Product category:
Sensors and Data Acquisition
News Release from: AKM Semiconductor | Subject: AK8973S
Edited by the Electronicstalk Editorial
Team on 16 March 2007
Electronic compass shrinks to chip-size
packaging
AKM has completed development of the world's smallest and thinnest three-axis electronic compass with chip-size packaging of 2.5 x 2.5 x 0.5mm.
AKM has completed development of the AK8973S, the world's smallest and thinnest three-axis electronic compass with chip-size packaging of 2.5 x 2.5 x 0.5mm The small size is made possible by forming silicon monolithic Hall elements together with amplifier and logic circuitry on a single chip
This article was originally published on Electronicstalk on 23 Nov 2004 at 8.00am (UK)
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Samples of the AK8973S will be on display at Sensor Expo Japan 2007 from 4th to 6th April in Tokyo, as will applications and demonstrations of the AK8976A, at 4.5 x 4.5 x 0.9mm - the world's smallest and thinnest six-axis electronic compass.
Applications foreseen for the digital-interface AK8973S include pedestrian navigation systems in cellphones and personal navigation devices, and motion input in video game controllers.
AKM is a world leader in the development of electronic compasses for portable applications, and its AK8970, the world's first three-axis electronic compass developed for cellphone use, began shipping in commercial volume in fiscal 2003.
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It and its successor the AK8970N have been employed in more than fifteen handset models throughout the world.
Wide adoption of AKM's three-axis electronic compasses for cellphones has been driven by the outstanding performance enabled by Asahi Kasei EMD's Dynamic Offset Estimation (DOE) algorithm to automatically compensate for magnetic offset inside a handset.
It is the extremely high sensing linearity and wide measurement range of the Hall elements, together with the exceptional AKM architecture for uniform sensitivity in all three axes, that ensures the effective performance of DOE, resulting in a clearly superior electronic compass functionality that has been recognised by customers around the world.
While maintaining its hallmark performance, AKM has continued to miniaturise the electronic compass in anticipation of the needs of designers and developers of cellular handsets and other advanced portable electronics for successive size reductions.
Following the AK8970, which at 5.9 x 6.3 x 1.0mm was the world's smallest three-axis electronic compass at the time of its introduction, AKM introduced the AK8970N in fiscal 2004, which at 5.0 x 5.0 x 1.0 mm has its volume reduced to 67% of that of its predecessor.
In fiscal 2006 AKM introduced its then smallest electronic compass the AK8973 at 4.0 x 4.0 x 0.7mm, with a volume reduced to 45% of that of the AK8970N.
The AK8973S announced today, with chip-size packaging of 2.5 x 2.5 x 0.5mm, has its volume reduced to 28% of that of the AK8973 and a mere 8% of the volume of the bellwether AK8970.
A succession of technological advances has enabled this extraordinary course of miniaturisation.
The first-generation products, the AK8970, AK8970N, and the AK8971N which included an accelerometer interface, were multi-chip modules comprising three compound semiconductor Hall elements from Asahi Kasei Electronics, one for each spatial axis, and an AKM signal processing LSI packaged together.
The AK8970 and the AK8970N contained the same four component chips, with the size reduction in the latter obtained by a change in packaging technology.
In order to attain even greater size reduction, the AK8976A and AK8973 introduced in fiscal 2006 are produced with silicon monolithic Hall elements formed together with the amplifier and logic circuitry, resulting in a one-chip electronic compass.
With the AK8973S, the potential size reduction of a one-chip conformation is taken to the limit by using new technology for chip-size packaging.
The development of silicon monolithic Hall elements to serve as magnetic sensors, and their integration with amplifier and logic circuitry on a single chip, is itself a major advance both conceptually and in terms of applied technology.
Any magnetic sensor, Hall element or otherwise, can only measure a magnetic field in a single axis.
This is why conventional three-axis sensors were of necessity multi-chip modules incorporating three separate magnetic sensors, emplaced in three different planar orientations corresponding to the spatial axes of x, y and z.
Because the Hall element, unlike other magnetic sensors, measures magnetic field in the axis perpendicular to the plane of the chip, many had considered it to be an unfavourable choice for three-axis sensors, as two of the Hall elements needed to stand vertically with respect to the plane of the chip package.
With the development of the silicon monolithic Hall element, the perpendicular measurement direction of Hall elements becomes an advantage that enables sensors for all three spatial axes to be formed on a single wafer plane.
The principles of magnetic field measurement using this technology will be presented on 17th March 2007 at a symposium of The Institute of Electrical Engineers of Japan.
Chip-size packaging (CSP), unlike QFN packaging, enables the three-axis electronic compass to be used in circuit board designs with extremely high mounting density.
For many portable electronics, cellular handsets in particular, recent years have seen a rapidly expanding adoption of CSP technology.
The AK8973S uses wafer-level CSP, or WLCSP, in which LSIs are encapsulated in resin before the wafer is cut into individual chips.
Software compatibility with previous AKM electronic compasses enables customers to utilise existing software assets, including the patented DOE algorithm for automatic adjustment of magnetic offset and software for calculations to compensate for tilt.
DOE has been provided to customers since before the beginning of volume shipment of AKM's first electronic compass product.
With the AK8973S, as before, DOE enables greatly improved productivity by eliminating the need for adjustment to be performed individually for each handset before shipment, and makes it unnecessary for the consumer to perform adjustments when the ambient magnetic field changes.
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