NOT RECOMMENDED FOR NEW DESIGN USE AH3781 AH921 HIGH SENSITIVITY CMOS HALL-EFFECT LATCH Description Pin Assignments The AH921 is a Hall-effect latch designed in mixed signal CMOS (Front View) technology. It is quite suitable for use in automotive, industrial and consumer applications. 3 OUT Superior high-temperature performance is made possible through 2 GND dynamic offset cancellation, which reduces the residual offset voltage 1 VCC normally caused by device over-molding, temperature dependencies, and thermal stress. The device integrates a voltage regulator, Hall- voltage generator, small-signal amplifier, chopper stabilization, TO-92S-3 schmitt trigger, and is directly drivable by the output. An on-board regulator permits operation with supply voltage from (Top View) 3.5V to 24V. GND The AH921 is available in TO-92S-3 and SOT-23-3 packages, which 3 are optimized for most applications. 1 2 Features VCC OUT Wide Operating Voltage Range from 3.5V to 24V Symmetrical Switch Points SOT-23-3 Chopper-stabilized Amplifier Stage Superior Temperature Stability Compact Size Applications Built-in Pull-up Resistor Brushless DC Motor Commutation Wide Operating Temperature Range: -40C to +125C Brushless DC Fan ESD Rating: 3500V (Human Body Model) Solid-state Switch Totally Lead-free & Fully RoHS Compliant (Note 1 & 2) Revolution Counting Halogen and Antimony Free. Green Device (Note 3) Speed Detection High Sensitivity and Unconnected Switch Notes: 1. No purposely added lead. Fully EU Directive 2002/95/EC (RoHS) & 2011/65/EU (RoHS 2) compliant. 2. See NOT RECOMMENDED FOR NEW DESIGN AH921 USE AH3781 Pin Descriptions Pin Number Pin Name Function TO-92S-3 SOT-23-3 1 1 VCC Supply voltage 2 3 GND Ground pin 3 2 OUT Output Pin Functional Block Diagram VCC OUT 1 (1) 3 (2) 100k W Reference Voltage Chopper AMP Switch Hall Sense 2 (3) GND A (B) A for TO-92S-3 B for SOT-23-3 2 of 14 AH921 June 2017 Diodes Incorporated www.diodes.com Document number: DS37028 Rev. 3 -3