Specifications

BMA180
Preliminary data sheet
Bosch Sensortec
Rev. 1.0 Page 67 / - proprietary information - 06 March 2009
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Specifications within this document are preliminary and subject to change without notice. Document is not intended for publication.
Compared to the calibration method in 7.10.3 the usage of offset fine-tuning is much simpler (all
calculations are done within the chip), but might take longer – depending on the initial offset.
9.4.1.3 High-pass or band-pass usage
A third method to get a very small offset is the usage of the internal high-pass or band-pass of
the sensor. In this case almost no offset occurs, if acceleration amplitudes in the small
frequency range are not too high.
Advantage of this method is a almost perfect removal of offsets. Drawback is, that accelerations
at very small frequency signals, as they occur in some navigation situations – long curves with
almost no acceleration in small frequency range – cannot be measured at all.
9.4.2 Sensitivity/TCO/TCS re-calibration/software
Similar to an offset recalibration, a sensitivity re-calibration could be performed. As a drawback,
sensitivity measurements require turning off the device in the production, which is not always
possible.
Same remark is valid for TCS recalibration. In addition different temperatures must be applied.
Due to the same reason a TCO-recalibration at production line is very difficult.
A last method to optimize offset, etc. is the usage of good software algorithms in the device
itself. For optimized behaviour (e. g. navigation, using Kalman filters), the best performance
could be achieved by using a very high performance sensor (as BMA180) together with high
performance software. In this case, minimum position errors will be achieved.
To achieve optimized behaviour an in-line calibration at device production line might be useful.
Dedicated information is given in a separate application note (under preparation).