Data Sheet

AD5761/AD5721

Rev. C | Page 27 of 31

Table 19. Readback DAC Register, 24-Bit Data Read from SDO Pin

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB18

DB17

DB16

DB15 to DB0

0

Register address

Register data

0

1011

Data read from DAC register

1

X means don’t care.

WRITE AND UPDATE DAC REGISTER

The write and update DAC register (Register Address 0011) updates the input register and the DAC register with the entered data-word

from the input shift register, irrespective of the state of LDAC.

Setting the register address to 0001 writes the input register with the data from the input shift register, clocked in MSB first on the SDI

pin.

Table 20. Write and Update DAC Register

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB18

DB17

DB16

DB15 to DB0

0

Register address

Register data

0

0001

Data loaded

0

0011

Data loaded

1

X means don’t care.

READBACK INPUT REGISTER

The readback input register operation provides the contents of the input register by setting the register address to 1010. Table 21 outlines

the 24-bit shift register for this command. During the next command, the input register contents are shifted out of the SDO pin with MSB

shifted out first. Table 22 outlines the 24-bit data read from the SDO pin, where DB23 is the first bit shifted out.

Table 21. Read Back Input Register, 24-Bit Shift Register to the SDI Pin

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB18

DB17

DB16

DB15 to DB0

0

Register address

Register data

0

1010

Don’t care

1

X means don’t care.

Table 22. Readback Input Register, 24-Bit Data Read from the SDO Pin

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB18

DB17

DB16

DB15 to DB0

0

Register address

Register data

0

1010

Data read from input register

1

X means don’t care.

DISABLE DAISY-CHAIN FUNCTIONALITY

The daisy-chain feature can be disabled to save the power consumed by the SDO buffer when this functionality is not required (see Table 23).

When disabled, a readback request is not accepted because the SDO pin remains in tristate.

Table 23. Disable Daisy-Chain Functionality Register

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB18

DB17

DB16

DB15 to DB1

DB0

0

Register address

Register data

0

1001

Don’t care

DDC

1

X means don’t care.