JAJSOS3B September 2023 – September 2023 AMC131M03
PRODUCTION DATA
Synchronization can be performed by the host to make sure the ADC conversions are synchronized to an external event. For example, synchronization can realign the data capture to the expected timing of the host if a glitch on the clock causes the host and device to become out of synchronization.
The SYNC/RESET pin is a multifunction digital input pin that allows the host to synchronize conversions to an external event or to reset the device. See the SYNC/RESET Pin SYNC/RESET Pin section for more details regarding how the device is reset.
Provide a negative pulse on the SYNC/RESET pin with a duration less than tw(RSL) but greater than a CLKIN period to trigger synchronization. The device internally compares the leading negative edge of the SYNC/RESET pulse to the internal clock that tracks the data rate. The internal data rate clock has timing equivalent to the DRDY pin if configured to assert with a phase calibration setting of 0b. If the negative edge on SYNC/RESET aligns with the internal data rate clock, the device is determined to be synchronized and therefore no action is taken. If there is misalignment, the digital filters on the device are reset to be synchronized with the SYNC/RESET pulse.
Figure 8-21 shows the behavior after a synchronization pulse on the SYNC/RESET pin for OSR = 1024. As explained in the SINC3 and SINC3 + SINC1 Filter section, because of the settling of the digital filter, the first two conversion results are unsettled data and must be ignored.
In global-chop mode, conversions are always immediately restarted at the falling edge of the SYNC/RESET pin.
The phase calibration settings on all channels are retained during synchronization. Thus, channels with non-zero phase calibration settings generate conversion results less than a data rate period after the synchronization event occurs. However, the results are not settled until the respective channels have at least three conversion cycles for the sinc3 filter to settle.