PRELIMINARY

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Running mode:

In running mode the output is triggered by the comparator. An offset cancellation

feedback loop is formed by the A/D converter, dsp and offset cancellation D/A

converter. In running mode switching always occurs at zero-crossing. It is only affected

by the (small) remaining offset of the comparator and by the remaining propagation

delay time of the signal path, mainly determined by the noise-shaping filter. Nevertheless

signals below a defined threshold are not detected to avoid unwanted parasitic

switching.

Figure 3: Startup of the device

At transition from startup-mode to running mode switching timing is moving

from low-accuracy to high accuracy zero-crossing.

startup-mode

running-mode

offset

peak detection

offset= (max + min) / 2

offset

correction