MH281 Low Sensitivity Unipolar Hall Effect Switch

MH281 Low Sensitivity Unipolar Hall Effect Switch is a high-reliability integrated circuit designed for magnetic sensing applications that require a specific magnetic threshold to prevent false triggering. This sensor employs advanced chopper-stabilization technology. Consequently, the device provides excellent temperature stability and high immunity to physical stress. The MH281 operates as a unipolar switch, meaning it responds only to a single magnetic pole (typically the South pole) while remaining inactive in the absence of a strong enough magnetic field. Furthermore, the low sensitivity characteristic ensures the sensor only activates when the magnet is in close proximity. Therefore, engineers frequently select this component for precise position sensing and speed detection in industrial and consumer electronics where magnetic interference might otherwise cause issues.

Key Features:

• Unipolar Response: The sensor activates in the presence of a sufficiently strong South magnetic pole and deactivates when the field is removed.
• Low Sensitivity: Designed with a higher magnetic operating point (Bop) to ensure the device ignores weak stray magnetic fields.
• Chopper-Stabilized Design: This feature minimizes output offset voltage and provides superior stability across a wide temperature range.
• Open-Drain Output: The CMOS output structure allows for easy interfacing with various logic levels through the use of an external pull-up resistor.
• Wide Operating Voltage: Supports a broad supply range, making it compatible with both battery-operated devices and regulated industrial power rails.

Technical Specifications:

• Supply Voltage (V_DD): 2.5 V to 24 V
• Operating Point (B_OP): 100 G to 250 G (Typical range for low sensitivity)
• Release Point (B_RP): 80 G to 230 G
• Hysteresis (B_HYS): ≈ 20 G
• Output Current (I_OUT): 25 mA maximum
• Supply Current (I_DD): ≈ 2.5 mA to 5 mA
• Operating Temperature: −40°C to +125°C

Mechanical Specifications:

• Package Type: TO-92S (Through-Hole) or SOT-23 (Surface Mount)
• Material: Molded Plastic Case
• Lead Finish: Tin Plated (RoHS Compliant)
• Magnetic Sensitivity Direction: Parallel to the branded face of the package.

Dimensions:

• Package Height: ≈ 3.0 mm (TO-92S body)
• Package Width: ≈ 4.0 mm
• Lead Length: ≈ 14.5 mm (Standard through-hole)
• Thickness: ≈ 1.5 mm

Pinout and Wiring:

• Pin 1 (V_DD): Connect to the positive DC power supply (2.5 V to 24 V).
• Pin 2 (GND): Connect to the circuit common ground.
• Pin 3 (OUT): Connect to the digital input of a microcontroller or logic circuit. However, you must include a pull-up resistor (typically 10 kΩ) between Pin 3 and V_DD.

Datasheet Reference:

• Download MH281 Hall Effect Switch Datasheet

Commonly Used in:

• Brushless DC (BLDC) Motors: Used to detect rotor position and facilitate electronic commutation.
• Automotive Systems: Integrated into seatbelt buckles and door lock mechanisms for status detection.
• Consumer Appliances: Found in washing machines and blenders to verify lid closure or speed.

Applications:

• Proximity Switching: Acts as a non-contact switch for security alarms or limit switches.
• Speed Sensing: Operates in conjunction with a rotating magnet to count revolutions per minute (RPM).
• Flow Metering: Monitors the rotation of an internal paddle wheel to measure liquid flow rates.

Equivalent Models:

• Honeywell SS441A: A unipolar Hall effect sensor with similar voltage ratings and standard sensitivity.
• Allegro A1104: A continuous-time unipolar switch often used as a functional alternative in automotive designs.
• Melexis US1881: Note that this is a latch-type sensor; nevertheless, it is often discussed alongside the MH281 for magnetic sensing.

Package Includes:

• 1 x MH281 Low Sensitivity Unipolar Hall Effect Switch