News Release

iC-MQ: Encoder evaluation with x100 interpolation and diagnosis memory 12.11.2007
Sensor conditioning with 100-fold sine interpolation and line drivers
iC-MQ's universal signal conditioning facility is suitable for optical and magnetic linear and angle sensors. For the very first time, outstanding diagnostic features are now available. Operational errors, such as signal loss or clipping, exceeding a pre-set operating temperature range or RPM speed and – as a totally new feature – a line count error of the scale or disc pattern, are detected, signalled to the PLC and transferred to a non-volatile diagnostic memory.

iC-MQ provides up to 400 angle steps for sine interpolation; to improve angle accuracy, this basic function is supplemented by a finely adjustable signal conditioning circuitry, a signal path multiplexer (which keeps pin functions variable) and fault-tolerant RS422 line drivers. Device installation with incorrectly connected wires is tolerated by iC-MQ – even when the supply voltage is reversed.

Differential or referenced input signals from a few millivolts upwards are sufficient for the offset-free instrumentation amplifiers; a low impedance can also be set if required for current signals in the µA range.

iC-MQ itself ensures that the parameters set initially for the offset, amplitude and phase correction are kept valid. To this end sensor energizing can be tracked via a 50 mA high-side source output; the LED current of an optical encoder or the supply of magnetic XMR bridge sensors can be regulated. Temperature and aging effects or varying operating distances are automatically compensated for.

All of the chip's major functions are monitored and can be configured for alarm indication, allowing typical sensor errors, such as signal loss due to wire breakage, short circuiting, dirt or ageing, for instance, to be recognized. The mode of error handling can be extensively configured using event masks; an alarm can be displayed at the error output, set the output drivers to tristate and be transmitted to the error memory for later diagnosis.

The encoder signals are supplemented by a generated index signal whose position, width and logic can be set as required. At the same time a patented signal conditioning unit provides glitch-free quadrature signals with hysteresis which always maintain a preselectable minimum transition distance. This enables counting errors to be avoided and enhances the circuit’s EMI tolerance with sensor applications.

iC-MQ is available as a 20-pin TSSOP which takes up just approx. 6.4 x 6.4 mm board space. It is configured using the integrated I2C multimaster interface, either by a microcontroller or a serial EEPROM. Via an integrated supply switch iC-MQ also protects the peripheral electronics against a reversed supply voltage.

Typical applications include:
  • Optical rotary encoders
  • Magnetic rotary encoders
  • Linear scales
  • Motor commutation
  • DC motor feedback
  • Automotive applications.
With a single supply of +5 V the device functions within an industrial operating temperature range of -25 to +100 °C. An extended temperature range can also be provided, as the converter chip has been designed to cope with operating temperatures of -40 to +125 °C.

Product iC-MQ
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