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description the ats627 is a true zero-speed gear tooth sensor ic consisting of an optimized hall ic and rare earth pellet configuration in a single overmolded package. the integrated circuit provides a manufacturer-friendly solution for digital gear tooth sensing applications. this small package can be easily assembled and used in conjunction with gears of various shapes and sizes. the dual-element hall ic switches in response to differential magnetic signals created by a ferrous target. digital processing of the analog signal provides zero-speed performance independent of air gap as well as dynamic adaptation of device performance to the typical operating conditions found in automotive applications. high-resolution peak detecting dacs are used to set the adaptive switching thresholds of the device. bounded tracking and switchpoint hysteresis reduce the negative effects of any anomalies in the magnetic signal associated with the targets used in many automotive applications. this sensor ic system is optimized for engine crank applications that utilize targets that possess signature regions. this device is available in a lead (pb) free 4-pin sip package (sg) with a 100% matte tin plated leadframe. ATS627LSG-ds features and benefits ? highly accurate in presence of: ? anomalous target geometry (tooth-tooth variation) ? signature teeth or valleys ? target runout ? highly repeatable output edges (low jitter) ? true zero-speed operation ? undervoltage lockout ? air gap independent switchpoints ? defined power-on state ? high operating temperature ? single-chip sensing ic for high reliability ? enhanced quality through scan path and iddq measurement ? enhanced emc performance true zero speed, low jitter, high accuracy position sensor ic package: 4-pin sip (suffix sg) functional block diagram not to scale ATS627LSG gnd vout vcc test multiplexed test signals current limit reference generator and lockout synchronous digital controller + ? pdac agc hall amp ndac filter analog regulators digital regulator offset adjust
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 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 cc refer to power derating section 26.5 v output off voltage v outoff 26.5 v reverse supply voltage v rcc ?18 v reverse output voltage v rout ?0.5 v output current i outsink 25 ma operating ambient temperature t a l temperature range ?40 to 150 oc maximum junction temperature t j (max) 165 oc storage temperature t stg ?65 to 170 oc terminal list table number name function 1 vcc supply voltage 2 vout open drain output 3 test test pin 4 gnd ground selection guide part number packing* ATS627LSGtn-t 800 pieces per 13-in. reel *contact allegro ? for additional packing options 24 3 1
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 3 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com operating characteristics valid through full operating supply voltage and ambient temperature ranges, using reference target 60+2; unless otherwise specified characteristics symbol test conditions min. typ. 1 max. unit electrical characteristics supply voltage 2 v cc operating, t j < t j (max) 4.0 ? 24 v undervoltage lockout v cc(uv) v cc = 0 5 v or 5 0 v ? 3.6 3.95 v reverse supply current 3 i rcc v cc = v rcc (max) ? ? ?10 ma supply zener clamp voltage v zsupply i cc = i cc (max) + 3 ma, t a = 25oc 28 ? ? v supply current i cc ? 7 12 ma test pin zener clamp voltage 4 v ztest ?6 ?v power-on characteristics power-on state pos v out , ic connected as in figure 8 ? high ? v output stage characteristics low output voltage v out(sat) vout = on (v out = low), i out = 20 ma 0 ? 450 mv output zener clamp voltage v zoutput i out = 3 ma, t a = 25c 28 ? ? v output leakage current i out(off) vout = off (v out = high) ? ? 10 a output current limit i out(lim) vout = on (v out = low), t j < t j (max) 25 45 70 ma output rise time t r v pu = 12 v, r pu = 1.0 k , c load = 4.7 nf ? 10 ? s output fall time t f v pu = 12 v, r pu = 1.0 k , c load = 4.7 nf ? 0.6 2 s dac characteristics allowable user-induced offset 5 b diffext ?60 ? 60 g other operating characteristics, with continuous update method, bounded for increasing and decreasing ag running mode lockout enable loe ? 115 ? mv running mode lockout release lor ? 220 ? mv operate point b op % of peak-to-peak v proc , referenced from pdac to ndac, v out high low ? 60 ? % release point b rp % of peak-to-peak v proc , referenced from pdac to ndac, v out low high ? 40 ? % bandwidth f -3db cutoff frequency for low pass filter ? 20 ? khz operational speed s rot 0 ? 12 000 rpm performance characteristics operational magnetic range b in peak-to-peak differential signal 30 ? 1200 g air gap ag compliant to accuracy specifications, measured from package branded face to target tooth 0.5 ? 2.5 mm no missed edges, measured from package branded face to target tooth 0.5 ? 3.0 mm relative timing accuracy, sequential mechanical rising edges err rr 0.5 mm ag 2.5 mm; constant target speed, running mode; relative to measurement taken at ag = 1.5 mm ? ? 0.4 deg. continued on the next page?
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 4 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com relative timing accuracy, sequential mechanical falling edges err ff 0.5 mm ag 2.5 mm; constant target speed, running mode; relative to measurement taken at ag = 1.5 mm ? ? 0.4 deg. relative timing accuracy, signature mechanical rising edge err sigr 0.5 mm ag 2.5 mm; constant target speed, running mode; relative to measurement taken at ag = 1.5 mm ? ? 0.4 deg. relative timing accuracy, signature mechanical falling edge err sigf 0.5 mm ag 2.5 mm; constant target speed, running mode; relative to measurement taken at ag = 1.5 mm ? ? 1.5 deg. relative repeatability, sequential rising and falling edges 6 t e 0.5 mm ag 2.5 mm ? ? 0.08 deg. output propagation delay t dout ? 20 ? s initial edge accuracy 7 edge accuracy ? first and second output edges see figure 1 ?t target ?t target deg. edge accuracy ? third through sixth output edges see figure 1 ?0.5 x t target ? +0.5 x t target deg. full edge accuracy output edge count (see figure 1), b sig / b seq = 1, or no signature tooth encountered ??6 ? output edge count (see figure 1), signature region encountered during calibration, and b sig / b seq 1 ?9 ?? input magnetic characteristics allowable differential sequential signal variation 8 b seq(min) / b seq(max) total variation over 60 cycles (see figure 2) 0.5 ? ? ? b seq(n+1) / b seq(n) single cycle-to-cycle variation (see figure 2) 0.6 ? ? ? allowable signature amplitude ratio b sig / b seq one instance per target revolution (see figure 2) 0.8 ? 1.6 ? 1 typical values are at t a = 25c and v cc = 12 v. 2 maximum voltage must be adjusted for power dissipation and junction temperature; see power derating section. 3 negative current is defined as current coming out of (sourced from) the specified device terminal. 4 sustained voltages beyond the clamp voltage may cause permanent damage to the ic. 5 1 g (gauss) = 0.1 mt (millitesla). 6 the repeatability specification is based on statistical evaluation of a sample population, evaluated at 1000 hz. 7 power-on frequencies 200 hz. higher power-on frequencies may result in a delay of full output accuracy or undetected target edges. 8 excludes effects caused by signature region. operating characteristics (continued) valid through full operating supply voltage and ambient temperature ranges, using reference target 60+2; unless otherwise specified characteristics symbol test conditions min. typ. 1 max. unit performance characteristics (continued)
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 5 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com b seq(n) b seq(n+1) b seq (max) b seq (min) sequential regions sequential regions signature region b sig v proc target t vproc v proc = the processed analog signal of the sinusoidal magnetic input (per channel) t target = period between successive sensed target mechanical edges of the same orientation (either both rising or both falling) t target valley tooth figure 1. definition of t target figure 2. differential signature amplification and sequential signal variation
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 6 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com characteristic performance output current, i out (ma) low output voltage, v out(sat) (mv) 0 5 10 15 25 20 30 450 400 350 300 250 200 150 100 50 0 t a (c) -40 25 85 150 output voltage (on) versus output current supply voltage, v cc (v) supply current, i cc (ma) 12 10 8 6 4 2 0 0 5 10 15 25 20 30 t a (c) -40 25 85 150 supply current (off) versus supply voltage 0 5 10 15 25 20 30 supply voltage, v cc (v) supply current, i cc (ma) 12 10 8 6 4 2 0 t a (c) -40 25 85 150 supply current (on) versus supply voltage 450 400 350 300 250 200 150 100 50 0 ambient temperature, t a (c) low output voltage, v out(sat) (mv) -50 -25 0 25 50 75 100 150 125 175 i out (ma) 10 15 20 25 output voltage (on) versus temperature ambient temperature, t a (c) supply current, i cc (ma) -50 -25 0 25 50 75 100 150 125 175 12 10 8 6 4 2 0 v cc (v) 4 12 18 24 supply current (off) versus temperature 12 10 8 6 4 2 0 -50 -25 0 25 50 75 100 150 125 175 ambient temperature, t a (c) supply current, i cc (ma) v cc (v) 4 12 18 24 supply current (on) versus temperature
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 7 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com air gap, ag (mm) sequential region, 3 falling edges at each t a 360 repeatability 6-sigma, () 0.30 0.25 0.20 0.15 0.10 0.05 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 t a = 150c t a = ?40c t a = 25c specification limit 360 repeatability versus air gap air gap, ag (mm) sequential region, 3 rising edges at each t a 360 repeatability 6-sigma, () 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0.30 0.25 0.20 0.15 0.10 0.05 0 t a = 150c t a = ?40c t a = 25c specification limit 360 repeatability versus air gap 5.0 4.0 3.0 2.0 1.0 0 -1.0 -2.0 -3.0 -4.0 -5.0 -50 -25 0 25 50 75 100 150 125 175 ambient temperature, t a (c) output current, i out (ma) v out = 28 v output current (off) versus temperature
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 8 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, rising edge ambient temperature, t a (c) ?40 25 85 150 ag = 0.5 mm; relative to t a = 25c, s rot = 1000 rpm timing accuracy versus operational speed
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 9 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, rising edge ambient temperature, t a (c) ?40 25 85 150 ag = 2.5 mm; relative to t a = 25c, s rot = 1000 rpm timing accuracy versus operational speed
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 10 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 air gap, ag (rpm) relative timing accuracy () 0 0.5 1.0 2.0 1.5 2.5 3.0 sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 air gap, ag (rpm) relative timing accuracy () 0 0.5 1.0 2.0 1.5 2.5 3.0 sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 air gap, ag (rpm) relative timing accuracy () 0 0.5 1.0 2.0 1.5 2.5 3.0 signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 0.5 1.0 2.0 1.5 2.5 3.0 air gap, ag (rpm) relative timing accuracy () signature feature, rising edge operational speed, s rot (rpm) 500 1000 1500 2000 t a = 25c; relative to ag = 1.5 mm, s rot = 1000 rpm timing accuracy versus air gap
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 11 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 signature feature, rising edge operational speed, s rot (rpm) 500 1000 1500 2000 ag = 0.5 mm; relative to t a = 25c, s rot = 1000 rpm timing accuracy versus ambient temperature
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 12 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 relative timing accuracy () ambient temperature, t a (c) -50 -25 0 25 50 75 100 150 125 175 signature feature, rising edge operational speed, s rot (rpm) 500 1000 1500 2000 ag = 2.5 mm; relative to t a = 25c, s rot = 1000 rpm timing accuracy versus ambient temperature
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 13 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () sequential features, rising edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, falling edge 1.5 1.0 0.5 0 -0.5 -1.0 -1.5 0 500 1000 1500 2000 2500 operational speed, s rot (rpm) relative timing accuracy () signature feature, rising edge air gap, ag (mm) 0.50 0.75 1.00 1.50 2.25 2.50 t a = 25c; relative to ag = 1.5 mm, s rot = 1000 rpm timing accuracy versus operational speed
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 14 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 copper 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 power derating curve 2 3 4 5 6 7 8 9 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 (c) maximum allowable v cc (v) v cc(max) v cc(min) (r ja = 84 c/w) (r ja = 126 c/w) 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
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 15 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com reference target 60+2 characteristics symbol test conditions typ. unit symbol key outside diameter d o outside diameter of target 120 mm t,t sig t v ? d o h t f branded face of package air gap face width f breadth of tooth, with respect to branded face 6mm angular tooth thickness t length of tooth, with respect to branded face; measured at d o 3 deg. signature region angu- lar tooth thickness t sig length of signature tooth, with respect to branded face; measured at d o 15 deg. angular valley thickness t v length of valley, with respect to branded face; measured at d o 3 deg. tooth whole depth h t 3mm material low carbon steel ? ? reference gear magnetic profile two tooth-to-valley transitions -500 -400 -300 -200 -100 0 100 200 300 400 500 gear rotation () differential b* (g) 024681012 0.50 (mm) air gap 0.50 mm ag 3.00 mm ag 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 reference gear magnetic gradient amplitude with reference to air gap air gap (mm) peak-to-peak differential magnetic flux density, b diff (g) 11.52 0.5 2.5 3 1400 1200 1000 800 600 400 200 0 reference target signature region 60+2 of package branded face pin 4 pin 1 reference target characteristics
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 16 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com functional description sensing technology the ats627 contains a single-chip differential hall-effect sensor ic, a samarium cobalt pellet, and a flat ferrous pole piece (con- centrator). as shown in figure 4, the hall ic supports two hall elements, which sense the magnetic profile of the ferrous gear target simultaneously, but at different points (spaced at a 2.2 mm pitch), generating a differential internal analog voltage, v proc , that is processed for precise switching of the digital output signal. the hall ic is self-calibrating and also possesses a temperature compensated amplifier and offset cancellation circuitry. the built-in voltage regulator provides supply noise rejection through- out the operating voltage range. changes in temperature do not greatly affect this device due to the stable amplifier design and the offset compensation circuitry. the hall transducers and signal processing electronics are integrated on the same silicon sub- strate, using a proprietary bicmos process. target profiling during operation an operating device is capable of providing digital information that is representative of the mechanical features of a rotating gear. the waveform diagram in figure 6 presents the automatic transla- tion of the mechanical profile, through the magnetic profile that it induces, to the digital output signal of the ats627. no addi- tional optimization is needed and minimal processing circuitry is required. this ease of use reduces design time and incremental assembly costs for most applications. determining output signal polarity in figure 6 the top panel, labeled mechanical position, represents the mechanical features of the target gear and orientation to the device. the bottom panel, labeled device output signal, displays the square waveform corresponding to the digital output signal that results from a rotating gear configured as shown in figure 5, and electrically connected as in figure 8. that direction of rota- tion (of the gear side adjacent to the package face) is: perpen- dicular to the leads, across the face of the device, from the pin 1 side to the pin 4 side. this results in the ic output switching from low state to high state as the leading edge of a tooth (a rising mechanical edge, as detected by the ic) passes the package face. in this configuration, the device output switches to its high polar- ity when a tooth is the target feature nearest to the package. if the direction of rotation is reversed, so that the gear rotates from the pin 4 side to the pin 1 side, then the output polarity inverts. that is, the output signal goes high when a falling edge is detected, and a valley is nearest to the package. figure 4. relative motion of the target is detected by the dual hall elements in the hall ic. figure 5. this left-to-right (pin 1 to pin 4) direction of target rotation results in a high output state when a tooth of the target gear is nearest the package face (see figure 3). a right-to-left (pin 4 to pin 1) rotation inverts the output signal polarity. figure 6: the magnetic profile reflects the geometry of the target, allowing the ats627 to present an accurate digital output response. b op(#1) b rp(#1) b rp(#2) b op(#2) on off off on device internal switch state device orientation to target device internal differential analog signal, v proc mechanical position (target movement pin 1 to pin 4) device output signal, v out target (gear) (package top view) sensor branded face pin 1 side pin 4 side branded face hall element pitch target magnetic profile +b this tooth sensed earlier this tooth sensed later ic back-biasing rare-earth pellet rotating target branded face of sensor pin 1 pin 4 target (gear) back-biasing magnet south pole north pole case (pin 1 side) (pin 4 side) hall ic pole piece element pitch (concentrator) dual-element hall effect device hall element 1 hall element 2
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 17 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 undervoltage lockout voltage, v cc(uv) , the device enters reset, where the output state returns to the power-on state (pos) until sufficient v cc is supplied. this lockout feature prevents false signals, caused by undervoltage conditions, from propagating to the output of the ic. power supply protection the device contains an on-chip regulator and can operate over a wide v cc range. for devices that must 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 8 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. this feature is also active in running mode, though very conser- vatively invoked, to optimize the signal amplitude in the scenario where signal amplitude during the initial calibration period is not representative of the running mode signal. automatic offset adjust (aoa) the aoa circuitry automatically compensates for the effects of chip, magnet, and installation offsets. this circuitry is continu- ously active, including during both power-on mode and running mode, compensating for any offset drift (within the allowable user induced differential offset). continuous operation also allows it to compensate for offsets induced by temperature varia- tions over time. this circuitry works with the agc during cali- bration to adjust v proc in the internal range to allow the dacs to acquire the signal peaks. bounded update the ats627 continuously updates its switchpoints based on the actual signal being received from the target. when the output switches, the sensor resets the tracking dacs so that each proper magnetic signal peak can be acquired. to prevent establishing switchpoints on outlier signal maxima, tracking is limited, or bounded, in magnitude. if such limiting were not applied, then anomalous target features, such as bent, broken or misformed teeth, could create significant output accuracy errors (see fig- ure 7). running mode lockout the ats627 has a running mode lockout feature to prevent switching in response to small amplitude input signals that are characteristic of vibration signals. the internal logic of the chip interprets small signal amplitudes below a certain level to be the result of target vibration. the output is held to the state present prior to lockout, until the amplitude of the signal returns to nor- mal operational levels.
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 18 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com np np np pp pp pp outlier v proc ndac tracking pdac tracking bounded limit enforced figure 7. operation of bounded update method (for illustrative purposes only, values may not be to scale) ? two dacs track the v proc signal: pdac tracks positive (high) peaks, and ndac tracks negative (low) peaks. ? the dacs track the v proc signal until a peak is reached or the bounding limit is reached. successive pp and np values are used to establish the next switchpoint.
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 19 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com power derating 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 website.) 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 = 7 ma, and r ? ja = 126 c/w, then: p d = v cc i cc = 12 v 7 ma = 84 mw ?? t = p d r ? ja = 84 mw 126 c/w = 10.6c t j = t a + ? t = 25c + 10.6c = 35.6c 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 = 160c, package sg, using single layer pcb. observe the worst-case ratings for the device, specifically: r ? ja = 126c/w, t j (max) = 175c, v cc(absmax) = 24 v, and i cc = 12 ma. calculate the maximum allowable power level, p d (max). first, invert equation 3: ? t(max) = t j (max) ? t a = 175 c ? 160 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 12 ma = 9.9 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. application information
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 20 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com c bypass 0.1 f v s v pu r pu c l 1 4 3 2 vcc vout test (recommended) output gnd ats627 figure 8. basic typical application circuit typical application
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 21 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com package sg, 4-pin sip 0.710.05 5.500.05 4.700.10 0.600.10 0.400.10 24.650.10 15.300.10 1.0 ref 0.71 0.10 0.71 0.10 1.60 0.10 1.270.10 5.50 0.10 8.000.05 5.800.05 1.700.10 24 3 1 a a d b for reference only, not for tooling use (reference dwg-9002) dimensions in millimeters a b c c d e f f f dambar removal protrusion (16x) metallic protrusion, electrically connected to pin 4 and substrate (both sides) thermoplastic molded lead bar for alignment during shipment e e2 e1 hall elements (e1, e2), not to scale active area depth, 0.43 mm 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 1.10 1.10
true zero speed, low jitter, high accuracy position sensor ic ATS627LSG 22 allegro microsystems, inc. 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com copyright ?2011, allegro microsystems, inc. 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. for the latest version of this document, visit our website: www.allegromicro.com

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