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Signal conditioner features fault-tolerant line driver

Posted: 27 Jul 2006 ?? ?Print Version ?Bookmark and Share

Keywords:iC-Haus? iC-MSB? signal conditioner?

The iC-MSB from iC-Haus is a signal conditioner with a fault-tolerant line driver for sine/cosine sensors which are used to determine positions in linear and angular encoders, for example. Precision instrumentation amplifiers with differential current or voltage inputs are available for three channels and can be set independently with regard to amplification, offset and phase correction.

An integrated controller supplies the sensor with power and ensures that the chip's output levels are stabilized to 1Vpp exactly. At the same time the finely adjustable calibration parameters permit an utmost degree of accuracy during the ensuing interpolation process. The inputs can either be set to high impedance for voltage signals from magneto resistor sensor bridges, for example, or to low impedance for adaptation and use with photosensors which provide current signals. This enables the device to be directly connected to a number of different optical and magnetic sensors.

By tracking the sensor energy supply, any signal variations and temperature and aging effects can be compensated for and the set signal amplitude maintained with absolute accuracy. At the same time, the control circuitry monitors whether the sensor is functioning correctly and whether it is properly connected. Signal loss due to wire breakage, short circuiting, dirt or aging, for example, is recognized when control limits are reached. To this end, either an alarm can be displayed at the error output or the output drivers shut down.

iC-MSB is protected against reverse polarity and provides the power supply for peripheral circuitry. There is no need for the usual reverse polarity protection diode. Furthermore, the analog output drivers are directly cable-compatible including 100-ohm termination and tolerant to false wiring. If supply voltage is connected up to these pins, the device is not damaged.

The calibration parameters are CRC protected and stored in an external EEPROM. They are loaded automatically via the I2C interface once the supply voltage is connected up. The IC requires very little board space; the TSSOP has just 20 pins and a reduced number of external components.

- Henri Arnold

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