The AD7147 dynamic measurement range is set at +/-8pF, this cannot be changed as the range is set by the power supply voltage applied to the chip and an internal reference capacitor. However through dynamic use of the offset control DACs it may be possible to measure higher capacitances, but the polarity of the measured capacitance must be predictable and enough time must be available to complete the measurement. For example if the Offset control DACs are configured to their maximum values and connected to the negative AFE input the measurement range is now ~40pF to 56pF. By adjusting the DAC values the capacitance value can be found using a search algorithm.
