Datasheet

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3-Wire Serial Interface

DAC7554

SLAS399A – OCTOBER 2004 – REVISED NOVEMBER 2004

The DAC7554 digital interface is a standard 3-wire SPI/QSPI/Microwire/DSP-compatible interface.

Table 1. Serial Interface Programming

CONTROL DATA BITS DAC(s) FUNCTION

LD1 LD0 Sel1 Sel0 DB11-DB0

0 0 0 0 data A Input register updated

0 0 0 1 data B Input register updated

0 0 1 0 data C Input register updated

0 0 1 1 data D Input register updated

0 1 0 0 data A DAC register updated, output updated

0 1 0 1 data B DAC register updated, output updated

0 1 1 0 data C DAC register updated, output updated

0 1 1 1 data D DAC register updated, output updated

1 0 0 0 data A Input register and DAC register updated, output updated

1 0 0 1 data B Input register and DAC register updated, output updated

1 0 1 0 data C Input register and DAC register updated, output updated

1 0 1 1 data D Input register and DAC register updated, output updated

1 1 0 0 data A-D Input register updated

1 1 0 1 data A-D DAC register updated, output updated

1 1 1 0 data A-D Input register and DAC register updated, output updated

1 1 1 1 data -- Power-Down Mode - See Table 2

Sel1 Sel0 CHANNEL SELECT

0 0 Channel A

0 1 Channel B

1 0 Channel C

1 1 Channel D

LD1 LD0 FUNCTION

0 0 Single channel store. The selected input register is updated.

0 1 Single channel DAC update. The selected DAC register is updated with input register information.

1 0 Single channel update. The selected input and DAC register is updated.

1 1 Depends on the Sel1 and Sel0 Bits