ams AG (SIX: AMS), a leading provider of high performance sensors and
analog ICs, today released the AS5147P, an ultra-high speed magnetic
rotary position sensor which offers reliable performance in automotive
applications compatible with the requirements of the ISO26262 functional
safety standard.
Providing accurate absolute and incremental measurement outputs at
speeds up to 28,000 revolutions per minute (rpm), the AS5147P is ideal
for safety-critical applications such as electric power steering (EPS),
brake and accelerator pedals, pumps, double-clutch transmissions,
starter motors, alternators and windscreen wiper motors.
Its appeal to automotive system designers rests on a combination of high
measurement accuracy at high rotation speeds, high reliability, low
system cost and support for standards compliance.
The AS5147P draws on patented DAEC™ (Dynamic Angle Error Correction)
technology to deliver accurate position measurements even at extremely
high rotation speeds. The DAEC compensation scheme reduces the
propagation delay inherent in the sensor’s signal chain to almost zero.
As a result, the AS5147P’s angle error is a negligible 0.02° at 1.7krpm,
0.17° at 14.5krpm and 0.34° at 28krpm. The DAEC function also enables
the device to refresh its measurement output every 1.9µs.
High reliability and low system cost in automotive applications are
assured by the AS5147P’s intrinsic immunity to stray magnetic fields.
Strong stray magnetic fields are present in vehicles, particularly those
with a partially or wholly electric drivetrain, which contain powerful
electric motors and high current-carrying conductors. These stray
magnetic fields are much stronger than that of the small target magnet
with which a magnetic position sensor is paired.
The unique differential sensing principle of the magnetic position
sensors from ams makes them immune by design to stray magnetism. This
means that automotive system designers can avoid the need to incorporate
bulky and expensive magnetic shielding into their products, reducing
their size, weight and cost when compared to designs based on competing
magnetic position sensor ICs. The high sensitivity of the AS5147P also
enables the use of a small (6mm diameter), low-cost target magnet.
In addition, the AS5147P supports automotive OEMs’ ISO26262 compliance
programmes in various ways:
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the AS5147P was developed in accordance with the ISO26262 flow,
following the SEooC (Safety Element out of Context) and AoU
(Assumption of Use) guidelines specified in the standard, thus helping
manufacturers to achieve the requirements of any ASIL grade
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ams provides a safety manual and failure mode effects diagnostic
analysis (FMEDA) document for the AS5147P, guiding customers on the
way to achieve their target ASIL grade in various applications
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evidence – safety case, certifications and the AECQ-100 qualificaion
(PPAP) – is ready to provide the documentation of the AS5147P’s
development process
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the complete SEooC process according to the ISO26262 and the
documentation supporting it are certified by an independent third party
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the AS5147P provides internal diagnostic functions supporting ISO26262
processes, including magnetic field strength threshold detection, and
detection of loss of magnet
The AS5147P provides both absolute and incremental angle measurements of
a continuously rota-ting shaft, with a zero-position setting. A standard
four-wire serial peripheral interface allows a host microcontroller to
read 14-bit absolute angle position data and to program non-volatile
settings without a dedicated programmer.
Incremental movements are indicated by a set of ABI signals with a
maximum resolution of 4,096 steps/1,024 pulses per revolution. The
resolution of the ABI signal is programmable to 4,096 steps/1,024 pulses
per revolution, 2,048 steps/512 pulses per revolution or 1,024 steps/256
pulses per revolution. Brushless DC (BLDC) motors may be controlled
through a standard UVW commutation interface with a programmable number
of pole pairs from 1 to 7. The absolute angle position is also provided
as a PWM-encoded output signal.
‘Offering a combination of high accuracy, compact size and low system
cost, magnetic position sensors are widely regarded as the best solution
for rotary position sensing in vehicles. Now with the AS5147P, ams has
made a magnetic position sensor which fits seamlessly into OEMs’
ISO26262 compliance programmes, and which also eliminates any concerns
over the effect of stray magnetic fields’, said Heinz Oyrer, senior
marketing manager at ams.
The AS5147P is available now in production volumes in a TSSOP-14
package. Unit pricing is $5.31 in 1,000-unit quantities.
A demonstration board for the AS5147P is available from the ams ICdirect
online shop. For sample requests and for more technical information,
please go to www.ams.com/Magnetic-Position-Sensors/AS5147P.
Download press picture and block diagram at http://www.ams.com/eng/Press/Press-Releases/
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