Honeywell Sensing and Control SS351AT and SS451A Omnipolar Hall-Effect Digital Position Sensors

Honeywell has expanded its Hall-effect sensor portfolio with the new SS351AT Series and SS451A Series Omnipolar Hall-effect Digital Position sensors that are designed to respond to either a North pole or a South pole. These products join the recently introduced SS311PT, SS411P, SS30AT, SS361RT, SS461R, SS340RT, and SS440R Series digital Hall-effect sensors that utilize a downsized integrated circuit, resulting in lower costs for customers.

The SS351AT and SS451A are small, versatile digital Hall-effect devices that are operated by the magnetic field from a permanent magnet or an electromagnet. They are designed for high-volume, cost-sensitive motion control, lid closure detection, and displacement sensing applications.

Two package styles:
  • SS351AT: Subminiature SOT-23 surface mount package; supplied on tape and reel (3000 units per reel)
  • SS451A: Small leaded, flat TO-92-style package; available in bulk package (1000 units per bag)

The new SS351AT and SS451A provide value by:

Price competitive: Honeywell has downsized the integrated circuit, saving on manufacturing costs while still meeting customer requirements; these savings result in lower costs to customers

Helps reduce total system cost: Because they can be operated by a North pole or a South pole, they do not require the magnet polarity to be identified, thus making the installation easier and potentially reducing system cost

Reduces manufacturing costs: SS351AT is supplied on tape and reel, often allowing for automated, lower-cost pick and place assembly which can help the customer reduce manufacturing costs

Subminiature size: SS351AT’s subminiature package size requires less printed circuit board (PCB) space, allowing for use in smaller assemblies

Promotes energy efficiency: Low 3 Vdc supply voltage capability allows for use in low voltage applications, promoting energy efficiency

Versatile: Omnipolar capability allows for use in a variety of potential applications, including motion control, lid closure detection, and displacement sensing

Prevents damage during installation: Built-in reverse polarity protects the device from potential damage during installation


  • Speed and RPM sensing in fitness equipment
  • Magnetic encoder for building access
  • Damper or valve position control in HVAC equipment
  • Flow rate sensing in appliances and water softeners
  • Printer head position sensing

  • Flow rate sensing in industrial processes
  • Robotic control (cylinder position monitoring)
  • Float-based fluid level sensing

  • Displacement sensor in hospital beds and medical equipment
  • Medication bin monitor on portable drug carts