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general description the max971?ax974 and max981?ax984 single/ dual/quad low-voltage comparators feature the lowest power consumption available. these micropower devices draw less than 4? supply current over temperature (max971/max972/max981/max982), and include an internal 1.182v ?% (max971/max973/ MAX974) or ?% (max981?ax984) voltage reference and programmable hysteresis. ideal for 3v or 5v single-supply applications, these devices operate from a single 2.5v to 11v supply (or ?.25v to ?.5v dual supplies), and each comparator? input voltage ranges from the negative supply rail to within 1.3v of the positive supply. the single max971/max981 and the dual max973/ max982/max983 provide a unique, simple method for adding hysteresis without feedback or complicated equations, simply by using the hyst pin plus two resistors. the max971?ax974 and max981?ax984? open- drain outputs permit wire-ored configurations. thanks to an 11v output range and separate gnd pin for the output transistor (max971/MAX974, max981/max984), these devices are ideal for level translators and bipolar to single- ended converters. for similar devices with complementary output stages, see the max921?ax924 (1% reference) and the max931?ax934 (2% reference). features available in ultra-small packages: ucsp (max972) max (max9_1/max9_2/max9_3) ultra-low quiescent current (4a, max) over extended temp range (max971/max981) power supplies: single 2.5v to 11v dual 1.25v to 5.5v input voltage range includes negative supply internal bandgap reference 1.182v 1% (max97_) 1.182v 2% (max98_) 12s propagation delay (10mv overdrive) output has separate gnd pin (max9_1/max9_4) applications max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators ________________________________________________________________________________________ 1 max971 max981 out in+ hyst ref v- gnd v+ 21 4 5 6 8 3 7 in- threshold detector v in typical operating circuit 19-0450; rev 3; 2/03 ordering information continued at end of data sheet. ucsp is a trademark of maxim integrated products, inc. part internal precision reference internal hysteresis package max971 1% yes 8-pin dip/so/?ax max972 none no 8-pin ucsp/ dip/so/?ax max973 1% yes 8-pin dip/so/?ax MAX974 1% no 16-pin dip/so max981 2% yes 8-pin dip/so/?ax max982 2% yes 8-pin dip/so/?ax max983 2% yes 8-pin dip/so/?ax max984 2% no 16-pin dip/so comparators per package 1 2 2 4 1 2 2 4 ordering information 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. part temp range pin-package max971 cpa 0 c to +70 c 8 plastic dip max971csa 0 c to +70 c 8 so max971cua 0 c to +70 c 8 max battery-powered systems threshold detectors window comparators level translators oscillator circuits free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 2 _______________________________________________________________________________________ v+ to v-, v+ to gnd, gnd to v-................................-0.3v, +12v inputs current: in_+, in_-, hyst..............................................20ma voltage: in_+, in_-, hyst ...............(v+ + 0.3v) to (v- - 0.3v) outputs current: ref...................................................................20ma out_ ................................................................50ma voltage: ref ....................................(v+ + 0.3v) to (v- - 0.3v) out_ (max9_1/9_4)..................12v to (gnd - 0.3v) (max9_2/9_3).......................12v to (v- - 0.3v) out_ short-circuit duration ..................................continuous continuous power dissipation (t a = +70 c) 8-bump ucsp (derate 4.7mw/ c above +70 c) ........379mw 8-pin plastic dip (derate 9.09mw/ c above +70 c) ...727mw 8-pin so (derate 5.88mw/ c above +70 c)................471mw 8-pin max (derate 4.1mw/ c above +70 c) .............330mw 16-pin plastic dip (derate 10.53mw/ c above +70 c)..842mw 16-pin so (derate 8.70mw/ c above +70 c) ................696mw operating temperature ranges max97_c_ _/max98_c_ _ ..................................0 c to +70 c max97_e_ _/max98_e_ _ ...............................-40 c to +85 c storage temperature range .............................-65 c to +150 c lead temperature (soldering, 10s) .................................+300 c bump temperature (soldering) reflow ..........................................................................+235 c electrical characteristics 5v operation (v+ = 5v, v- = gnd = 0v, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (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. absolute maximum ratings parameter conditions min typ max units power requirements supply voltage range (note 2) 2.5 11 v output voltage range 0 11 v t a = +25 c 2.5 3.2 max9_1, hyst = ref c/e temp ranges 4 t a = +25 c 2.5 3.2 max972 c/e temp ranges 4 t a = +25 c 3.1 4.5 max982/ max9_3, hyst = ref c/e temp ranges 6 t a = +25 c 5.5 6.5 supply current in+ = in- + 100mv max9_4 c/e temp ranges 8.5 a comparator input offset voltage v cm = 2.5v 10 mv input leakage current (in-, in+) in+ = in- = 2.5v c/e temp ranges 0.01 5 na input leakage current (hyst) max9_1/max982/max9_3 0.02 na input common-mode voltage range v- v+ - 1.3 v common-mode rejection ratio v- to (v+ - 1.3v) 0.1 1.0 mv/v power-supply rejection ratio v+ = 2.5v to 11v 0.1 1.0 mv/v voltage noise 100hz to 100khz 20 v rms hysteresis input voltage range max9_1/max982/max9_3 ref - 0.05 ref v overdrive = 10mv 12 response time (high-to-low transition) t a = +25 c, 100pf load, 1m ? pullup to v+ overdrive = 100mv 4 s response time (low-to-high transition) (note 3) t a = +25 c, 100pf load, 1m ? pullup to v+ 300 s free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators _______________________________________________________________________________________ 3 electrical characteristics 5v operation (continued) (v+ = 5v, v- = gnd = 0v, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) electrical characteristics 3v operation (v+ = 3v, v- = gnd = 0v, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) parameter conditions min typ max units max9_2/max9_3, i out = 1.8ma v- + 0.4 output low voltage max9_1/max9_4, i out = 1.8ma gnd + 0.4 v output leakage current v out = 11v 100 na reference (max9_1/max982/max9_3/max9_4 only) c temp range 1% 1.170 1.182 1.194 max971/max973/ MAX974 e temp range 2% 1.158 1.206 c temp range 2% 1.158 1.182 1.206 reference voltage max981 max984 e temp range 3% 1.147 1.217 v t a = +25 c1525 source current c/e temp ranges 6 a t a = +25 c815 sink current c/e temp ranges 4 a voltage noise 100hz to 100khz 100 v rms parameter conditions min typ max units power requirements t a = +25 c 2.4 3.0 max9_1 c/e temp ranges 3.8 t a = +25 c 2.4 3.0 max972 c/e temp ranges 3.8 t a = +25 c 3.4 4.3 max982/ max9_3 c/e temp ranges 5.8 t a = +25 c 5.2 6.2 supply current hyst = ref, in+ = (in- + 100mv) max9_4 c/e temp ranges 8.0 a comparator input offset voltage v cm = 1.5v 10 mv input leakage current (in-, in+) in+ = in- = 1.5v c/e temp ranges 0.01 5 na input leakage current (hyst) max9_1/max982/max9_3 0.02 na input common-mode voltage range v- v+ - 1.3 v common-mode rejection ratio v- to (v+ - 1.3v) 0.2 1 mv/v power-supply rejection ratio v+ = 2.5v to 11v 0.1 1 mv/v voltage noise 100hz to 100khz 20 v rms hysteresis input voltage range max9_1/max982/max9_3 ref - 0.05 ref v free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 4 _______________________________________________________________________________________ electrical characteristics 3v operation (continued) (v+ = 3v, v- = gnd = 0v, t a = t min to t max , unless otherwise noted. typical values are at t a = +25 c.) (note 1) note 1: the max972ebl is 100% tested at t a = +25 c. temperature limits are guaranteed by design. note 2: MAX974/max984 comparators work below 2.5v; see low-voltage operation section for more details. note 3: low-to-high response time is the result of the 1m ? pullup and the 100pf capacitive load, based on three time constants. a faster response time is achieved with a smaller rc. parameter conditions min typ max units overdrive = 10mv 12 response time (high-to-low transition) t a = +25 c, 100pf load, 1m ? pullup to v+ overdrive = 100mv 4 s response time (low-to-high transition) (note 3) t a = +25 c, 100pf load, 1m ? pullup to v+ 300 s max9_2/max9_3, i out = 0.8ma v- + 0.4 output low voltage max9_1/max9_4, i out = 0.8ma gnd + 0.4 v output leakage current v out = 11v 100 na reference c temp range 1% 1.170 1.182 1.194 max971/max973/ MAX974 e temp range 2% 1.158 1.206 c temp range 2% 1.158 1.182 1.206 reference voltage max981 max984 e temp range 3% 1.147 1.217 v t a = +25 c1525 source current c/e temp ranges 6 a t a = +25 c815 sink current c/e temp ranges 4 a voltage noise 100hz to 100khz 100 v rms free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators _______________________________________________________________________________________ 5 2.0 -60 140 max9_1 supply current vs. temperature 2.5 4.5 max971-4/981-4 toc4 temperature ( c) supply current ( a) 60 3.5 3.0 -20 20 100 4.0 v+ = 5v, v- = - 5v v+ = 3v, v- = 0v v+ = 5v, v- = 0v in+ = in- + 100mv 4.5 1.5 -60 140 max972 supply current vs. temperature 2.0 4.0 max971-4/981-4 toc5 temperature ( c) supply current ( a) 60 3.0 2.5 -20 20 100 3.5 in+ = (in- + 100mv) v+ = 5v, v- = 0v v+ = 3v, v- = 0v v+ = 10v, v- = 0v 4.5 5.0 -60 140 max982/max9_3 supply current vs. temperature 2.0 4.0 max971-4/981-4 toc6 temperature ( c) supply current ( a) 60 3.0 2.5 -20 20 100 3.5 v+ = 5v, v- = 0v v+ = 3v, v- = 0v 10 3 -60 140 max9_4 supply current vs. temperature 4 8 max971-4/981-4 toc7 temperature ( c) supply current ( a) 60 6 5 -20 20 100 7 9 in+ = (in- + 100mv) v+ = 5v, v- = 0v v+ = 3v, v- = 0v v+ = 5v, v- = -5v 10 0.01 1.0 2.0 2.5 max9_4 supply current vs. low supply voltages 0.1 1 max971-4/981-4 toc8 single-supply voltage (v) supply current ( a) 1.5 80 -80 010 30 50 max9_1/max982/max9_3 hysteresis control -40 40 max971-4/981-4 toc9 v ref - v hyst (mv) in+ - in- (v) 20 40 0 60 -60 20 -20 no change output low output high __________________________________________typical operating characteristics (v+ = 5v, v- = gnd = 0v, t a = +25 c, unless otherwise noted.) 0 020 output voltage low vs. load current 0.5 2.5 max971-4/981-4-toc1 load current (ma) v ol (v) 12 1.5 1.0 48 16 2.0 v+ = 5v v+ = 3v 1.155 0 5 15 25 reference output voltage vs. output load current 1.165 1.185 max971-4/981-4 toc2 output load current ( a) reference output voltage (v) 10 20 1.175 1.190 1.160 1.180 1.170 v+ = 5v or v+ = 3v 30 sink source 1.22 1.14 -60 -20 60 140 max971/max973/MAX974 reference voltage vs. temperature 1.16 1.20 max971-4/981-4 toc3 temperature ( c) reference voltage (v) 20 100 1.18 1.21 1.15 1.19 1.17 -40 0 80 40 120 extended temp range commercial temp range free datasheet http:///
ultra-low-power, open-drain, single/dual-supply comparators 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v+ = 5v, v- = gnd = 0v, t a = +25 c, unless otherwise noted.) 1000 1 1.0 2.0 2.2 2.4 response time at low supply voltages (v ohl ) 10 100 max971-4/981-4 toc13 single-supply voltage (v) response time ( s) 1.2 1.4 1.6 1.8 -20mv -100mv r pullup = 10k ? 100 0.1 1.0 2.0 2.5 max9_4 sink current at low supply voltages 1 10 max971-4/981-4 toc14 single-supply voltage (v) current (ma) 1.5 sink current at v out = 0.4v 20 15 0 010 short-circuit sink current vs. supply voltage max971-4/981-4 toc15 total supply voltage (v) sink current (ma) 5 10 5 25 out connected to v+ gnd connected to v- 5.0 0 -0.3 -0.1 0.3 max9_1/max972/max9_4 transfer function 1.0 4.0 max971-4/981-4 toc10 in+ input voltage (mv) output voltage (v) 0.1 3.0 2.0 4.5 0.5 3.5 2.5 1.5 -0.2 0 0.2 100k ? +5v 10k ? v 0 10 f 18 2 0 20 60 100 response time vs. load capacitance 6 14 max971-4/981-4 toc11 load capacitance (nf) response time ( s) 40 80 10 16 4 12 8 v- = 0v v ohl -2 2 10 18 response time for various input overdrives (v ohl ) 0 4 max971-4/981-4 toc12 response time ( s) v out (v) 614 2 0 5 100 3 1 50mv 100mv 20mv 10mv v in (mv) free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators _______________________________________________________________________________________ 7 pin max971/ max981 max972 max982 max973/ max983 dip/so/ max dip/so/ max ucsp dip/so/ max dip/so/ max name function 1 gnd ground. connect to v- for single-supply operation. 2 2 c2 2 2 v- negative supply. connect to gnd for single-supply operation (max9_1). 3 in+ noninverting comparator input 4 in- inverting comparator input 5 5 5 hyst hysteresis input. connect to ref if not used. input voltage range is from v ref to (v ref - 50mv). 6 6 6 ref reference output. 1.182v with respect to v-. 7 7 a2 7 7 v+ positive supply 8 out comparator output. sinks current to gnd. 1 a1 1 1 outa comparator a open-drain output. sinks current to v-. 3 c1 3 3 ina+ noninverting input of comparator a 4b1 ina- inverting input of comparator a 5b3 4 inb- inverting input of comparator b 6c3 4 inb+ noninverting input of comparator b 8 a3 8 8 outb comparator b open-drain output. sinks current to v-. pin description free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 8 _______________________________________________________________________________________ pin description (continued) comparator c open-drain output. sinks current to gnd. outc 16 comparator d open-drain output. sinks current to gnd. outd 15 ground. connect to v- for single-supply operation. gnd 14 noninverting input of comparator d ind+ 13 inverting input of comparator d ind- 12 noninverting input of comparator c inc+ 11 inverting input of comparator c inc- 10 negative supply. connect to ground for single-supply operation. v- 9 reference output. 1.182v with respect to v-. ref 8 noninverting input of comparator b inb+ 7 inverting input of comparator b inb- 6 noninverting input of comparator a ina+ 5 inverting input of comparator a ina- 4 positive supply v+ 3 comparator a open-drain output. sinks current to gnd. outa 2 comparator b open-drain output. sinks current to gnd. outb 1 function name pin MAX974 max984 free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators _______________________________________________________________________________________ 9 detailed description the max971 MAX974/max981 max984 comprise various combinations of a micropower 1.182v reference and micropower comparators. the typical operating circuit shows the max971/max981 configuration, and figures 1a 1d show the max9_2 max9_4 configurations. internal hysteresis in the max9_1, max982, and max9_3 provides the easiest method for implementing hysteresis. it also produces faster hysteresis action and consumes much less current than circuits using external positive feedback. power-supply and input signal ranges this family of devices operates from a single 2.5v to 11v power supply. the max9_1 and max9_4 have a separate ground for the output driver, allowing operation with dual supplies ranging from 1.25v to 5.5v. connect v- to gnd when operating the max9_1 or max9_4 from a single supply. the maximum total supply voltage in this case is still 11v. for proper comparator operation, the input signal can range from the negative supply (v-) to within one volt of the positive supply (v+ - 1v). the guaranteed common- mode input voltage range extends from v- to (v+ - 1.3v). the inputs can be taken above and below the supply rails by up to 300mv without damage. outa v- ina+ ina- outb v+ inb+ inb- max972 1 (a1) 2 (c2) 3 (c1) 4 (b1) 8 (a3) 7 (a2) 6 (c3) 5 (b3) ( ) bumps for the ucsp figure 1a. max972 functional diagram outa v- ina+ inb- outb v+ ref hyst max9_3 1 2 3 4 8 7 6 5 v- figure 1c. max973/max983 functional diagram (window comparator) outa v- ina+ inb+ outb v+ ref hyst max982 1 2 3 4 8 7 6 5 v- figure 1b. max982 functional diagram outa v+ ina- ina+ outd gnd ind+ ind- max9_4 2 3 4 5 15 14 13 12 16 11 10 9 1 6 7 8 outb inb- inb+ ref outc inc+ inc- v- figure 1d. MAX974/max984 functional diagram free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 10 ______________________________________________________________________________________ low-voltage operation: v+ = 1v (max9_4 only) the guaranteed minimum operating voltage is 2.5v (or 1.25v). as the total supply voltage falls below 2.5v, performance degrades and the supply current falls. the reference will not function below about 2.2v, although the comparators will continue to operate with a total supply voltage as low as 1v. while the max9_4 has comparators that may be used at supply voltages below 2v, the max9_1/max9_2/max9_3 may not be used with supply voltages below 2.5v. at low supply voltages, the comparators output sink capability is reduced and the propagation delay increases (see typical operating characteristics ). the useful input voltage range extends from the negative supply to a little under 1v below the positive supply, which is slightly closer to the positive rail than when the device operates from higher supply voltages. test your prototype over the full temperature and supply-voltage range if you anticipate operation below 2.5v. comparator output with 100mv of overdrive, propagation delay is typically 3s. the typical operating characteristics show the propagation delay for various overdrive levels. the open-drain outputs are intended for wire-ored and level-shifting applications. the maximum output voltage is 11v above v-, and may be applied even when no supply voltage is present (v+ = v-). the max9_1 and max9_4 outputs sink current to gnd, making these devices ideal for bipolar to single-ended conversion and level-shifting applications. the negative supply does not affect the output sink current. the positive supply provides gate drive for the output n-channel mosfet and heavily influences the output current capability, especially at low supply voltages (see typical operating characteristics section). the max9_2 and max9_3 have no gnd pin, and their outputs sink current to v-. voltage reference the internal bandgap voltage reference has an output of 1.182v above v-. note that the ref voltage is referenced to v-, not to gnd. its accuracy is 1% (max971/max973/MAX974) or 2% (max981 max984) in the 0 c to +70 c range. the ref output is typically capable of sourcing 25a and sinking 15a. do not bypass the ref output. noise considerations although the comparators have a very high gain, useful gain is limited by noise. this is shown in the transfer function graph (see typical operating characteristics ). as the input voltage approaches the comparator s offset, the output begins to bounce back and forth; this peaks when v in = v os . (the lowpass filter shown on the graph averages out the bouncing, making the transfer function easy to observe.) consequently, the comparator has an effective wideband peak-to-peak noise of around 300v. the voltage reference has peak-to-peak noise approaching 1mv. thus, when a comparator is used with the reference, the combined peak-to-peak noise is about 1mv. this, of course, is much higher than the rms noise of the individual components. take care in your layout to avoid capacitive coupling from any output to the reference pin. crosstalk can significantly increase the actual noise of the reference. thresholds out in- in+ v hb hysteresis band v ref - v hyst figure 2. threshold hysteresis band 7 2 5 6 hyst ref v- v+ r1 r2 max9_1 max982 max9_3 2.5v to 11v i ref figure 3. programming the hyst pin free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators ______________________________________________________________________________________ 11 __________applications information hysteresis hysteresis increases the comparators noise margin by increasing the upper threshold and decreasing the lower threshold (figure 2). hysteresis (max9_1/max982/max9_3) to add hysteresis to the max9_1, max982, or max9_3, connect resistor r1 between ref and hyst, and connect resistor r2 between hyst and v- (figure 3). if no hysteresis is required, connect hyst to ref. when hysteresis is added, the upper threshold increases by the same amount that the lower threshold decreases. the hysteresis band (the difference between the upper and lower thresholds, v hb ) is approximately equal to twice the voltage between ref and hyst. the hyst input can be adjusted to a maximum voltage of ref and to a minimum voltage of (ref - 50mv). the maximum difference between ref and hyst (50mv) will therefore produce a 100mv (max) hysteresis band. use the following equations to determine r1 and r2: where i ref (the current sourced by the reference) should not exceed the ref source capability, and should be significantly larger than the hyst input current. i ref values between 0.1a and 4a are usually appropriate. if 2.4m ? is chosen for r2 (i ref = 0.5a), the equation for r1 and v hb can be approximated as: when hysteresis is obtained in this manner for the max982/max9_3, the same hysteresis applies to both comparators. hysteresis (max972/max9_4) hysteresis can be implemented with any comparator using positive feedback, as shown in figure 4. this approach generally draws more current than circuits using the hyst pin on the max9_1/max982/max9_3, and the high feedback impedance slows hysteresis. in addition, because the output does not source current, any increase in the upper threshold is dependent on the load or pullup resistor on the output. board layout and bypassing power-supply bypass capacitors are not needed if the supply impedance is low, but 100nf bypass capacitors should be used when the supply impedance is high or when the supply leads are long. minimize signal lead lengths to reduce stray capacitance between the input and output that might cause instability. do not bypass the reference output. window detector the max9_3 is ideal for making window detectors (undervoltage/overvoltage detectors). the schematic is shown in figure 5, with component values selected for a 4.5v undervoltage threshold and a 5.5v overvoltage threshold. choose different thresholds by changing the values of r1, r2, and r3. to prevent chatter at the output when the supply voltage is close to a threshold, hysteresis has been added using r4 and r5. taken alone, outa would provide an active-low undervoltage indication, and outb would give an active-low overvoltage indication. wired-oring the two outputs provides an active-high, power-good signal. the design procedure is as follows: 1) choose the required hysteresis level and calculate values for r4 and r5 according to the formulas in the hysteresis (max9_1/max982/max9_3) section. in this example, 5mv of hysteresis has been added at the comparator input (v h = v hb /2). this means that the hysteresis apparent at v in will be larger because of the input resistor divider. r1 (k ) = v (mv) hb ? r1 = v 2 i r2 = 1.182 v 2 i hb ref hb ref () ? ? ? ? ? ? gnd v- v+ max9_4 out r h r pullup v ref v in v+ figure 4. external hysteresis free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 12 ______________________________________________________________________________________ 2) select r1. the leakage current into inb- is normally under 1na, so the current through r1 should exceed 100na for the thresholds to be accurate. r1 values up to about 10m ? can be used, but values in the 100k ? to 1m ? range are usually easier to deal with. in this example, choose r1 = 294k ? . 3) calculate r2 + r3. the overvoltage threshold should be 5.5v when v in is rising. the design equation is as follows: 4) calculate r2. the undervoltage threshold should be 4.5v when v in is falling. the design equation is as follows: 5) calculate r3: choose r3 = 1m ? (1% standard value) 6) verify the resistor values. the equations are as follows, evaluated for the above example: battery switchover circuit the switchover from line-powered dc to a backup battery is often accomplished with diodes. but this simple method is sometimes unacceptable, due to the voltage drop and associated power loss across the diode in series with the battery. figure 6 s circuit replaces the diode with a p-channel mosfet controlled by one of the max9_3 comparator outputs. when the dc wall adapter drops below 4v (determined by r1 and r2), outa goes low, turning on q1. comparator b is used to measure the battery voltage, and gives a low-battery indication when the battery drops below 3.6v. level-shifter figure 7 shows a circuit to shift from bipolar 5v inputs to single-ended 5v outputs. the 10k ? resistors protect the comparator inputs, and do not materially affect the circuit s operation. overvoltage threshold: v (v v ) (r1 r2 r3) r1 5.474v undervoltage threshold : v (v v ) (r1 r2 r3) (r1 + r2) 4.484v where the hysteresis voltage v v r5 r4 oth ref h uth ref h h ref =+ ++ = =? ++ = = . rrrr mk m 3232 1 068 61 9 1 006 ( + ) . . . =? =??? =? rrrr vv v r km k k choose r k s dard value ref h uth 2123 1 294 1 068 1 182 0 005 45 294 62 2 26191 ( + + ) ( ) ( + . ) (. . ) . . . (% ). = ? ? =? ? ? ?? =? =? tan rr r v vv k m oth ref h 231 1 294 55 1 182 0 005 1 1 068 . (. . ) . += + ? ? ? ? ? ? ? =? + ? ? ? ? ? ? ? =? max9_3 inb- ref hyst ina+ 3 5 6 4 1 8 v- 2 v+ 7 1m ? outa outb r5 10k ? r1 294k ? r2 62.2k ? r3 1m ? power good v in v oth = 5.5v v uth = 4.5v r4 2.4m ? 5v figure 5. window detector free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators ______________________________________________________________________________________ 13 max973 max983 v+ 7 3.3v logic supply 10k ? 20k ? 2.4m ? low batt outb 8 ref 6 hyst 5 2 v- r2 47k ? r1 110k ? step-down regulator 3 ina+ 1 outa 4 inb- 1m ? battery (4 cells) 953k ? q1 9v dc wall adapter 470k ? dc ok inb+ inb- inc+ inc- ind+ ind- ina+ ina- 4 5 3 7 6 11 10 13 12 outa 2 1 16 15 8 outb outc outd 9 14 10k ? v+ gnd MAX974 max984 5v 3.3v 10k ? 10k ? 10k ? ref v- n.c. -5v v ina v inb v inc v ind figure 6. battery switchover circuit figure 7. level shifter: ?v input to single-ended 3.3v output ucsp applications information for the latest application details on ucsp contruction, dimensions, tape carrier information, printed circuit board techniques, bump-pad layout and recommended reflow temperature profile as well as the latest information on reliability testing results, go to maxim s web site at www.maxim-ic.com/ucsp to find the application note: ucsp? wafer-level chip-scale package . free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 14 ______________________________________________________________________________________ 1 2 3 4 out v+ ref hyst in- in+ v- gnd max971 max981 dip/so/ max top view dip/so/ max dip/so/ max 8 7 6 5 1 2 3 4 outb v+ inb+ inb- ina- ina+ v- outa max972 8 7 6 5 1 2 3 4 outb v+ ref hyst inb+ ina+ v- outa max982 8 7 6 5 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 outc outd gnd ind+ ina- v+ outa outb MAX974 max984 ind- inc+ inc- v- ref inb+ inb- ina+ dip/narrow so 1 2 3 4 outb v+ ref hyst inb- ina+ v- outa max973 max983 dip/so/ max 8 7 6 5 top view (bumps on bottom) a b c 12 3 outa v+ outb ina- inb- inb+ v- ina+ ucsp max972 pin configurations free datasheet http:///
max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators ______________________________________________________________________________________ 15 *ucsp top mark is ?bc. ordering information (continued) part temp range pin-package max971epa -40 c to +85 c 8 plastic dip max971esa -40 c to +85 c 8 so max972 cpa 0 c to +70 c 8 plastic dip max972csa 0 c to +70 c 8 so max972cua 0 c to +70 c 8 max max972ebl-t* -40 c to +85 c 8 ucsp-8 max972epa -40 c to +85 c 8 plastic dip max972esa -40 c to +85 c 8 so max973 cpa 0 c to +70 c 8 plastic dip max973csa 0 c to +70 c 8 so max973cua 0 c to +70 c 8 max max973epa -40 c to +85 c 8 plastic dip max973esa -40 c to +85 c 8 so MAX974 cpe 0 c to +70 c 16 plastic dip MAX974cse 0 c to +70 c 16 narrow so MAX974epe -40 c to +85 c 16 plastic dip MAX974ese -40 c to +85 c 16 narrow so max981 cpa 0 c to +70 c 8 plastic dip part temp range pin-package max981csa 0 c to +70 c 8 so max981cua 0 c to +70 c 8 max max981epa -40 c to +85 c 8 plastic dip max981esa -40 c to +85 c 8 so max982 cpa 0 c to +70 c 8 plastic dip max982csa 0 c to +70 c 8 so max982cua 0 c to +70 c 8 max max982epa -40 c to +85 c 8 plastic dip max982esa -40 c to +85 c 8 so max983 cpa 0 c to +70 c 8 plastic dip max983csa 0 c to +70 c 8 so max983cua 0 c to +70 c 8 max max983epa -40 c to +85 c 8 plastic dip max983esa -40 c to +85 c 8 so max984 cpe 0 c to +70 c 16 plastic dip max984cse 0 c to +70 c 16 narrow so max984epe -40 c to +85 c 16 plastic dip max984ese -40 c to +85 c 16 narrow so max971/max972/max973/max981/max982/max984 transistor count: 164 MAX974/max984 transistor count: 267 ___________________chip information free datasheet http:///
soicn .eps package outline, .150" soic 1 1 21-0041 b rev. document control no. approval proprietary information title: top view front view max 0.010 0.069 0.019 0.157 0.010 inches 0.150 0.007 e c dim 0.014 0.004 b a1 min 0.053 a 0.19 3.80 4.00 0.25 millimeters 0.10 0.35 1.35 min 0.49 0.25 max 1.75 0.050 0.016 l 0.40 1.27 0.394 0.386 d d mindim d inches max 9.80 10.00 millimeters min max 16 ac 0.337 0.344 ab 8.75 8.55 14 0.189 0.197 aa 5.004.80 8 n ms012 n side view h 0 .2440.228 5.80 6.20 e 0 .050 bsc 1.27 bsc c h e e b a1 a d 0-8 l 1 variations: max971?ax974/max981?ax984 ultra-low-power, open-drain, single/dual-supply comparators 16 ______________________________________________________________________________________ 8lumaxd.eps package outline, 8l umax/usop 1 1 21-0036 j rev. document control no. approval proprietary information title: max 0.043 0.006 0.014 0.120 0.120 0.198 0.026 0.007 0.037 0.0207 bsc 0.0256 bsc a2 a1 c e b a l front view side view e h 0.60.1 0.60.1 ? 0 .500.1 1 top view d 8 a2 0.030 bottom view 1 6 s b l h e d e c 0 0.010 0.116 0.116 0.188 0.016 0.005 8 4x s inches - a1 a min 0.002 0.950.75 0.5250 bsc 0.25 0.36 2.95 3.05 2.95 3.05 4.78 0.41 0.65 bsc 5.03 0.66 6 0 0.13 0.18 max min millimeters - 1.10 0.05 0.15 dim package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) free datasheet http:///
max971?ax974/max981?ax984 ultra low-power, open-drain, single/dual-supply comparators 9lucsp, 3x3.eps package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline information, go to www.maxim-ic.com/packages .) pdipn.eps 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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 17 ? 2003 maxim integrated products printed usa is a registered trademark of maxim integrated products. free datasheet http:///

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