Hi,
the calibration is a quite complex process and the MM9Z1_638 device allows different options on how to use it, e.g. automatic temperature gain compensation or manual gain compensation using chip temperature result and lookup tables. Also the acquisition channel configuration used during operation has to be considered.
The system calibration should be performed as an incremental (incremental to NXP provided device calibration data) calibration.
The basic steps are:
- Characterize system behavior (applying device compensation values)
- Estimate deviation between real and ideal behavior (calculate delta between ideal behavior and measured behavior)
- Calculate incremental compensation values (delta values)
- Apply compensation during operation and verify system behavior
The following picture indicates which information / data is required to calculate the incremental gain and offset adjustments (gainsteps, offsetsteps).
For a good estimation of the acquisition channels behavior, e.g. a 5-point measurement is suitable.
The selection of the individual data points should consider application requirements like:
- desired input range
- area where highest accuracy is desired
- capability of the module / device (e.g. minimum supply voltage for Vsup)
- capability of equipment (e.g. max. Iout of power supplies, max. input range of DMM and related accuracy in the range)
- select current points for ISENSE calibration such that no gain switching is required
The picture below shows an example setup for the ISENSE channel compensation:
To discuss further details it might be better to directly discuss your applications needs?
Rgds
Wolfgang
