JAJSFT4C August 2018 – June 2019 ADS9224R , ADS9234R
PRODUCTION DATA.
In this mode of conversion control and data transfer, the device starts conversion on the rising edge of CONVST. The CONVST pin can be pulled low after a minimum time of tWH_CONVST. After a time of tD_CONVST_CS (see tD_CONVST_CS for zone 2 transfer in the Specifications section), the host must pull CS low and provide clocks on the SCLK pin to read the data in zone 2. As shown in Figure 45, a zone 2 transfer provides more read time (tread). The read time available for reading data is maximized when tD_CONVST_CS is set to the minimum permissible value. The data for the previous sample (sample N-1) is provided by the device on the SDO pins. After all bits are read, the host can pull the CS pin high to end the data transfer frame. After pulling CS high, the host can pull the CONVST pin high to start the next conversion. In this mode of conversion control, a minimum time of tCYCLE (see tCYCLE for zone 2 transfer in the Specifications section) is required between two adjacent rising edges of the CONVST signal. The host must keep the SDI pin low (NOP0) or high (NOP1) for conversion control and for getting conversion results from the device.
NOTE
For optimum performance with zone 2 transfer, TI recommends masking the READY output by setting the READY_MASK bit in the OUTPUT_DATA_WORD_CFG register and using a data transfer protocol with a bus width of more than 2 SDOs or the parallel byte protocol to keep [tD_CONVST_CS + tREAD] below 150 ns. See the Protocols for Reading From the Device section for details on different protocols for reading the data.