Zooming in on submicrons
12 May 2009
Hall-effect sensor based linear magnetic encoder offers submicron resolution.
An integrated linear Hall encoder that can be used as an alternative to optical encoders has been released by austriamicrosystems. The AS5311 is the first Hall-effect sensor based linear magnetic encoder to offer submicron resolution. For linear motion sensing, a multi-pole magnetic strip is used and for rotary motion sensing the magnetic strip is replaced by a multi-pole magnetic ring. For applications like this, an incremental output with a resolution of 10 bit per pole pair and a travelling speed up to 650 mm per second is available. Using for example a multi-pole magnetic ring with a diameter of 41.7 mm, a resolution of 16 bit (65.536 steps per revolution) can be achieved.
In conjunction with a 2 mm pole-pair magnetic strip, the AS5311 provides a 1.95 micrometer resolution signal at its incremental output and a 488 nanometer resolution signal at its serial output.
“austriamicrosystems’ AS5311 together with the magnetic strip are the only two components required to build a robust submicron-resolution position feedback system”, says Josef Janisch, Encoder Product Manager at austriamicrosystems. “This small form factor allows AS5311 to be integrated in autofocus, zoom and vibration reduction systems in cameras, switching systems in fiber optics or other micro-positioning applications where tight space is a concern and high resolution is demanded.”
“The AS5311 is the first linear magnetic encoder with submicron resolution, based on our successful integrated Hall sensor technology”, says Matjaz Novak, Director of Marketing Industry & Medical at austriamicrosystems. “It offers an attractive solution for applications where cost, high precision and small form factor are the constraints. With the AS5311, we want to offer a device which will allow system designers to implement position sensing solutions meeting all these constraints at the same time.”
Austriamicrosystems’ encoder chip also provides extended diagnostic features that constantly monitor the placement of the magnet above the device. These features allow early detection of mechanical systems failures. In addition, the device compensates for the adverse effects of unwanted external magnetic fields thus ensuring additional safety and robustness of the system.
The AS5311 can be operated with either 3.3 V or 5 V supply voltage and is available in a 20-lead TSSOP-package. The device is specified for an ambient temperature range from -40° to +125°C.
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