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note: for detailed information on purchasing options, contact your local allegro field applications engineer or sales representative. allegro microsystems, llc. reserves the right to make, from time to time, revisions to the anticipated product life cycle plan for a product to accommodate changes in production capabilities, alternative product availabilities, or market demand. the information included herein is believed to be accurate and reliable. however, allegro microsystems, llc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. recommended substitutions: precision hall effect angle sensor ic with i 2 c interface a1332 for existing customer transition, and for new customers or new appli- cations, refer to the a1335lletr-t . date of status change: december 1, 2015 these parts are in production but have been determined to be not for new design. this classification indicates that sale of this device is currently restricted to existing customer applications. the device should not be purchased for new design applications because obsolescence in the near future is probable. samples are no longer available. not for new design
a1332-ds, rev. 4 ? 360 contactless high resolution angle position sensor ? cvh (circular vertical hall) technology ? digital i 2 c output ? refresh rate: 32 s, 12-bit resolution ? automotive temperature range -40 to 85c as well as -40 to 125c ? t wo types of linearization schemes offered: harmonic linearization and segmented linearization ? linearization features enable use in of f-axis applications ? eeprom with error correction control (ecc) for trimming calibration ? 1 mm thin (tssop-14) package ? automatic calibration features maintain angle accuracy over air gap precision hall effect angle sensor ic with i 2 c interface functional block diagram a1332 multisegment cvh element regulator analog front end digital subsystem to all internal circuits eeprom 32-bit microprocessor i 2 c interface diagnostics byp c byp(byp) vcc (also programming) v+ adc sa0 sa1 sda vcc (programming) scl c byp(vcc) dgnd agnd soc die test package: 14-pin tssop (le suffix) not to scale the a1332 is a 360 contactless high resolution programmable magnetic angle position sensor ic. it is designed for digital systems using an i 2 c interface. this system-on-chip (soc) architecture includes a front end based on circular vertical hall (cvh) technology, programmable microprocessor based signal processing, and digital i 2 c interface. besides providing full-turn angular measurement, the a1332 also provides scaling for angle measurement applications less than 360 . it includes on-chip eeprom technology for flexible programming of calibration parameters. digital signal processing functions, including temperature compensation and gain/offset trim, as well as advanced output linearization algorithms, provide an extremely accurate and linear output for both end of shaft applications, as well as off - axis applications. the a1332 is ideal for automotive applications requiring high speed 360 angle measurements, such as: electronic power steering (eps), transmission, torsion bar, and other systems that require accurate measurement of angles. the a1332 linearization schemes were designed with challenging off-axis applications in mind. the device is offered in a 14-pin tssop (le) package, which has a single die. the package is lead (pb) free, with 100% matte tin leadframe plating. features and benefits description
2 table of contents specifications 3 absolute maximum ratings 3 thermal characteristics 3 pin-out diagram and terminal list 3 operating characteristics table 4 functional description 6 overview 6 operation 6 diagnostic features 8 programming modes 8 application information 10 serial interface description 10 magnetic t arget requirements 11 on-axis applications 11 of f-axis applications 11 ef fect of orientation on signal 12 linearization 13 correction for eccentric orientation 14 harmonic coef ficients 15 pcb layout 15 typical characteristics 16 package outline drawing 19 selection guide part number application package packing* operating ambient tem - perature, t a a1332eletr-t i 2 c digital output single die, 14-pin tssop 4000 pieces per 13-in. reel C40c to 85c A1332KLETR-T i 2 c digital output single die, 14-pin tssop 4000 pieces per 13-in. reel C40c to 125c *contact allegro ? for additional packing options refer to the programming reference addendum for information on programming the device. precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
3 absolute maximum ratings characteristic symbol notes rating unit forward supply voltage v cc 24 v reverse supply voltage v rcc C18 v logic input voltage for i 2 c pins v in C0.5 to 5.5 v operating ambient temperature t a for a1332eletr-t, e temperature range C40 to 85 oc for A1332KLETR-T, k temperature range C40 to 125 oc maximum junction temperature t j (max) 165 oc storage temperature t stg C65 to 170 oc thermal characteristics may require derating at maximum conditions, see application information characteristic symbol test conditions* value unit package thermal resistance r ja on 4-layer pcb based on jedec standard 82 oc/w *additional thermal information available on the allegro website specifications 1 2 3 4 5 6 7 14 13 12 11 10 9 8 dgnd byp dgnd agnd vcc vcc agnd dgnd sa0 sa1 scl sda dgnd test package le, 14-pin tssop pin-out diagram terminal list table pin- name pin num- ber function agnd 4, 7 device analog ground terminal byp 2 internal bypass node, connect with bypass capacitor to dgnd dgnd 1, 3, 9, 14 device digital ground terminal sa0 13 digital input: sets slave address bit 0 (lsb)*; tie to byp for 1, tie to dgnd for 0 sa1 12 digital input: sets slave address bit 0 (lsb)*; tie to byp for 1, tie to dgnd for 0 scl 11 digital input: serial clock; open drain, pull up externally to 3.3 v sda 10 digital control output: digital output of evaluated target angle, also programming data input i 2 c data terminal; open drain, pull up externally to 3.3 v test 8 test terminal, must be tied to dgnd for correct operation vcc 5, 6 device power supply; also input for eeprom writing pulse *for additional information, refer to the programming reference addendum, eeprom description and programming section, regarding the intf register, i2cm field. precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
4 continued on the next page characteristic symbol test conditions min. typ. 1 max. unit 2 electrical characteristics supply voltage v cc 4.5 5 5.5 v supply current i cc C 16 20 ma vcc low flag threshold 3 v cclow(th) 4.4 4.55 4.75 v supply zener clamp voltage 6 v zsup i zcc = i cc + 3 ma, t a = 25c 26.5 C C v reverse battery voltage v rcc i rcc = C3 ma, t a = 25c C C C18 v power-on time 4,5 t po t a = 25c 2 C 40 ms i 2 c interface specifcation (v pu = 3.3 v on sda and scl pins) bus free time between stop and start 4 t buf 1.3 C C s hold time start condition 4 t hd(sta) 0.6 C C s setup time for repeated start condition 4 t su(sta) 0.6 C C s scl low time 4 t low 1.3 C C s scl high time 4 t high 0.6 C C s data setup time 4 t su(dat) 100 C C ns data hold time 4 t hd(dat) 0 C 900 ns setup time for stop condition 4 t su(sto) 0.6 C C s logic input low level (sda and scl pins) 6 v il(i2c) t a = 25oc C C 0.9 v logic input high level (sda and scl pins) 6 v ih(i2c) t a = 25oc 2.1 C 3.63 v logic input current 6 i in v in = 0 v to v cc, t a = 25oc C1 C 1 a output voltage (sda pin) 6 v ol(i2c) r pu n b = 100 pf, t a = 25oc C C 0.6 v logic input rise time (sda and scl pins) 4 t r(in) C C 300 ns logic input fall time (sda and scl pins) 4 t f(in) C C 300 ns sda output rise time 4 t r(out) r pu n b = 100 pf C C 300 ns sda output fall time 4 t f(out) r pu n b = 100 pf C C 300 ns scl clock frequency 6 f clk t a = 25oc C C 400 khz sda and scl bus pull-up resistor r pu C 1 C n total capacitive load for each of sda and scl buses 6 c b t a = 25oc C C 100 pf pull-up voltage v pu r pu n b = 100 pf 2.97 3.3 3.63 v 1 typical data is at t a = 25c and v cc = 5 v and it is for design information only. 2 1 g (gauss) = 0.1 mt (millitesla). 3 vcc low threshold flag will be sent via the i 2 c interface as part of the angle measurement. when v cc goes below the minimum value of v cclow(th) . the vcc low flag is set. see programming manual for details. 4 0lqdqg0dsdudphwhuviruwklvfkdudfwhulvwlfduhghwhuplqhgeghvljq 7khduhqrwphdvxuhgdwqdowhvw 5 end user can customize what power-on tests are conducted at each power-on that causes a wide range of power-on times. for more information, see the description of the cfg register, which is available in the programming manual. 6 this parameter is tested at wafer probe only. operating characteristics : valid throughout full operating voltage and ambient temperature ranges, unless other- wise specifed precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
5 characteristic symbol test conditions min. typ. 1 max. unit 2 magnetic characteristics magnetic field 9 b range of input field 300 C 1000 g angle characteristics output 10 res angle C 12 C bits effective resolution 11 b = 300 g, t a = 25oc, orate = 0 C 10.1 C bits angle refresh rate 12 t ang orate = 0 C 32 C s response time 13 t response all linearization and computations disabled, see figure 1, note 12 C 68 C s angle error for a1332eletr-t, t a = 25 to 85c, ideal magnet alignment, b = 300 g, target rpm = 0, no linearization C2 C 2 deg. for A1332KLETR-T, t a = 25 to 125c, ideal magnet alignment, b = 300 g, target rpm = 0, no linearization C2 C 2 deg. angle noise 14,15 n ang3 for a1332eletr-t, t a = 25c, 30 samples, b = 300 g, no internal filtering. C 0.6 C deg. for a1332eletr-t, t a = 85c, 30 samples, b = 300 g, no internal filtering C 0.8 C deg. for A1332KLETR-T, t a = 25c, 30 samples, b = 300 g, no internal filtering. C 0.6 C deg. for A1332KLETR-T, t a = 125c, 30 samples, b = 300 g, no internal filtering C 0.8 C deg. temperature drift angle drift for a1332eletr-t, t a = C40c, b = 300 g, drift measured relative to t a = 25c C2 C 2 deg. for a1332eletr-t, t a = 85c, b = 300 g, drift measured relative to t a = 25c C1.5 C 1.5 deg. for A1332KLETR-T, t a = C40c, b = 300 g, drift measured relative to t a = 25c C2 C 2 deg. for A1332KLETR-T, t a = 125c, b = 300 g, drift measured relative to t a = 25c C1.5 C 1.5 deg. angle drift over life-time 16 angle drift- life b = 300g, drift observed after aec-q100 qualification testing C 1 C deg. operating characteristics (continued) : valid throughout full operating voltage and ambient temperature ranges, qohvvrwkhulvh vshflhg 7 typical data is at t a = 25c and v cc = 5 v and it is for design information only. 8 1 g (gauss) = 0.1 mt (millitesla). 9 this represents a typical input range. 10 res angle represents the number of bits of data available for reading from the device registers. 11 effective resolution is calculated using the formula below: log 2 2 (360) - log ( 3 x ) 32 l l = 1 where is the standard deviation based on thirty measurements taken at each of the 32 angular positions, i = 11.25, 22.5, 360. 12 the rate at which a new angle reading is ready. this value varies with the orate selection. 13 this value assumes no linearization, (harmonic, or segmented) , no iir or orate fltering, and no short-stroke features enabled. this number also does not account for the added latency associated with the i2c interface sampling rate. this value only represents the time to read the magnetic position with no further computations made. actual response time is dependent on eeprom settings. settings related to flter design, signal path computations, and linearization will increase the response time. 14 error and noise values are with no further signal processing. angle error can be corrected with linearization algorithm, and angle noise can be reduced with internal fltering and slower angle refresh rate value. the parameters are characterized, but not measured at fnal test. 15 this value represents 3-sigma or thrice the standard deviation of the measured samples. 16 the angle error of most devices tested did not shift appreciably after aec-q100 qualifcation testing. however, the angle error of some devices was observed to drift by ap - proximately 2 degrees after aec-q100 (grade 1) testing. transducer output 50 0 response time, t response t angle (degrees) applied magnetic field )ljxuh'h?qlwlrqri5hvsrqvh7lph precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
6 functional description overview the a1332 incorporates a hall sensor ic that measures the direc- tion of the magnetic field vector through 360 in the x-y plane (parallel to the branded face of the device). the a1332 computes the angle based on the actual physical reading, as well as any internal parameters that have been set by the user. the end user can configure the output dynamic range, output scaling, and filtering. this device is an advanced, programmable internal microproces- sor-driven system-on-chip (soc). it includes a circular vertical hall (cvh) analog front end, a high speed sampling a-to-d con- verter, digital filtering, a 32-bit custom microprocessor, a digital control i 2 c interface, and digital output of processed angle data. advanced linearization, offset, and gain adjustment options are available in the a1332. these options can be configured in onboard eeprom providing a wide range of sensing solutions in the same device. device performance can be optimized by enabling individual functions or disabling them in eeprom to minimize latency. operation the device is designed to acquire angular position data by sam- pling a rotating bipolar magnetic target using a multi-segmented circular vertical hall effect (cvh) detector. the analog output is processed, and then digitized, and compensated before being loaded into the output register. refer to figure 2 for a depiction of the signal process flow described here. ? analog front end in this stage, the applied magnetic signal is detected and digitized for more advanced processing. a1 cvh element. the cvh is the actual magnetic sensing ele- ment that measures the direction of the applied magnetic vector. a2 analog signal conditioning. the signal acquired by the cvh is sampled. a3 a to d converter. the analog signal is digitized and handed off to the digital front end stage. ? digital front end in this preprocessing stage, the digitized signal is conditioned for analysis. d1 digital signal conditioning . the digitized signal is deci- mated and band pass filtered. d2 raw angle computation . for each sample, the raw angle value is calculated. ? microprocessor the preprocess signal is subjected to various standard and user-selected computations. the type and selection of computations used involves a trade-off between precision and increased response time in producing the final output. p1 angle averaging . the raw angle data is received in a peri- odic stream (every 32 s), and several samples are accumulated and averaged, based on user selected output rate. this feature increases the effective resolution of the system. the amount of averaging is determined by the user-programmable orate (out- put rate) field. the user can configure the quantity of averaged samples by powers of two to determine the refresh rate , the rate at which successive averaged angle values are fed into the post processing stages. the available rates are set as follows: orate [2:0] quantity of samples averaged refresh rate (s) 000 1 32 001 2 64 010 4 128 011 8 256 100 16 512 101 32 1024 110 64 2048 111 128 4096 p1a iir filter (optional) the optional iir filter can provide more advanced multi-order filtering of the input signal. filter coefficients can be user-programmed, and the fi bit can be pro- grammed by the user to enable or disable this feature. p1b angle compensation over temperature and magnetic field (optional) the a1332 is capable of compensating for drift in angle readings that result from changes in the device tempera- ture through the operating ambient temperature range. the device comes from the factory pre-programmed with coefficient settings to allow compensation of linear shifts of angle with temperature. the tc bit can be programmed by the user to enable or disable this feature. the default value from allegro factory is enabled. please note, this bit must be set, to meet specifications on angle error related items in the data-sheet. p1c prelinearization 0 offset (optional, but required if linear- ization used.) the expected angle values should be distributed throughout the input dynamic range to optimize angle post- precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
7 cvh element analog signal conditioning a to d converter digital signal conditioning raw angle computation digital front end (digital logic for processing) analog front end (applied magnetic signal detection) a1 a2 a3 d1 d2 p1 p2 p3 p4 p5 p6 p1a p1b p1c p1d p3a p4a p6a angle averaging sram eeprom (optional) ir filter angle compensation (optional) prelinearization 0 offset (optional) prelinearization rotation (optional) postlinearization rotation minimum/ maximum angle check* gain adjust* * short stroke applications only (optional) linearization segmented or harmonic postlinearization 0 offset angle rounding to 12 bits (optional) angle clamping* (optional) angle inversion primary serial interface microprocessor (angle processing) sample rate (resolution) figure 2: signal processing flow (refer by index number to text descriptions) precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
8 processing. this is mostly needed for applications that utilize full 360-degree rotations. this value establishes the position that will correspond to zero error. this value should be set such that the 360 0 degree range corresponds to the 4095 0 code range. setting this point is critical if linearization is used, whether segmented or harmonic. this is required, prior to going through linearization, because both linearization methods require a continuous input function to operate correctly. set using the lin_offset field. p1d prelinearization rotation (optional, but required if linear- ization used). the linearization algorithms require input functions that are both continuous and monotonically increasing. the lr bit sets which relative direction of target rotation results in an increasing angle value. the bit must be set such that the input to the linearization algorithm is increasing. p2 minimum/maximum angle check . the device compares the raw angle value to the angle value boundaries set by the user programming the min_angle_s or max_angle_s fields. if the angle is excessive, an error flag is set at err[ah] (high boundary violation) or err[al] (low boundary viola- tion). (note: to bypass this feature, set min_angle_s to 0 and max_angle_s to 4095.) p3 gain adjust . this bit adjusts the output dynamic range of the device. for example, if the application only requires 45 degrees of stroke, the user can set this field (to 8 in this example) such that a 45-degree angular change would be distributed across the entire 4095 0 code range. set using the gain field. p3a linearization (optional). applies user-programmed error correction coefficients (set in the linc registers) to the raw angle measurements. use the hl bit to enable harmonic linearization and the sl bit to enable segmented linearization (along with the lin_sel field to select the type of segmented linearization). p4 postlinearization 0 offset . this computation assigns the final angle offset value, to set the low expected angle value to code 0 in the output dynamic range, after all linearization and processing has been completed. set using the zero_offset field. p4a postlinearization rotation (optional). this feature allows the user to chose the polarity of the final angle output, relative to the result of the prelinearization rotation direction setting (lr bit, described above). set using the ro bit. p5 angle rounding to 12 bits . all of the internal calculations for angle processing in the a1332 take place with 16-bit preci- sion. this step truncates the data into a 12 bit word for output through the primary serial interface. p6 angle clamping. the a1332 has the ability to apply digi- tal clamps to the output signal. this feature is most useful for applications that use angle strokes less than 360 degrees. if the output signal exceeds the upper clamp, the output will stay at the clamped value. if the output signal is lower than the lower clamp, the output will stay at the low clamp value. set using the clamp_hi] and clamp_lo fields. (note: to bypass this feature, set clamp_hi to 4095 and clamp_lo to 0.) p6a angle inversion (optional). this calculation subtracts the angle from the high clamp. diagnostic features the a1332 features several diagnostic features and status flags to let the user know if any issues are present with the a1332 or associated magnetic system: condition diagnostic response v cc < v cclow(th) (min) uv error flag is set v cc > 8.8 v ov error flag is set field > mag_high mh flag is set field < mag_low ml flag is set angle processing errors at flag is set angle out of range ahf, alf flags are set system status alive always counting indicating angles being processed the sda pin state changes according to the state of the vcc ramp, as shown in figure 3. for more information on diagnostic features and flags, please refer to the programmers guide for a more complete description of the available flags and settings. precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
9 programming modes the eeprom can be written through the primary serial interface to enter process coefficients and select options. certain operating commands also are available by writing directly to sram. the eeprom and sram provide parallel data structures for operat- ing parameters. the sram provides a rapid test and measure- ment environment for application development and bench testing. the eeprom provides persistent storage at end of line for final parameters. at initialization, the eeprom contents are read into the corresponding sram. the sram can be overwritten during operation (although it is not recommended). the eeprom is permanently locked by setting the lock eeprom [le] bit in the eeprom. the a1332 is programmed through the primary serial interface, an i 2 c interface receiving pulses through the sda and scl pins, with additional power provided by pulses on the vcc pin to set the eeprom bit fields. v cc (v) 4.4 3.8 sda pin state t 3.7 vcc low flag threshold, v cclow(th) por por high impedance accurate angle output high impedance error flag set error flag set angle output accuracy reduced angle output accuracy reduced figure 3: relationship of vcc and sda output precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
10 application information the a1332 features an i 2 c compliant interface for communica- tion with a host microcontroller, or master. a basic circuit for configuring the a1332 package is shown in figure 4. it is recom- mended that both the scl and sda lines be tied to 3.3 v via a 1 k? pull-up resistor. if using a pull-up voltage of 5 v, it is recommended to limit current by using a higher value pull-up resistance that 1 k. serial interface description if the sda pin is tied to 5 v, instead of 3.3 v, this results in the forward biasing of an internal diode in the a1332 which could conduct current into the digital voltage regulator internal to the device. this may result in degraded voltage regulation per- formance. current- limiting resistors have been implemented on-chip to limit this effect. measurements show that exposure to this condition does not damage the ic in any permanent manner. however, for best results, it is recommended that the serial logic pins sda and scl be tied to 3.3 v and not 5 v vcc. 3.3 v internal regulator 3.3 v internal regulator 3.3 v external supply 5 v external supply sda pin sda pin pull-up resistor pull-up resistor internal resistor internal resistor digital sub-system digital sub-system current flows from vcc into 3.3 v internal regulator. regulator may suffer some degradation in performance. a1332 will continue to function with the 5 v sda pull-up, but this is not a desirable conigur- ation. internal diode: off internal diode: on + + + + - - - - sda pull-up = 3.3 v sda pull-up = 5 v figure 4: sda pin schematic precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
11 magnetic target requirements there are two main sensing configurations for magnetic angle sensing, on axis and off axis. on-axis (end of shaft) refers to when the center axis of a magnet lines up with the center of the sensing element. off-axis (side shaft) refers to when the angle sensor is mounted along the edge of a magnet. figure 9 illustrates on and off axis sensing configurations. on-axis applications some common on-axis applications for the device include digital potentiometer, motor sensing, power steering, and throttle sens- ing. the a1332 is designed to operate with magnets constructed with a variety of magnetic materials, cylindrical geometries, and field strengths, as shown in table 1. the device has two internal linearization algorithms that can compensate for much of the error due to alignment. contact allegro for more detailed infor- mation on magnet selection and theoretical error. off-axis applications there are two major challenges with off axis angle sensing applications. the first is field strength. all efforts should be conducted to maximize magnetic signal strength as seen by the device. the goal is a minimum of 300 g. field strength can be maximized by using high quality magnetic material, and by mini- mizing the distance between the sensor and the magnet. another challenge is overcoming the inherent non-linearity of the mag- netic field vector generated at the edge of a magnet. the device has two linearization algorithms that can compensate for much of the geometric error. harmonic linearization is recommended for off-axis applications. )lxuhslfdorxudwlr a1332 set up for serial address 0xc host/master microprocessor a1332 test sa0 sa1 sda agnd agnd agnd dgnd dgnd dgnd scl vccvcc 0.1 f 1 k 1 k 0.1 f 3.3 v v cc = 5 v byp 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 0 0.5 1.0 1.5 eccentricity of soc chip relative to magnet rotation axis (mm) angle error () 2.5 3.5 2.0 3.0 table 1: target magnet parameters magnetic material diameter (mm) thickness (mm) neodymium (bonded) 15 4 neodymium (sintered)* 10 4 neodymium (sintered) 8 3 neodymium / smco 6 2.5 n s thickness diameter *a sintered neodymium magnet with 10 mm (or greater) diameter and 4 mm thick- ness is the recommended magnet for redundant applications. figure 6: simulated error versus eccentricity for a 10 mm x 4 mm neodymium magnet at a 2.7 mm air gap. typical systemic error versus magnet to sensor eccentricity (d axial ), note: systemic error refers to application errors in alignment and system timing. it does not refer to sensor ic device errors. the data in this graph is simulated with ideal magnetization. precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
12 hall element figure 9: centering the axis of magnet rotation on the hall element centering the axis of magnet rotation on the hall element pro- vides the strongest signal in all degrees of rotation. figure 7: magnetic field flux lines the magnetic field flux lines run fixed field lines coming out of the north pole and going into the south pole of the magnet. the peak flux densities are between the poles. d axial (off-axis) d axial (on-axis) ag (off axis) ag (on axis) magnetic flux lines axis of rotation ag (on axis, centered) figure 10: rapid degeneration of magnetic flux density the magnetic flux density degenerates rapidly away from the plane of peak north-south polarity. when the axis of rotation is placed away from the hall element, the device must be placed closer to the magnetic poles to maintain an adequate level of flux at the hall element. +|b| 0 g effect of orientation on signal figure 8: hall element detects rotating relative polarity of magnetic field as the magnet rotates, the hall element detects the rotating relative polarity of the magnetic field (solid line); when the center of rotation is centered on the hall element, the magnetic flux amplitude is constant (dashed line). +|b| 0 g 0 360 zero crossing magnetic flux detected rotation 90 180 270 360 precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
13 linearization magnetic fields are generally not completely linear throughout the full range of target positions. this can be the result of non- uniformities in mechanical motion or of material composition. in some applications, it may be required to apply a mathematical transfer function to the angle that is reported by the a1332. the a1332 has built-in functions for performing linearization on the acquired angle data. it is capable of performing one of two different linearization methods: harmonic linearization and piece- wise (segmented) linearization. segmented linearization breaks up the output dynamic range into 16 equal segments. each segment is then represented by the equation of a straight line between the two endpoints of the seg- ment. using this basic principle, it is possible to tailor the output response to compensate for mechanical non-linearity. one example is a fluid level detector in a vehicle fuel tank. because of requirements to conform the tank and to provide stiffening, fuel tanks often do not have a uniform shape. a level detector with a linear sensor in this application would not cor- rectly indicate the remaining volume of fuel in the tank without some mathematical conversion. figure 11 graphically illustrates the general concept. harmonic linearization utilizes the fourier series in order to compensate for periodic error components. in the most basic of terms, the fourier series is used to represent a periodic signal using a sum of ideal periodic waveforms. the a1332 is capable of utilizing up to 15 fourier series components to linearize the output transfer function. while it can be used for many applications, harmonic lineariza- tion is most useful for 360-degree applications. the error curve for a rotating magnet that is not perfectly aligned will most often have an error waveform that is periodic. this is phenomenon is especially true for systems where the sensor is mounted off-axis relative to the magnet. figure 12 illustrates this periodic error. an initial set of linearization coefficients is created by character- izing the application experimentally. with all signal processing options configured, the device is used to sense the applied mag- netic field, b: at a target zero-degrees of rotation reference angle and at regular intervals. for segmented linearization, 16 samples are taken: at nominal zero degrees and every 1/16 interval (22.5) of the full 360 rotational input range. each angle is read from the ang[angle] register and recorded. these values are loaded into the allegro asek programming utility for the device, or an equivalent customer software pro- gram, and to generate coefficients corresponding to the values. the user then uses the software load function to transmit the coefficients to the eeprom. each of the coefficient values can be individually overwritten during normal operation by writing directly to the corresponding sram. wall stiffener cavities uniform walls angled walls angled walls, uneven bottom fill pipe linear depth fuel volume linearized rate 0 meter and sender figure 11: varying volumes in an integrated vehicle fuel tank an integrated vehicle fuel tank has varying volumes according to depth due to structural elements. as shown in the chart, this results in a variable rate of fuel level change, depending on volume at the given depth, and a linearized transfer function can be used against the integral volume. precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
14 +v 0 90 180 270 360 0 ?d axial correction inversion result detected angle () error correction (v) magnetic input linearization target inversion function device output position () 360 270 180 90 0 0 90 180 270 360 target rotational position () corrected angle output ?d axial = + phase, + amplitude ?d axial ?d axial ?d axial ?d axial ?d axial = + phase, ? amplitude ?d axial = + phase, + + amplitude ?d axial = + phase, ? ? amplitude figure 12a: linear- ization coeffcients with the axis of rotation aligned with the hall element, linearization coefficients are a simple inversion of the input. figure 12b: any eccen- tricity is evaluated as an error. systematic eccentricity can be factored out by appropri- ate linearization coefficients. for off-axis applications, the harmonic linearization method is recommended. correction for eccentric orientation precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
15 figure 13: sample of linearization function transfer characteristic. harmonic coefficients the device supports up to 15 harmonics. each harmonic is char- acterized by an amplitude and a phase coefficient. to apply harmonic linearization, the device: 1. calculates the error factors. 2. applies any programmed of fsets. 3. calculates the linearization factor as: a n sin(n t + n ) pcb layout bypass and decoupling capacitor should be placed as close as possible to corresponding pins, with low impedance traces. capacitors should be tied to a low impedance ground plane when- ever possible. interpolated linear position (y-axis values represent 16 equal intervals) magnetic input values (15 x-axis values read and used to calculate coefficients) minimum full scale input b in0 b in1 b in2 b in3 0 ?640 2432 4095 x lin_10 ?x lin_3 b in16 b in10 maximum full scale input coefficients stored in eeprom input function input function output function output function a a a precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
16 typical characteristics 05 0 100 150 200 250 300 350 -0.6 -0.8 -1 -0.4 -0.2 0 0.2 0.4 0.6 0.8 1 encoder position (degrees) angle error (degrees) -40 02 0 -20 40 60 80 100 120 0.4 0.2 -1 0.6 0.8 1.0 1.2 1.4 1.6 1.8 1 temperature (oc) angle error (degrees) mean 3 sigma figure 14: angle error versus encoder position figure 15: peak angle error over temperature 05 0 100 0.5 -1 1.0 1.5 2.0 temperature (oc) drift (degrees) mean 3 sigma figure 16: maximum absolute drift from 25oc measurement precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
17 0 0.2 0.4 0.6 1 0 2 4 6 8 10 14 12 16 noise in degrees frequency (%) 125oc 25oc ?40oc 0.8 -50 0 50 100 150 0 0.2 1 0.8 mean +3 sigma -3 sigma a1332 noise in degrees ambient temperature (oc) 0.4 0.6 figure 17: noise distribution vs. temperature (1 , 300 g, v cc = 4.5 v) figure 18: noise distribution vs. temperature (1 , 300 g, v cc = 4.5 v) 12 14 16 18 20 0 2 4 6 8 10 12 icc in ma frequency (%) 125oc 25oc ?40oc figure 19: i cc distribution vs. temperature (v cc = 5.5 v) -50 0 50 100 150 12 13 14 15 16 17 18 19 20 ambient temperature in degrees c a1332 icc in ma mean +3 sigma -3 sigma figure 20: i cc vs. temperature (v cc = 5.5 v) precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
18 for reference only ? not for tooling use (reference mo-153 ab-1) nott o scale dimensions in millimeters dimensions exclusive of mold ?ash, gate burrs, and dambar protrusions exact case and lead con?guration at supplier discretion within limits shown a 1.10 max 0.15 0.00 0.30 0.19 0.20 0.09 8o 0o 0.60 1.00 ref c seat ing plane c 0.10 16x 0.65 bsc 0.25 bsc 21 14 1.45 5.00 0.10 4.40 0.10 6.40 bsc gauge plane seating plane a b b d d e branding scale and appearance at supplier discretion hall element, not to scale active area depth = 0.36 mm (ref) c d e 6.00 0.65 0.45 1.70 14 21 1 c branded face pcb layout reference vi ew standard branding reference vi ew = device part number = supplier emblem = last two digits of year of manufacture = we ek of manufacture = lot number n y w l terminal #1 mark area reference land pattern layout (reference ipc7351 tsop65p640x120-14m); all pads a minimum of 0.20 mm from all adjacent pads; adjust as necessary to meet application process requirements and pcb layout tolerances; when mounting on a multilayer pcb, thermal vias at the exposed thermal pad land can improve thermal dissipation (reference eia/jedec standard jesd51-5) nnnnnnnnnnnn yyww llllllllllll +0.15 ?0.10 figure 21: package le, 14-pin tssop (single die version) package outline drawing precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com
19 copyright ?2011-2015, allegro microsystems, llc i 2 c? is a trademark of philips semiconductors. allegro microsystems, llc reserves the right to make, from time to time, such departures from the detail specifications as may be required to permit improvements in the performance, reliability, or manufacturability of its products. before placing an order, the user is cautioned to verify that the information being relied upon is current. allegros products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of allegros product can reasonably be expected to cause bodily harm. the information included herein is believed to be accurate and reliable. however, allegro microsystems, llc assumes no responsibility for its use; nor for any infringement 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 revision history revision no. revision date description C september 11, 2014 initial release 1 january 21, 2015 added k variant and typical characteristic graphs 2 january 23, 2015 revised noise distribution plots 3 december 1, 2015 status of product changed to not for new design 4 december 17, 2015 corrected cvh location in single-die package outline drawing precision hall effect angle sensor ic with i 2 c interface a1332 allegro microsystems, llc 115 northeast cutoff worcester, massachusetts 01615-0036 u.s.a. 1.508.853.5000; www.allegromicro.com

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