Allegro’s Latest Hall Effect Current Sensor Requires no Shield or Core

The ACS37610 delivers a typical accuracy of 1%, and is the second in a series, along with the ACS37612, to exploit differential Hall-based sensing to protect against stray magnetic fields. With no need for a u-shaped magnetic shield or for a core, weight, space and costs are all reduced. 

 

The ACS37610. Image courtesy of Allegro

 

What is the Hall Effect?

When electric current traverses a conductor and there is a magnetic field applied perpendicular to current flow, the result of the Hall effect is that the positive and negative charge carriers migrate towards the edges of the conductor. This produces a voltage difference between the two edges of the sensor that is readily measured. That voltage difference is a function of the applied magnetic field.

 

The Hall Effect. Image courtesy of the Optical Society

 

In the case of Hall effect current sensors, that magnetic field is produced by the current traversing through the busbar or PCB trace whose current load is being measured. The voltage generated by the Hall effect is a function of that magnetic field, which, as explained, is itself dependent on the current being measured.

Thus, flowing current can be measured with no direct electrical connection, which of course, translates into very high electrical isolation.

 

Stray Magnetic Fields

Stray magnetic fields can be the nemesis of Hall effect sensors. But, as per Shaun Milano, Director of Current Sensors at Allegro. “Our differential Hall-based sensors provide excellent immunity to stray magnetic fields without the need of a shield, required by competing solutions, that slows down response and adds non-linearity error into the system.” He also stated that, “As a leading innovator in current sensing solutions for more than 20 years, Allegro was first to market with coreless differential Hall-effect current sensing technology, and our new ACS37610 IC enables our customers to accurately measure hundreds or thousands of amps in a very economical and simple way.

 

Features of the ACS37610

The 2.5 mm separation between the two differential Hall elements not only eliminates errors due to common mode stray magnetic fields, but also enables the ACS37610 to provide improved resolution and improved SNR performance. 

The unit is programmable, and features a 250 kHz bandwidth and it sports a dedicated over temperature and overcurrent fault pin. Response time is under 2µs.

 

Notching

When measuring current across a busbar as illustrated on the right side of the image below, a small notch, while not mandatory, will provide further improvements to the overall SNR. 

Current passing through PCB and busbar. Image courtesy of ACS37610 datasheet

 

The ACS37610’s larger Hall element spacing (2.5 mm compared to 1.8 mm for the ACS37612) will  accommodate a wider notch. This results in almost no hotspots or thermal performance degradation.

The sensor is mountable in either a horizontal or vertical orientation relative to the busbar. This results in greater flexibility for designers. 

 

Applications

• Power supply 
• Power distribution unit (PDU) 
• High voltage traction motor inverter
• 48 V / 12 V auxiliary inverter 
• Battery monitoring
• Overcurrent detection
• DC/DC converter
• Smart fuse 

 

Physical

• Operates over a -40 to +150°C temperature range

 

Regulatory

• AEC-Q100 Grade 0, automotive qualified 

 

Getting to Market Faster

In the product announcement, Allegro announces the availability of an evaluation kit for the ACS37610, but no further information is apparent at this time.

 

About Allegro MicroSystems

Allegro MicroSystems, LLC is a leader in developing, manufacturing and marketing high-performance semiconductors. Allegro’s innovative solutions serve high-growth applications within the automotive market, with additional focus on office automation, industrial, and consumer/communications solutions. Allegro is headquartered in Worcester, Massachusetts (USA) with design, applications, and sales support centers located worldwide. Allegro MicroSystems Europe, headquartered in Chertsey, United Kingdom, is the European sales and marketing operation, and operates a network of representatives and distributors throughout Europe. Allegro also has an engineering design centre in Edinburgh in Scotland and an application and marketing centre in Annecy in France.