View MAX920_8134598.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

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. general description the max917?ax920 nanopower comparators in space-saving sot23 packages feature beyond-the- rails inputs and are guaranteed to operate down to +1.8v. the max917/max918 feature an on-board 1.245v ?.5% reference and draw an ultra-low supply current of only 750na, while the max919/MAX920 (with- out reference) require just 380na of supply current. these features make the max917?ax920 family of comparators ideal for all 2-cell battery applications, including monitoring/management. the unique design of the output stage limits supply-cur- rent surges while switching, virtually eliminating the supply glitches typical of many other comparators. this design also minimizes overall power consumption under dynamic conditions. the max917/max919 have a push-pull output stage that sinks and sources current. large internal output drivers allow rail-to-rail output swing with loads up to 8ma. the max918/MAX920 have an open-drain output stage that makes them suit- able for mixed-voltage system design. applications 2-cell battery monitoring/management ultra-low-power systems mobile communications notebooks and pdas threshold detectors/discriminators sensing at ground or supply line telemetry and remote systems medical instruments features ? ultra-low supply current 380na per comparator (max919/MAX920) 750na per comparator with reference (max917/max918) ? guaranteed to operate down to +1.8v ? internal 1.245v ?.5% reference (max917/max918) ? input voltage range extends 200mv beyond-the-rails ? cmos push-pull output with ?ma drive capability (max917/max919) ? open-drain output versions available (max918/MAX920) ? crowbar-current-free switching ? internal hysteresis for clean switching ? no phase reversal for overdriven inputs ? space-saving sot23 package max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference ________________________________________________________________ maxim integrated products 1 v ee in- (ref) in+ 1 5 v cc out max917 max918 max919 MAX920 sot23-5 top view 2 3 4 ( ) are for max917/max918. part pin-package top mark pkg code max917 euk-t 5 sot23-5 adiq u5-1 max917esa 8 so s8-4 max918 euk-t 5 sot23-5 adir u5-1 max918esa 8 so s8-4 max919 euk-t 5 sot23-5 adis u5-1 max919esa 8 so s8-4 MAX920 euk-t 5 sot23-5 adit u5-1 MAX920esa 8 so s8-4 pin configurations continue at end of data sheet. typical application circuit appears at end of data sheet. pin configurations selector guide ordering information open-drain yes max918 750 380 380 750 supply current (na) open-drain no MAX920 part push-pull no max919 push-pull yes max917 output type internal reference beyond-the-rails is a trademark of maxim integrated products, inc. 19-1512; rev 1; 1/07 note: all devices are specified over the -40? to +85? operating temperature range.
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics?ax917/max918 (v cc = +5v, v ee = 0v, v in+ = v ref , t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (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. supply voltage (v cc to v ee )..................................................+6v voltage inputs (in+, in-, ref) .........(v ee - 0.3v) to (v cc + 0.3v) current into input pins......................................................?0ma output voltage max917/max919 ........................(v ee - 0.3v) to (v cc + 0.3v) max918/MAX920 ......................................(v ee - 0.3v) to +6v output current..................................................................?0ma output short-circuit duration .............................................10sec continuous power dissipation (t a = +70?) 5-pin sot23 (derate 7.31mw/? above +70?).........571mw 8-pin so (derate 5.88mw/? above +70?)...............471mw operating temperature range ...........................-40? to +85? storage temperature range .............................-65? to +150? lead temperature (soldering, 10sec) .............................+300? v cc = 1.8v v cc = 1.8v v cc = 5v v cc = 1.8v v cc = 5v output-voltage swing low v ol 190 400 mv 500 55 200 t a = t min to t max t a = +25? 300 v cc = 5v, i sink = 8ma t a = t min to t max v cc = 1.8v, i sink = 1ma t a = +25? t a = t min to t max t a = +25? t a = t min to t max t a = +25? t a = t min to t max t a = +25? t a = t min to t max t a = +25? t a = t min to t max t a = +25? parameter symbol min typ max units 10 input offset voltage v os 15 mv in+ voltage range v in+ v ee - 0.2 v cc + 0.2 v 1.60 input-referred hysteresis v hb 4 mv input bias current i b 0.15 1 na 2 power-supply rejection ratio psrr 0.1 1 mv/v supply current supply voltage range v cc 1.8 5.5 v i cc 0.75 ? 0.80 1.30 output-voltage swing high v cc - v oh 190 400 mv 500 55 200 300 output leakage current i leak 0.001 1 ? output short-circuit current i sc 95 ma 8 98 10 conditions max917 only, v cc = 5v, i source = 8ma (note 2) inferred from the output swing test (note 3) max917 only, v cc = 1.8v, i source = 1ma v cc = 1.8v to 5.5v max918 only, v o = 5.5v sourcing, v o = v ee inferred from the psrr test sinking, v o = v cc v cc = 5v
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference _______________________________________________________________________________________ 3 electrical characteristics?ax919/MAX920 (v cc = +5v, v ee = 0v, v cm = 0v, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) v cc = 1.8v v cc = 5v inferred from the psrr test -0.2v v cm (v cc + 0.2v) (note 3) t a = +25? inferred from the cmrr test -0.2v v cm (v cc + 0.2v) (note 2) t a = +25? conditions t a = t min to t max 0.45 0.80 ? 0.38 i cc v 1.8 5.5 v cc supply voltage range supply current na 0.15 1 i b input bias current mv 4 v hb input-referred hysteresis 1.2 t a = +25? v v ee - 0.2 v cc + 0.2 v cm input common-mode voltage range mv 15 v os input offset voltage 10 units min typ max symbol parameter t a = t min to t max 2 t a = t min to t max v cc = 5v, r pullup = 100k ? v cc = 1.8v, r pullup = 100k ? v cc = 5v v cc = 1.8v v cc = 1.8v max917 only 95 ? 30 t pd+ low-to-high propagation delay (note 4) 35 max918 only 120 ? 95 conditions t a = +25? ms 1.2 22 17 t pd- high-to-low propagation delay (note 4) t on power-up time ? i out = 10na mv/na ?.2 ? v ref / ? i out reference load regulation units min typ max symbol parameter c l = 15pf 1.8v v cc 5.5v bw = 10hz to 100khz, c ref = 1nf max917 only, c l = 15pf v cc = 5v bw = 10hz to 100khz t a = t min to t max mv/v 0.1 ? v ref / ? v cc reference line regulation 215 ? rms e n reference output voltage noise 1.200 1.290 v 1.227 1.245 1.263 v ref reference voltage ? 4 t fall fall time ? 6 t rise rise time ppm/? tc ref reference voltage temperature coefficient 600 electrical characteristics?ax917/max918 (continued) (v cc = +5v, v ee = 0v, v in+ = v ref , t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1)
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 4 _______________________________________________________________________________________ electrical characteristics?ax919/MAX920 (continued) (v cc = +5v, v ee = 0v, v cm = 0v, t a = -40? to +85?, unless otherwise noted. typical values are at t a = +25?.) (note 1) note 1: all specifications are 100% tested at t a = +25?. specification limits over temperature (t a = t min to t max ) are guaranteed by design, not production tested. note 2: v os is defined as the center of the hysteresis band at the input. note 3: the hysteresis-related trip points are defined as the edges of the hysteresis band, measured with respect to the center of the band (i.e., v os ) (figure 2). note 4: specified with an input overdrive (v overdrive ) of 100mv, and load capacitance of c l = 15pf. v overdrive is defined above and beyond the offset voltage and hysteresis of the comparator input. for the max917/max918, reference voltage error should also be added. sinking, v o = v cc sourcing, v o = v ee MAX920 only, v o = 5.5v t a = +25? t a = +25? max919 only, v cc = 1.8v, i source = 1ma t a = t min to t max v cc = 1.8v, i sink = 1ma max919 only, v cc = 5v, i source = 8ma conditions ms 1.2 10 t on power-up time 98 8 ma 95 i sc output short-circuit current ? 0.001 1 i leak output leakage current t a = t min to t max 300 t a = +25? t a = t min to t max v cc = 5v, i sink = 8ma 55 200 300 t a = +25? t a = t min to t max 500 55 200 500 mv 190 400 v cc - v oh output-voltage swing high pa 10 i os input offset current mv 190 400 v ol output-voltage swing low v cc = 5v v cc = 1.8v v cc = 5v v cc = 1.8v units min typ max symbol parameter max919 only, c l = 15pf ? 6 t rise high-to-low propagation delay (note 4) rise time ? 17 t pd- v cc = 1.8v to 5.5v mv/v 0.1 1 psrr power-supply rejection ratio (v ee - 0.2v) v cm (v cc + 0.2v) mv/v 0.5 3 cmrr common-mode rejection ratio 22 v cc = 1.8v v cc = 5v max919 only low-to-high propagation delay (note 4) ? 30 t pd+ v cc = 5v v cc = 1.8v 95 MAX920 only v cc = 1.8v r pullup = 100k ? 35 v cc = 5v r pullup = 100k ? 120 c l = 15pf ? 4 t fall fall time
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference _______________________________________________________________________________________ 5 500 600 700 800 900 1.5 2.5 3.5 4.5 2.0 3.0 4.0 5.0 5.5 max917/max918 supply current vs. supply voltage and temperature max917-920 toc01 supply voltage (v) supply current (na) t a = +85? t a = +25? t a = -40? 300 400 500 600 1.5 2.5 3.5 4.5 2.0 3.0 4.0 5.0 5.5 max919/MAX920 supply current vs. supply voltage and temperature max917-920 toc02 supply voltage (v) supply current (na) t a = +85? t a = +25? t a = -40? 500 550 600 650 700 750 800 850 900 -40 -15 10 35 60 85 max917/max918 supply current vs. temperature max917-920 toc03 temperature (?) supply current (na) v cc = 3v v cc = 5v v cc = 1.8v 300 350 400 450 500 550 -40 -15 10 35 60 85 max919/MAX920 supply current vs. temperature max917-920 toc04 temperature (?) supply current (na) v cc = 3v v cc = 5v v cc = 1.8v 0 100 50 250 200 150 400 350 300 450 068 2 4 10 12 14 16 output-voltage low vs. sink current max917-920 toc07 sink current (ma) v ol (mv) v cc = 1.8v v cc = 3v v cc = 5v 10 12 14 16 0 1 10 100 1k 10k 100k max917/max918 supply current vs. output transition frequency 2 max917-920 toc05 output transition frequency (hz) supply current ( a) 4 6 8 v cc = 1.8v v cc = 3v v cc = 5v 10 12 14 0 1 10 100 1k 10k 100k max919/MAX920 supply current vs. output transition frequency 2 max917-920 toc06 output transition frequency (hz) supply current ( a) 4 6 8 v cc = 1.8v v cc = 3v v cc = 5v 0 100 200 500 400 300 600 068 2 4 10 12 14 16 output-voltage low vs. sink current and temperature max917-920 toc08 sink current (ma) v ol (mv) t a = +25 c t a = -40 c t a = +85 c 0 0.3 0.2 0.1 0.4 0.5 0.6 08 6 2 4 10 12 14 16 18 20 max917/max919 output-voltage high vs. source current max917-920 toc09 source current (ma) v cc - v oh (v) v cc = 1.8v v cc = 3v v cc = 5v typical operating characteristics (v cc = +5v, v ee = 0v, c l = 15pf, v overdrive = 100mv, t a = +25?, unless otherwise noted.)
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 6 _______________________________________________________________________________________ 0 0.3 0.2 0.1 0.4 0.5 0.6 08 6 2 4 10 12 14 16 18 20 max917/max919 output-voltage high vs. source current and temperature max917-920 toc10 source current (ma) v cc - v oh (v) t a = +25 c t a = -40 c t a = +85 c 0 40 20 80 60 100 120 -40 10 -15 356085 short-circuit sink current vs. temperature max917-920 toc11 temperature (?) sink current (ma) v cc = 3v v cc = 5v v cc = 1.8v 0 40 20 80 60 120 100 140 -40 10 -15 356085 max917/max919 short-circuit source current vs. temperature max917-920 toc12 temperature (?) source current (ma) v cc = 3v v cc = 5v v cc = 1.8v 0.03 0.05 0.04 0.07 0.06 0.09 0.08 0.10 -40 10 -15 356085 offset voltage vs. temperature max917-920 toc13 temperature (?) v os (mv) v cc = 3v v cc = 5v v cc = 1.8v 1.2440 1.2445 1.2450 1.2455 1.2460 1.5 2.5 3.5 4.5 2.0 3.0 4.0 5.0 5.5 max917/max918 reference voltage vs. supply voltage max917-920 toc16 supply voltage (v) reference voltage (v) 2.5 3.5 3.0 4.5 4.0 5.0 -40 10 -15 356085 hysteresis voltage vs. temperature max917-920 toc14 temperature (?) v hb (mv) 1.241 1.243 1.242 1.245 1.244 1.246 -40 10 -15 356085 max917/max918 reference voltage vs. temperature max917-920 toc15 temperature (?) reference voltage (v) v cc = 3v v cc = 5v v cc = 1.8v 1.2415 1.2420 1.2425 1.2430 1.2435 1.2440 045 23 1 678910 max917/max918 reference output voltage vs. reference source current max917-920 toc17 source current (na) v ref (v) v cc = 3v v cc = 5v v cc = 1.8v 1.2435 1.2440 1.2445 1.2450 1.2455 1.2460 045 23 1 678910 max917/max918 reference output voltage vs. reference sink current max917-920 toc18 sink current (na) v ref (v) v cc = 3v v cc = 5v v cc = 1.8v typical operating characteristics (continued) (v cc = +5v, v ee = 0v, c l = 15pf, v overdrive = 100mv, t a = +25?, unless otherwise noted.)
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference _______________________________________________________________________________________ 7 0 10 5 20 15 25 30 -40 10 -15 356085 propagation delay (t pd- ) vs. temperature max917-920 toc19 temperature (?) t pd- ( s) v cc = 5v v cc = 1.8v v cc = 3v 0 40 20 80 60 100 120 140 -40 10 -15 356085 max917/max919 propagation delay (t pd+ ) vs. temperature max917-920 toc20 temperature (?) t pd+ ( s) v cc = 5v v cc = 1.8v v cc = 3v 0 40 20 80 60 100 120 0.01 1 0.1 10 100 1000 propagation delay (t pd- ) vs. capacitive load max917-920 toc21 capacitive load (nf) t pd- ( s) v cc = 5v v cc = 1.8v v cc = 3v 0 40 20 80 60 100 120 140 160 0.01 1 0.1 10 100 1000 max917/max919 propagation delay (t pd+ ) vs. capacitive load max917-920 toc22 capacitive load (nf) t pd+ ( s) v cc = 5v v cc = 1.8v v cc = 3v 10 30 20 50 40 60 70 020 10 30 40 50 propagation delay (t pd- ) vs. input overdrive max917-920 toc23 input overdrive (mv) t pd- ( s) v cc = 5v v cc = 1.8v v cc = 3v 0 30 20 10 40 50 60 70 80 90 100 020 10 30 40 50 max917/max919 propagation delay (t pd+ ) vs. input overdrive max917-920 toc24 input overdrive (mv) t pd+ ( s) v cc = 5v v cc = 3v v cc = 1.8v 10 100 1k 10k max918/MAX920 propagation delay (t pd- ) vs. pullup resistance max917-920 toc25 r pullup (k ? ) t pd- ( s) 20 14 15 16 17 18 19 v cc = 5v v cc = 1.8v v cc = 3v 10 100 1k 10k max918/MAX920 propagation delay (t pd+ ) vs. pullup resistance max917-920 toc26 r pullup (k ? ) t pd- ( s) 250 0 50 100 150 200 v cc = 5v v cc = 1.8v v cc = 3v in+ (50mv/ div) out (2v/div) propagation delay (t pd- ) (v cc = 5v) 20 s/div max917-920 toc27 typical operating characteristics (continued) (v cc = +5v, v ee = 0v, c l = 15pf, v overdrive = 100mv, t a = +25?, unless otherwise noted.)
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 8 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = +5v, v ee = 0v, c l = 15pf, v overdrive = 100mv, t a = +25?, unless otherwise noted.) in+ (50mv/ div) out (2v/div) max917/max919 propagation delay (t pd+ ) (v cc = 5v) 20 s/div max917-920 toc28 in+ (50mv/ div) out (2v/div) propagation delay (t pd- ) (v cc = 3v) 20 s/div max917-920 toc29 in+ (50mv/ div) out (2v/div) max917/max919 propagation delay (t pd+ ) (v cc = 3v) 20 s/div max917-920 toc30 in+ (50mv/ div) out (1v/div) propagation delay (t pd- ) (v cc = 1.8v) 20 s/div max917-920 toc31 in+ (50mv/div) out (2v/div) max917/max919 1khz response (v cc = 5v) 200 s/div max917-920 toc34 in+ (50mv/ div) out (1v/div) max917/max919 propagation delay (t pd+ ) (v cc = 1.8v) 20 s/div max917-920 toc32 in+ (50mv/ div) out (1v/div) max917/max919 10khz response (v cc = 1.8v) 20 s/div max917-920 toc33 v cc (2v/div) out (2v/div) power-up/down response 40 s/div max917-920 toc35
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference _______________________________________________________________________________________ 9 pin description functional diagrams max917 max918 in+ out v cc v ee ref ref 1.245v max919 MAX920 in+ out v cc v ee in- max917/max918 so pin sot23-5 max919/MAX920 sot23-5 so n.c. v cc v ee in- ref in+ out 1, 5, 8 7 4 2 3 6 5 2 4 3 1 1, 5, 8 no connection. not internally connected. 5 7 positive supply voltage 2 4 negative supply voltage comparator inverting input 4 2 1.245v reference output and comparator inverting input 3 3 comparator noninverting input 1 6 comparator output name function detailed description the max917/max918 feature an on-board 1.245v ?.5% reference, yet draw an ultra-low supply current of 750na. the max919/MAX920 (without reference) consume just 380na of supply current. all four devices are guaranteed to operate down to +1.8v. their com- mon-mode input voltage range extends 200mv beyond-the-rails. internal hysteresis ensures clean out- put switching, even with slow-moving input signals. large internal output drivers allow rail-to-rail output swing with up to ?ma loads. the output stage employs a unique design that mini- mizes supply-current surges while switching, virtually eliminating the supply glitches typical of many other comparators. the max917/max919 have a push-pull output stage that sinks as well as sources current. the max918/MAX920 have an open-drain output stage that can be pulled beyond v cc to an absolute maximum of 6v above v ee . these open-drain versions are ideal for implementing wire-ored output logic functions. input stage circuitry the input common-mode voltage range extends from v ee - 0.2v to v cc + 0.2v. these comparators operate at any differential input voltage within these limits. input bias current is typically ?.15na if the input voltage is between the supply rails. comparator inputs are pro- tected from overvoltage by internal esd protection diodes connected to the supply rails. as the input volt- age exceeds the supply rails, these esd protection diodes become forward biased and begin to conduct.
output stage circuitry the max917?ax920 contain a unique break-before- make output stage capable of rail-to-rail operation with up to ?ma loads. many comparators consume orders of magnitude more current during switching than dur- ing steady-state operation. however, with this family of comparators, the supply-current change during an out- put transition is extremely small. in the typical oper- ating characteristics , the supply current vs. output transition frequency graphs show the minimal supply- current increase as the output switching frequency approaches 1khz. this characteristic reduces the need for power-supply filter capacitors to reduce glitches created by comparator switching currents. in battery- powered applications, this characteristic results in a substantial increase in battery life. reference (max917/max918) the internal reference in the max917/max918 has an output voltage of +1.245v with respect to v ee . its typi- cal temperature coefficient is 95ppm/? over the full -40? to +85? temperature range. the reference is a pnp emitter-follower driven by a 120na current source (figure 1). the output impedance of the voltage refer- ence is typically 200k ? , preventing the reference from driving large loads. the reference can be bypassed with a low-leakage capacitor. the reference is stable for any capacitive load. for applications requiring a lower output impedance, buffer the reference with a low-input-leakage op amp, such as the max406. applications information low-voltage, low-power operation the max917?ax920 are ideally suited for use with most battery-powered systems. table 1 lists a variety of battery types, capacities, and approximate operating times for the max917?ax920, assuming nominal conditions. internal hysteresis many comparators oscillate in the linear region of oper- ation because of noise or undesired parasitic feed- back. this tends to occur when the voltage on one input is equal or very close to the voltage on the other input. the max917?ax920 have internal hysteresis to counter parasitic effects and noise. the hysteresis in a comparator creates two trip points: one for the rising input voltage (v thr ) and one for the falling input voltage (v thf ) (figure 2). the difference between the trip points is the hysteresis (v hb ). when the comparator? input voltages are equal, the hystere- sis effectively causes one comparator input to move quickly past the other, thus taking the input out of the region where oscillation occurs. figure 2 illustrates the case in which in- has a fixed voltage applied, and in+ is varied. if the inputs were reversed, the figure would be the same, except with an inverted output. max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 10 ______________________________________________________________________________________ 120na ref v cc v ee figure 1. max917/max918 voltage reference output equivalent circuit no alkaline (2 cells) yes lithium-ion (1 cell) yes nickel-metal- hydride (2 cells) yes nickel-cadmium (2 cells) 3.0 3.5 2.4 2.4 1.8 2.7 1.8 1.8 v end-of-life (v) v fresh (v) battery type rechargeable 2000 1000 1000 750 2.5 x 10 6 1.25 x 10 6 1.25 x 10 6 937,500 5 x 10 6 2.5 x 10 6 2.5 x 10 6 1.875 x 10 6 max919/MAX920 operating time (hr) max917/max918 operating time (hr) capacity, aa size (ma-h) table 1. battery applications using max917?ax920
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference ______________________________________________________________________________________ 11 thresholds out in+ in- v hb hysteresis band v thf v thr figure 2. threshold hysteresis band v cc max917 max919 out r3 r1 r2 v ref v ee v in v cc figure 3. max917/max919 additional hysteresis additional hysteresis (max917/max919) the max917/max919 have a 4mv internal hysteresis band (v hb ). additional hysteresis can be generated with three resistors using positive feedback (figure 3). unfortunately, this method also slows hysteresis re- sponse time. use the following procedure to calculate resistor values. 1) select r3. leakage current at in is under 2na, so the current through r3 should be at least 0.2? to minimize errors caused by leakage current. the cur- rent through r3 at the trip point is (v ref - v out )/r3. considering the two possible output states in solving for r3 yields two formulas: r3 = v ref /i r3 or r3 = (v cc - v ref )/i r3 . use the smaller of the two resulting resistor values. for example, when using the max917 (v ref = 1.245v) and v cc = 5v, and if we choose i r3 = 1?, then the two resistor values are 1.2m ? and 3.8m ? . choose a 1.2m ? standard value for r3. 2) choose the hysteresis band required (v hb ). for this example, choose 50mv. 3) calculate r1 according to the following equation: r1 = r3 (v hb / v cc ) for this example, insert the values r1 = 1.2m ? (50mv/5v) = 12k ? 4) choose the trip point for v in rising (v thr ) such that v thr > v ref (r1 + r3)/r3 (v thf is the trip point for v in falling). this is the threshold voltage at which the comparator switches its output from low to high as v in rises above the trip point. for this example, choose 3v. 5) calculate r2 as follows: r2 = 1/[v thr /(v ref r1) - (1 / r1) - (1 / r3)] r2 = 1/[3.0v/(1.2v 12k ? ) - (1 / 12k ? ) - (1/1.2m ? )] = 8.05k ? for this example, choose an 8.2k ? standard value. 6) verify the trip voltages and hysteresis as follows: v in rising: v thr = v ref r1 [(1 / r1) + (1 / r2) + (1 / r3)] v in falling: v thf = v thr - (r1 v cc / r3) hysteresis = v thr - v thf additional hysteresis (max918/MAX920) the max918/MAX920 have a 4mv internal hysteresis band. they have open-drain outputs and require an external pullup resistor (figure 4). additional hysteresis can be generated using positive feedback, but the for- mulas differ slightly from those of the max917/ max919. use the following procedure to calculate resistor values. 1) select r3 according to the formulas r3 = v ref / 1? or r3 = (v cc - v ref )/1? - r4. use the smaller of the two resulting resistor values. 2) choose the hysteresis band required (v hb ). 3) calculate r1 according to the following equation: r1 = (r3 + r4) (v hb /v cc ) 4) choose the trip point for v in rising (v thr ) (v thf is the trip point for v in falling). this is the threshold voltage at which the comparator switches its output from low to high as v in rises above the trip point. 5) calculate r2 as follows: r2 1/ v / v r1 1 r1 1 r3 thr ref = () ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 12 ______________________________________________________________________________________ MAX920 in- 100k ? 100k ? r pullup 3v (5v) logic out out v cc +5v (+3v) +3v (+5v) v ee 5v (3v) logic in in+ logic-level translator v ee v cc out r3 r2 r1 r4 v ref v in v cc max918 MAX920 figure 4. max918/MAX920 additional hysteresis max919 in+ out v cc 100mv p-p v cc v ee in- figure 5. zero-crossing detector typical application circuit out n.c. ( ) are for max917/max918. v ee 1 2 8 7 n.c. v cc in- (ref) in+ n.c. so top view 3 4 6 5 max917 max918 max919 MAX920 pin configurations (continued) 6) verify the trip voltages and hysteresis as follows: hysteresis = v thr - v thf board layout and bypassing power-supply bypass capacitors are not typically needed, but use 100nf bypass capacitors close to the device? supply pins when supply impedance is high, supply leads are long, or excessive noise is expected on the supply lines. minimize signal trace lengths to reduce stray capacitance. a ground plane and sur- face-mount components are recommended. zero-crossing detector figure 5 shows a zero-crossing detector application. the max919? inverting input is connected to ground, and its noninverting input is connected to a 100mv p-p signal source. as the signal at the noninverting input crosses 0v, the comparator? output changes state. logic-level translator the typical application circuit shows an application that converts 5v logic to 3v logic levels. the MAX920 is powered by the +5v supply voltage, and the pullup resistor for the MAX920? open-drain output is connect- ed to the +3v supply voltage. this configuration allows the full 5v logic swing without creating overvoltage on the 3v logic inputs. for 3v to 5v logic-level translations, simply connect the +3v supply voltage to v cc and the +5v supply voltage to the pullup resistor. v rising : v v r1 1 r1 1 r2 1 r3 v falling : v in thr ref in thf = ++ ? ? ? ? ? ? = v r1 1 r1 1 r2 1 r3 r4 r1 r3 r4 v ref cc ++ + ? ? ? ? ? ? ? +
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference ______________________________________________________________________________________ 13 package information (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) sot-23 5l .eps
max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference 14 ______________________________________________________________________________________ package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) 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 min dim 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 5.00 4.80 8 n ms012 n side view h 0.244 0.228 5.80 6.20 e 0.050 bsc 1.27 bsc c h e e b a1 a d 0 -8 l 1 variations:
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. maxim integrated products, 120 san gabriel drive, sunnyvale, ca 94086 408-737-7600 ____________________ 15 2007 maxim integrated products is a registered trademark of maxim integrated products, inc. max917?ax920 sot23, 1.8v, nanopower, beyond-the-rails comparators with/without reference package information (continued) (the package drawing(s) in this data sheet may not reflect the most current specifications. for the latest package outline info rmation go to www.maxim-ic.com/packages .) sot-23 5l .eps revision history pages changed at rev 1: 1?5

▲Up To Search▲

Price & Availability of MAX920

	To Download MAX920 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .