ATS672LSB

ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Discontinued Product These parts are no longer in production The device should not be purchased for new design applications. Samples are no longer available. Date of status change: May 1, 2006 Recommended Substitutions: NOTE: For detailed information on purchasing options, contact your local Allegro field applications engineer or sales representative. Allegro MicroSystems, Inc. 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, Inc. assumes no responsibility for its use; nor for any infringements of patents or other rights of third parties which may result from its use. ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture The ATS672 true zero-speed gear tooth sensors provide manufacturer-friendly solutions for digital gear tooth sensing applications, through an optimized configuration of Hall-effect IC and magnet, packaged together in a single SIP (Single In Line Package) module. The SIP consists of an overmolded enclosure, which encapsulates a samarium cobalt magnet, a pole piece, and a true zero-speed Halleffect IC that has been optimized to the magnetic circuit. This package can be easily assembled and used in conjunction with gears of various shapes and sizes. The ATS672 sensor incorporates a single-element Hall-effect IC that switches in response to the magnetic signal created by a ferrous target (the gear). The IC contains a sophisticated digital circuit designed to eliminate the detrimental effects of magnet and system offsets. Signal processing is used to provide zero-speed performance, independent of air gap, and also to dynamically adapt device performance to the typical operating conditions found in automotive applications, such as reducing sensitivity to vibration. High resolution (9 bit) peak-detecting DACs are used to set the adaptive switching thresholds of the device. Hysteresis in the thresholds reduces the negative effects of any anomalies in the magnetic signal (such as magnetic overshoot) associated with the targets used in many automotive applications. The ATS672 also includes a low-bandwidth filter that increases the noise immunity and the signal-to-noise ratio of the sensor. These features result in potential improvements in both the timing accuracy and the jitter performance of the device. The ATS672LSB version is optimized for gear tooth sensing applications. The ATS672LSB-LT is optimized for cam sensing. Package SB, 4-pin SIP 4 3 21 1. VCC 2. VOUT 3. Test pin (tie to GND) 4. GND ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC .......................................... 28 V Reverse-Supply Voltage, VRCC ........................ –18 V Reverse-Output Voltage, VROUT ...................... ??? V Continuous Output Current, IOUT .................. 20 mA Reverse Output Current, IROUT ...................... 50 mA Operating Temperature Ambient, TA,............................... –40ºC to 150ºC Maximum Junction, TJ(max)........................170ºC Maximum Junction ≤ 100 hr, TJ(max) .........180ºC Storage Temperature, TS .................. –65ºC to 170ºC Package Thermal Resistance, RθJA ........... 150 °C/W Features and Benefits • Tight timing accuracy throughout temperature range • True zero-speed operation • Air gap-independent switch points • Large operating air gaps • Operation down to 3.3 V • Digital output representing target profiles • Single-chip solution for high reliability • Small mechanical dimensions • Optimized Hall-effect IC/magnetic systems • AGC and reference-adjust circuits • Undervoltage lockout Use the following complete part numbers when ordering: Part Number ATS672LSB ATS672LSB-LT Package 4-pin plastic SIP 4-pin plastic SIP Application Gear tooth sensing Cam sensing 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Functional Block Diagram VCC Regulator (Analog) Regulator (Digital) Offset TC Dynamic Offset Cancellation TC Adjust Low Pass Filter Automatic Gain Control (Analog) Amp VREF Threshold Comparator Power On Reset Output Driver VOUT VTHRESH GND Test 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 2 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture OPERATING CHARACTERISTICS Valid at Ta = –40ºC to 150ºC, and VCC within specification, unless otherwise noted Characteristics Electrical Characteristics Supply Voltage Reverse Supply Voltage Supply Zener Clamp Voltage Output Zener Clamp Voltage Supply Zener Current Output Zener Current Supply Current Power-On State Characteristics Power-On Time Undervoltage Lockout Output Stage Low Output Voltage Output Current Limit Output Leakage Current Output Rise Time Output Fall Time Switch Point Characteristics Tooth Speed Bandwidth Operate Point Release Point Output Polarity Calibration Initial Calibration AGC Disable CI Cf Number of rising mechanical edges on the target that are required for accurate edge detection Number of rising mechanical edges on the target that are required to complete the AGC calibration – – 2 – 3 3 Smax f – 3 dB BOP BRP VOUT % of peak-to-peak, referenced to tooth sensing signal; AG < AGMax % of peak-to-peak, referenced to tooth sensing signal; AG < AGMax Valley opposite the sensor Tooth opposite the sensor 0 – – – – – – 40 30 40 HIGH LOW 8 – – – – – kHz kHz % % VLOUT Ilim IOFF tr tf ISINK = 15 mA, Output = ON Output = ON; TJ < TJ(max) Output = OFF; VOUT = VCC(max) RLOAD = 500 Ω; CLOAD = 10 pF; TA = 25°C RLOAD = 500 Ω; CLOAD = 10 pF; TA = 25°C – 25 – – – 0.2 45 – 0.9 0.5 0.45 70 10 5 5 V mA µA µs µs tPO VUV Gear Speed < 100 RPM; VCC > 3.3 V – – – – 500 < VCC(min) µs V VCC VRCC Operating; TJ < TJ(max) IRCC = –5 mA, maximum 3.3 – 28 30 – – 3 3 – – – – – – 6.5 6.5 26.5 –18 – – ICC(max) + 3 3 11 11 V V V V mA mA mA mA Symbol Test Conditions Min. Typ. Max. Units VZSupply ICC = 14 mA (≈ICC(max) + 3 mA); TA = 25°C VZOutput IOUT = 3 mA; TA = 25°C IZSupply IZOutput ICC Test conditions only; VCC = 28 V VOUT = 30 V Output = OFF Output = ON 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 3 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Output Rise Time (tr) and Fall Time (tf) VOUT (V) Output High 90% 100% 10% tr tf t (s) Output Low Output Voltage Rise Duration RLOAD = 500 Ω, CLOAD = 10 pF 10.00 8.00 VOUT (V) 6.00 4.00 2.00 0.00 0.0 1.0 2.0 t (µs) 3.0 4.0 5.0 Output Voltage Fall Duration RLOAD = 500 Ω, CLOAD = 10 pF 10.00 8.00 VOUT (V) 6.00 4.00 2.00 0.00 0.0 1.0 2.0 3.0 4.0 5.0 t (µs) 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 4 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture OPERATING CHARACTERISTICS using reference target 8X and test circuit #1; air gap within AG range, and over rated ambient temperature range, unless otherwise noted Characteristics Symbol TICRel Relative Timing Accuracy* TRel Operational Air Gap Range *Relative Test Conditions During initial calibration; rising and falling mechanical edges; RPM = 1000; gear eccentricity < 0.1 mm After initial calibration; rising mechanical edge; RPM = 1000; gear eccentricity < 0.1 mm After initial calibration; falling mechanical edge; RPM = 1000; gear eccentricity < 0.1 mm Output switching: Running mode only Min. – – – – Typ. 3 0.3 0.5 0.5 Max. 6 0.6 0.8 2.5 Units deg. deg. deg. mm AG Timing Accuracy range is the change in edge position over the AG range and the device operating temperature range. ICC Off, VCC = 4.0 V 10 8 ICC On, VCC = 4.0 V 10 8 ICC (mA) -40 25 TA (°C) 150 ICC (mA) 6 4 2 0 6 4 2 0 -40 25 TA (°C) 150 VSAT at ISINK = 15 mA, VCC = 4.0 V 450 375 VSAT (mV) 300 225 150 75 0 -40 25 150 TA (°C) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 5 30Dec03, Rev. 1.42 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Functional Description POR. (Power-On Reset) Allows complete reset to the original power-on state, when initial calibration occured, regardless of the state of the device immediately prior to POR. TC. (Temperature Coefficient) This supports fine tuning of the ATS672 for flat parametric performance over the full rated operating temperature range. Sensor Integration. The ATS672 contains a self-calibrating Hall-effect IC that possesses temperature compensated amplifier circuitry and a voltage regulator that provides supply noise rejection over the operating voltage range. The Hall transducer and the electronics are integrated on the same silicon substrate using a proprietary BiCMOS process. Changes in temperature do not greatly affect this device due to the stable amplifier design and the offset rejection circuitry. Assembly Description. The ATS672 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. Operation. When proper power is applied to the sensor, it is capable of providing digital information that is representative of the profile of a rotating gear. No additional optimization is needed and minimal processing circuitry is required. This ease of use should reduce design time and incremental assembly costs for most applications. Sensing Technology. The sensor contains a single-chip Halleffect sensor IC, a 4-pin leadframe, and a specially-designed rare earth magnet. The Hall IC possesses a Hall element that measures the magnetic gradient created by the passing of a ferrous object. The difference in the magnetic gradients created by a tooth and valley allow the generation of the digital output signal. The following output diagram corresponds to a sensor with the standard polarity. Digital Output Signal Magnetic Gradient Ferrous Target Mechanical Profile Sensing technology. As the target moves by the sensor, there is a change in the magnetic flux density, B, which is measured in gauss (G). The left panel shows the effect of a tooth opposite the sensor, a higher B. The right panel shows the effect of a valley, a lower B. 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 6 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Start-Up Detection. The ATS672 generates a digital output transition when the first rising or falling mechanical edge is detected after being powered-on, indicating when the first significant motion in the target is detected. Undervoltage Lockout. When the supply voltage falls below the minimum operating voltage, VCCUV, the device turns off. It then stays off, regardless of the state of the magnetic field, until an operating range VCC is restored. It then turns on again. This lockout feature prevents false signals, caused by undervoltage conditions, from propagating to the output of the 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. Automatic Gain Control (AGC). The patented self-calibrating circuitry is unique. Each time the device is powered-on, the device starts measuring the peak-to-peak magnetic gradient. The gain of the sensor is automatically adjusted, keeping the internal electrical signal amplitude constant over the air gap range, AG, of the device. This feature provides consistent operational characteristics independent of variances in the air gap. Switch Points. Switch points are the levels of magnetic flux density, B, which trigger switch turn-on and turn-off. When B exceeds a certain limit, referred to as the Operate point (Bop), the trigger provides a clean transition from off to on. When the magnetic field falls below Bop by a certain limit, referred to as the Release point, Brp, the trigger provides a clean transition from on to off. In the ATS672, switch points are established dynamically as a percentage of the amplitude of the normalized magnetic signal. Two DACs track the peaks of the normalized magnetic signal, and the switching thresholds are established at fixed percentages of the two DAC values. The values of the thresholds have been carefully selected to provide the most accurate and consistent switching where the signal is steepest and least affected by air gap variation. The figure below graphically demonstrates the establishment of the switching threshold levels. The low hysteresis of 10% provides high performance over the full AG, and immunity to false switching due to noise, vibration, backlash, or other transient events. Electrical Signal Response, with AGC AGMax AGMin AGMin AGMax V Valley Signal Bop Bop% Brp% Bhys Tooth Signal Switch Points. The ATS672 design minimizes hysteresis, Bhys. Brp 100% Magnetic Gradient (No amplification) t Ferrous Target Mechanical Profile 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. 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 7 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Application Information For additional general application information, visit the Allegro MicroSystems Web site at www. allegromicro.com. Target Design The Hall-effect sensor can detect variations in magnetic flux density generated by features of a target. To distinguish between two features of a target, such as between a tooth and a valley of a spur gear, there must be a minimum differential of 120 G in the magnetic flux densities corresponding to the features, as measured at the sensor. The target must be mounted with an air gap in the range AG, the distance between the target object and the plane of the Halleffect sensor as installed. In general, the nearer a target feature is to the active area of the sensor, the greater the magnetic flux density at the sensor. The following figures and table specify a design that can be used to construct a reference target. The target represents a ferrous spur gear, with uniform tooth and valley widths. The target would be mounted so that its axis of rotation is parallel to the plane of the Hall-effect sensor element, and centered on the element. When the target is produced to the specifications listed in the Reference Target column of the table, the required differential (tooth peak to valley) in magnetic flux densities is generated. Also in the table, the Minimum Required for TPOS column provides specifications for a similar application. These values are the minimum required for the TPOS function to operate accurately, as defined in the Operating Characteristics table. Target Sensor 8X Reference Target Reference Target Characteristics Characteristic Material Diameter Tooth Thickness Tooth Height Tooth Width Valley Width *Resulting Symbol Description Target has uniform composition Reference Target 8X Only CRS1018 120 6 5 22.5* 22.5* Minimum Required for TPOS – – 5 5 5 13 Units – mm mm mm deg. deg. DO F Ht T PC – T Diameter of target, to valley Breadth of tooth, with respect to sensor Height of tooth, measured from the valley (DO) Width of tooth Width of valley, with PC = pitch of teeth arc measures 23.6 mm in length at DO 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 8 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Typical Circuit Design The following circuit is the most basic configuration required for proper device operation. A pull-up resistor is used. VCC 1 0.1 uF 2 ATS672 3 Sensor/Target Evaluation In order to establish the proper operating specification for a particular sensor/target configuration, a systematic evaluation of the magnetic circuit should be performed. The first step is the generation of a magnetic map of the target. By using a calibrated device, a magnetic signature of the system is made. A magnetic map of the 8X reference target, created using the LSB sensor package, is shown below. From this map data, a pair of curves can be derived that describe the tooth and valley magnetic fields versus air gap. Knowing the minimum amount of magnetic flux density that guarantees operation of the sensor, one can determine the maximum operational air gap of the sensor/target system. VOUT 4 Magnetic Map, 8X Reference Target, Using LSB Package 500 450 400 350 300 250 200 150 100 50 0 -50 -100 -150 -200 0 30 60 90 120 150 180 210 240 270 300 330 360 Magnetic Flux Density, B (G) Position (°) Magnetic Flux Density, B, Versus Air Gap 8X Reference Target Using LSB Package 600 Magnetic Flux Density, B (G) 500 400 300 200 100 0 -100 -200 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 Tooth Valley Air Gap (mm) Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 9 30Dec03, Rev. 1.42 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture SENSOR EVALUATION: ACCURACY The self-calibration algorithm allows the sensor to adapt to system changes such as air gap increase. However, major changes in air gap can adversely affect switching performance. When characterizing sensor performance over a significant air gap range, be sure to power-off and then power-on the device at each air gap. This ensures that self-calibration occurs for each installation condition. See the Operating Charactersitics table for information on timing accuracy performance. 105 Edge Position vs. Air Gap Electrical Rising Edge (Mechanical Falling Edge) ATS672LSB; 8X Reference Target ROOM 150ºC -40ºC Edge Position (Degrees) 104.8 104.6 104.4 104.2 104 103.8 103.6 103.4 103.2 103 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 Air Gap (mm) Edge Position vs. Air Gap Electrical Falling Edge (Rising Mechanical Edge) ATS672LSB; 8X Reference Target ROOM 150ºC -40ºC 127 Edge Position (Degrees) 126.8 126.6 126.4 126.2 126 125.8 125.6 125.4 125.2 125 0.50 0.75 1.00 1.25 1.50 1.75 2.00 2.25 2.50 Air Gap (mm) ) Relative Timing Accuracy Target Valley Operational Air Gap Tooth Air Gap Device Output TAbsRise (Max - Min) TAbsFall (Max - Min) 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 10 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Temperature Compensation The device should be operated at or below the maximum junction temperature of the device, TJ(max) (see the Absolute Maximum Ratings section, on page 1). The actual operating TJ of the device is affected by several factors. Under certain combinations of peak conditions (corresponding to the gray area of the Power De-Rating Curve chart), operation may require power de-rating or heat sinking. The relevent factors are characteristic of the device and package, as well as the application, including the effect of adjacent external sources of heat. The Package Thermal Resistance, RθJA, indicates the resitance to heat transfer from the heat-generating portions of the die (the “junction”) through all paths to the ambient air. This includes heat sinking through the PCB, as well as direct radiation from the die through the package, RθCA. Thermal information on packages is available on the Allegro Web site. The Allowable Power Dissipation, PD, represents the amount of power that can be applied to the device at a given RθCA and ambient temperature, TA, without causing the temperature of the die to exceed , TJ(max). This section presents a procedure for correlating these factors with operating voltage, VCC, and operating current, ICC, to estimate their effect on TJ. If the estimated operating TJ exceeds TJ(max), then power levels can be reduced or external heat sinking can be applied. Typically, VCC is the factor reduced, to accommodate the required TA. A power de-rating curve can be constructed, representing the maximum allowable VCC per TA. If the calculated VCC exceeds the power de-rating curve at the required TA, and heat sinking is not preferred, estimate the amount to reduce VCC. This can be estimated through calculating PD(max), the maximum allowable PD for the given device and package. PD(max) is related to RθJA and TA. The following formulas represent the fundamental relationships used to calculate the VCC adjustment, based on the temperature effect, ∆T. TJ = TA + ∆T (1) where ∆T denotes the increase in TJ due to power dissipation within the device. ∆T = PD × RθJA PD = VCC × ICC (2) (3) Examples for estimating VCC are provided on the next page. These formulas and results can also be used to estimate TJ. For example, given common conditions such as: TA= 25°C, VCC = 5 V, ICC(on) = 6.5 mA, and RθJA = 150 °C/W then: PD = VCC × ICC(on) = 5 V × 6.5 mA = 32.5 mW ∆T = PD × RθJA = 32.5 mW × 150 °C/W = 4.9°C TJ = TA + ∆T = 25°C + 4.9°C = 29.9°C Power De-Rating Curve VCC(max) = 26.5 V; TJ(max) = 170ºC 28.0 26.0 24.0 22.0 20.0 18.0 16.0 14.0 12.0 10.0 8.0 6.0 4.0 2.0 0.0 20 Maximum Allowable VCC (V) Allowable operating range without additional heat sinking Some combinations of peak ratings may require heat sinking when operating in shaded area 40 60 80 100 120 140 160 180 TA (ºC) 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 11 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Example: VCC Adjustment, Package SE Observe the absolute maximum ratings for the package, specifically: RθJA = 150 °C/W TJ(max) = 170°C Also observe the characteristic operating maximums: VCC(max) = 26.5 V ICC(max) = 11 mA For a given TA (e.g., 150°C), first calculate the Maximum Allowable Power Dissipation, PD(max). Invert equation 1: ∆Tmax = TJ(max) – TA = 170°C – 150°C = 20°C This provides the allowable increase to TJ resulting from internal power dissipation. Then, invert equation 2: PD(max) = ∆Tmax ÷ RθJA = 20°C ÷ 150 °C/W = 133 mW This provides the corresponding allowable increase in power level. Finally, invert equation 3 to determine the corresponding supply voltage VCC: VCC = PD(max) ÷ ICC(max) = 133 mW ÷ 11 mA = 12 V The result indicates that the device and package can dissipate adequate amounts of heat at voltages up to 12 V, at TA = 150ºC. Because VCC(max) is more than the calculated VCC, however, the device requires additional heat sinking for operation between the calculated VCC and VCC(max), under these conditions. If the calculated VCC were greater than or equal to VCC(max), then operation up to VCC(max) would not require additional heat sinking. Maxim um Pow er Dissipation vs. Am bient Temperature Package SB: RθJA = 150ºC/W, TJ(max) = 170ºC 1600 1500 1400 1300 1200 1100 1000 900 800 700 600 500 400 300 200 100 0 20 PD(max) (m W) 40 60 80 100 120 140 160 180 TA (ºC) 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 12 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture Package SB, 4-pin SIP AAD 0.42 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 13 ATS672LSB Self-Calibrating Gear Tooth Sensor with 9-Bit Signal Capture 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 Allegro MicroSystems, Inc. 30Dec03, Rev. 1.42 Allegro MicroSystems, Inc. 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 www.allegromicro.com 14