The A3187LUA-T is a unipolar Hall-effect switch from Allegro MicroSystems, LLC. These switches are activated by a south pole magnetic field of sufficient strength. When the magnetic field is removed or is below the release point, the switch turns off. The -T suffix generally indicates tape and reel packaging.

Applications

• Brushless DC (BLDC) motor commutation: Provides position feedback for motor control systems.
• Position sensing: Detects the presence or absence of a magnetic field for position indication.
• Simple on/off switching: Can be used as a magnetic proximity switch in various applications.
• Door/lid detection: Used to sense the opening or closing of doors and lids.
• Flow meters: Senses rotation of a magnetic component to measure flow rate.

Features

• Unipolar Hall-effect switch: Requires a south magnetic pole to activate.
• Low voltage operation: Operates from a low supply voltage, suitable for battery-powered applications.
• Small package size: LUA package for space-constrained applications.
• High sensitivity: Detects weak magnetic fields.
• Solid-state reliability: Contactless switching for long operational life.

Benefits

• Simple to use: Easy to integrate into existing circuits.
• Reliable operation: Provides consistent and dependable switching performance.
• Long life: Solid-state design eliminates mechanical wear.
• Cost-effective: Offers a competitive price for magnetic sensing applications.
• Space-saving: Small package allows for compact designs.

Additional Details

The A3187LUA-T's key specifications are its operate point (Bop) and release point (Brp), which define the magnetic field strengths at which the switch turns on and off, respectively. Hysteresis, the difference between Bop and Brp, ensures clean switching behavior. The output is typically an open-collector or open-drain configuration, requiring a pull-up resistor.

The datasheet provides guidance on selecting the appropriate pull-up resistor value. Proper bypass capacitors are crucial for stable operation. The device is sensitive to electrostatic discharge (ESD), so precautions are necessary during handling and assembly. The A3187LUA-T provides an effective solution for basic magnetic sensing applications where a south pole activation is needed. Exceeding the absolute maximum ratings can cause permanent damage.