The HAL^® 401 is a Linear Hall Effect Sensors produced in CMOS technology. The sensor includes a temperaturecompensated Hall plate with choppered offset compensation, two linear output stages, and protection devices.

The output voltage is proportional to the magnetic flux density through the hall plate. The choppered offset compensation leads to stable magnetic characteristics over supply voltage and temperature.

The HAL 401 can be used for magnetic field measurements, current measurements, and detection of any mechanical movement. Very accurate angle measurements or distance measurements can also be done. The sensor is very robust and can be used in electrical and mechanical hostile environments.

The sensor is designed for industrial and automotive applications and operates in the ambient temperature range from –40 °C up to 150 °C and is available in the SMD-package SOT89B-1.

System Architecture

The Linear Hall Sensor measures constant and low frequency magnetic flux densities accurately. The differential output voltage V_OUTDIF (difference of the voltages on pin 2 and pin 3) is proportional to the magnetic flux density passing vertically through the sensitive area of the chip. The common mode voltage V_CM (average of the voltages on pin 2 and pin 3) of the differential output amplifier is a constant 2.2 V.

The differential output voltage consists of two components due to the switching offset compensation technique. The average of the differential output voltage represents the magnetic flux density. This component is overlaid by a differential AC signal at a typical frequency of 147 kHz. The AC signal represents the internal offset voltages of amplifiers and hall plates that are influenced by mechanical stress and temperature cycling.

Block diagram of the HAL 401 (top view)

Main Features