SBAS813 June 2018 ADS8688AT
PRODUCTION DATA.
The device can be programmed to convert a particular analog input channel by operating in manual channel n scan mode (MAN_Ch_n). This programming is done as shown in Figure 98 by writing a valid manual channel n select command (MAN_Ch_n) in the command register. As shown in Figure 98, the CS signal can be pulled high immediately after the MAN_Ch_n command or after reading the output data of the frame. However, in order to accurately acquire and convert the input signal on the next channel, the command frame must be a complete frame of 32 SCLK cycles. See Table 7 for a list of commands to select individual channels during MAN_Ch_n mode.
The manual channel n select command (MAN_Ch_n) is executed and the device samples the analog input on the selected channel on the CS falling edge of the next data frame following this write operation. The input voltage range for each channel in the MAN_Ch_n mode can be configured by setting the range select registers in the program registers. The device continues to sample the analog input on the same channel if no other valid command is executed and SDI is kept low (see the Continued Operation in the Selected Mode (NO_OP) section) during subsequent data frames. The timing diagram in Figure 99 shows this behavior using an example in which channel 1 is selected in the manual sequencing mode. For switching between MAN_Ch_n mode and AUTO_RST mode; see the Channel Sequencing Modes section.