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Rotary sensor boasts accuracy at high speeds

Posted: 11 Jun 2012 ?? ?Print Version ?Bookmark and Share

Keywords:rotary sensor? angular measurements? position sensing?

Analog chip manufacturer austriamicrosystems AG (AMS) has debuted the AS5132 magnetic rotary position sensor SoC that the company says offers accurate angular measurements at high rotation speeds. The IC integrates Hall elements, an analog front end and a DSP, making it suitable for industrial and automotive brushless DC motors.

Resistant to interference from stray magnetic fields, the chip gives designers a small, robust and easily assembled position sensing solution. It claims to improve on previous generations of magnetic encoders by dynamically compensating for angle errors attributable to propagation delay, which are most noticeable at high speeds. Error compenzation is achieved through integrated pre-commutation functions that can be configured in the AS5132 without need for external software routines. This frees up host MCUs and electronic control units (ECUs). The chip's configuration can be changed in response to changes in operating conditions such as variations in rotation speed, while the device is operating.

The sensor's signal-processing circuitry enables propagation delay of The AS5132 can operate in a magnetic field input as low as 20mT so it can be used with an inexpensive ferrite magnet. It claims to offer a simplified interface for easier integration. Also, it includes an external clock mode, synchronizing sensor and controller systems. And, it allows for the implementation of a 3V interface mode in addition to a 5V mode, cutting the need for a level shifter.

When the AS5132 is paired with a simple two-pole magnet, it provides absolute angle measurement at a resolution of 8.5bits, or 360 positions per revolution. This measurement is available as a serial output and as a pulse width modulated (PWM) signal.

The SoC offers additional U, V, W output can be used for block commutation in a BLDC motor; alternatively an incremental ABI signal is available. In addition to the angle information, the strength of the magnetic field is represented as a 5bit value.

The zero position can be set by software on the production line. This simplifies assembly, as the magnet does not need to be precisely aligned with a fixed starting position.

The AS5132 is suitable for contactless rotary position sensing, rotary switches (human machine interface), AC/DC motor position control and BLDC motor position control in automotive applications such as pump BLDC motors (stop-start system) and steering column BLDC motors. The AS5132 is also particularly well suited to position sensing in double-clutch BLDC motors.

The AS5132 rotary position sensor is available in volume production now, in 1,000-piece quantities.

A demonstration board for the AS5132 rotary position sensor is also available.

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