A3064

A3064 ALLEGRO

Document overview

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Technical content

The A3064LKA ac-coupled Hall-effect gear-tooth sensor is a monolithic integrated circuit that switches in response to changing differential magnetic fields created by moving ferrous targets. This device is ideal for use in non-zero-speed, gear-tooth-based speed, position, and timing applications such as in anti-lock braking systems, transmissions, and crankshafts. When coupled with a back-biasing magnet, the sensor 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. This differential sensing design provides immunity to radial vibration within the device’s operating air gap. Steady-state magnet and system offsets are eliminated using an on-chip differential band-pass filter. This filter also provides relative immunity to interference from RF and electro- magnetic sources. The on-chip temperature compensation and Schmitt trigger circuitry minimizes shifts in effective working air gaps and switch points over temperature, allowing operation to low frequencies over a wide range of air gaps and temperatures. Each Hall-effect digital Integrated circuit includes a voltage regulator, two quadratic Hall-effect sensing elements, temperature compensating circuitry, a low-level amplifier, band-pass filter, 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 easily switch 20 mA over the full frequency response range of the sensor and is compatible with bipolar and MOS logic circuits. The device is packaged in a 5-pin plastic SIP.

FEATURES

I Senses Motion of Ferrous Targets I Wide Operating Temperature Range I Operation to 30 kHz I Resistant to EMI I Large Effective Air Gap I 4.5 V to 24 V Operation I Output Compatible With All Logic Families I Reverse Battery Protection I Resistant to Physical Stress HALL-EFFECT GEAR-TOOTH SENSOR —AC COUPLED Always order by complete part number, e.g., A3064LKA . Data Sheet 27612.21 ABSOLUTE MAXIMUM RATINGS at TA = +25°C Package Power Dissipation, Operating Temperature Range, Storage Temperature Range, VCC 1 432 5 X X Dwg. PH-011-1 SUPPLY OUTPUT GROUND FILTER FILTER Pinning is shown viewed from branded side. 3064

—AC COUPLED

115 Northeast Cutoff, Box 15036

Worcester, Massachusetts 01615-0036 (508) 853-50002 MAGNETIC CHARACTERISTICS over operating temperature and supply voltage range. Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Operate Point B OP Output switches on to off 0 15 27.5 G Release Point B RP Output switches off to on -12.5 0 7.5 G Hysteresis B hys BOP - BRP 5.0 15 35 G FUNCTIONAL BLOCK DIAGRAM ELECTRICAL CHARACTERISTICS over operating temperature and supply voltage range. Limits Characteristic Symbol Test Conditions Min. Typ. Max. Units Supply Voltage V CC Operating 4.5 — 24 V Output Saturation Voltage V OUT(SAT) IOUT = 18 mA, B < BRP — 141 400 mV Output Leakage Current I OFF VOUT = 24 V, B > BOP — — 5.0 µA Supply Current I CC B < BRP —1 12 0m A B > BOP — 9.6 — mA High-Frequency Cutoff f coh -3 dB 30 — — kHz Output Rise time t r VOUT = 12 V, RL = 820 Ω — 0.04 0.2 µs Output Fall time t f VOUT = 12 V, RL = 820 Ω — 0.18 0.3 µs 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 convention). 3. Typical values are at T A = 25°C and VCC = 12 V. 4. 1 gauss (G) is exactly equal to 0.1 millitesla (mT). OUTPUT X X Dwg. FH-008-1 SUPPLY GROUND FILTER FILTER REG 4 5 Copyright © 2001 Allegro MicroSystems, Inc.

—AC COUPLED www.allegromicro.com 3 TYPICAL OPERATING CHARACTERISTICS SWITCH POINTS OUTPUT SATURATION VOLTAGE OPERATE POINT 0 50 100 AMBIENT TEMPERATURE IN °C -50 Dwg. GH-056-1 DIFFERENTIAL FLUX DENSITY IN GAUSS

0 RELEASE POINT

V = 12 V CC 150 -10 -25 25 75 125 200 150 100 Dwg. GH-055-2 SATURATION VOLTAGE IN mV SUPPLY VOLTAGE IN VOLTS 51 0 1 52 0 2 5 I = 18 mA T = +25°C OUT A 0 25 50 75 100 300 AMBIENT TEMPERATURE IN °C 200 100 -50 Dwg. GH-029-6 SATURATION VOLTAGE IN mV 150-25 125 I = 18 mA V = 12 V OUT CC

—AC COUPLED Worcester, Massachusetts 01615-0036 (508) 853-50004 TYPICAL OPERATING CHARACTERISTICS SUPPLY CURRENT The A3064LKA is a versatile high-precision differential sensing device that can be used in a wide range of applications. Careful choice of the sensor IC, target material and shape, magnet material and shape, and assembly techniques enables large working air gaps and high switch-point accuracy over the system operating temperature range. Magnet Biasing. 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 be used without a back-biasing magnet. For example, the sensor can be used to detect a rotating ring magnet such as those found in brushless dc motors or in speed sensing applications. Sensor Operation. These sensor ICs each contain two integrated Hall transducers (E1 and E2) that are used to sense a magnetic field differential across the face of the IC (see Sensor Location drawing). Referring to the Typical Transfer Charac- teristic (Figure 1), the trigger switches the output off (output high) when B E1 - BE2 > B OP and switches the output on (output APPLICATIONS INFORMATION SUPPLY CURRENT IN mA 0 2 55 07 51 0 0 AMBIENT TEMPERATURE IN °C -50 Dwg. GH-028-9 125-25 V = 24 VCC 150 B < B RP B > B OP OUTPUT VOLTAGE FLUX DENSITY Dwg. GH-007-6 CCV VOUT(SAT) OPBRPB Figure 1 TYPICAL TRANSFER CHARACTERISTIC SUPPLY CURRENT IN mA SUPPLY VOLTAGE IN VOLTS Dwg. GH-031-3 5 10 15 20 25 T = +25°CA B < BRP B > B OP SUPPLY CURRENT IN mA

—AC COUPLED Worcester, Massachusetts 01615-0036 (508) 853-50006 the teeth create transitions in the magnetic field that have a much higher frequency content than the basic rotational speed of the target. This allows the device to sense speeds much lower than those indicated by the graph for a given capacitor value. Capacitor Characteristics. The major requirement for the external capacitor is its ability to operate in a bipolar (non- polarized) mode. Another important requirement is the low leakage current of the capacitor (equivalent parallel resistance should be greater than 500 kΩ ). To maintain proper operation with frequency, capacitor values should be held to within ±30% over the operating temperature range. The commonly available Z5U ceramic capacitor temperature code should not be used in this application. Magnet Selection. The A3064LKA 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 air gaps 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 opera- tional air gaps can be expected. Neodymium iron boron (NeFeB) can be used over moderate temperature ranges when large working air gaps are required. Of these three magnet materials, AlNiCo 8 is the least expensive by volume and SmCo is the most expensive. Extensive applications information for Hall-effect sensors is available in:

• Hall-Effect IC Applications Guide, Application Note 27701;
• Hall-Effect Devices: Soldering, Gluing, Potting, Encapsulat- ing, and Lead Forming, Application Note 27703.1;
• Soldering of Through-Hole Hall-Sensor Dervices, Application Note 27703; and
• Soldering of Surface-Mount Hall-Sensor Devices, Application Note 27703.2. All are provided in Allegro Electronic Data Book, AMS-702. or at www.allegromicro.com APPLICATIONS INFORMATION (cont’d) Figure 4 SENSOR LOCATIONS (±0.005 [0.13 mm] die placement) A Dwg. MH-007E 0.0165" 0.42 mm NOM BRANDED SURFACE ACTIVE AREA DEPTH 0.087" 2.20 mm 12 4 5 3 E1 E2 0.083" 2.10 mm 0.075" 1.91 mm Allegro

—AC COUPLED www.allegromicro.com 7 CRITERIA FOR DEVICE QUALIFICATION Qualification Test Test Method and Test Conditions Test Length Samples Comments Biased Humidity (HAST) JESD22-A101, 2000 hrs 320 V CC = VOUT = 12 V RH = 85% 116 pcs at TA = 25°C 116 pcs at TA = 150°C High-Temperature JESD22-A108, 2000 hrs 146 V CC = VOUT = 12 V Operating Life (HTOL) T J ≤ 190°C 116 pcs at TA = 25°C 30 pcs at TA = 150°C Accelerated HTOL T A = 175°C, TJ ≤ 190°C 500 hrs 50 V CC = VOUT = 7.5 V Autoclave, Unbiased JESD22-A102, Condition C, 192 hrs 77 TA = 121°C at 15 psig Solder Heat 22 High-Temperature MIL-STD-883, Method 1008, 2000 hrs 77 (Bake) Storage Life T A = 170°C Temperature Cycle MIL-STD-883, Method 1010, 2000 cycles 153 (unbiased) +25 °C to +150°C ESD, MIL-STD-883, Method 3015 Pre/Post 3 per Test to failure, Human Body Model Reading test All leads > 2 kV All Allegro sensors are subjected to stringent qualification requirements prior to being released to production. To become qualified, except for the destructive ESD tests, no failures are permitted. 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.

—AC COUPLED Worcester, Massachusetts 01615-0036 (508) 853-50008 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. Supplied in bulk pack (500 pieces per bag). Surface-Mount Lead Form (order A3064LKA-TL) 2.41 ±0.13 0.51 MIN FLAT Dwg. MH-015 mm 0.10 MAX 0.051 MAX 0°–8° 0.095 ±0.005 0.020 MIN FLAT Dwg. MH-015 in 0.004 MAX 0.002 MAX 0°–8° Dwg. MH-010H in 0.018 0.0173 0.0138 0.0189 0.0142 0.050 BSC 13 4 5 2 0.063 0.059 45° 0.600 0.560 0.083 MAX 0.252 0.247 0.181 0.176 SEE NOTE Dimensions in Inches (controlling dimensions) Dimensions in Millimeters (for reference only) Dwg. MH-010H mm 0.46 0.44 0.35 0.48 0.36 1.27 BSC 13 4 5 2 1.60 1.50 45° 15.24 14.23 2.11 MAX 6.40 6.27 4.60 4.47 SEE NOTE