A1688 Two-Wire, True Zero-Speed, High Accuracy Sensor IC FEATURES AND BENEFITS DESCRIPTION Integrated capacitor reduces need for external EMI The A1688 is a Hall-effect-based integrated circuit (IC) that protection components provides a user-friendly solution for true zero-speed digital Wide leads facilitate ease of assembly ring magnet and gear tooth sensing in two-wire applications. True zero-speed operation The A1688 is offered in the UB package, which integrates Automatic Gain Control (AGC) for air gap independent the IC and a high temperature ceramic capacitor in a single switchpoints overmolded SIP package. The integrated capacitor provides Automatic Offset Adjustment (AOA) for signal enhanced EMC performance with reduced external components. processing optimization The integrated circuit incorporates a dual-element Hall-effect Large operating air gap range circuit and signal processing that switches in response to Internal current regulator for two-wire operation differential magnetic signals created by magnetic encoders, or, Undervoltage lockout when properly backbiased with a magnet, from ferromagnetic Single chip sensing IC for high reliability targets. The device contains a sophisticated digital circuit that On-chip voltage regulator with wide operating voltage reduces magnet and system offsets, calibrates the gain for air range and stability in the presence of a variety of gap independent switchpoints, and provides true zero-speed complex load impedances operation. Fully synchronous digital logic with Scan and IDDQ testing Signal optimization occurs at power-up through the combination of offset and gain-adjust and is maintained throughout operation with the use of a running-mode calibration scheme. Running- mode calibration provides immunity from environmental effects Package: 2-pin SIP (suffix UB) such as micro-oscillations of the sensed target or sudden air gap changes. The regulated current output is configured for two-wire interface circuitry and is ideally suited for obtaining speed information in wheel speed applications. The Hall element spacing is optimized for high resolution, small diameter targets. The package is lead (Pb) free, with 100% matte-tin leadframe plating. Not to scale VCC Internal Regulator Analog to Digital Offset Output Amp AGC Digital Controller Adjust Control Converter GND Chopper Stabilization Functional Block Diagram A1688-DS, Rev. 6A1688 Two-Wire, True Zero-Speed, High Accuracy Sensor IC SPECIFICATIONS SELECTION GUIDE Part Number Packing* Power-On State A1688LUBTNLT 4000 pieces per 13-in. reel I CC(LOW) A1688LUBTNHT 4000 pieces per 13-in. reel I CC(HIGH) *Contact Allegro for additional packing options. ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Notes Rating Unit Supply Voltage V 28 V CC Reverse Supply Voltage V 18 V RCC Operating Ambient Temperature T L temperature range 40 to 150 C A Maximum Junction Temperature T (max) 165 C J Storage Temperature T 65 to 170 C stg Internal Discrete Capacitor Ratings Value Characteristic Symbol Test Conditions* Unit (Typ.) Nominal Capacitance C Connected between VCC and GND 2200 pF SUPPLY Terminal List Table Name Number Function 1 2 VCC 1 Supply Voltage GND 2 Ground UB Package, 2-Pin SIP Pinout Diagram Allegro MicroSystems, LLC 2 115 Northeast Cutoff Worcester, Massachusetts 01615-0036 U.S.A. 1.508.853.5000 www.allegromicro.com