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Magnetic encoder offers up to 18bit absolute resolution

Posted: 25 Nov 2013 ?? ?Print Version ?Bookmark and Share

Keywords:iC-Haus? magnetic encoder? brushless motor?

iC-Haus has released what it describes as a fully integrated, single-chip device iC-MU intended for the scanning of magnetic pole wheels and tapes for typical motion control applications such as absolute position encoders, incremental encoders and commutation encoders for brushless motors. The position data is generated in real time and provided through serial interfaces (BiSS, SSI and SPI) and as an incremental signal without processing delay. Thanks to special FlexCount interpolation, any pulse count can be configured, noted the firm.

The magnetic target for iC-MU has two incremental tracks with pole widths of about 1.28mm. A typical operating distance of 4/10mm is sufficient for the sensor. Two simultaneous sine-to-digital converters are used to achieve the best real time characteristics; these initialize the cyclic nonius calculation. No movement is necessary to determine the absolute position.


Traversing rates of up to 16m/s are possible in linear systems at an absolute position resolution of 0.16um across a distance of 164mm. To increase this distance, the iC-MU devices can be cascaded or initiated using multiturn information. In rotary systems or rotary encoders iC-MU permits speeds of up to 24,000rpm at a resolution of five angle seconds.

Optimum reliability, a high resistance to shock and vibration, no breakable parts, insensitivity to dirt and moisture: these are the many benefits that speak for magnetic systems, boasted the firm. iC-MU achieves its high immunity to magnetic interference, another prerequisite of such devices, through multiple differential field scanning.

The SoC design integrates all of the required encoder functions onto the smallest possible area as a 16-pin DFN package, requiring just 5 x 5mm of board space. Off-center or off-axis placement permits hollow shafts for high-resolution, magnetic absolute encoders for the very first time. With the standard MU2S disc with a diameter of 30mm, axes of up to 10mm can be used, for example.

The interfaces available for data output are extremely flexible; MCUs can be easily connected up through SPI, bidirectional BiSS C and SSI can be used as encoder interfaces, incremental A/B/Z encoder quadrature signals can be programmed with 1-65,536 pulses and zero position preset, and U/V/W commutation signals are provided for motors with 1-16 pole pairs. Additional Hall sensors are thus no longer required for commutation. If we consider the total system, iC-MU is a remarkably cost-effective resolver substitute, added the company.

iC-MU runs on 5V in an operating temperature range of -40°C to 110°C. The device comes in a space-saving 16-pin DFN package and requires just 5 x 5mm of board space. Various magnetic measurement standards, demo boards, PC adapters and operating software for Windows are available for evaluation.

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