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general description the max9924?ax9927 variable reluctance (vr or mag- netic coil) sensor interface devices are ideal for position and speed sensing for automotive crankshafts, camshafts, transmission shafts, etc. these devices inte- grate a precision amplifier and comparator with selectable adaptive peak threshold and zero-crossing circuit blocks that generate robust output pulses even in the presence of substantial system noise or extremely weak vr signals. the max9926/max9927 are dual versions of the max9924/max9925, respectively. the max9924/ max9926 combine matched resistors with a cmos input precision operational amplifier to give high cmrr over a wide range of input frequencies and temperatures. the max9924/max9926 differential amplifiers provide a fixed gain of 1v/v. the max9925/max9927 make all three ter- minals of the internal operational amplifier available, allowing greater flexibility for gain. the max9926 also provides a direction output that is useful for quadrature- connected vr sensors that are used in certain high-per- formance engines. these devices interface with both new-generation differential vr sensors as well as legacy single-ended vr sensors. the max9924/max9925 are available in the 10-pin ?ax package, while the max9926/max9927 are available in the 16-pin qsop package. all devices are specified over the -40? to +125? automotive temper- ature range. applications camshaft vrs interfaces crankshaft vrs interfaces vehicle speed vrs interfaces features differential input stage provides enhanced noise immunity precision amplifier and comparator allows small-signal detection user-enabled internal adaptive peak threshold or flexible external threshold zero-crossing detection provides accurate phase information max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ________________________________________________________________ maxim integrated products 1 ordering information 19-4283; rev 3; 3/11 for pricing, delivery, and ordering information, please contact maxim direct at 1-888-629-4642, or visit maxim? website at www.maxim-ic.com. part temp range pin-package max9924 uaub+ -40? to +125? 10 ?ax max9925 aub+ -40? to +125? 10 ?ax max9926 uaee+ -40? to +125? 16 qsop max9927 aee+ -40? to +125? 16 qsop selector guide part amplifier gain max9924uaub 1 x differential 1v/v max9925aub 1 x operational externally set max9926uaee 2 x differential 1v/v max9927aee 2 x operational externally set simplified block diagram c differential amplifier adaptive/minimum and zero-crossing thresholds internal/external bias voltage vr sensor engine block max9924 + denotes a lead(pb)-free/rohs-compliant package. ?ax is a registered trademark of maxim integrated products, inc.
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 2 _______________________________________________________________________________________ absolute maximum ratings electrical characteristics (v cc = 5v, v gnd = 0v, max9925/max9927 gain setting = 1v/v, mode a1, v bias = 2.5v, v pullup = 5v, r pullup = 1k , c cout = 50pf. t a = t min to t max , unless otherwise noted. typical values are at t a = +25?.) (note 2) 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. v cc to gnd .............................................................-0.3v to + 6v all other pins..............................................-0.3v to (v cc + 0.3v) current into in+, in-, in_+, in_-.......................................?0ma current into all other pins ................................................?0ma output short-circuit (out_, out) to gnd.............................10s continuous power dissipation (t a = +70?) (note 1) 10-pin ?ax (derate 8.8mw/? above +70?) ........707.3mw 16-pin qsop (derate 9.6mw/? above +70?)........771.5mw operating temperature range .........................-40? to +125? junction temperature ......................................................+150? storage temperature range .............................-65? to +150? lead temperature (soldering, 10s) .................................+300? soldering temperature (reflow) .......................................+260? parameter symbol conditions min typ max units power supply operating supply range v cc (note 3) 4.5 5.5 v max9924/max9925 2.6 5 supply current i cc max9926/max9927 4.7 10 ma power-on time p on v cc > v uvlo = 4.1v, step time for v cc ~ 1? 30 150 ? input operational amplifier (max9925/max9927) input voltage range in+, in- guaranteed by cmrr 0 v cc v temperature drift 5 ?/ c input offset voltage v os-oa 0.5 3 mv input bias current i bias (note 4) 0.1 6 na input offset current i offset (note 4) 0.05 2 na common-mode rejection ratio cmrr from v cm = 0 to v cc 75 102 db max9925 88 105 power-supply rejection ratio psrr max9927 77 94 db output voltage low v ol i ol = 1ma 0.050 v output voltage high v oh i oh = -1ma v cc - 0.050 v recovery time from saturation t sat to 1% of the actual v out after output saturates 1.2 ? gain-bandwidth product gbw 1.4 mhz slew rate sr 2.3 v/? charge-pump frequency f cp 1.3 mhz note 1: package thermal resistances were obtained using the method described in jedec specification jesd51-7, using a four-layer board. for detailed information on package thermal considerations, refer to www.maxim-ic.com/thermal-tutorial . ?ax junction-to-ambient thermal resistance ( ja ) ......113.1?/w junction-to-case thermal resistance ( jc ) ................42?/w qsop junction-to-ambient thermal resistance ( ja ) ......103.7?/w junction-to-case thermal resistance ( jc ) ................37?/w package thermal characteristics (note 1)
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold _______________________________________________________________________________________ 3 parameter symbol conditions min typ max units input differential amplifier (max9924/max9926) input voltage range in+, in- guaranteed by cmrr -0.3 v cc + 0.3 v max9924 (note 5) 60 87 differential amplifier common-mode rejection ratio cmrr max9926 (note 5) 55 78 db input resistance r in (note 5) 65 100 135 k adaptive peak detection max9924/max9925 -6.5 0 +6.5 zero-crossing threshold v zero_thresh mode b operation (notes 5, 6) max9926/max9927 -6.5 0 +10 mv v adaptive adaptive peak threshold 33 %pk minimum threshold of hysteresis comparator max9924/max9926 (notes 5, 6) 41530 minimum threshold of hysteresis comparator max9925/max9927 (notes 5, 6) 20 30 50 v min-thresh - v zero-thresh for max9924 (notes 5, 6) 71526 v min-thresh - v zero-thresh for max9926 (notes 5, 6) 21530 fixed and adaptive peak threshold v min-thresh v min-thresh - v zero-thresh for max9925/max9927 (notes 5, 6) 19 30 50 mv watchdog timeout for adaptive peak threshold t wd timing window to reset the adaptive peak threshold if not triggered (input level below threshold) 45 85 140 ms entire system comparator output low voltage v cout_ol 0.2 v t pdz overdrive = 2v to 3v, zero-crossing 50 propagation delay t pda overdrive = 2v to 3v, adaptive peak 150 ns cout transition time t hl-lh 2ns propagation delay jitter t pd-jitter includes noise of differential amplifier and comparator, f = 10khz, v in = 1v p-p sine wave 20 ns electrical characteristics (continued) (v cc = 5v, v gnd = 0v, max9925/max9927 gain setting = 1v/v, mode a1, v bias = 2.5v, v pullup = 5v, r pullup = 1k , c cout = 50pf. t a = t min to t max , unless otherwise noted. typical values are at t a = +25?.) (note 2)
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 4 _______________________________________________________________________________________ parameter symbol conditions min typ max units ext mode b, t a = +125 c 1.5 v cc - 1.1 ext voltage range v ext mode c, t a = +125 c 0.14 v cc - 1.1 v input current to ext i ext mode b, v ext > v bias ; and mode c 10 a dirn (max9926 only) output low voltage 0.2 v int_thrs, zero_en low input v il 0.3 x v cc v high input v ih 0.7 x v cc v input leakage i leak 1a input current zero_en i sink pullup resistor = 10k , v zero_en = v gnd 500 800 ? switching time between modes a1, a2, and modes b, c t sw with int_thrs = gnd, auto peak- detect is disabled, and ext_thrs is active 3s bias input current to bias i bias modes a1, a2, b, c 1 ? modes a1, b, t a = +125 c 1.5 v cc - 1.1 bias voltage range v bias mode c, t a = +125 c 0.2 v cc - 1.1 v internal bias reference voltage v int_bias mode a2 (max9924/max9926) 2.46 v electrical characteristics (continued) (v cc = 5v, v gnd = 0v, max9925/max9927 gain setting = 1v/v, mode a1, v bias = 2.5v, v pullup = 5v, r pullup = 1k , c cout = 50pf. t a = t min to t max , unless otherwise noted. typical values are at t a = +25?.) (note 2) note 2: specifications are 100% tested at t a = +125?, unless otherwise noted. all temperature limits are guaranteed by design. note 3: inferred from functional psrr. note 4: cmos inputs. note 5: guaranteed by design. note 6: includes effect of v os of internal op amp and comparator.
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold _______________________________________________________________________________________ 5 0 5 10 15 20 input offset voltage distribution max9924 toc01 input offset voltage ( v) percentage of units (%) -2000 -500 0 -1500 -1000 500 1000 1500 3000 2500 2000 v cm = 0 bin size = 250 0 0.1 0.3 0.2 0.4 0.5 -0.5 1.5 0.5 2.5 3.5 4.5 5.5 input offset voltage vs. input common-mode voltage max9924 toc02 input common-mode voltage (v) input offset voltage (mv) v out = 2.5v max9925 common-mode rejection ratio vs. frequency max9924 toc03 frequency (hz) cmrr (db) 10k 1k 100 10 20 40 60 80 100 120 0 1100k v bias = v out = 2.5v v cm = 2v p-p cmrr = 20log(a dm /a cm ) power-supply rejection ratio vs. frequency max9924 toc04 frequency (hz) pssr (db) 10k 1k 100 10 -100 -80 -60 -40 -20 0 -110 -90 -70 -50 -30 -10 -120 1 100k v ripple = 100mv p-p v bias = v out = 2.5v inputs coupled to gnd open loop frequency response max9924 toc05 frequency (khz) gain (db) 0.1 25 50 75 100 125 0 0.001 10 v cc = 5v v bias = 2.5v v out = 2v p-p max9925 v ol and v oh vs. temperature max9924 toc06 temperature ( c) v ol and v oh (mv) 50 75 100 25 0 -25 15 20 40 5 10 25 30 35 0 -50 125 v cc - v oh v ol 0 0.2 0.1 0.4 0.3 0.5 0.6 -50 25 50 -25 0 75 100 125 input offset voltage vs. temperature max9924 toc07 temperature ( c) input offset voltage (mv) v cm = 0 v out = 2.5v max9925 v cm = 2.5v adaptive threshold and ratio vs. signal level max9924 toc08 signal level (v p ) adaptive threshold level (mv) 1.5 2.0 1.0 0.5 400 500 900 100 200 300 600 700 800 0 02.5 f in = 1khz max9924 adaptive threshold vs. temperature max9924 toc09 temperature ( c) threshold (mv) 25 50 75 100 0 -25 200 250 400 50 100 150 300 350 0 -50 125 v in = 2v p-p f in = 1khz max9924 typical operating characteristics (v cc = 5v, v gnd = 0v, max9925/max9927 gain setting = 1v/v. all values are at t a = +25?, unless otherwise noted.)
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 6 _______________________________________________________________________________________ typical operating characteristics (continued) (v cc = 5v, v gnd = 0v, max9925/max9927 gain setting = 1v/v. all values are at t a = +25?, unless otherwise noted.) -5 5 0 15 10 25 20 30 -50 0 25 -25 50 75 100 125 minimum and zero-crossing threshold vs. temperature max9924 toc10 temperature ( c) threshold (mv) v cm = 2.5v f in = 5hz zero crossing at 5hz minimum threshold zero crossing at 1hz 0 25 50 75 100 cmrr vs. temperature max9924 toc11 temperature ( c) cmrr (db) -50 25 50 -25 0 75 100 125 max9924 v cm = 0 to 5v input signal vs. cout with watchdog timer expired max9924 toc12 20ms/div v bias 5v f in = 5hz cout input signal input signal vs. cout with watchdog timer expired max9924 toc13 100 s/div v bias 5v f in = 1khz cout input signal 833mv max9924 toc14 100 s/div overdriven input voltages (max9924) max9924 toc15 200 s/div dirn operation (max9924) max9924 toc16 input referred noise density vs. frequency 10 20 60 40 80 100 10 1k 100 10k 100k 1m frequency (hz) input voltage noise (nv/ hz)
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold _______________________________________________________________________________________ 7 pin description pin max9924 max9925 max9926 max9927 name function 1 1 in+ noninverting input 2 2 in- inverting input 3 out amplifier output 3 n.c. no connection. not internally connected. 4 4 bias input bias. connect to an external resistor-divider and bypass to ground with a 0.1? and 10? capacitor. 5 5 11 11 gnd ground 6 6 13 zero_en zero-crossing enable. mode configuration pin, internally pulled up to v cc with 10k resistor. 7 7 cout comparator output. open-drain output, connect a 10k pullup resistor from cout to v pullup . 8 8 ext external reference input. leave ext unconnected in modes a1, a2. apply an external voltage in modes b, c. 9 9 int_thrs internal adaptive threshold. mode configuration pin. 10 10 14 14 v cc power supply 1 1 int_thrs1 internal adaptive threshold 1. mode configuration pin. 2 2 ext1 external reference input 1. leave ext unconnected in modes a1, a2. apply an external voltage in modes b, c. 3 3 bias1 input bias 1. connect to an external resistor-divider and bypass to ground with a 0.1? and 10? capacitor. 4 4 cout1 comparator output 1. open-drain output, connect a 10k pullup resistor from cout1 to v pullup . 5 5 cout2 comparator output 2. open-drain output, connect a 10k pullup resistor from cout2 to v pullup . 6 6 bias2 input bias 2. connect to an external resistor-divider and bypass to ground with a 0.1? and 10? capacitor. 7 7 ext2 external reference input 2. leave ext unconnected in modes a1, a2. apply an external voltage in modes b, c. 8 8 int_thrs2 internal adaptive threshold 2. mode configuration pin. 9 9 in2+ noninverting input 2 10 10 in2- inverting input 2 12 dirn rotational direction output. open-drain output, connect a pullup resistor from dirn to v pullup . 12 out2 amplifier output 2 13 out1 amplifier output 1 15 15 in1- noninverting input 1 16 16 in1+ inverting input 1
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 8 _______________________________________________________________________________________ functional diagrams max9924 100k 100k 10k 100k v cc v cc mode logic int_thrs ext in- 100k v cc in+ bias op amp comparator 30% buffer internal reference 2.5v v min threshold 65ms watchdog peak detector mode logic cout zero_en int_thrs gnd v cc
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold _______________________________________________________________________________________ 9 functional diagrams (continued) max9925 10k v cc v cc mode logic ext in- v cc in+ bias op amp comparator 30% buffer v min threshold 85ms watchdog peak detector cout zero_en gnd out v cc int_thrs
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 10 ______________________________________________________________________________________ functional diagrams (continued) max9926 100k 100k 10k 100k v cc v cc mode logic in1- 100k v cc in1+ bias1 op amp comparator 30% buffer internal reference 2.5v v min threshold 85ms watchdog peak detector ext1 cout1 zero_en gnd v cc 100k 100k 100k v cc in2- 100k v cc in2+ bias2 op amp comparator 30% buffer v min threshold 85ms watchdog peak detector ext2 cout2 dirn dirn flip-flop clk int_thrs1 int_thrs2
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 11 functional diagrams (continued) max9927 v cc in1- v cc in1+ bias1 op amp comparator 30% buffer v min threshold 85ms watchdog peak detector cout1 ext1 gnd out1 v cc v cc in2- v cc in2+ bias2 op amp comparator 30% buffer v min threshold 85ms watchdog peak detector cout2 out1 ext2 mode logic int_thrs2 int_thrs1
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 12 ______________________________________________________________________________________ detailed description the max9924?ax9927 interface with variable reluc- tance (vr) or magnetic coil sensors. these devices produce accurate pulses aligned with flywheel gear- teeth even when the pickup signal is small and in the presence of large amounts of system noise. they inter- face with new-generation differential vr sensors as well as legacy single-ended vr sensors. the max9924/max9925 integrate a precision op amp, a precision comparator, an adaptive peak threshold block, a zero-crossing detection circuit, and precision matched resistors (max9924). the max9926 and max9927 are dual versions of the max9924 and max9925, respectively. the max9926 also provides a rotational output that is useful for quadrature-connected vr sensors used in certain high-performance engines. the input op amp in the max9925/max9927 are typical- ly configured as a differential amplifier by using four external resistors (the max9924/max9926 integrate precision-matched resistors to give superior cmrr per- formance). this input differential amplifier rejects input common-mode noise and converts the input differential signal from a vr sensor into a single-ended signal. the internal comparator produces output pulses by compar- ing the output of the input differential amplifier with a threshold voltage that is set depending on the mode that the device is in (see the mode selection section). mode selection the max9924/max9926 provide four modes of opera- tion: mode a1, mode a2, mode b, and mode c as deter- mined by voltages applied to inputs zero_en and int_thrs (see tables 1, 2, and 3). in modes a1 and a2, the internal adaptive peak threshold and the zero- crossing features are enabled. in mode a2, an internally generated reference voltage is used to bias the differen- tial amplifier and all internal circuitry instead of an exter- nal voltage connected to the bias input?his helps reduce external components and design variables lead- ing to a more robust application. in mode b, the adap- tive peak threshold functionality is disabled, but zero-crossing functionality is enabled. in this mode, an external threshold voltage is applied at ext allowing application-specific adaptive algorithms to be imple- mented in firmware. in mode c, both the adaptive peak threshold and zero-crossing features are disabled and the device acts as a high-performance differential ampli- fier connected to a precision comparator (add external hysteresis to the comparator for glitch-free operation). table 1. max9924/max9926 operating modes setting device functionality operating mode zero_en int_thrs zero crossing adaptive peak threshold bias voltage source a1 v cc v cc enabled enabled external a2 gnd gnd enabled enabled internal ref bv cc gnd enabled disabled external c gnd v cc disabled disabled external table 2. max9925 operating modes setting device functionality operating mode zero_en int_thrs zero crossing adaptive peak threshold a1 v cc v cc enabled enabled bv cc gnd enabled disabled c gnd v cc disabled disabled table 3. max9927 operating modes setting device functionality operating mode int_thrs zero crossing adaptive peak threshold a1 v cc enabled enabled b gnd enabled disabled
differential amplifier the input operational amplifier is a rail-to-rail input and output precision amplifier with cmos input bias cur- rents, low offset voltage (v os ) and drift. a novel input architecture eliminates crossover distortion at the oper- ational amplifier inputs normally found in rail-to-rail input structures. these features enable reliable small-signal detection for vr sensors. the max9924/max9926 include on-chip precision- matched low-ppm resistors configured as a differential amplifier. high-quality matching and layout of these resistors produce extremely high dc and ac cmrr that is important to maintain noise immunity. the matched ppm-drift of the resistors guarantees perfor- mance across the entire -40? to +125? automotive temperature range. bias reference in modes a1, b, and c, a well-decoupled external resistor-divider generates a v cc /2 signal for the bias input that is used to reference all internal electronics in the device. bias should be bypassed with a 0.1? and 10? capacitor in parallel with the lower half of the resistor-divider forming a lowpass filter to provide a sta- ble external bias reference. the minimum threshold, adaptive peak threshold, zero- crossing threshold signals are all referenced to this voltage. an input buffer eliminates loading of resistor- dividers due to differential amplifier operation. connect bias to ground when operating in mode a2. an internal (2.5v typical) reference is used in mode a2, eliminating external components. adaptive peak threshold modes a1 and a2 in the max9924?ax9927 use an internal adaptive peak threshold voltage to trigger the output comparator. this adaptive peak threshold volt- age scheme provides robust noise immunity to the input vr signal, preventing false triggers from occurring due to broken tooth or off-centered gear-tooth wheel. see figure 1. the sensor signal at the output of the differential gain stage is used to generate a cycle-by-cycle adaptive peak threshold voltage. this threshold voltage is 1/3 of the peak of the previous cycle of the input vr signal. as the sensor signal peak voltage rises, the adaptive peak threshold voltage also increases by the same ratio. conversely, decreasing peak voltage levels of the input vr signal causes the adaptive peak threshold voltage used to trigger the next cycle also to decrease to a new lower level. this threshold voltage then provides an arming level for the zero-crossing circuit of the com- parator (see the zero crossing section). if the input signal voltage remains lower than the adap- tive peak threshold for more than 85ms, an internal watchdog timer drops the threshold level to a default minimum threshold (v min_thresh ). this ensures pulse recognition recovers even in the presence of intermit- tent sensor connection. the internal adaptive peak threshold can be disabled and directly fed from the ext input. this mode of opera- tion is called mode b, and allows implementations of cus- tom threshold algorithms in firmware. this ext voltage is typically generated by filtering a pwm-modulated output from an onboard microcontroller (?). an external opera- tional amplifier can also be used to construct an active lowpass filter to filter the pwm-modulated ext signal. max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 13 20ms v1 40ms 60ms cout vr signal adaptive threshold set by v1 adaptive threshold set by v2 min threshold 80ms 100ms 120ms 140ms 160ms 85ms v1 1 3 v2 1/3 v2 180ms 200ms figure 1. adaptive peak threshold operation
max9924?ax9927 zero crossing the zero-crossing signal provides true timing informa- tion for engine-control applications. the zero-voltage level in the vr sensor signal corresponds to the center of the gear-tooth and is the most reliable marker for position/angle-sensing applications. since the output of the differential amplifier is level-shifted to the bias volt- age, the zero of the input vr signal is simply bias. the comparator output state controls the status of the input switch that changes the voltage at its noninverting input from the adaptive/external threshold level to the bias level. the difference in these two voltages then effec- tively acts as hysteresis for the comparator, thus pro- viding noise immunity. comparator the internal comparator is a fast open-drain output comparator with low input offset voltage and drift. the comparator precision affects the ability of the signal chain to resolve small vr sensor signals. an open-drain output allows the comparator to easily interface to a variety of ? i/o voltages. when operating the max9924/max9925/max9926 in mode c, external hysteresis can be provided by adding external resistors (see figures 5 and 8). the high and low hysteresis thresholds in mode c can be calculated using the following equations, and rotational direction output (max9926 only) for quadrature-connected vr sensors, the open-drain output dirn indicates the rotational direction of inputs in1 and in2 based on the output state of cout1 and cout2. dirn goes high when cout1 is leading cout2, and low when cout1 is following cout2. applications information bypassing and layout considerations good power-supply decoupling with high-quality bypass capacitors is always important for precision analog circuits. the use of an internal charge pump for the front-end amplifier makes this more important. bypass capacitors create a low-impedance path to ground for noise present on the power supply. the minimum impedance of a capacitor is limited to the effective series resistance (esr) at the self-resonance frequency, where the effective series inductance (esl) cancels out the capacitance. the esl of the capacitor dominates past the self-resonance frequency resulting in a rise in impedance at high frequencies. bypass the power supply of the max9924?ax9927 with multiple capacitor values in parallel to ground. the use of multiple values ensures that there will be multiple self-resonance frequencies in the bypass network, low- ering the combined impedance over frequency. it is recommended to use low-esr and low-esl ceramic surface-mount capacitors in a parallel combination of 10nf, 0.1? and 1?, with the 10nf placed closest between the v cc and gnd pins. the connection between these capacitor terminals and the power-sup- ply pins of the part (both v cc and gnd) should be through wide traces (preferably planes), and without vias in the high-frequency current path. v r rr v tl bias = + ? ? ? ? ? ? 2 12 v rv v rr r v th pullup bias pullup bias = ? ++ ? ? ? ? ? ? + 1 12 () variable reluctance sensor interfaces with differential input and adaptive peak threshold 14 ______________________________________________________________________________________
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 15 application circuits in+ in- bias v cc zero_en int_thrs gnd cout ext tpu c v pullup r pullup 1nf 10k 10k vr sensor +5v 1k 1k 10 f || 0.1 f max9924 max9926 figure 2. max9924/max9926 operating mode a1 in+ in- bias v cc zero_en int_thrs gnd cout ext tpu c v pullup r pullup 1nf 10k 10k vr sensor +5v max9924 max9926 figure 3. max9924/max9926 operating mode a2
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 16 ______________________________________________________________________________________ application circuits (continued) in+ in- bias v cc zero_en int_thrs gnd cout ext tpu pwm c v pullup r pullup 1nf 10k 10k vr sensor +5v 1k 1k 10 f || 0.1 f max9924 max9926 filter figure 4. max9924/max9926 operating mode b in+ in- bias v cc zero_en int_thrs r1 gnd cout ext tpu c v pullup r pullup r2 1nf 10k 10k vr sensor +5v 1k 1k 10 f || 0.1 f max9924 max9926 figure 5. max9924/max9926 operating mode c
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 17 application circuits (continued) in- in+ bias v cc zero_en int_thrs gnd cout out ext tpu c v pullup r pullup 1nf 10k 10k vr sensor +5v 1k 1k 10 f || 0.1 f max9925 max9927 figure 6. max9925/max9927 operating mode a in- in+ bias v cc zero_en int_thrs gnd cout out ext tpu c v pullup r pullup 1nf 10k 10k vr sensor +5v 1k 1k 10 f || 0.1 f max9925 max9927 pwm filter figure 7. max9925/max9927 operating mode b
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 18 ______________________________________________________________________________________ application circuits (continued) in- in+ bias v cc zero_en int_thrs r1 gnd cout out ext tpu c v pullup r pullup r2 +5v 1k 1k 10 f || 0.1 f max9925 1nf 10k 10k vr sensor figure 8. max9925 operating mode c
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 19 max9924 100k 100k 10k 100k v cc v cc 4.5v to 5.5v v cc r pullup v pullup mode logic int_thrs gnd ext in- 100k v cc in+ bias *the max9924 is configured in mode a2. op amp comparator 30% buffer bandgap reference voltage = 2 x v bg v min threshold 85ms watchdog c peak detector mode logic cout tpu zero_en vr sensor typical operating circuit
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 20 ______________________________________________________________________________________ pin configurations 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 in_thrs1 in1+ in1- v cc zero_en dirn gnd in2- in2+ top view max9926 qsop ext1 bias1 bias2 cout1 cout2 ext2 int_thrs2 + 16 15 14 13 12 11 10 9 1 2 3 4 5 6 7 8 in_thrs1 in1+ in1- v cc out1 out2 gnd in2- in2+ max9927 qsop ext1 bias1 bias2 cout1 cout2 ext2 int_thrs2 + 1 + 2 3 4 5 10 9 8 7 6 v cc int_thrs ext cout bias n.c. in- in+ max9924 max top view zero_en gnd 1 2 3 4 5 10 9 8 7 6 v cc int_thrs ext cout bias out in- in+ max9925 max zero_en gnd + chip information process: bicmos
max9924?ax9927 10lumax.eps variable reluctance sensor interfaces with differential input and adaptive peak threshold ______________________________________________________________________________________ 21 package type package code outline no. land pattern no. 10 ?ax u10+2 21-0061 90-0330 16 qsop e16+1 21-0055 90-0167 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 per - tains to the package regardless of rohs status.
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 22 ______________________________________________________________________________________ package information (continued) 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 per - tains to the package regardless of rohs status.
max9924?ax9927 variable reluctance sensor interfaces with differential input and adaptive peak threshold 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 ____________________ 23 2011 maxim integrated products maxim is a registered trademark of maxim integrated products, inc. revision history revision number revision date description pages changed 0 10/08 initial release 1 2/09 removed future product references for the max9926 and max9927, updated ec table 1? 2 3/09 corrected various errors 2, 3, 4, 6, 13 3 3/11 updated figures 6, 7, and 8 17, 18

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