AMS DAEC magnetic position sensors improve accuracy for motor control

AMS, the sensor specialist and analogue chip supplier, has announced a new series of integrated magnetic position sensors. Designed to provide very accurate angle measurements of rotors spinning at high speed, they are suited for motor control and angle measurement related applications.


AS5147-5047D block diagram

The “47 series” features the company’s DAEC system – dynamic angle error compensation – to help eliminate measurement errors (dynamic angle errors, system propagation delays, and other errors that need compensation).

The improved accuracy of the parts should enable improved system performance, in areas such as torque, power efficiency and smoothness of operation, for example.

DAEC involves an algorithm, says AMS, that performs error compensation internally and responds automatically to changes in the speed of rotation. It is dynamically compensating every measurement sample for the speed of rotation at the time the sample is captured.

A demo of AMS motor control

A demo of AMS motor control

This means DAEC is very accurate for angle measurements of rotors spinning at high speeds, reducing dynamic angle errors to almost zero (the parts are specified with a maximum ±0.17° angle error, excluding integral non-linearity).


Specifically, the sensors provide angle measurements accurate to ±0.08° at 7,000rpm, to ±0.14° at 12,000rpm and to ±0.17° at 14,500rpm. They provide high 14-bit resolution (to 0.022°) in their digital SPI output, and maximum resolution of 2,000 steps per revolution in decimal mode and 2,048 steps per revolution in binary ABI mode.

Parts in the series include AS5047D (replacing optical encoders for industrial applications such as robotics, factory automation, and building automation) and AS5147 (for automotive, AEC-Q100 qualified – electric power steering, for example). There is also the dual-die AS5247 (AEC-Q100 qualified), again suited for automotive applications.

All three devices provide absolute position measurements as a digital PWM output, and UVW outputs for use in field-oriented commutation schemes. They also provide an incremental ABI output equivalent to the output of an optical encoder. This means, says AMS, that an AS5047D IC can replace an optical encoder without requiring the user to change the software interface in the host system’s microcontroller or DSP.

The company sees the e-motor market growing 40% between 2012 and 2017, with electrified power trains becoming more common, and they see the trend to PMSMs (permanent-magnet synchronous motors) needing improved sensor technology.

“The introduction of the 47 series marks a radical step forward in magnetic position sensor technology,” said Bernd Gessner, General Manager of the Automotive Business Unit at AMS. “For the first time, designers of high-speed motors can use robust, compact magnetic position sensors without the need to implement a complex error compensation scheme in an external microcontroller or DSP.”


The AS5047D is available for sampling in a 14-pin TSSOP package, priced at $4.21 in 1,000-piece quantities.

Thomas Riener - AMS - Executive Vice President General Manager Full Service Foundry - Executive Vice President Marketing Communications

Thomas Riener – AMS, Executive Vice President General Manager Full Service Foundry

The AS5147, priced at $4.84, is also in a 14-pin TSSOP package.

The AS5247, priced on request, is in an MLF-40, 7mm x 7mm package.

General product availability is the end of July 2014.

The system was unveiled at a company event in Graz, Austria. Earlier at the presentation, Thomas Riener – general manager full service foundry – had highlighted the company’s approach to sensor solutions, describing them as the key interface between people and technology.

“Hot market segments, such as wearable tech, NFC, and IoT, all rely on sophisticated sensors.”

This particularly applies to the automotive sector, he said, “where there’s a lot of movement you want to measure – steering wheel angle, transmission, gear shifts, etc.”

See also: Lightning detector on a chip

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