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description the ATS657 includes an optimized hall-effect sensing integrated circuit (ic) and rare earth pellet to create a user- friendly solution for direction detection and true zero-speed, digital gear tooth sensing in two-wire applications. the small package can be easily assembled and used in conjunction with a wide variety of gear tooth sensing applications. the ic employs patented algorithms for the special operational requirements of automotive transmission applications. the speed and direction of the target are communicated by this two-wire device through a variable pulse width output protocol. the advanced vibration detection algorithm systematically calibrates the ic on the initial teeth of a true rotation signal and not on vibration, always guaranteeing an accurate signal in running mode. even the high angular vibration caused by engine cranking is completely rejected by the device. patented running mode algorithms also protect against air gap changes whether or not the target is in motion. advanced signal processing and innovative algorithms make the ATS657 an ideal solution for a wide range of speed and direction sensing needs. the device package is lead (pb) free, with 100% matte tin leadframe plating. ATS657-ds, rev. 3 features and benefits ? rotational direction detection ? high start-up and running mode vibration immunity ? single-chip sensing ic for high reliability ? internal current regulator for two-wire operation ? variable pulse width output protocol ? automatic gain control (agc) and offset adjust circuit ? true zero-speed operation ? wide operating voltage range ? undervoltage lockout ? esd and reverse polarity protection dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic package: 4-pin sip (suffix sh) functional block diagram not to scale ATS657 internal regulator vcc offset adjust pdac ndac threshp reference generator and update threshn offset adjust pdac ndac threshp reference generator threshn agc agc ? threshold logic threshold logic speed and direction logic peak detection logic output protocol control and update ? ? ? gnd
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 2 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com pin-out diagram absolute maximum ratings characteristic symbol notes rating unit supply voltage v supply see power derating curve; proper operation at v supply = 24 v requires circuit configuration with a series 100 load resistor. please refer to figure 7. voltage between pins 1 and 4 of greater than 22 v may partially turn on the esd protection zener diode in the ic. 24 v reverse supply voltage v rcc ?18 v operating ambient temperature t a range l ?40 to 150 oc maximum junction temperature t j (max) 165 oc storage temperature t stg ?65 to 170 oc terminal list number name function 1 vcc connects power supply to chip 2 nc no connection 3 nc float or tie to gnd 4 gnd ground terminal selection guide part number packing* ATS657lshtn-t 800 pieces per 13-in. reel *contact allegro ? for additional packing options 24 3 1
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 3 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com electrical characteristics valid over operating voltage and temperature ranges, unless otherwise noted characteristics symbol test conditions min. typ. 1 max. unit 2 supply voltage v cc operating, t j < t j (max) 4.0 ? 18 v undervoltage lockout v cc(uv) v cc = 0 >4 v, or >4 0 v ? 3.5 4.0 v reverse supply current i rcc v cc = ?18 v ? ? ?10 ma supply zener clamp voltage v z(supply) i cc = i cc (max) + 3 ma, t a = 25c 24.0 ? ? v supply zener resistance r z ?<5? supply current i cc(low) low-current state (running mode) 5.0 6.5 8.0 ma i cc(high) high-current state (running mode) 12 14.0 16 ma i cc(su)(low) startup current level and power-on mode 5.0 7.0 8.5 ma i cc(su)(high) high-current state (calibration) 12 14.5 16.5 ma current level difference ? i cc i cc(high) ? i cc(low) 5??ma power-on characteristics 3 power-on time t on speed < 200 hz ? ? 2.0 ms initial calibration first output pulse with direction 4 n dir speed < 200 hz, constant rotation direction ? ? 6 edge first output pulse 5 n nondir speed < 200 hz, constant rotation direction ? ? 2 edge agc disable n f speed < 200 hz, constant rotation direction ? ? 5 edge vibration check n vibcheck speed < 200 hz, after agc disable ? 3 ? edge time until correct direction output on high-speed startup t highsu 10 khz startup, b = 300 g pk-pk ?5?ms running mode calibration 6 non-direction pulse output on direction change n nondir_dc running mode, direction change ? 1 2 pulse first direction pulse output on direction change n dc running mode, direction change ? 2 3 pulse dac characteristics allowable user-induced differential offset 7 b diffext both differential channels ? 60 ? g output stage output slew rate sr out r l = 100 , c l = 10 pf; i cc(high) i cc(low) , i cc(low) i cc(high) , 10% to 90% points 7 16.0 ? ma/ s 1 typical data is at v cc = 8 v and t a = +25c, unless otherwise noted. performance may vary for individual units, within the specified maximum and minimum limits. 2 1 g (gauss) = 0.1 mt (millitesla). 3 power-on time is the time required to complete the initial internal automatic offset adjust; the dacs are then ready for peak a cquisition. 4 direction of the first output pulse on the 6 th edge may not be correct when undergoing vibration. 5 non-direction pulse output only. see figure 3 for more details. 6 direction pulse will typically occur on the 2 nd output pulse after a direction change. this will hold true unless an offset change at zero speed results in an offset correction event. note that no output blanking occurs after a direction change. 7 the device will compensate for magnetic and installation offsets up to 60 g. offsets greater than 60 g may cause inaccuracies in the output.
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 4 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com operating characteristics: switchpoint characteristics valid over operating voltage and temperature ranges, unless otherwise noted (refer to figure below) characteristics symbol test conditions min. typ. max. unit target frequency, forward rotation f fwd ? ? 12 khz target frequency, reverse rotation f rev ? ? 6 khz target frequency, non-direction pulses * f nd ? ? 4 khz bandwidth f -3db cutoff frequency for low-pass filter 15 20 ? khz operate point b op % of peak-to-peak v proc referenced from pdac to ndac, ag < ag max ?70? % release point b rp % of peak-to-peak v proc referenced from pdac to ndac, ag < ag max ?30? % *at power-on, rotational speed or vibration leading to a target frequency greater than 4 khz may result in a constant high outp ut state until true direction is detected. operating characteristics: output pulse characteristics * valid over operating temperature range, unless otherwise noted characteristics symbol test conditions min. typ. max. unit pulse width, forward rotation t w(fwd) r l = 500 , c l = 10 pf 38 45 52 s pulse width, reverse rotation t w(rev) r l = 500 , c l = 10 pf 76 90 104 s pulse width, non-direction t w(nd) r l = 500 , c l = 10 pf 153 180 207 s *measured at a threshold of ( i cc(high) + i cc(low) ) / 2. differential magnetic flux density, b diff (g) valley tooth forward reverse +b ?b differential processed signal, v proc (v) +v ?v t b op(fwd) b v proc(bop) v proc(brp) b rp(fwd) b op % b rp % 100 % b op(rev) b b rp(rev) sensed edge a a sensed edge: leading (rising) mechanical edge in forward rotation, trailing (falling) mechanical edge in reverse rotation b b op(fwd) triggers the output transition during forward rotation, and b op(rev) triggers the output transition during reverse rotation
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 5 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com to o t h valley definition of terms for input characteristics v proc(bop) v proc(brp) v sp [b op ] [b rp ] v proc(pk-pk) t vproc v proc = the processed analog signal of the sinusoidal magnetic input (per channel) t tooth = period of 2 successive sensed target edges v sp t tooth v sp(sep) = v sp v proc(pk-pk) operating characteristics: input characteristics valid over operating temperature range and using reference target 60-0, unless otherwise noted characteristics symbol test conditions min. typ. max. unit operating input range 1 b diff differential magnetic signal; correct direction output on 6 th edge 60 ? 1200 g pk-pk maximum operation air gap 1 ag max correct direction output on 6 th edge ? ? 2.2 mm vibration immunity (startup) err vib(su) allowed rotation detected due to vibration; t tooth = period between 2 successive sensed edges, sinusoidal signal; t a <10c; b diff(ag) = 0 t tooth ?? ? vibration immunity (running mode) 2 err vib allowed rotation detected due to vibration; t tooth = period between 2 successive sensed edges, sinusoidal signal; t a <10c; b diff(ag) = 0 t tooth 0.5 ?? ? maximum sudden air gap change induced signal reduction 3,4 b diff(ag) differential magnetic signal reduction due to instantaneous air gap change; symmetrical signal reduction, target frequency < 500 hz ? ? 40 % pk-pk axial / radial runout / wobble induced signal reduction 5,6 b diff(ro) differential magnetic signal reduction due to instantaneous runout per edge; symmetrical signal reduction, multiple edges ??5% pk-pk relative repeatability 7 t e differential magnetic signal, b diff = 100 g pk-pk , ideal sinusoidal signal, t a = 150c, reference target rotational speed = 1000 rpm (f = 1000 hz) ? 0.12 ? deg. switchpoint separation v sp(sep) minimum separation between channels as a percentage of v proc amplitude at each switchpoint (see figure below) 20 ? ? % 1 under certain extreme conditions, especially for smaller differential magnetic signals, the device may require more than 6 edge s to output correct direction on startup. please contact the allegro factory for assistance when using this device. 2 small amplitude vibration while in running mode may result in one additional direction pulse, prior to non-direction pulse. se e section running small amplitude vibration detection for details. 3 if the minimum v sp(sep) is not maintained after a sudden air gap change, output may be blanked or non-direction pulses may occur. 4 sudden air gap change during startup may increase the quantity of edges required to get correct direction pulses. 5 if the minimum v sp(sep) is not maintained, output may be blanked or non-direction pulses may occur. 6 minimum v proc(pk-pk) signal of 200 mv and minimum v sp(sep) must be maintained 7 the repeatability specification is based on statistical evaluation of a sample population, evaluated at 1000 hz.
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 6 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com reference target 60-0 (60 tooth target) characteristics symbol test conditions typ. units symbol key outside diameter d o outside diameter of target 120 mm face width f breadth of tooth, with respect to branded face 6mm angular tooth thickness t length of tooth, with respect to branded face 3 deg. angular valley thickness t v length of valley, with respect to branded face 3 deg. tooth whole depth h t 3mm material low carbon steel ? ? d o h t f air gap branded face of package t t v reference target 60-0 of package branded face
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 7 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com functional description data protocol description when a target passes in front of the branded face of the pack- age, each tooth of the target generates a pulse at the output of the ic. each pulse provides target speed and direction data: speed is provided by the pulse rate, while direction of target rotation is provided by the pulse width. the ATS657 can sense target movement in both the forward and reverse directions. the maximum allowable target rotational speed is limited by the width of the output pulse and the shortest low-state duration the system controller can resolve. forward rotation (see panel a in figure 1) when the target is rotating such that a tooth near the package passes from pin 4 to pin 1, this is referred to as forward rotation . forward rotation is indicated on the output by a t w(fwd) (45 s typical) pulse width. reverse rotation (see panel b in figure 1) when the target is rotating such that a tooth passes from pin 1 to pin 4, it is referred to as reverse rotation . reverse rotation is indicated on the output by a t w(rev) (90 s typical) pulse width, twice as long as the pulse generated by forward rotation. non-direction output in situations where the ic is not able to discern direction of target rotation, as occurs during initial cali- bration or during target vibration, the output pulse width is t w(nd) . timing as shown in figure 2, the pulse appears at the output slightly before the sensed magnetic edge traverses the branded face. for targets in forward rotation, this shift, fwd, results in the pulse corresponding to the valley with the sensed mechanical edge, and for targets in reverse rotation, the shift, rev, results in the pulse corresponding to the tooth with the sensed edge. the sensed mechanical edge that stimulates output pulses is kept the same for both forward and reverse rotation by using only channel 1 for switching. the overall range between the forward and reverse pulse occur- rences is determined by the 1.5 mm spacing between the hall elements of the corresponding differential channel. in either direction, the pulses appear close to the sensed mechanical edge. the size of the target features, however, can slightly bias the occurrence of the pulses. (a) forward rotation (b) reverse rotation rotating target branded face of package pin 1 pin 4 pin 1 pin 4 rotating target branded face of package figure 1. target rotation figure 2. output pulse timing ? rev t w(rev) 90 s reverse rotation forward rotation output pulse (forward rotation) output pulse (reverse rotation) tooth valley ? fwd t w(fwd) 45 s t t
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 8 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com after the power-on time is complete, the ATS657 internally detects the profile of the target. the output becomes active at the first detected switchpoint. figure 3 shows where the first output pulse occurs for various starting target phases. after calibration is complete, direction information is available and this information is communicated through the output pulse width. figure 3. start-up position effect on first device output switching t ic output power-on opposite valley power-on opposite rising edge power-on opposite falling edge power-on opposite tooth target differential magnetic profile forward target rotation (target passes from pin 4 to pin 1) device location at power-on t w(nd) t w(nd) t w(nd) tooth valley start-up detection
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 9 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com the processed differential internal analog signal, v proc , of each of the two channels is used to determine switchpoints, at which the device determines direction information and changes to out- put signal polarity. because the value of v proc is directly propor- tional to the differential magnetic flux density, b diff , induced by the target and sensed by the hall elements, the switchpoints occur at threshold levels that correspond to certain levels of b diff . the operate point , b op , occurs when v proc rises through a cer- tain limit, v proc(bop) . when b op occurs, the channel internally switches from low to high. when v proc falls below v proc(bop) through a certain limit, v proc(brp) , the release point , b rp , occurs and the channel state switches from high to low. as shown in panel c of figure 4, the threshold levels for the ATS657 switchpoints are established as a function of the two previous signal peaks detected. the ATS657 incorporates an algorithm that continuously monitors v proc and then updates the switching thresholds to correspond to any amplitude reduction. for any given target edge transition, the change in threshold level is limited. each channel operates in this manner, independent of each other, so independent switchpoint thresholds are calculated for each channel. continuous update of switchpoints (a) teag varying; cases such as eccentric mount, out-of-round region, normal operation position shift (b) internal analog signal, v proc , typically resulting in the ic 0 360 target rotation () hysteresis band (delimited by switchpoints) v proc (v) v+ larger teag smaller teag ic target larger teag target ic smaller teag smaller teag pk (#4) pk (#5) pk (#7) pk (#9) pk (#2) pk (#3) pk (#1) pk (#6) pk (#8) v proc (v) b hys(#4) b hys(#3) v+ b rp(#1) b op(#1) b rp(#2) b rp(#3) b op(#3) b rp(#4) b op(#4) b op(#2) v proc(bop) (#1) v proc(bop) (#2) v proc(bop) (#3) v proc(bop) (#4) v proc(brp) (#1) v proc(brp) (#2) v proc(brp) (#3) v proc(brp) (#4) b hys(#1) b hys(#2) figure 4. the continuous update algorithm allows the allegro ic to immediately interpret and adapt to variances in the magnetic field generated by the target as a result of eccentric mounting of the target, out-of-round target shape, elevation due to lubricant build-up in journ al gears, and similar dynamic application problems that affect the teag (total effective air gap). not detailed in the figure are the boundaries for peak cap ture dac movement which intentionally limit the amount of internal signal variation the ic is able to react to over a single transition. the algorithm is used to dynamically establish and subsequently update the device switchpoint levels (v proc(bop) and v proc(brp) ). the hysteresis, b hys(#x) , at each target feature configuration results from this recalibration, ensuring that it remains properly proportioned and centered within the peak-to-peak range of the inter nal analog signal, v proc . as shown in panel a, the variance in the target position results in a change in the teag. this affects the ic as a varying magn etic field, which results in proportional changes in the internal analog signal, v proc , shown in panel b. the continuous update algorithm is used to establish accurate switchpoint levels based on the fluctuation of v proc , as shown in panel c. b hys switchpoint determinant peak values 1 b op(#1) pk (#1) , pk (#2) b rp(#1) pk (#2) , pk (#3) 2 b op(#2) pk (#3) , pk (#4) b rp(#2) pk (#4) , pk (#5) 3 b op(#3) pk (#5) , pk (#6) b rp(#3) pk (#6) , pk (#7) 4 b op(#4) pk (#7) , pk (#8) b rp(#4) pk (#8) , pk (#9) (c) referencing the internal analog signal, v proc , to continuously update device response
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 10 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com during normal running mode, vibration can interfere with the direction detection functions. in that case, during the vibration the device may continue to output speed data with non-directional pulses. if the vibration that occurs has a large enough amplitude such that the peaks of the v proc signals continue to pass through both switchpoints, non-direction pulses will be outputted during the vibration, as shown in figure 5. if the vibration has a low enough amplitude such that its posi- tive peak is less than v proc(bop) , no pulses are outputted and no switchpoint updating occurs until the vibration becomes large enough that v proc exceeds v proc(bop) . if its negative peak is greater than v proc(brp) , then there is no output or update until v proc falls below v proc(brp) . as shown in figure 6, when that does occur, a single direction pulse may be outputted, however, regardless of whether or not that single pulse occurs, non-direction pulses are outputted throughout the remainder of the vibration. figure 6. small amplitude vibration during running mode operation figure 5. large amplitude vibration during running mode operation operation during running mode vibration +v switchpoint hysteresis t w(fwd) or t w(rev) t w(nd) +t +t normal rotation vibration } v proc v proc(bop) v proc(brp) +i i out +v switchpoint hysteresis t w(fwd) or t w(rev) t w(fwd) or t w(rev) t w(nd) v proc +t +t normal rotation vibration } v proc > v proc(bop) v proc(bop) v proc(brp) +i i out
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 11 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com undervoltage lockout when the supply voltage falls below the minimum operating volt- age, v cc(uv) , i cc goes to the power-on state and remains regard- less of the state of the magnetic gradient from the target. this lockout feature prevents false signals, caused by undervoltage conditions, from propagating to the output of the ic. i cc levels may not meet datasheet limits when v cc < v cc(min) . power supply protection the device contains an on-chip regulator and can operate over a wide v cc range. for devices that need to operate from an unregu- lated power supply, transient protection must be added externally. for applications using a regulated line, emi/rfi protection may still be required. contact allegro for information on the circuitry needed for compliance with various emc specifications. refer to figure 7 for an example of a basic application circuit. automatic gain control (agc) this feature allows the device to operate with an optimal internal electrical signal, regardless of the air gap (within the ag speci- fication). at power-on, the device determines the peak-to-peak amplitude of the signal generated by the target. the gain of the ic is then automatically adjusted. figure 8 illustrates the effect of this feature. the two differential channels have their gain set independent of each other, so both channels may or may not have the same gain setting. automatic offset adjust (aoa) the aoa circuitry, when combined with agc, automatically compensates for the effects of chip, magnet, and installation offsets. (for capability, see allowable user induced differential offset, in the electrical characteristics table.) this circuitry is continuously active, including both during power-on mode and running mode, compensating for offset drift. continuous opera- tion also allows it to compensate for offsets induced by tempera- ture variations over time. similar to agc, the aoa is set inde- pendently for each channel, so the offset adjust is set per channel, based on the offset characteristics of that specific channel. figure 8. automatic gain control (agc). the agc function corrects for variances in the air gap. differences in the air gap cause differences in the magnetic field at the device, but agc prevents that from affecting device performance, as shown in the lowest panel. figure 7. typical application circuit mechanical profile ag small ag large ag small ag large internal differential signal response, without agc internal differential signal response, with agc ferrous target v+ v+ 2 ATS657 1 3 4 0.01 m f (optional) 100 7 r l c l c bypass v cc
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 12 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com thermal characteristics may require derating at maximum conditions, see power derating section characteristic symbol test conditions* value unit package thermal resistance r ja single layer pcb, with copper limited to solder pads 126 oc/w single layer pcb, with limited to solder pads and 3.57 in. 2 (23.03 cm 2 ) copper area each side 84 oc/w *additional thermal information available on the allegro website 6 7 8 9 2 3 4 5 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 20 40 60 80 100 120 140 160 180 temperature (oc) maximum allowable v cc (v) power derating curve r q ja = 126 oc/w r q ja = 84 oc/w v cc (min) v cc(absmax) 0 100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700 1800 1900 20 40 60 80 100 120 140 160 180 temperature (c) power dissipation, p d (m w) power dissipation versus ambient temperature r q ja = 126 oc/w r q ja = 84 oc/w
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 13 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com the device must be operated below the maximum junction tem- perature of the device, t j (max). under certain combinations of peak conditions, reliable operation may require derating supplied power or improving the heat dissipation properties of the appli- cation. this section presents a procedure for correlating factors affecting operating t j . (thermal data is also available on the allegro microsystems web site.) the package thermal resistance, r ? ja , is a figure of merit sum- marizing the ability of the application and the device to dissipate heat from the junction (die), through all paths to the ambient air. its primary component is the effective thermal conductivity, k, of the printed circuit board, including adjacent devices and traces. radiation from the die through the device case, r ? jc , is a relatively small component of r ? ja . ambient air temperature, t a , and air motion are significant external factors, damped by overmolding. the effect of varying power levels (power dissipation, p d ), can be estimated. the following formulas represent the fundamental relationships used to estimate t j , at p d . p d = v in i in (1) ? ???????????????????????? t = p d r ? ja (2) t j = t a + t (3) for example, given common conditions such as: t a = 25c, v cc = 12 v, i cc = 6.5 ma, and r ? ja = 126 c/w, then: p d = v cc i cc = 12 v 6.5 ma = 78 mw ?? t = p d r ? ja = 78 mw 126 c/w = 9.8c t j = t a + ? t = 25c + 9.8c = 34.8c a worst-case estimate, p d (max), represents the maximum allow- able power level (v cc (max), i cc (max)), without exceeding t j (max), at a selected r ? ja and t a . example : reliability for v cc at t a = 150c, package sh, using single layer pcb. observe the worst-case ratings for the device, specifically: r ? ja = 126c/w, t j (max) = 165c, v cc(absmax) = 24 v, and i cc = 13 ma (note: at maximum target frequency, i cc(low) = 8 ma, i cc(high) = 16 ma, and maximum pulse widths, the result is a duty cycle of 62.4% and a worst case mean i cc of 13 ma.) calculate the maximum allowable power level, p d (max). first, invert equation 3: ? t(max) = t j (max) ? t a = 165 c ? 150 c = 15 c this provides the allowable increase to t j resulting from internal power dissipation. then, invert equation 2: ???? p d (max) = ? t(max) r ? ja = 15c 126 c/w = 119 mw finally, invert equation 1 with respect to voltage: v cc(est) = p d (max) i cc = 119 mw 13 ma = 9.2 v the result indicates that, at t a , the application and device can dissipate adequate amounts of heat at voltages v cc(est) . compare v cc(est) to v cc (max). if v cc(est) v cc (max), then reli- able operation between v cc(est) and v cc (max) requires enhanced r ? ja . if v cc(est) v cc(max) , then operation between v cc(est) and v cc (max) is reliable under these conditions. power derating
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 14 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 0.710.05 5.000.10 4.000.10 1.000.10 0.600.10 24.650.10 13.100.10 1.0 ref 0.71 0.10 0.71 0.10 1.60 0.10 1.270.10 5.50 0.10 5.500.05 8.000.05 5.800.05 1.700.10 24 3 1 a a b d for reference only, not for tooling use (reference dwg-9003) dimensions in millimeters a b c c d dambar removal protrusion (16x) metallic protrusion, electrically connected to pin 4 and substrate (both sides) thermoplastic molded lead bar for alignment during shipment active area depth 0.43 mm ref branded face standard branding reference view = supplier emblem l = lot identifier n = last three numbers of device part number y = last two digits of year of manufacture w = week of manufacture lllllll yyww nnn branding scale and appearance at supplier discretion 0.38 +0.06 ?0.04 f e f f e 1.50 e2 e3 e1 1.50 hall elements (e1, e2, e3); not to scale package sh 4-pin sip
dynamic, self-calibrating, threshold-detecting, differential speed and direction hall-effect gear tooth sensor ic ATS657 15 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com for the latest version of this document, visit our website: www.allegromicro.com copyright ?2009, allegro microsystems, inc. the products described herein are manufactured under one or more of the following u.s. patents: 5,264,783; 5,389,889; 5,442,28 3; 5,517,112; 5,581,179; 5,619,137; 5,621,319; 5,650,719; 5,686,894; 5,694,038; 5,729,130; 5,917,320; 6,091,239; 6,100,680; 6,232,768; 6,242, 908; 6,265,865; 6,297,627; 6,525,531; 6,690,155; 6,693,419; 6,919,720; 7,046,000; 7,053,674; 7,138,793; 7,199,579; 7,253,614; 7,365,530; 7,368, 904; or other patents pending. allegro microsystems, inc. reserves the right to make, from time to time, such de par tures from the detail spec i fi ca tions as may be required to per- mit improvements in the per for mance, reliability, or manufacturability of its products. before placing an order, the user is cautioned to verify that the information being relied upon is current. allegro?s products are not to be used in life support devices or systems, if a failure of an allegro product can reasonably be expected to cause the failure of that life support device or system, or to affect the safety or effectiveness of that device or system. the in for ma tion in clud ed herein is believed to be ac cu rate and reliable. how ev er, allegro microsystems, inc. assumes no re spon si bil i ty for its use; nor for any in fringe ment of patents or other rights of third parties which may result from its use.

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