Allegro Spins Out “Industry’s Smallest” Hall Effect Sensor IC for Sine/Cosine Output

January 13, 2022 by Jake Hertz

Hall effect sensors (HESs) can be a great option for position sensing. Hoping to push this technology forward, Allego is releasing a 3D Hall effect sensor IC for sine/cosine outputs.

Sensing has become a completely integral component of almost every electrical product today. 

Between applications like robotics, the Internet of Things (IoT), and industrial automation, interpreting information about the environment through onboard sensors is a crucial aspect of any electrical design.

One popular sensor type for position and angle sensing is the Hall effect sensor. 


An overview of a Hall-effect sensor circuit.

An overview of a Hall-effect sensor circuit. Image used courtesy of Microcontrollers Lab


This week, Allegro announced the release of its newest sine/cosine Hall effect sensor, which it claims to be the industry's smallest to date.

In this article, we'll talk about Hall effect sensors and the new release from Allegro.


Sine/Cosine Hall Effect Sensors

The Hall effect describes the potential difference that appears across a conductor when in the presence of a magnetic field. 

In electronics, engineers have exploited this phenomenon to perform distance and angle sensing of magnetic materials. 

If a magnet moves closer to a HES, the potential difference created across the conductor will become greater, and we can read this analog value to understand how far a magnetic material is away from the sensor.


HES on the end of a rotating shaft.

HES on the end of a rotating shaft. Screenshot used courtesy of Allegro [PDF]


When placed on the edge of a rotating device, a HES output will provide a sinusoidal output, tracking the location of the magnet as it rotates around the HES. 

This sine/cosine output then provides even more information to the engineer, as information about the magnet's distance from the sensor can be encoded in the relative phase shift between the output sinusoids.


A HES sine/cosine output can be interpolated to determine a magnet's relative angle.

A HES sine/cosine output can be interpolated to determine a magnet's relative angle. Screenshot used courtesy of ICHaus


Converting these sinusoids into quadrature signals allows us to interpret these values digitally, where we can accurately infer information about our device's position, distance, and angle relative to our sensor.

This behavior has made HES an essential and useful tool in various applications including, industrial automation, electric vehicles, and many more.


Allegro's A33230 Hall Effect Sensor IC

This week, Allegro announced the release of its newest sine/cosine HES, the A33230.

The new IC is a 3D HES, meaning that it can measure angles in any plane relative to the device (i.e., XY, XZ, or YZ). 

Generally speaking, the device integrates vertical and planar Hall effect elements orthogonally to one another, creating 90 degrees of separation between one another to cover all three axes. 

As outputs, the device also offers two independent sine/cosine outputs that allow the sensor to be used for angle sensing and distance sensing.


Functional block diagram of the A33230.

Functional block diagram of the A33230. Image used courtesy of Allegro [PDF]


Most notably, Allegro claims that the A33230 is the industry's smallest sine/cosine HES, coming in at roughly 2.95 mm x 2.9 mm x 1 mm footprint. 

Thanks to its size, Allegro hopes to have opened its sensor up to a new variety of applications in automotive and industrial such as factory robotics, windshield wipers, in-cabin motors, and more. 

Overall, Allegro hopes that its new sensor will allow designers the ability to minimize PCB area while also decreasing weight, cost, and bill of materials (BOM).



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