DIRECTION-DETECTION SENSORS

3422 PRELIMINARY INFORMATION (subject to change without notice) Februaryt 21, 2003 HALL-EFFECT, DIRECTION-DETECTION SENSORS The A3422xKA Hall-effect, direction-detection sensor is a new generation of special-function integrated sensors that is capable of sensing the direction of rotation of a ring magnet. This transducer provides separate digital outputs that provide information on magnet rotation speed, direction, and magnet pole count. This device eliminates the major manufacturing hurdles encountered in fine-pitch direction-detection applications, namely maintaining accurate mechanical location between the two active Hall elements. Here, the two Hall elements are photolithographically aligned to better than 1 µm, as contrasted with 100 µm or worse mechanical location tolerance when manufactured discretely. This highly sensitive, temperature-stable, magnetic transducer is ideal for use in digital-encoder systems in the harsh environments of automotive or industrial applications. The A3422xKA is a high-sensitivity device optimized for use with highdensity magnets. The A3422xKA monolithic integrated circuit contains two indepenwww.DataSheet4U.com dent Hall-effect latches whose digital outputs are internally coupled to CMOS logic circuitry that decodes signal speed and direction. Extremely low-drift BiCMOS circuitry is used for the amplifiers to ensure symmetry between the two latches so that signal quadrature can be maintained. An on-chip voltage regulator allows the use of this device from a 4.5 V to 18 V supply. The outputs are standard open-collector outputs. Two operating temperature ranges are provided; suffix ‘E–’ is for the automotive and industrial temperature range of -40°C to +85°C, suffix ‘L–’ is for the automotive and military temperature range of -40°C to +150°C. The 5-pin ‘KA’ SIP package provides a costcompetitive solution to magnetic sensing in harsh environments. Data Sheet 27650.1A* E1 E2 X X LOGIC VCC 1 2 3 4 5 DIRECTION GROUND E1 OUTPUT SUPPLY Dwg. PH-015 Pinning is shown viewed from branded side. ABSOLUTE MAXIMUM RATINGS Supply Voltage, VCC . . . . . . . . . . . . . 18 V Magnetic Flux Density, B . . . . Unlimited Output OFF Voltage, VOUT . . . . . . . . VCC Output Sink Current, IOUT . . . . . . . 30 mA Package Power Dissipation, PD . . . . . . . . . . . . . . . . . . . . . . 500 mW Operating Temperature Range, TA Suffix ‘E–’ . . . . . . . . . -40˚C to +85˚C Suffix ‘L–’ . . . . . . . . -40˚C to +150˚C Storage Temperature Range, TS . . . . . . . . . . . . . . . -65˚C to +170˚C SPEED FEATURES s s s s Internal Direction-Decoding Circuitry Two Matched Hall Latches On A Single Substrate Superior Temperature Stability 4.5 V to 18 V Operation Electrically Defined Power-On State Under-Voltage Lockout Always order by complete part number: the prefix ‘A’ + the basic fourdigit part number + a suffix to indicate operating temperature range + a suffix to indicate package style, e.g., A3422EKA . 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR FUNCTIONAL BLOCK DIAGRAM 1 SUPPLY 2 DIRECTION UVLO REG LOGIC POWER-ON LOGIC 3 GROUND 4 E1 OUTPUT E2 X E1 X 5 SPEED Dwg. FH-018 TIMING DIAGRAM CHANGE IN DIRECTION td DIRECTION Dwg. WH-012A +B 0 BOP1 BRP1 -B +B 0 BRP2 -B BOP2 OUT E1 OUT E2 (INTERNAL) SPEED (OUT E1 XOR OUT E2) 2 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 Copyright © 2001, 2003 Allegro MicroSystems, Inc. 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR ELECTRICAL CHARACTERISTICS over operating temperature range. Limits Characteristic Supply Voltage Range Output Leakage Current Output Saturation Voltage Power-On State Under-Voltage Lockout Under-Voltage Hysteresis Power-On Time Output Rise Time Output Fall Time Direction Change Delay Supply Current Symbol VCC IOFF VOUT(SAT) POS VCC(UV) VCC(hys) tpo tr tf td ICC Test Conditions Operating, TJ < 165°C1 VOUT = VCC = 18 V IOUT = 20 mA VCC = 0 → 5 V, BRP1 < B < BOP1, BRP2 < B < BOP2 IOUT = 20 mA, VCC = 0 → 5 V Lockout (VCC(UV)) - Shutdown VCC > 4.5 V CL = 20 pF, RL = 820 Ω CL = 20 pF, RL = 820 Ω CL = 20 pF, RL = 820 Ω VCC = 8 V, All outputs OFF Min. 4.5 — — OFF — — — — — 0.5 5.0 Typ. — <1.0 0.21 OFF 3.5 0.5 — 200 200 1.0 9.0 Max. 18 10 0.50 OFF — — 50 — — 5.0 18 Units V µA V — V V µs ns ns µs mA NOTES:1. Maximum supply voltage must be adjusted for power dissipation and ambient temperature. 2. Typical Data is at VCC = 12 V and TA = +25°C and is for design information only. ALLOWABLE PACKAGE POWER DISSIPATION IN WATTS 0.6 0.5 0.4 0.3 RθJA = 164°C/W 0.2 0.1 0 25 50 75 100 125 TEMPERATURE IN ° C 150 175 Dwg. GH-069 www.allegromicro.com 3 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR MAGNETIC CHARACTERISTICS over operating voltage range. Limits Characteristic Operate Point Symbol BOP Test Conditions TA = -40°C TA = +25°C TA = Maximum Release Point3 BRP TA = -40°C TA = +25°C TA = Maximum Hysteresis Bhys TA = -40°C TA = +25°C TA = Maximum Operate Differential Release Differential — — BOP1 - BOP2 BRP1 - BRP2 Min. — — — -85 -75 -75 10 10 10 — — Typ. — 29 — — -17 — — 46 — — — Max. 85 75 75 — — — — — — ±60 ±60 Units G G G G G G G G G G G NOTES:1. Magnetic flux density is measured at most sensitive area of device, nominally located 0.0165” (0.42 mm) below the branded face of the package. 2. Typical Data is at VCC = 12 V and TA = +25°C and is for design information only. 3. As used here, negative flux densities are defined as less than zero (algebraic convention). Typical Magnetic Characteristics 50 40 30 OPERATE POINT 100 80 V =8V CC SWITCH POINTS IN GAUSS HYSTERESIS IN GAUSS 20 10 0 -10 RELEASE POINT -20 -30 -40 -50 -50 -25 0 25 50 75 100 125 150 V =8V CC 60 40 20 0 -50 -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE IN °C AMBIENT TEMPERATURE IN ° C Dwg. GH-026-1 Dwg. GH-051-1 4 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR Typical Electrical Characteristics 300 10 250 I OUT = 20 mA V =8V CC 9.0 SATURATION VOLTAGE IN mV 200 SUPPLY CURRENT IN mA ALL OUTPUTS ON 150 8.0 100 ALL OUTPUTS OFF 7.0 50 0 -50 -25 0 25 50 75 100 125 150 6.0 -50 -25 0 25 50 75 100 125 150 AMBIENT TEMPERATURE IN ° C Dwg. GH-029-2 AMBIENT TEMPERATURE IN ° C Dwg. GH-053-1 13 12 T = 25°C A 11 SUPPLY CURRENT IN mA 10 ALL OUTPUTS ON 9.0 8.0 ALL OUTPUTS OFF 7.0 6.0 5.0 2.0 6.0 10 14 18 SUPPLY VOLTAGE IN VOLTS Dwg. GH-058-3 www.allegromicro.com 5 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR Functional Description The integrated circuit contains an internal voltage regulator that powers the Hall sensors and both the analog and digital circuitry. This regulator allows operation over a wide supply voltage range and provides some immunity to supply noise. The device also contains CMOS logic circuitry that decodes the direction of rotation of the ring magnet. Quadrature/Direction Detection. Internal logic circuitry provides outputs representing speed and direction of the magnetic field across the face of the package. For the direction signal to be appropriately updated, a quadrature relationship must be maintained between the ring magnet pole width*, the sensor-tosensor spacing, and, to a lesser extent, the magnetic switch points. For optimal design, the sensor should be actuated with a ring magnet pole width* two times the sensor-to-sensor spacing. This will produce a sinusoidal magnetic field whose period (denoted as Τ) is then four times the sensor-to-sensor spacing. A quadrature relationship can also be maintained for a ring magnet that has a period that satisfies the relationship nΤ/4 = 1.5 mm, where n is any odd integer. Therefore, ring magnets with pole-pair spacings equal to 6 mm (n = 1), 2 mm (n = 3), 1.2 mm (n = 5), etc. are permitted. The response of the device to the magnetic field produced by a rotating ring magnet is shown on page 2. Note the phase shift between the two integrated sensors. Outputs. The device provides three saturated outputs: DIRECTION, E1 OUTPUT, and SPEED. DIRECTION provides the direction output of the sensor and is defined as OFF (high) for the direction E1 to E2 and ON (low) for the direction E2 to E1. SPEED provides an XOR’d output of the two sensors. Because of internal delays, DIRECTION will always be updated before SPEED and is updated at every transition of E1 OUTPUT and E2 OUTPUT (internal) allowing the use of up-down counters without the loss of pulses. Power-On State. At power on, the logic circutry is reset to provide an OFF (high) at DIRECTION and an OFF (high) for E1 and E2 (internal) for magnetic fields less than BOP. This eliminates ambiguity when the device is powered up and either sensor detects a field between BOP and BRP. If either sensor is subjected to a field greater than BOP, the internal logic will set accordingly. *“Pole” refers to a single pole (North or South) unless stated as “pole pair” (North and South). 6 115 Northeast Cutoff, Box 15036 Worcester, Massachusetts 01615-0036 (508) 853-5000 3422 HALL-EFFECT, DIRECTION-DETECTION SENSOR Applications Information Operation with Fine-Pitch Ring Magnets. For targets with a circular pitch of less than 4mm, a performance improvement can be observed by rotating the front face of the sensor subassembly (see below). This sensor rotation decreases the effective sensor-to-sensor spacing, provided that the Hall elements are not rotated beyond the width of the target. Applications. It is strongly recommended that an external 0.01 µF bypass capacitor be connected (in close proximity to the Hall sensor) between the supply and ground of the device to reduce both external noise and noise generated by the internal logic. The simplest form of magnet that will operate these devices is a ring magnet. Other methods of operation, such as lin