SENSORS:Honeywell’s two new Hall-effect digital position sensors - the SS345PT and SS445P Unipolar Hall-effect Digital Position Sensors - reduce total system cost for customers by having built-in pull-up resistors, eliminating the need for customers to purchase an external pull-up resistor.
As unipolar devices, the new sensors respond to either a North pole or a South pole, depending upon the sensor. The SS345PT responds to a single North pole; the SS445P responds to a single South pole. The open collector output with built-in pull-up resistor easily interfaces with common electronic circuits.
Honeywell has also downsized the sensor’s integrated circuit, saving on manufacturing costs while still meeting customer requirements. These manufacturing cost savings result in lower costs to customers. The low 2.7V dc to 7V dc low supply voltage range allows for use in a variety of applications.
The SS345PT’s subminiature SOT-23 surface mount package uses less space on the printed circuit board than standard Hall-effect sensor packages such as TO-92 or SOT-89, allowing for use in smaller assemblies. Additionally, the SS345PT is supplied on tape and reel, allowing for automated, lower-cost pick and place assembly which can help reduce manufacturing costs. The SS445P’s leaded, flat TO-92 package is available in bulk packaging (1000 units per bag).
These small, versatile Hall-effect devices are operated by the magnetic field from a permanent magnet or an electromagnet. Both sensors feature enhanced sensitivity which allows for the use of smaller, often less expensive magnets.
Designed for high-volume, cost-sensitive position and motion sensing applications, the SS345PT and SS445P may be used in commercial, industrial, and medical applications. Potential commercial applications include door or lid closure detection in appliances, speed and RPM sensing in fitness equipment, flow rate sensing in appliances and water softeners, damper or valve position control in HVAC equipment, and printer head position sensing. Potential industrial applications include flow rate sensing in industrial processes, robot control (cylinder position monitoring), and float-based fluid level sensing. Potential medical applications include displacement sensing in hospital beds and medical equipment, and medication bin monitors on portable drug carts.