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Analog accelerometers integrates 4-channel multiplexer

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

Keywords:Kionix? analogue sensors? accelerometers? consumer? automotive?

Kionix has rolled out the KXR94 and the KXD94 two series of high-performance analogue sensors offering ultra-low noise, high data sampling rates, an internal low-pass filter, and multiplexed output (plus SPI in the KXR94). Both are available in Both are available in a 5x5x1.2mm, 14-pin DFN package in either consumer or automotive grades.

The KXD94 is also the company's highest g part, offering 5g to 15g ranges. It is available in our standard 2g range. Both sensors feature an integrated 4-channel multiplexer, reducing system MCU requirements to only 1 ADC and 2 digital I/O's.

A Kionix tri-axis accelerometer with analogue outputs, such as the KXR94 or KXD94, provides three output voltages (Xout, Yout, Zout), which are proportional to the respective accelerations in those directions. However, with three analogue outputs to digitize, it is possible that the system microprocessor does not have the necessary A-D converters. Either the KXD94 or KXR94's internal multiplexing capability, or an off-the-shelf multiplexer, can be used to multiplex the three outputs to one analogue signal.

By multiplexing, only one A-D channel is required and the system will maintain the performance of the analogue output at a high data sampling rate. Even when multiplexing all three accelerometer outputs, the maximum data sampling rate is still gated by the speed of the system microprocessor's A-D converter.

When operating in their multiplexed mode, Kionix analogue parts have the ability to achieve very high data sampling rates. Internally, the sensor elements (X,Y, and Z) are sequentially sampled in a "round robin" fashion at a rate of 32kHz per axis. Combine this high sampling rate with the short 5?S settling time of the integrated multiplexer, and the user can achieve a performance very close to that of the 3 separate analogue outputs. This enables the elimination of any aliasing in the final application since the accelerometer will be operating with a typical bandwidth of between ~50Hz and 2500Hz.

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