AS1543/44
Data Sheet - Detailed Description
Shadow Register Conversion (SEQ = 0, SHADOW = 1)
Figure 29 shows how to program the AS1543/44 to continuously convert from a particular sequence of channels. To
exit this mode of operation and revert back to the normal mode of operation of a multi-channel ADC (as outlined in
Figure 28), verify bit WRITE (page 14) = 1 and bits SEQ and SHADOW = 0 on the next serial transfer.
Note: If all 0s are written into the Shadow Register (see Table 12 on page 18) channel 3/7 will be chosen by default.
Figure 29. Bit SEQ = 0, Bit SHADOW = 1 Flowchart
Power On
DOUT: Dummy Conversion Result
DIN: Write to Control Register;
Bit WRITE = 1;
CSN Falling
Select Coding, Range, SE/FDN,
Edge
WEAK/TRIN and Power Mode;
Select Channel ADDR3:ADDR0 (see Table 5 on
page 14) for Conversion
Bit SEQ = 0, Bit SHADOW = 1
DOUT: Conversion Result from previously selected ADDR3:ADDR0 Channel;
CSN Falling
Edge
DIN: Write to Shadow Register (see Table 12 on page 18)
* Need not be consecutive channels.
Selecting Channels for Conversion*
Bit WRITE = 1, Bit SEQ = 1, Bit SHADOW = 0
Bit WRITE = 0
Bit WRITE = 0
Bit WRITE = 1
Bit SEQ = 1
Bit SHADOW = 0
DOUT: Conversion Result from
DOUT: Conversion Result from
previously selected ADDR3:ADDR0 Chan-
nel
previously selected ADDR3:ADDR0
Channel
CSN Falling
Edge
Bit WRITE = 1
Bit SEQ = 1,
Bit SHADOW = 0
Bit WRITE = 0
Continuously Convert the selected
sequence of Channels and allow Changes
to Control Register without Conversion
Interruption
Continuously Convert the selected
sequence of Channels
CSN Falling
Edge
Exit this flow whenever WRITE = 1 and NOT (SEQ = 1, SHADOW = 0)
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