ATS645LSH Two-Wire True Zero Speed Miniature Differential Peak-Detecting Gear Tooth Sensor Features and Benefits Description • • • • • • • The components in speed sensing applications continue to diminish in size to meet spatial constraints and weight reduction requirements. As the geometries of gears become smaller, this can compromise the capabilities of a gear speed sensor. The ATS645 Hall-element-to-Hall-element spacing of only 1.5 mm makes this device uniquely capable of accommodating very fine-pitch gears. In addition, the ATS645 signal peak-detecting algorithm supports consistent switching at relatively large air gaps, where the peak-to-peak amplitude is small. These features make the ATS645 the ideal solution to detect the speed of finepitch targets such as those found in ABS (antilock braking) systems. Fully optimized differential digital gear tooth sensor Single chip IC for high reliability Internal current regulator for 2-wire operation Small mechanical size (8 mm diameter x 5.5 mm depth) Air gap independent switchpoints Digital output representing gear profile Precise duty cycle signal over operating temperature range • Large operating air gaps • Automatic Gain Control (AGC) Continued on the next page… The ATS645 combines a Hall-effect sensing integrated circuit and magnet to provide a manufacturer-friendly solution for true zero-speed digital gear-tooth sensing in two-wire applications. The device consists of a single-shot molded plastic package that includes a samarium cobalt magnet, a pole piece, and a Hall-effect integrated circuit that has been optimized to the magnetic circuit. This small package can be easily assembled and used in conjunction with a wide variety of gear shapes and sizes. Packages: 4 pin SIP (suffix SH) Continued on the next page… Not to scale Functional Block Diagram Hall Amplifier Automatic Offset Control Tracking DAC VCC Gain AOA DAC AGC DAC Internal Regulator Peak Hold GND Test Signals ATS645-DS, Rev. 3 Test True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH Features and Benefits (continued) • Automatic Offset Adjustment (AOA) • True zero-speed operation • Undervoltage lockout • Wide operating voltage range • Defined power-on state Description (continued) The integrated circuit incorporates a dual-element Hall effect sensor as well as signal processing that switches the output state in response to changes in the magnetic gradients created by ferrous gear teeth. The circuitry contains a sophisticated digital circuit to eliminate magnet and system offsets and to achieve true zero speed operation (U.S. Patent 5,917,320). A-D and D-A converters are used to adjust the device gain at power-on and to allow switching independent of the breadth of the air gap. The regulated current output is configured for two wire applications, requiring one less wire for operation than do switches with the more traditional open-collector output.The package is available in a lead (Pb) free version, with 100% matte tin leadframe plating. Part Number Pb-free1 Packing2 ICC Typical ATS645LSHTN-I1-T Yes Tape and Reel 13-in. 800 pcs./reel 6.0 Low to 14.0 High mA ATS645LSHTN-I2-T Yes Tape and Reel 13-in. 800 pcs./reel 7.0 Low to 14.0 High mA 1Pb-based variants are being phased out of the product line. a. Certain variants cited in this footnote are in production but have been determined to be LAST TIME BUY. 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. Status change: October 31, 2006. Deadline for receipt of LAST TIME BUY ORDERS: April 27, 2007. These variants include: ATS645LSHTN-I1. b. Certain variants cited in this footnote 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. Status change: May 1, 2006. These variants include: ATS645LSHTN-I2. 2Contact Allegro for additional packing options. 3Some restrictions may apply to certain types of sales. Contact Allegro for details. Absolute Maximum Ratings Characteristic Symbol Supply Voltage VCC Reverse-Supply Voltage VRCC – V ºC TJ(max) 165 ºC Tstg –65 to 170 ºC Maximum Junction Temperature Range L Terminal List Name VCC NC 1 2 3 4 Units 28 –18 TA Pin-out Diagram Rating –40 to 150 Operating Ambient Temperature Storage Temperature Notes Description Number Connects power supply to chip 1 No connection 2 TEST For Allegro use, float or tie to GND 3 GND Ground terminal 4 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH OPERATING CHARACTERISTICS using reference target 60-0, TA and VCC within specification, unless otherwise noted CHARACTERISTIC Min. Typ.1 Max. Units 4.0 – 24 V VCC 0 → 5 V and 5 → 0 V – – 4.0 V Symbol Test Conditions ELECTRICAL CHARACTERISTICS Supply Voltage2 Undervoltage Lockout VCC VCC(UV) Operating; TJ < 165 °C Supply Zener Clamp Voltage VZ ICC = ICC(max) + 3 mA; TA = 25°C 28 – – V Supply Zener Current IZ Test conditions only; VZ = 28 V – – ICC(max)+ 3 mA mA ATS645LSH-I1 4.0 6 8.0 mA ATS645LSH-I2 5.9 7 8.4 mA ATS645LSH-I1 12.0 14.0 16.0 mA ATS645LSH-I2 11.8 14.0 16.8 mA 1.85 – 3.05 – t > tPO – ICC(High) – – ICC(Low) Supply Current ICC(High) Supply Current Ratio ICC(High)/ Ratio of high current to low current ICC(Low) POWER-ON STATE CHARACTERISTICS Power-On State POS Power-On Time3 tPO Target gear speed < 100 rpm – 1 2 ms dI/dt RLOAD = 100 Ω, CLOAD = 10 pF – 10 – mA/μs OUTPUT STAGE Output Slew Rate4 Continued on the next page. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH OPERATING CHARACTERISTICS (continued) using reference target 60-0, TA and VCC within specification, unless otherwise noted Characteristic Symbol Min. Typ.1 Max. Units Reference Target 60-0 0 – 8,000 rpm Equivalent to f – 3dB 20 40 – kHz – 120 – mV – 120 – mV – – 3 Edge Output switching only; may not meet datasheet specifications –60 – 60 G ∆DC within specification 0.5 – 2.75 mm – – 3 mm 43 53 63 % Operating within specification 30 – 1000 G Output switching (no missed edges); ∆DC not guaranteed 20 – – G Test Conditions SWITCHPOINT CHARACTERISTICS Rotation Speed SROT Analog Signal Bandwidth BW Operate Point BOP Release Point BRP Transitioning from ICC(High) to ICC(Low); positive peak referenced; AG < AGMAX Transitioning from ICC(Low) to ICC(High); negative peak referenced; AG < AGMAX CALIBRATION Initial Calibration CI Quantity of rising output (current) edges required for accurate edge detection DAC CHARACTERISTICS Allowable User-Induced Differential Offset FUNCTIONAL CHARACTERISTICS5 Operational Air Gap Range6 Maximum Operational Air Gap Range Duty Cycle Variation7 Operating Magnetic Flux Density Differential8 Minimum Operating Signal AG AGOP(max) ∆DC BAG(p-p) SigOP(min) Output switching (no missed edges); ∆DC not guaranteed Wobble < 0.5mm; Typical value at AG = 1.5 mm, for max., min., AG within specification 1Typical values are at TA = 25°C and VCC = 12 V. Performance may vary for individual units, within the specified maximum and minimum limits. voltage must be adjusted for power dissipation and junction temperature; see Power Derating section. 3Power-On Time includes the time required to complete the internal automatic offset adjust. The DACs are then ready for peak acquisition. 4dI is the difference between 10% of I CC(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. 5Functional characteristics valid only if magnetic offset is within the specified range for Allowable User Induced Differential Offset. 6AG 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. 7Duty cycle specification may not be met if the magnetic signal during the calibration period is not representative of the installation air gap. 8In 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. 2Maximum Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH REFERENCE TARGET, 60-0 (60 Tooth Target) Characteristics Symbol Test Conditions Typ. Units 120 mm Outside Diameter Do Outside diameter of target Face Width F Breadth of tooth, with respect to sensor 6 mm Circular Tooth Length t Length of tooth, with respect to sensor; measured at Do 3 mm Circular Valley Length tv Length of valley, with respect to sensor; measured at Do 3 mm Tooth Whole Depth ht 3 mm – – Material Low Carbon Steel Symbol Key Reference Gear Magnetic Gradient Amplitude With Reference to Air Gap 800 600 500 400 300 200 Branded Face of Sensor 100 0 0.5 1 1.5 2 2.5 Reference Target 60-0 3 Air Gap (mm) Reference Gear Magnetic Profile Two Tooth-to-Valley Transitions 500 Air Gap 400 (mm) 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 2.75 3.00 300 Differential B* (G) Peak-to-Peak Differential B (G) 700 200 100 0 -100 -200 3.00 mm AG -300 0.50 mm AG -400 -500 0 2 4 6 8 10 12 Gear Rotation (°) *Differential B corresponds to the calculated difference in the magnetic field as sensed simultaneously at the two Hall elements in the device (BDIFF = BE1 – BE2). Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH Characteristic Data I1 Trim Duty Cycle vs. Air Gap 100 RPM, VCC = 12 V 65 TA, (ºC) -40 25 150 60 TA, (ºC) -40 25 150 60 55 Duty Cycle (%) 55 Duty Cycle (%) Duty Cycle vs. Target Speed Air Gap 1.5 mm, VCC = 12 V 65 50 45 40 50 45 40 35 35 0 0.5 1 1.5 2 2.5 3 3.5 0 200 400 600 Air Gap (mm) Duty Cycle vs. Air Gap 1000 RPM, VCC = 12 V 65 800 1000 1200 1400 1600 Target Speed (RPM) Supply Current vs. Supply Voltage 18 60 ICC(High) 15 12 ICC (mA) Duty Cycle (%) 55 50 45 9 ICC(Low) 6 TA, (ºC) -40 25 150 40 35 0 0.5 1 1.5 2 Air Gap (mm) 2.5 3 TA, (ºC) -40 25 150 3 3.5 0 0 5 10 15 20 25 30 VCC (V) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH THERMAL CHARACTERISTICS may require derating at maximum conditions, see application information CHARACTERISTIC Symbol TEST CONDITIONS* RθJA Package Thermal Resistance Value Units Single-layer PCB with copper limited to solder pads 126 ºC/W Two-layer PCB with 3.8 in.2 of copper area on each side connected with thermal vias and to device ground pin 84 ºC/W Maximum Allowable VCC (V) *Additional information is available on the Allegro Web site. Power Derating Curve TJ(max) = 165ºC; ICC = ICC(max) 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 VCC(max) (RθJA = 84 ºC/W) (RθJA = 126 ºC/W) VCC(min) 20 40 60 80 100 120 140 160 180 Power Dissipation, PD (m W) Temperature (ºC) Maximum Power Dissipation, PD(max) TJ(max) = 165ºC; VCC = VCC(max); ICC = ICC(max) 1900 1800 1700 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 (R θJ (R θJ 20 40 60 A =1 26 ºC A = /W 84 ºC /W ) ) 80 100 120 Temperature (°C) 140 160 180 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH Functional Description Sensing Technology Output Polarity The gear tooth sensor subassembly contains a single-chip differential Hall effect sensor IC, an optimized samarium cobalt magnet, and a flat ferrous pole piece. The Hall IC supports two Hall elements, which sense the magnetic profile of the ferrous target simultaneously, 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. 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, ICC(High), to low ICC(Low), 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 rotation is reversed, then the output polarity inverts. The Hall IC is self-calibrating and also possesses a temperature compensated amplifier and offset cancellation 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 rejection circuitry. The Hall transducers and signal processing 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 target. The waveform diagram shown in figure 3 presents the automatic translation of the mechanical profile, through the magnetic profile that it induces, to the digital output signal of the sensor. Note that output voltage polarity is dependent on the position of the sense resistor, RSENSE (see figure 4). Target Mechanical Profile Representative Differential Magnetic Profile Sensor Electrical Output Profile, IOUT Figure 3. Output Profile of a ferrous target for the polarity indicated in figure 2. VCC VCC Target (Gear) RSENSE Element Pitch Hall Element 2 Dual-Element Hall Effect Device ICC VOUT(H) Hall Element 1 Hall IC Pole Piece (Concentrator) South Pole Back-biasing Magnet North Pole Case (Pin 4 Side) (Pin 1 Side) 1 1 VCC VCC ATS645 ATS645 GND 4 GND 4 VOUT(L) Figure 1. Relative motion of the target is detected by the dual Hall elements mounted on the Hall IC. ICC RSENSE Branded Face of Sensor Rotating Target I+ IOUT V+ 1 4 VOUT(L) V+ Figure 2. This left-to-right (pin 1 to pin 4) direction 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) rotation inverts the output signal polarity. VOUT(H) Figure 4: Voltages profiles for high side and low side two-wire sensing. Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 ATS645LSH True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor sate for offsets induced by temperature variations over time. 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 specification). During calibration, the device determines the peak-topeak 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 cancels the effects of chip, magnet, and installation offsets. (For capability, see Dynamic Offset Cancellation, in the Operating Characteristics table.) This circuitry is continuously active, including both during calibration mode and running mode, compensating for any offset drift. Continuous operation also allows it to compen- Digital Peak 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 hysteresis, the output would switch and the DAC would begin tracking the signal downward toward the negative VPROC peak. Once the DAC acquires the negative peak, the output will again switch states when VPROC is greater than the peak by the value BRP. 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. Ferrous Target Mechanical Profile V+ Internal Differential Analog Signal Response, without AGC V+ AGLarge Internal Differential Analog Signal BOP BRP AGSmall V+ Internal Differential Analog Signal Response, with AGC I+ AGSmall AGLarge 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. Device Output Current Figure 6: Peak Detecting Switchpoint Detail Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9 ATS645LSH True Zero Speed Miniature Differential PeakDetecting 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 protection may still be required. Contact Allegro Microsystems for 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, VCC(UV), the device enters Reset, where the output state returns to the Power-On State (POS) until sufficient VCC is supplied. ICC levels may not meet datasheet limits when VCC < VCC(min). 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. V+ 1 VCC ATS645 Pins 2 and 3 floating CBYP 0.01 µF GND 4 ECU 100 Ω RSENSE Figure 7: Typical Application Circuit 10 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ATS645LSH True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor SENSOR OPERATION internal analog signal is properly centered. Each operating mode is described in detail below. During this mode, the tracking DAC is active and output switching occurs, but the duty cycle is not guaranteed to be within specification. Power-On When power (VCC > VCCMIN) is applied to the device, a short period of time is required to power the various portions of the IC. During this period, the ATS645 is guaranteed to power-on in the high current state, ICC(High). 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. Diagnostics The regulated current output is configured for two wire applications, 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. Any current level not within these ranges indicates a fault condition. Calibration Mode Running Mode The calibration mode allows the sensor to automatically select the proper signal gain and continue to adjust for offsets. The 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 After the initial calibration period, CI, during which a signal gain is established, 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. 11 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ATS645LSH True Zero Speed Miniature Differential PeakDetecting 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 supplied power or improving the heat dissipation properties of the application. This section presents a procedure for correlating factors affecting operating TJ. (Thermal data is also available on the Allegro MicroSystems Web site.) The Package Thermal Resistance, RθJA, is a figure of merit summarizing 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, RθJC, is relatively small component of RθJA. Ambient air temperature, TA, and air motion are significant external factors, damped by overmolding. The effect of varying power levels (Power Dissipation, PD), can be estimated. The following formulas represent the fundamental relationships used to estimate TJ, at PD. PD = VIN × IIN (1) ΔT = PD × RθJA (2) TJ = TA + ΔT Example: Reliability for VCC at TA = 150°C, package SH (I1 trim), using minimum-K PCB Observe the worst-case ratings for the device, specifically: RθJA = 126°C/W, TJ(max) = 165°C, VCC(max) = 24 V, and ICC(max) = 16 mA. Calculate the maximum allowable power level, PD(max). First, invert equation 3: ΔTmax = TJ(max) – TA = 165 °C – 150 °C = 15 °C This provides the allowable increase to TJ resulting from internal power dissipation. Then, invert equation 2: PD(max) = ΔTmax ÷ RθJA = 15°C ÷ 126 °C/W = 119 mW Finally, invert equation 1 with respect to voltage: VCC(est) = PD(max) ÷ ICC(max) = 119 mW ÷ 16 mA = 7 V The result indicates that, at TA, the application and device can dissipate adequate amounts of heat at voltages ≤VCC(est). Compare VCC(est) to VCC(max). If VCC(est) ≤ VCC(max), then reliable operation between VCC(est) and VCC(max) requires enhanced RθJA. If VCC(est) ≥ VCC(max), then operation between VCC(est) and VCC(max) is reliable under these conditions. (3) For example, given common conditions such as: TA= 25°C, VCC = 12 V, ICC = 4 mA, and RθJA = 140 °C/W, then: PD = VCC × ICC = 12 V × 4 mA = 48 mW ΔT = PD × RθJA = 48 mW × 140 °C/W = 7°C TJ = TA + ΔT = 25°C + 7°C = 32°C A worst-case estimate, PD(max), represents the maximum allowable power level (VCC(max), ICC(max)), without exceeding TJ(max), at a selected RθJA and TA. 12 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor ATS645LSH Package SH Module 5.5 .217 0.43 .017 E 0.75 .0294 C 0.75 .0294 8.0 5.8 .315 .228 2.9 4.0 5.0 B .244 .114 E .157 0.38 .015 A 1.7 .067 1 2 3 4 1.08 .043 1 .039 20.95 .825 13.05 .514 A 0.6 .024 D 0.6 .024 1.27 .050 Dimensions in millimeters. Untoleranced dimensions are nominal. U.S. Customary dimensions (in.) in brackets, for reference only A Dambar removal protrusion (16X) B Metallic protrusion, electrically connected to pin 4 and substrate (both sides) C Active Area Depth D Thermoplastic Molded Lead Bar for alignment during shipment E Hall elements (2X); controlling dimension inches 13 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ATS645LSH True Zero Speed Miniature Differential PeakDetecting Gear Tooth Sensor 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 components 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 responsibility for its use; nor for any infringement of patents or other rights of third parties which may result from its use. Copyright © 2004, 2006 Allegro MicroSystems, Inc. 14 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com