Allegro Packs Power, Voltage, and AC/DC Current Monitoring Into New Hall-Effect IC

January 11, 2021 by Jake Hertz

Many Hall-effect sensors specialize in one area of power monitoring—voltage, current, or power from either AC or DC signals. Allegro says its new IC monitors all of these metrics in one chip.

Engineers are continually searching for ways to decrease power consumption in edge devices. This trend is catalyzed, in part, by new IoT technologies demanding on-edge computing while also maintaining low power consumptions so that they can be portable and battery-powered. 

Along with developing new, lower power components, an important aspect of optimizing power consumption is to effectively monitor the device. One method of doing this is to use Hall-effect ICs. 


The Challenges of Hall-Effect Sensors

At its core, the Hall effect is concerned with the potential difference between two sides of a conducting material when exposed to a magnetic field


Visual depiction of the Hall effect

Visual depiction of the Hall effect. Image (modified) used courtesy of Melexis

The idea is that when undisturbed, electrons flow through a conductor in a mostly straight line. If that conductor is placed in a magnetic field, the electrons are deflected from their straight line by the Lorentz Force. This unequal spatial distribution of electrons causes a potential difference to develop in the conductor. In this way, the Hall effect can be used to measure current through a conductor. This Hall effect can also be exploited to measure voltages in a system

One of the challenges associated with using Hall-effect sensors is that they’re sometimes specialized. Some ICs work only to measure current, some only voltage, and some only AC or DC power. 

Comprehensive mixed-signal monitoring can be an issue since IoT devices often need the smallest footprint possible. Using multiple ICs to gain comprehensive monitoring takes up board real estate. Furthermore, multiple ICs will consume more power than a single IC, also negatively impacting IoT devices that require low power consumption. 


Allegro Aims for an All-in-One Power-Monitoring IC 

Allegro is one of the companies looking to address these issues, and it did so this week when the company announced its newest product, the ACS37800 Hall-effect power-monitoring IC. This device is said to simultaneously monitor power, voltage, and current for both AC and DC signals with isolation ratings up to 1480 Vpk. The aim of the new IC is to significantly reduce BOM and PCB footprint.


Functional block diagram of the ACS37800

Functional block diagram of the ACS37800. Image used courtesy of Allegro

The sensor can be powered by the same supply as the MCU, which removes the need for multiple power supplies and saves space on components and power rails. Finally, the sensor does not require external sense resistors or current transformers, as some ICs do.


The Goal to Save Board Space and Power 

Allegro says that its new IC is optimized for use cases such as IoT building automation, motor control, and power supplies. Applications such as smart lighting, smart appliances, and server/telecom power supplies may stand to benefit from the new IC as well.


Typical application of the ACS37800

Typical application of the ACS37800. Image used courtesy of Allegro

The ACS37800 may be useful to designers because it provides the ability to simultaneously monitor current, voltage, and power of both AC and DC signals. The result is less design complexity, less area, and less power consumption, the importance of which cannot be understated in IoT design.