. because the max6314 includes the standard 4.7k ? pullup resistor, no external pullup resistor is required. to minimize current consumption, the internal pullup resistor is disconnected whenever the max6314 asserts reset . manual reset input many ?-based products require manual reset capabil- ity, allowing the operator, a test technician, or external logic circuitry to initiate a reset. a logic low on mr asserts reset. reset remains asserted while mr is low, and for the reset active timeout period after mr returns high. to minimize current consumption, the internal 4.7k ? pullup resistor on reset is disconnected whenever reset is asserted.
max6314 68hc11/bidirectional-compatible p reset circuit 6 _______________________________________________________________________________________ mr has an internal 63k ? pullup resistor, so it can be left open if not used. connect a normally open momen- tary 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 if the device is used in a noisy environment, connecting a 0.1? capacitor from mr to ground provides additional noise immunity. __________applications information negative-going v cc transients in addition to issuing a reset to the ? during power-up, power-down, and brownout conditions, these devices are relatively immune to short-duration negative-going transients (glitches). the typical operating character- istics show the maximum transient duration vs. reset threshold overdrive, for which reset pulses are not generated. the graph was produced using negative- going pulses, starting at v rst max and ending below the programmed reset threshold by the magnitude indicated (reset threshold overdrive). the graph shows the maximum pulse width that a negative-going v cc transient may typically have without causing a reset pulse to be issued. as the amplitude of the transient increases (i.e., goes farther below the reset threshold), the maximum allowable pulse width decreases. a 0.1? bypass capacitor mounted close to v cc provides addi- tional transient immunity. ensuring a valid reset output down to v cc = 0v when v cc falls below 1v, reset no longer sinks current?t becomes an open circuit. therefore, high- impedance cmos-logic inputs connected to reset can drift to undetermined voltages. this presents no problem in most applications, since most ? and other circuitry is inoperative with v cc below 1v. however, in applications where reset must be valid down to v cc = 0v, adding a pull-down resistor to reset will cause any stray leakage currents to flow to ground, holding reset low (figure 3). r1? value is not critical; 100k ? is large enough not to load reset and small enough to pull reset to ground. figure 2. max6314 supports additional devices on the reset bus 4.7k? mr c in reset reset circuitry v cc max6314 c stray 68hc11 reset circuitry c in reset v cc other devices c in reset figure 3. reset valid to v cc = ground circuit max6314 v cc gnd reset r1
max6314 68hc11/bidirectional-compatible p reset circuit _______________________________________________________________________________________ 7 figure 4. reset timing diagram t r t s reset reset pulled low by c or reset generator active pull-up turns on v cc 0.5v 0.8 x v cc t rp or c reset delay ? the max6314 is available in a sot143 package, -40? to +85? temperature range. ?? the first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code. ??? sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities. non-bolded products have 10,000 piece minimum-order quantities. contact factory for details. devices are available in both leaded and lead-free packaging. specify lead-free by replacing ?t?with ?t?when ordering. note: all devices available in tape-and-reel only. contact factory for availability. ___________________________________________ordering information (continued) part ? nominal v th (v) min t rp (ms) top mark ?? max6314us44d1-t ??? 4.39 1 ag_ _ max6314us43d1-t 4.30 1 ah_ _ max6314us42d1-t 4.20 1 ai_ _ max6314us41d1-t 4.10 1 aj_ _ MAX6314US40D1-T 4.00 1 ak_ _ max6314us39d1-t 3.90 1 al_ _ max6314us38d1-t 3.80 1 ca_ _ max6314us37d1-t 3.70 1 cb_ _ max6314us36d1-t 3.60 1 cc_ _ max6314us35d1-t 3.50 1 cd_ _ max6314us34d1-t 3.40 1 ce_ _ max6314us33d1-t 3.30 1 cf_ _ max6314us32d1-t 3.20 1 cg_ _ max6314us31d1-t 3.08 1 ch_ _ max6314us30d1-t 3.00 1 ci_ _ max6314us29d1-t 2.93 1 cj_ _ max6314us28d1-t 2.80 1 ck_ _ max6314us27d1-t 2.70 1 cl_ _ max6314us26d1-t ??? 2.63 1 cm_ _ part ? nominal v th (v) min t rp (ms) top mark ?? max6314us25d1-t 2.50 1 cn_ _ max6314us50d2-t 5.00 20 co_ _ max6314us49d2-t 4.90 20 cp_ _ max6314us48d2-t 4.80 20 cq_ _ max6314us47d2-t 4.70 20 cr_ _ max6314us46d2-t 4.63 20 cs_ _ max6314us45d2-t 4.50 20 ct_ _ max6314us44d2-t ??? 4.39 20 cu_ _ max6314us43d2-t 4.30 20 cv_ _ max6314us42d2-t 4.20 20 cw_ _ max6314us41d2-t 4.10 20 cx_ _ max6314us40d2-t 4.00 20 cy_ _ max6314us39d2-t 3.90 20 cz_ _ max6314us38d2-t 3.80 20 da_ _ max6314us37d2-t 3.70 20 db_ _ max6314us36d2-t 3.60 20 dc_ _ max6314us35d2-t 3.50 20 dd_ _ max6314us34d2-t 3.40 20 de_ _ max6314us33d2-t 3.30 20 dj_ _
max6314 68hc11/bidirectional-compatible p reset circuit 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. 8 _____________________maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 2005 maxim integrated products printed usa is a registered trademark of maxim integrated products, inc. _____________________________ordering and marking information (continued) ? the max6314 is available in a sot143 package, -40? to +85? temperature range. ?? the first two letters in the package top mark identify the part, while the remaining two letters are the lot tracking code. ??? sample stocks generally held on the bolded products; also, the bolded products have 2,500 piece minimum-order quantities. non-bolded products have 10,000 piece minimum-order quantities. contact factory for details. devices are available in both leaded and lead-free packaging. specify lead-free by replacing ?t?with ?t?when ordering. note: all devices available in tape-and-reel only. contact factory for availability. chip information transistor count: 519 part ? nominal v th (v) min t rp (ms) top mark ?? max6314us32d2-t 3.20 20 dk_ _ max6314us31d2-t 3.08 20 dl_ _ max6314us30d2-t 3.00 20 dm_ _ max6314us29d2-t 2.93 20 dn_ _ max6314us28d2-t 2.80 20 do_ _ max6314us27d2-t 2.70 20 dp_ _ max6314us26d2-t ??? 2.63 20 dq_ _ max6314us25d2-t 2.50 20 dr_ _ max6314us50d3-t 5.00 140 ds_ _ max6314us49d3-t 4.90 140 dt_ _ max6314us48d3-t 4.80 140 du_ _ max6314us47d3-t 4.70 140 dv_ _ max6314us46d3-t ??? 4.63 140 dw_ _ max6314us45d3-t 4.50 140 dx_ _ max6314us44d3-t ??? 4.39 140 dy_ _ max6314us43d3-t 4.30 140 dz_ _ max6314us42d3-t 4.20 140 ea_ _ max6314us41d3-t 4.10 140 eb_ _ max6314us40d3-t 4.00 140 ec_ _ max6314us39d3-t 3.90 140 eg_ _ max6314us38d3-t 3.80 140 eh_ _ max6314us37d3-t 3.70 140 ei_ _ max6314us36d3-t 3.60 140 ej_ _ max6314us35d3-t 3.50 140 ek_ _ max6314us34d3-t 3.40 140 el_ _ max6314us33d3-t 3.30 140 em_ _ max6314us32d3-t 3.20 140 en_ _ max6314us31d3-t ??? 3.08 140 eo_ _ max6314us30d3-t 3.00 140 ep_ _ max6314us29d3-t ??? 2.93 140 es_ _ part ? nominal v th (v) min t rp (ms) top mark ?? max6314us28d3-t 2.80 140 et_ _ max6314us27d3-t 2.70 140 eu_ _ max6314us26d3-t ??? 2.63 140 ev_ _ max6314us25d3-t 2.50 140 ew_ _ max6314us50d4-t 5.00 1120 ex_ _ max6314us49d4-t 4.90 1120 ey_ _ max6314us48d4-t 4.80 1120 ez_ _ max6314us47d4-t 4.70 1120 fa_ _ max6314us46d4-t 4.63 1120 fb_ _ max6314us45d4-t 4.50 1120 fc_ _ max6314us44d4-t ??? 4.39 1120 fd_ _ max6314us43d4-t 4.30 1120 fe_ _ max6314us42d4-t 4.20 1120 ff_ _ max6314us41d4-t 4.10 1120 fg_ _ max6314us40d4-t 4.00 1120 fh_ _ max6314us39d4-t 3.90 1120 fi_ _ max6314us38d4-t 3.80 1120 fj_ _ max6314us37d4-t 3.70 1120 fk_ _ max6314us36d4-t 3.60 1120 fl_ _ max6314us35d4-t 3.50 1120 fm_ _ max6314us34d4-t 3.40 1120 fn_ _ max6314us33d4-t 3.30 1120 fo_ _ max6314us32d4-t 3.20 1120 fp_ _ max6314us31d4-t 3.08 1120 fq_ _ max6314us30d4-t 3.00 1120 fr_ _ max6314us29d4-t 2.93 1120 fs_ _ max6314us28d4-t 2.80 1120 ft_ _ max6314us27d4-t 2.70 1120 fu_ _ max6314us26d4-t ??? 2.63 1120 fv_ _ max6314us25d4-t 2.50 1120 fw_ _ package information for the latest package outline information, go to www.maxim-ic.com/packages .
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