Allegro ATS642LSH Manual
Contents
1. 11 Trim Supply Current High versus Ambient Temperature Supply Current High versus Supply Voltage ATS642 11 ATS642 11 16 16 15 15 T T S a O rem Lae 14 24 5 14 he 40 pals 5 m 25 2 mi 4 2 men 85 13 13 150 12 12 50 0 50 100 150 0 5 10 15 20 25 Ta C Voc V Supply Current Low versus Ambient Temperature Supply Current Low versus Supply Voltage ATS642 11 ATS642 11 8 8 7 7 lt T E Vcc V E Ta C j e P ee 8 4 5 25 150 5 5 4 T T T 4 T T T T 50 0 50 100 150 0 5 10 15 20 25 Ta C Vcc V Allegro MicroSystems Inc 6 ATS642LSH DS 115 Northeast Cutoff Box 15036 www allegromicro com Worcester Massachusetts 01615 0036 508 853 5000 ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Duty Cycle versus Air Gap Ta C ate 40 He 25 150 0 5 1 0 1 5 2 0 2 5 AG mm 3 0 The trend of duty cycle versus air gap is driven by the actual magnetic profile of the target see figure on page 5 Duty Cycle versus Ambient Temperature Duty Cycle Variance versus Air Gap Mean 3 Sigma 25 C ATS642LSH DS Allegro MicroSystems Inc 7 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 00362. Continued on the next page Allegro MicroSystems Inc 3 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor OPERATING CHARACTERISTICS continued using reference target 60 0 T and Vec within specification unless otherwise noted Characteristic Test Conditions SWITCHPOINT CHARACTERISTICS Rotation Speed Sror Reference Target 60 0 Analog Signal Bandwidth Equivalent to f 3 dB Transitioning from lcc High tO lcc Low Positive peak referenced AG lt AGmax Transitioning from Icc Low tO lec High Negative peak referenced AG lt AGmax Operate Point Release Point CALIBRATION Quantity of rising output current edges required for Initial Calibration accurate edge detection DAC CHARACTERISTICS Allowable User Induced Differential Output switching only may not meet datasheet speci Offset fications FUNCTIONAL CHARACTERISTICS Operational Air Gap Range ADC within specification Maximum Operational Air Gap Range Output switching no missed edges ADC not guaranteed Wobble lt 0 5 mm Typical value at AG 1 5 mm for max min AG within specification Duty Cycle Pitch Variance AG 1 5 mm AGopimax Duty Cycle Variation ADC Operating Signal Range i Operating within s
3. The products described herein are manufactured under one or more of the following U S patents 5 045 920 5 264 783 5 442 283 5 389 889 5 581 179 5 517 112 5 619 137 5 621 319 5 650 719 5 686 894 5 694 038 5 729 130 5 917 320 and other patents pending Allegro MicroSystems Inc 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 Allegro products are not authorized for use as critical compo nents in life support devices or systems without express written approval The information included herein is believed to be accurate and reliable However Allegro MicroSystems Inc assumes no respon sibility for its use nor for any infringement of patents or other rights of third parties which may result from its use Copyright 2004 2005 Allegro MicroSystems Inc Allegro MicroSystems Inc 16 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS
4. loc High max Range for Valid Icc HicH loc High min Fault ZZ loc Low max VW Range for Valid Icc Low loc Low min Figure 8 Diagnostic Characteristics of Supply Current Values Allegro MicroSystems Inc 12 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor SENSOR OPERATION Each operating mode is described in detail below Power On When power Vcc gt Vccmm is applied to the device a short period of time is required to power the various portions of the IC During this period the ATS642 will power on in the high current state IcC Hign After power on there are conditions that could induce a change in the output state Such an event could be caused by thermal transients but would require a static applied magnetic field proper signal polarity and particular direction and magnitude of internal signal drift Initial Offset Adjust The sensor intially cancels the effects of chip magnet and installation offsets Once offsets have been cancelled the digital tracking DAC is ready to track the signal and provide output switching The period of time required for both Power On and Initial Offset Adjust is defined as the Power On Time Calibration Mode The calibration mode allows the sensor to automatically select the proper signal gain and continue to adjust for
5. 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Characteristic Allowable Air Gap Movement 60 0 60 Tooth Target Allowable Air Gap Movement from TEAGcaL 1 2 NN fad a ATEAGOUT mm 0 0 2 0 4 0 6 0 8 1 0 1 2 1 4 1 6 1 8 ATEAGin mm The colored area in the chart above shows the region of allow The axis parameters for the chart are defined in the draw ings below As an example assume the case where the air gap output switching The output duty cycle is wholly dependent on is allowed to vary from from the nominal installed air gap a TEAGc a_ panel a within the range defined by an increase of the target s magnetic signature across the air gap range of move ATEAG ut 0 35 mm shown in panel b and a decrease of ment and may not always be within specification throughout the ATEAG 0 65 mm shown in panel c This case is plotted entire operating region to AG opmax with an x in the chart above able air gap movement within which the sensor will continue a p77 For more information on these figures and the calculations used to generate them please refer to the Applications Note Determining Allowable Air Gap Variation for the ATS642 Allegro MicroSystems Inc 8 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro
6. Detection A digital DAC tracks the internal analog voltage signal Vproc and is used for holding the peak value of the internal analog signal In the example shown in figure 6 the DAC would first track up with the signal and hold the upper peak s value When Vproc drops below this peak value by Bop the device hyster esis the output would switch and the DAC would begin tracking the signal downward toward the negative Vppoc peak Once the DAC acquires the negative peak the output will again switch states when Vproc is greater than the peak by the value Bgp At this point the DAC tracks up again and the cycle repeats The digital tracking of the differential analog signal allows the sensor to achieve true zero speed operation ve Internal Differential L Bop Analog Signal Bre Lt I l Device 7 M Output Current Figure 6 Peak Detecting Switchpoint Detail Allegro MicroSystems Inc 11 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Power Supply Protection The device contains an on chip regulator and can operate over a wide Vcc range For devices that need to operate from an unregulated power supply transient protection must be added externally For applications using a regulated line EMI RFI pro tection may still be required Contact Allegro Microsystems fo
7. offsets The Internal Differential Signal Veroc Sensor Electrical Output lour Figure 9 Operation of Running Mode Gain Adjust AGC is active and selects the optimal signal gain based on the amplitude of the Vproc signal Following each adjustment to the AGC DAC the Offset DAC is also adjusted to ensure the internal analog signal is properly centered During this mode the tracking DAC is active and output switch ing occurs but the duty cycle is not guaranteed to be within specification Running Mode After the Initial Calibration period Cy establishes a signal gain the device moves to Running mode During Running mode the sensor tracks the input signal and gives an output edge for every peak of the signal AOA remains active to compensate for any offset drift over time The ATS642 incorporates a novel algorithm for adjusting the signal gain during Running mode This algorithm is designed to optimize the Vppoc signal amplitude in instances where the magnetic signal seen during the calibration period is not repre sentative of the amplitude of the magnetic signal for the installed sensor air gap see figure 9 Position 1 The device is initially powered on Self calibration occurs Position 2 Small amplitude oscillation of the target sends an erroneously small differential signal to the sensor The ampli tude of Vprog is greater than the switching hysteresis Bop and Brp and the d
8. 036 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Functional Block Diagram Hall Amplifier a VCC Automatic Orset AOA DAC AGC DAC Internal Regulator Control Gain Control Tracking DAC Peak lo to O Test Signals Allegro MicroSystems Inc 2 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor OPERATING CHARACTERISTICS using reference target 60 0 T and Vcc within specification unless otherwise noted CHARACTERISTIC Test Conditions ELECTRICAL CHARACTERISTICS Supply Voltage2 Vec Operating Tj lt 165 C Undervoltage Lockout Vecuv Vcc 9 gt 5 V and5 gt 0V Supply Zener Clamp Voltage Vz loc lecmaxy 3 MA Ty 25 C Supply Zener Current lz Test conditions only Vz 28 V ATS642LSH I1 ATS642LSH I2 ATS642LSH I1 ATS642LSH I2 Ioc Low Supply Current Ic High Supply Current Ratio Icc igh Ratio of high current to low current Ioc Low Reverse Battery Current Iroc Vrece 18 V POWER ON STATE CHARACTERISTICS Power On State t gt tpo lcC High Power On Time4 Target gear speed lt 100 rpm 1 OUTPUT STAGE Output Slew Rate5 Rioap 100 O Cy gap 10 pF
9. 8 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor 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 During calibration the device determines the peak to peak amplitude of the signal generated by the target The gain of the sensor is then automatically adjusted Figure 5 illustrates the effect of this feature Automatic Offset Adjust AOA The AOA is patented circuitry that automatically compensates for the effects of chip magnet and installation offsets For capability see Dynamic Offset Cancellation in the Operat ing Characteristics table This circuitry is continuously active including both during calibration mode and running mode com pensating for any offset drift Continuous operation also allows it Ferrous Target Mechanical Profile E E E V Internal Differential Analog Signal Response without AGC V Internal Differential Analog Signal Response with AGC Figure 5 Automatic Gain Control AGC The AGC function corrects for variances in the air gap Differences in the air gap affect the magnetic gradient but AGC prevents that from affecting device performance a shown in the lowest panel ATS642LSH DS to compensate for offsets induced by temperature variations over time Digital Peak
10. O 0 ATSO42LSH OO ATS642LSH Two Wire True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor with Continuous Calibration Package SH 4 pin Module 1 234 1 VCC 2 No connection 3 Test pin float or tie to GND 4 GND ABSOLUTE MAXIMUM RATINGS Supply Voltage Vcc Reverse Supply Voltage Vacc Operating Temperature Ambient T Maximum Junction T ymax Storage Temperature Ts ATS642LSH DS The ATS642LSH is an optimized Hall effect sensing integrated circuit and magnet combination that provides a user friendly solution for true zero speed digital gear tooth sensing in two wire applications The sensor consists of a single shot molded plastic package that includes a samarium cobalt magnet a pole piece and a Hall effect IC that has been optimized to the magnetic circuit This small package with optimized two wire leadframe can be easily assembled and used in conjunction with a wide variety of gear shapes and sizes The integrated circuit incorporates a dual element Hall effect sensor and signal processing that switches in response to differential magnetic signals created by ferrous gear teeth The circuitry contains a sophisticated digital circuit to reduce magnet and system offsets to calibrate the gain for air gap independent switchpoints and to achieve true zero speed operation Signal optimization occurs at power up through the combination of offset and gain adjust and is maintained throughout th
11. com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor THERMAL CHARACTERISTICS may require derating at maximum conditions see application information CHARACTERISTIC Symbol TEST CONDITIONS Value Units Single layer PCB with copper limited to solder pads Two layer PCB with 3 8 in 2 of copper area on each side con nected with thermal vias and to device ground pin Additional information is available on the Allegro Web site Package Thermal Resistance Power Derating Curve Vec max 13 c Rosa 84 C W 10 C Ron 126 C Maximum Allowable Vcc V Vec min 20 40 60 80 100 120 140 160 180 Temperature C Maximum Power Dissipation Pp max Power Dissipation Pp mW 20 40 60 80 100 120 140 160 180 Temperature C Allegro MicroSystems Inc 9 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Functional Description Sensing Technology The gear tooth sensor subassembly contains a single chip dif ferential Hall effect sensor IC an optimized samarium cobalt magnet and a flat ferrous pole piece The Hall IC possesses two Hall elements which sense the magnetic profile of the ferrous target simultane
12. e operating time with the use of a running mode calibration The run ning mode calibration allows immunity to environmental effects such as microos cillations of the target or sudden air gap changes The regulated current output is configured for two wire applications and the sensor is ideally suited for obtaining speed and duty cycle information in ABS antilock braking systems The 1 5 mm Hall element spacing is optimized for fine pitch gear tooth based configurations The package is lead Pb free with 100 matte tin leadframe plating Features and Benefits e Running mode calibration for continu Large operating air gaps ous optimization e Automatic Gain Control AGC for air e Single chip IC for high reliability gap independent switchpoints e Internal current regulator for 2 wire Automatic Offset Adjustment AOA operation Sie as Small mechanical size 8 mm for signal processing optimization diameter x 5 5 mm depth e True zero speed operation e Precise duty cycle signal over e Undervoltage lockout operating temperature range e Wide operating voltage range Use the following complete part numbers when ordering Part Number loc Typical Packing ATS642LSHTN I1 T 6 0 Low to 14 0 High mA Tape and reel 13 inch reel ATS642LSHTN I2 T 7 0 Low to 14 0 High mA 800 pieces reel Contact Allegro for additional packing options Allegro MicroSystems Inc 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0
13. evice output switches Position 3 The calibration period completes on the third rising output edge and the device enters Running mode Position 4 True target rotation occurs and the correct magnetic signal is generated for the installation air gap The estab lished signal gain is too large for the target s rotational magnetic signal at the given air gap Position 5 Running Mode Calibration corrects the signal gain to an optimal level for the installation air gap ATS642LSH DS Allegro MicroSystems Inc 1 3 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Power Derating The device must be operated below the maximum junction temperature of the device Tj max Under certain combinations of peak conditions reliable operation may require derating sup plied power or improving the heat dissipation properties of the application This section presents a procedure for correlating factors affecting operating Ty Thermal data is also available on the Allegro MicroSystems Web site The Package Thermal Resistance Roya 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 includi
14. ng adjacent devices and traces Radiation from the die through the device case Rojc is relatively small component of Roy Ambient air temperature Ta and air motion are significant external factors damped by overmolding The effect of varying power levels Power Dissipation Pp can be estimated The following formulas represent the fundamental relationships used to estimate Tj at Pp Pp Vin X in 1 Ty T y AT 3 For example given common conditions such as Ta 25 C AT Pp X Roya 48 mW x 140 C W 7 C Ty Ta AT 25 C 7 C 32 C A worst case estimate Ppimaxy represents the maximum allow able power level Vec max ICC max Without exceeding T jimax at a selected Roy and Ty ATS642LSH DS Example Reliability for Voc at Ty 150 C package SH I1 trim using minimum K PCB Observe the worst case ratings for the device specifically Roya 126 C W Timax 165 C Veec max 24 V and Toc max 16mA Calculate the maximum allowable power level Ppmax First invert equation 3 AT max Timax Ta 165 C 150 C 15 C This provides the allowable increase to Ty resulting from internal power dissipation Then invert equation 2 Prax AT max Roya 15 C 126 C W 119 mW Finally invert equation 1 with respect to voltage Voceest Poimax lecgmaxy 119 mW 16mA 7 V The result indicates that at T the application and device can dissipate adequa
15. on of target rotation results in a low output signal when a tooth of the target gear is nearest the face of the sensor see figure 3 A right to left pin 4 to pin 1 rota tion inverts the output signal polarity ATS642LSH DS Output Polarity Figure 3 shows the output polarity for the orientation of target and sensor shown in figure 2 The target direction of rotation shown is perpendicular to the leads across the face of the device from the pin 1 side to the pin 4 side This results in the sensor output switching from high Iccign to low IccLow aS the leading edge of a tooth a rising mechanical edge as detected by the sensor passes the sensor face In this configuration the device output current switches to its low polarity when a tooth is the target feature nearest to the sensor If the direction of rota tion is reversed then the output polarity inverts Note that output voltage polarity is dependent on the position of the sense resistor Rgpygp See figure 4 Target Representative Mechanical Profile Differential ae NY Magnetic Profile Sensor Electrical Output Profile lout Figure 3 Output Profile of a ferrous target for the polarity indicated in figure 2 Voc VeuppLy I C A a O as S a V V iaa A aaa Figure 4 Voltages profiles for high side and low side two wire sensing Allegro MicroSystems Inc 1 0 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 50
16. ously but at different points spaced at a 1 5 mm pitch generating a differential internal analog voltage Vproc 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 compensation circuitry Its voltage regulator provides supply noise rejection throughout 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 process ing electronics are integrated on the same silicon substrate using a proprietary BiCMOS process Target Profiling An operating device is capable of providing digital information that is representative of the mechanical features on a rotating tar get The waveform diagram shown in figure 3 presents the auto matic translation of the mechanical profile through the magnetic profile that it induces to the digital output signal of the sensor Target Gear e jamm j Element Pitch An oO Hall Element 1 IR Hall IC Pole Piece Concentrator Hall Element 2 Dual Element Hall Effect Device Back biasing Magnet j North Pole Case Pin 4 Side Pin 1 Side Figure 1 Relative motion of the target is detected by the dual Hall ele ments mounted on the Hall IC Branded Face Rotating Target of Sensor Figure 2 This left to right pin 1 to pin 4 directi
17. pecification Output switching no missed edges ADC not guaranteed Typical values are at T4 25 C and Vgc 12 V Performance may vary for individual units within the specified maximum and minimum limits 2Maximum voltage must be adjusted for power dissipation and junction temperature see Power Derating section 3Please refer to Sensor Operation section page 13 4Power On Time includes the time required to complete the internal automatic offset adjust The DACs are then ready for peak acquisition 5dl is the difference between 10 of lcc Low and 90 of Icc High and dt is time period between those two points Note di dt is dependent upon the value of the bypass capacitor if one is used 6Functional characteristics valid only if magnetic offset is within the specified range for Allowable User Induced Differential Offset TAG is dependent on the available magnetic field The available field is dependent on target geometry and material and should be independently characterized The field available from the reference target is given in the reference target parameter section of the datasheet 8Epc represents the difference between consecutive duty cycles DC n DC n 1 Mean 3 sigma 9In order to remain in specification the magnetic gradient must induce an operating signal greater than the minimum value specified This includes the effect of target wobble Minimum Operating Signal Sigoprmin Allegro MicroSystem
18. r information on the circuitry needed for compliance with various EMC specifications Refer to figure 7 for an example of a basic application circuit Undervoltage Lockout When the supply voltage falls below the undervoltage lockout voltage Vcecuv the device enters Reset where the output state returns to the Power On State POS until sufficient Vcc is sup plied Icc levels may not meet datasheet limits when Vee lt Vecunin ATS642 Cgyp Pins 2 and 3 floating Figure 7 Typical Application Circuit ATS642LSH DS Assembly Description This sensor is integrally molded into a plastic body that has been optimized for size ease of assembly and manufacturability High operating temperature materials are used in all aspects of construction Diagnostics The regulated current output is configured for two wire appli cations requiring one less wire for operation than do switches with the more traditional open collector output Additionally the system designer inherently gains diagnostics because there is always output current flowing which should be in either of two narrow ranges shown in figure 8 as IcC High and Icc Low ANY current level not within these ranges indicates a fault condi tion If Icc gt IcC Highmaw then a short condition exists and if Toc lt Icc ow min then an open condition exists Any value of Icc between the allowed ranges for Icc Hign and Icc Low indicates a general fault condition mA
19. s Inc 4 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor REFERENCE TARGET 60 0 60 Tooth Target Characteristics Test Conditions Units Symbol Key Outside Diameter Outside diameter of target Breadth of tooth with respect to sensor Length of tooth with respect to sensor Face Width Angular Tooth Thickness Length of valley with Angular Valley Thickness respect to sensor Tooth Whole Depth Material Low Carbon Steel Reference Gear Magnetic Gradient Amplitude With Reference to Air Gap Peak to Peak Differential B G wo A 8 8 Branded Face e of Sensor 100 0 5 1 15 2 2 5 3 Reference Target Air Gap mm 60 0 Reference Gear Magnetic Profile Two Tooth to Valley Transitions Differential B G Allegro MicroSystems Inc 5 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Characteristic Data
20. te amounts of heat at voltages lt Vcc est Compare Voceest to Vocc max If Vc est lt Vocc max gt then reli able operation between Vecest and Vecimaxy requires enhanced Rosa If Voccest 2 Veccmaxy then operation between Vecyest and Veccmax S reliable under these conditions Allegro MicroSystems Inc 14 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor Package SH Module lt 55 217 A s8 2 ss fg O y 4 4 4 0 157 0 38 015 5 0 244 Y lt 1 08 043 A 20 95 825 13 05 514 LA A o 6 024 HU ULU i A oes A 0 6 024 gt a 1 27050 Dimensions in millimeters Untoleranced dimensions are nominal U S Customary dimensions in in brackets for reference only A Dambar removal protrusion 16X A Metallic protrusion electrically connected to pin 4 and substrate both sides A Active Area Depth Z Thermoplastic Molded Lead Bar for alignment during shipment A Hall elements 2X not to scale controlling dimension inches Allegro MicroSystems Inc 1 5 115 Northeast Cutoff Box 15036 Worcester Massachusetts 01615 0036 508 853 5000 www allegromicro com ATS642LSH DS ATS642LSH True Zero Speed Miniature Differential Peak Detecting Gear Tooth Sensor
Download Pdf Manuals
Related Search
Allegro ATS642LSH Manual