A3046

3046 ALLEGRO | Alldatasheet

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Operating Temp. Range Device Type Number -40°C to +85°C A3046EU A3058EU A3056EU -40°C to +150°C A3046LU A3058LU A3056LU HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED The A3046EU/LU, A3056EU/LU, and A3058EU/LU Hall effect gear-tooth sensors are monolithic integrated circuits that switch in response to differential magnetic fields created by ferrous targets. These devices are ideal for use in gear-tooth-based speed, position, and timing applications and operate down to zero rpm over a wide range of air gaps and temperatures. When combined with a back- biasing magnet and proper assembly techniques, devices can be configured to give 50% duty cycle or to switch on either leading, trailing, or both edges of a passing gear tooth or slot. The six devices differ only in their magnetic switching values and operating temperature ranges. The low hysteresis of the A3046/56EU and A3046/56LU makes them perfectly suited for ABS (anti-lock brake system) or speed sensing applications where maintaining large air gaps is important. The A3046EU/LU features improved switch point stability with temperature over the A3056EU/LU. The high hysteresis of the A3058EU and A3058LU, with their excellent temperature stability, makes them especially suited to ignition timing applications where switch-point accuracy (and latching requirements) is extremely important. Continued next page... BENEFITS I Senses Ferrous Targets Down to Zero RPM I Large Effective Air Gap I Wide Operating Temperature Range I Operation from Unregulated Supply I High-Speed Operation I Output Compatible With All Logic Families I Reverse Battery Protection I Solid-State Reliability I Resistant to Physical Stress Dwg. PH-012 1SUPPLY VCC GROUND OUTPUT X X Pinning is shown viewed from branded side. SELECTION GUIDE Data Sheet 27612A† ABSOLUTE MAXIMUM RATINGS Reverse Battery Voltage, Package Power Dissipation, P D . . 500 mW Operating Temperature Range, T A Storage Temperature Range, 3046, 3056, AND 3058

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-5000 All devices, when used with a back- biasing magnet, can be configured to turn ON or OFF with the leading or trailing edge of a gear tooth or slot. Changes in fields on the magnet face caused by a moving ferrous mass are sensed by two integrated Hall transducers and are differentially amplified by on-chip electronics. The on-chip temperature compensation and Schmitt trigger circuitry minimizes shifts in effective working air gaps and switch points over temperature making these devices ideal for use in ignition timing, anti-lock braking systems, and speed mea- surement systems in hostile automotive and industrial environments. Each Hall effect digital Integrated circuit includes two quadratic Hall effect sensing elements, a voltage regulator, temperature compensating circuitry, low-level amplifier, Schmitt trigger, and an open-collector output driver. The on-board regulator permits operation with supply voltages of 4.5 to 24 volts. The output stage can switch up to 20 mA at conservatively specified repetition rates to 20 kHz and is compatible with bipolar and MOS logic circuits. FUNCTIONAL BLOCK DIAGRAM Both magnetic characteristics are available in a choice of two operat- ing temperature ranges. Suffix EU devices have an operating range of -40°C to +85°C while suffix LU devices feature an operating range of -40°C to +150°C. All devices are packaged in a 3-pin plastic SIP. ELECTRICAL CHARACTERISTICS at VCC = 8 V, over operating temperature range. Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Supply Voltage V CC Operating 4.5 — 24 V Power-Up State — 3058* only, Output is OFF — VCC = 0 4.5 V, B < B OP Output Saturation Voltage V OUT(SAT) IOUT = 20 mA, B > BOP — 135 400 mV Output Leakage Current I OFF VCC = VOUT = 24 V, B < BRP — — 5.0 µA Supply Current I CC VCC = 24 V, B < BRP — 7.2 14 mA Output Rise time t r RL = 820 Ω, CL = 20 pF — 100 — ns Output Fall time t f RL = 820 Ω, CL = 20 pF — 100 — ns OUTPUT X X Dwg. FH-010 SUPPLY GROUND REG Copyright © 1989, 1995 Allegro MicroSystems, Inc.

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED www.allegromicro.com Part Numbers* 3046 3056 3058 Operate Point, BOP Output Switches OFF to ON, — — 150 — — 150 — — 250 Release Point, BRP Output Switches ON to OFF, -150 — — -150 — — -250 — — Hysteresis, Bhys BOP-BRP, TA = +25°C 15 50 90 15 50 90 150 200 250 Change in Trip Point, — — ±50 — — ±75 — — ±50 ∆BOP or ∆BRP MAGNETIC CHARACTERISTICS in gauss at VCC = 8 V. TA = +25°C TA = +25°C NOTES: 1. Magnetic switch points are specified as the difference in magnetic fields at the two Hall elements. 2. As used here, negative flux densities are defined as less than zero (algebraic conven- tion). 3. Typical values are at T A = +25°C. * Complete part number includes the prefix ‘A’ and a suffix to identify operating tempera- ture range and package style. See selection guide. Over operating temperature range, Ref. B OP or BRP at TA = +25°C TYPICAL OPERATING CHARACTERISTICS SUPPLY CURRENT IN mA SUPPLY VOLTAGE IN VOLTS Dwg. GH-031 51 0 1 5 2 0 2 5 T = +25°CA B > BOP B < BRP -50 100 SATURATION VOLTAGE IN mV AMBIENT TEMPERATURE IN °C Dwg. GH-033 180 160 140 120 0 50 100 150 200 V = 8 V I = 20 mA CC OUT -50 SUPPLY CURRENT IN mA AMBIENT TEMPERATURE IN °C Dwg. GH-032 0 50 100 150 V = 24 VCC B > BOP B < BRP

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED Worcester, Massachusetts 01615-0036 (508) 853-5000 24 V MAX 0+ B OUTPUT VOLTAGE IN VOLTS DIFFERENTIAL FLUX DENSITY, BE1 – BE2 Dwg. GH-034 OP RP B B V OUT(SAT) APPLICATIONS INFORMATION A gear-tooth sensing system consists of the sensor IC, a back- biasing magnet, an optional pole piece, and a target (Figure 1). The system requirements are usually specified in terms of the effective working air gap between the package and the target (gear teeth), the number of switching events per rotation of the target, temperature and speed ranges, minimum pulse duration or duty cycle, and switch point accuracy. Careful choice of the sensor IC, magnet material and shape, target material and shape, and assembly techniques enables large working air gaps and high switch-point accuracy over the system operating temperature range. Naming Conventions. With a south pole in front of the branded surface of the sensor, a north pole behind the sensor, the field at the sensor is defined as positive. As used here, negative flux densities are defined as less than zero (algebraic convention), e.g., -100 G is less than -50 G. Magnet Biasing. In order to sense moving non-magnetized ferrous targets, these devices must be back-biased by mounting the unbranded side on a small permanent magnet. Either magnetic pole (north or south) can be used. The devices can also be used without a back-biasing magnet. In this configuration, the sensor can be used to detect a rotating ring magnet such as those found in brushless dc motors or in speed sensing applications. Here, the sensor detects the magnetic field gradient created by the magnetic poles. Figure 2 TYPICAL TRANSFER CHARACTERISTIC Figure 1 TYPICAL GEAR-TOOTH SENSING APPLICATION BACK-BIASING MAGNET OPTIONAL POLE PIECE SENSOR IC NS TARGET GEAR A Dwg. AH-003 S

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED Worcester, Massachusetts 01615-0036 (508) 853-5000 SYSTEM ISSUES Optimal performance of a gear-tooth sensing system strongly depends on four factors: the IC magnetic parameters, the magnet, the pole piece configuration, and the target. Sensor Specifications. Shown in Figure 5 are graphs of the differential field as a function of air gap. A 48-tooth, 2.5 ” (63.5 mm) diameter, uniform wheel similar to that used in ABS applications is used. The samarium cobalt magnet is 0.32 ” diameter by 0.20” long (8.13 x 5.08 mm). The maximum functioning air gap with this typical gear/ magnet combination can be determined using the graphs and the specifications for the sensor IC. In this case, if an A3056EU/LU sensor with a B OP of +25 G and a BRP of -25 G is used, the maximum allowable air gap would be 0.110” (2.79 mm). If the switch points change +75 G with temperature (B OP = + 100 G, BRP = +50 G), the maximum air gap will be approximately 0.077” (1.96 mm). All system issues should be translated back to such a profile to aid the prediction of system performance. Magnet Selection. These devices can be used with a wide variety of commercially available permanent magnets. The selection of the magnet depends on the operational and environmental requirements of the sensing system. For systems that require high accuracy and large working airgaps or an extended temperature range, the usual magnet material of choice is rare earth samarium cobalt (SmCo). This magnet material has a high energy product and can operate over an extended temperature range. For systems that require low-cost solutions for an extended temperature range, Alnico-8 can be used. Due to its relatively low energy product, smaller operational airgaps can be expected. At this time, neodymium iron boron (NeFeB) is not a proven high-tempera- ture performer; at temperatures above Figure 4 POSITIVE AND NEGATIVE SWITCH OPERATION B – BE1 E2 150 G -150 G B = -50 GOP RP V OUT(SAT) VOUT OUTPUT DUTY CYCLE = 33% B = -100 G B – BE1 E2 150 G -150 G B = +100 GOP RP VOUT(SAT) VOUT B = +50 G OUTPUT DUTY CYCLE = 65% Dwg. WH-004 (a) (b) +150°C it may irreversibly lose magnetic strength. Of these three magnet materials, Alnico-8 is the least expensive by volume and SmCo is the most expensive. Either cylindrical- or cube-shaped magnets can be used, as long as the magnet pole face at least equals the facing surface(s) of the IC package and the pole piece. Choose the length of the magnet to obtain a high length-to-width ratio, up to 0.75:1 for rare earths, or 1.5:1 for Alnico-8. Any added magnet length may incrementally improve the allowable maximum air gap. Magnets, in general, have a non-uniform magnetic surface profile. The flux across the face of a magnet can vary by as much as 5% of the average field over a 0.10” (2.5 mm) region. If a Hall sensor is placed directly on a magnet face, the non-uniformity can appear to shift the operating parameters of the sensor. For example, if a device is placed on a 3000 G magnet with ±2% face offsets, each of the operating points might be shifted by ±60 G. When offsets are present, the operating characteristics may be greatly altered.

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED www.allegromicro.com Figure 5 DIFFERENTIAL FLUX DENSITY Pole Piece Design. A pole piece may be used at the face of the magnet to smooth out the magnet-face offsets. A 0.020 ” (0.51 mm) thick, soft-iron pole piece will bring the field non-uniformity down to the ±1%-to-±3% range. Note that pole pieces will minimize but not eliminate the non-uniformity in the magnet face field. Front pole pieces will almost always result in a reduced maximum air gap. Ferrous Targets. The best ferrous targets are made of cold-rolled low-carbon steel. Sintered-metal targets are also usable, but care must be taken to ensure uniform material composition and density. The teeth or slots of the target should be cut with a slight angle so as to minimize the abruptness of transition from metal to air as the target passes by the sensor. Sharp transitions will result in magnetic overshoots that can result in false triggering. Gear teeth larger than 0.10” (2.54 mm) wide and at least 0.10 ” (2.54 mm) deep provide reasonable working air gaps and adequate change in magnetic field for reliable switching. Generally, larger teeth and slots allow a larger air gap. A gear tooth width approximating the spacing between sensors (0.088 ” or 2.24 mm) requires special care in the system design and assembly techniques. ASSEMBLY TECHNIQUES Due to magnet face non-uniformities and device variations, it is recommended that applications requiring precision switching utilize a mechanical optimization procedure during assembly. Without a pole piece, the inherent magnet face offsets can be used to pre-bias the magnetic circuit to obtain any desired operating mode. This is achieved by physically changing the relative position of the magnet behind the sensor to achieve the desired system performance objec- tive. For example, with a rotating ABS gear, the objective might be a 50% duty cycle at maximum air gap. Similar objectives can be set for ignition (crank and cam position) sensing systems. Non-precision speed sensing applications do not require optimiza- tion. For applications where mechanical optimization is not feasible, non-zero speed devices such as the UGN/UGS3059KA ac-coupled gear-tooth sensor are available. A 1 3 Dwg. MH-002-8D 0.075" 1.89 mm BRANDED SURFACE ACTIVE AREA DEPTH 0.088" 2.23 mm 0.015" 0.38 mm NOM E2 0.046" 1.17 mm -2000 AIRGAP FROM PACKAGE FACE IN INCHES Dwg. GH-035 2000 1000 -1000 -1500 0.025 0.050 0.100 0.125 1500 0.075 -500 500 DIFFERENTIAL FLUX DENSITY IN GAUSS 0.070 -200 AIRGAP FROM PACKAGE FACE IN INCHES Dwg. GH-036 200 100 -100 -150 0.080 0.090 0.110 0.120 150 0.100 -50 DIFFERENTIAL FLUX DENSITY IN GAUSS SENSOR LOCATIONS (±0.005” [0.13 mm] die placement)

3046, 3056, AND 3058 HALL EFFECT GEAR-TOOTH SENSORS –ZERO SPEED Worcester, Massachusetts 01615-0036 (508) 853-5000 NOTES:1. Tolerances on package height and width represent allowable mold offsets. Dimensions given are measured at the widest point (parting line). 2. Exact body and lead configuration at vendor ’s option within limits shown. 3. Height does not include mold gate flash. 4. Recommended minimum PWB hole diameter to clear transition area is 0.035 ” (0.89 mm). 5. Where no tolerance is specified, dimension is nominal. 6. Minimum lead length was 0.500 ” (12.70 mm). If existing product to the original specifications is not acceptable, contact sales office before ordering. Dwg. MH-003E in 0.063 0.059 0.018 0.0173 0.0138 0.0189 0.0142 0.050 1 2 3 0.100 45° SEE NOTE 0.183 0.178 0.181 0.176 0.600 0.560 0.086 MAX Dwg. MH-003E mm 1.60 1.50 0.46 0.44 0.35 0.48 0.36 1.27 1 2 3 2.54 45° SEE NOTE 4.65 4.52 4.60 4.47 15.24 14.23 2.18 MAX Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only) 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; 5,686,894; 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 appliances, devices, or systems without express written approval. The information included herein is believed to be accurate and reliable. However, Allegro MicroSystems, Inc. assumes no responsi- bility for its use; nor for any infringements of patents or other rights of third parties that may result from its use.