Omnipolar, Hall-effect Digital Position Sensor

Part Number Information
Part #: Price/Availability:
SS551AT Buy Now

The SS551AT sensors are small, versatile digital Hall-effect devices that are operated by the magnetic field from a permanent magnet or an electromagnet. They are designed to respond to a either a North pole or a South pole.

These omnipolar sensors are sensitive and flexible devices designed to meet a wide range of potential applications. The SS551AT have a typical operating point of 85 G at 25 °C [77 °F]. 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 the system cost.

The SS551AT is supplied in the SOT-89B surface-mount package and is available on tape and reel (1000 units per reel).


  • Simple activation from a North pole or a South pole and sensitive magnetics make this omnipolar product suitable in a variety of potential motion control, lid closure detection, and displacement sensing applications
  • Low voltage 3 Vdc capability helps reduce power consumption
  • Built-in reverse polarity protection protects the device from potential damage during installation
  • Thermally balanced integrated circuit provides for stable operation over a wide temperature range of -40° to 150 °C [-40 °F to 302 °F]
  • RoHS-compliant materials meet Directive 2002/95/EC


  • Commercial:
    • Speed and RPM (revolutions per minute) sensing in fitness equipment
    • Magnetic encoder for building access
    • Damper or valve position control in HVAC (heating, ventilation and air conditioning) equipment
    • Flow rate sensing in appliances and water softeners
    • Printer head position sensing
  • Industrial:
    • Flow rate sensing in industrial processes
    • Robotic control (cylinder position monitoring)
    • Float-based fluid level sensing
  • Medical:
    • Displacement sensor in hospital beds and medical equipment
    • Medication bin monitor on portable drug carts