JAJSW71 February 2025 ADC3683-EP , ADC3683-SEP
PRODUCTION DATA
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The PDN/SYNC pin is used to synchronize multiple devices using an external SYNC signal. The PDN/SYNC pin is configured through SPI (SYNC EN bit) from power down to synchronization functionality, and is latched in by the rising edge of the sampling clock as shown in Figure 7-37.
Figure 7-37 External SYNC timing
diagramThe synchronization signal is only required when using the decimation filter - either using the SPI SYNC register or the PDN/SYNC pin. Resetting the internal clock dividers used in the decimation filter, and aligning the internal clocks as well as I and Q data within the same sample. If no SYNC signal is given, the internal clock dividers is not be synchronized, which can lead to a fractional delay across different devices. The SYNC signal also resets the NCO phase and loads the new NCO frequency (same as the MIXER RESTART bit).
When trying to resynchronize during operation, the SYNC toggle occurs at 64*K clock cycles, where K is an integer. This provides the phase continuity of the clock divider.