Datasheet

Ch 5 Data
Auto/0000h
Ch 0 Data
Man Ch 1
Ch 5 Data
Man Ch 0
Ch 1 Data
Man Ch 3
Ch 0 Data
Man Ch 7
Ch 5
Sample
Ch 0
Sample
Ch 5
Sample
Ch 1
Sample
Ch 0
Sample
Ch 0
Ch 5 Ch 1 Ch 0 Ch 3
SCLK
DOUT
DIN
Selected
Channel
Manual ScanAuto Scan
CS
Ch n 1 Data
Man Ch3
Ch n Data
Auto
Ch 3 Data
0000h
Ch 2 Data
0000h
Ch 5 Data
0000h
Ch n 1
Sample
Ch n
Sample
Ch 3
Sample
Ch 2
Sample
Ch 5
Sample
Ch n
Ch 3 Ch 2 Ch 5 Ch 2
SCLK
DOUT
DIN
Selected
Channel
Auto ScanManual Scan
CS
ADS8634
ADS8638
www.ti.com SBAS541A –MAY 2011– REVISED AUGUST 2011
CHANNEL SEQUENCING MODES
The ADS8634/8 offer two channel sequencing modes: auto and manual. In auto-scan mode, the channel number
automatically increments every frame. In manual mode, the channel is selected for every frame of a register
write. The analog inputs can be selected for an automatic scan with a register setting. The device automatically
scans only the selected analog inputs in ascending order.
The auto-mode sequence can be reset at any time during an automatic scan (refer to the Auto register in the
PAGE-0 Register Map for the ADS8638 section ). When the reset command has been received, the ongoing
auto-mode sequence is reset and restarts it from the lowest selected channel in the sequence.
Figure 86 shows the DIN command sequence for transitions from auto to manual mode. Figure 87 shows the
DIN command sequence for transitions from manual to auto-scan mode. Note that each DIN command is
executed on the next CS falling edge.
Figure 86. Transition from Auto to Manual Mode (Channels 0 and 5 are selected for auto sequence)
Figure 87. Transition from Manual to auto-scan mode (Channels 2 and 5 are selected for auto sequence)
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Product Folder Link(s): ADS8634 ADS8638