A1642 Two-Wire True Zero-Speed Miniature Differential Peak-Detecting Sensor with Continuous Calibration Features and Benefits Description Running mode calibration for continuous optimization The A1642 is an optimized Hall effect sensing integrated Single chip IC for high reliability circuit that provides a user-friendly solution for true zero-speed Internal current regulator for 2-wire operation digital ring-magnet sensing in two-wire applications. This small Precise duty cycle signal over operating temperature range package can be easily assembled and used in conjunction with Large operating air gaps a wide variety of target shapes and sizes. Automatic Gain Control (AGC) for air gap independent The integrated circuit incorporates a dual-element Hall effect switchpoints sensor and signal processing that switches in response to Automatic Offset Adjustment (AOA) for signal processing differential magnetic signals created by ring magnet poles. optimization The circuitry contains a sophisticated digital circuit to reduce True zero-speed operation system offsets, to calibrate the gain for air-gapindependent Undervoltage lockout switchpoints, and to achieve true zero-speed operation. Signal Wide operating voltage range optimization occurs at power-on through the combination of offset and gain adjust and is maintained throughout the operating time with the use of a running-mode calibration. The Package: 4-pin SIP (Suffix K) running-mode calibration allows immunity to environmental effects such as micro-oscillations of the target or sudden air gap changes. The regulated current output is configured for two-wire applications and the sensor is ideally suited for obtaining speed and duty cycle information in ABS (antilock braking systems). The 1.5 mm spacing between the dual Hall elements is optimized for fine pitch ring-magnet-based configurations. For applications requiring sensing of rotating ferrous gears and targets, refer to the Allegro ATS series of products. The package is lead (Pb) free, with 100% matte tin leadframe plating. Not to scale Functional Block Diagram Hall VCC Gain Amplifier Automatic Offset AOA DAC AGC DAC Internal Regulator Control Gain Control Tracking Peak Hold DAC GND Test Test Signals A1642LK-DS, Rev.1Two-Wire True Zero-Speed Miniature Differential A1642 Peak-Detecting Sensor with Continuous Calibration Selection Guide Part Number Package Packing* I Typical CC A1642LK-I1-T K, standard lead Bulk, 500 pieces/bag 6.0 Low to 14.0 High mA Tape and reel, 13-inch reel A1642LKTN-I1-T K, standard lead 4000 pieces/reel A1642LK-I2-T K, standard lead Bulk, 500 pieces/bag 7.0 Low to 14.0 High mA Tape and reel, 13-inch reel A1642LKTN-I2-T K, standard lead 4000 pieces/reel *Contact Allegro for additional packing options Absolute Maximum Ratings Characteristic Symbol Notes Rating Units Supply Voltage V 28 V CC Reverse Supply Voltage V 18 V RCC Operating Ambient Temperature T Range L 40 to 150 C A Maximum Junction Temperature T (max) 165 C J Storage Temperature T 65 to 170 C stg Pin-out Diagram Terminal List Table Number Name Function 1 VCC Connects power supply to chip 2 NC No connection 1234 3 Test Float or tie to GND 4 GND Ground connection Allegro MicroSystems, Inc. 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com