Position sensing at submicron resolutions

Useful for position feedback of micro-actuators or as an alternative to incremental optical encoders, austriamicrosystems AS5311 is a hall-effect sensor based linear magnetic encoder that the company says is the first such part to achieve submicron resolution.

The AS5311 can be used for both linear motion and rotary motion sensing, using a multi-pole magnetic strip and a multi-pole magnetic ring respectively. As an example, austriamicrosystems cites the AS5311 being used with a 41.7mm diameter multi-pole magnetic ring to achieve a resolution of 16bit (65.536 steps per revolution). Alternatively, used in conjunction with a 2mm pole-pair magnetic strip, the AS5311 could provide a 1.95um (micrometer) resolution signal at its incremental output and a 488 nanometer resolution signal at its serial output.

The part is available in a 20-lead TSSOP-package. Notes 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.”

Features include on-board diagnostics that monitor the position of the magnet to detect any signs of mechanical system failures. Apparently, the device compensates for the adverse effects of unwanted external magnetic fields to ensure system safety and robustness.

The AS5311 can be operated with either 3.3V or 5V supply voltage and is specified across the -40° to +125°C temperature range. More information, including samplescan be found at

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