The AMC131M01 selects the sinc³ filter path two conversions after power-up or device reset. For OSR settings of 64 to 1024, the sinc³ filter output directly feeds into the global-chop and calibration logic. For OSR settings of 2048 and higher, the sinc³ filter is followed by a sinc¹ filter. The sinc³ filter operates at a fixed OSR of 1024 in this case while the sinc¹ filter implements the additional OSRs of 2 to 16. Thus, when an OSR of 4096 (for example) is selected, the sinc³ filter operates at an OSR of 1024 and the sinc¹ filter operates at an OSR of 4.

The filter has infinite attenuation at integer multiples of the data rate except for integer multiples of f_MOD. As with all digital filters, the digital filter response of the AMC131M01 repeats at integer multiples of the modulator frequency, f_MOD. The data rate and filter notch frequencies scale with f_MOD.

When possible, plan frequencies for unrelated periodic processes in the application for integer multiples of the data rate such that any parasitic effect on data acquisition is effectively canceled by the notches of the digital filter. Avoid frequencies near integer multiples of f_MOD whenever possible because tones in these bands can alias to the band of interest.

The sinc³ and sinc³ + sinc¹ filters require time to settle after the ADC is enabled, the multiplexer or gain setting is changed, or a resynchronization event occurs. See the Synchronization section for more details on resynchronization. Table 8-5 lists the settling times of the sinc³ and sinc³ + sinc¹ filters for each OSR setting. The AMC131M01 does not gate unsettled data. Therefore, the host must account for the filter settling time and disregard unsettled data if any are read. Wait for the duration of the settling times listed in Table 8-5 plus one additional conversion cycle before the data that was read can be considered valid.