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AS1543/44

Data Sheet - D e t a i l e d D e s c r i p t i o n

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;

Select Coding, Range, SE/FDN,

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;

DIN: Write to Shadow Register (see Table 12 on page 18)

Selecting Channels for Conversion*

Bit WRITE = 1, Bit SEQ = 1, Bit SHADOW = 0

* Need not be consecutive channels.

Bit WRITE = 0

DOUT: Conversion Result from

previously selected ADDR3:ADDR0

Channel

Continuously Convert the selected

sequence of Channels

DOUT: Conversion Result from

previously selected ADDR3:ADDR0 Chan-

nel

Continuously Convert the selected

sequence of Channels and allow Changes

to Control Register without Conversion

Interruption

Bit WRITE = 1

Bit SEQ = 1,

Bit SHADOW = 0

Bit WRITE = 0

Bit WRITE = 0

CSN Falling

Edge

CSN Falling

Edge

CSN Falling

Edge

Bit WRITE = 1

Bit SEQ = 1

Bit SHADOW = 0

Exit this flow whenever WRITE = 1 and NOT (SEQ = 1, SHADOW = 0)

CSN Falling

Edge