Hall Effect Sensor

The Sensor Science

Hall Effect Sensors are stimulated by an external magnetic field. The output signal (Hall voltage) from the Hall effect sensor is proportional to the proximity of the magnet (flux density or magnetic strength). The Hall voltage output by the sensor is only a few microvolts, so it is typically amplified and sometimes compensated for linearity and hysteresis.

Types of Hall Effect Sensors

The net output from a Hall sensor is either designed to be analog (variable output), or digital (on/off switch). Analog Hall effect sensors have a saturation point at which no additional output will be realized for any increase in the magnetic field. Digital sensors have a particular flux density magnitude that will clearly distinguish between the on/off (switch) condition. Digital Hall effect sensors can be either bipolar or unipolar. Bipolar digital Hall effect sensors require a positive magnetic field (south pole) to change their state to on, and a negative magnetic field (north pole) to reverse the state to off. Unipolar digital Hall effect sensors only require a positive magnetic field (south pole) to change their state to on.

Hall Effect Sensor Detection

For the maximum sensor sensitivity, the magnetic lines of flux must be perpendicular to the sensing area of the sensor (and of the correct polarity). The most common path of motion relative to the Hall effect sensor is Head-on Detection and Sideways Detection.

Hall effect sensors are typically optimized for either switching applications, or analog output. A ratiometric hall effect sensor outputs an analog voltage proportional to the magnetic field intensity.

Products - Switching Applications

US5881

5V supply voltage (3.5 V minimum) @ 2.5 mA (5 mA max). Output 0.0 to 0.4 V output range. Adafruit product ID 158 Mouser P/N 482-5881LUAAAA000BU Another variant of the US5881 is Mouser #482-5881LUAAAA000BU

US5881 Application Circuit

The above circuit uses a TLV2462 Op Amp to amplify the US5881LUA hall effect sensor output from 0.022 V to 0.5 V (0.4 V range) to 1.2 to 3.3 V (2.1 V delta) range. If the TLV2462 Op Amp is powered by 5.0 V, then the output is 1.6 to 5.0 V (3.4 V delta) range.

Products - Analog Output Applications

Ratiometric hall effect sensors output an analog voltage proportional to the magnetic field intensity.

DRV5055-Q1

Mouser P/N 595-DRV5055A4ELPGMQ1

This is a radiometric linear hall effect sensor with a magnetic sensitivity of 12.5 mV/mT, or ±169-mT Range. It accepts a input voltage of 3.5 and 5.0 V (3.3 V or 5.0 recommended). The analog output voltage is in proportion to the input voltage (Vcc). This specific sensor is optimized for head-on detection, and provides a decrease in output from Vcc/2 in response to a magnet's north pole, and in increase in voltage from Vcc/2 as a magnet's south pole approaches.