Data Sheet

AD5791

Rev. E | Page 21 of 27

Table 9. Hardware Control Pins Truth Table

LDAC

CLR

RESET

Function

0

The AD5791 is in reset mode. The device cannot be programmed.

The AD5791 is returned to its power-on state. All registers are set to their default values.

0

0

1

The DAC register is loaded with the clearcode register value and the output is set accordingly.

0

1

1

The output is set according to the DAC register value.

1

0

1

The DAC register is loaded with the clearcode register value and the output is set accordingly.

1

1

The output is set according to the DAC register value.

0

1

The output remains at the clear code value.

1

1

The output remains set according to the DAC register value.

0

1

The output remains at the clear code value.

1

1

The DAC register is loaded with the clearcode register value and the output is set accordingly.

0

1

The DAC register is loaded with the clearcode register value and the output is set accordingly.

1

1

The output remains at the clear code value

0

1

The output is set according to the DAC register value.

1

X is don’t care.

ON-CHIP REGISTERS

DAC Register

Table 10 outlines how data is written to and read from the DAC register.

Table 10. DAC Register

MSB

LSB

DB23

DB22

DB21

DB20

DB19

DB0

R/W

Register address

DAC register data

R/W

0

0

1

20-bits of data

The following equation describes the ideal transfer function of the DAC:

(

)

REFN

REFN

REFP

OUT

V

D

V

V

V

+

−

×

−

=

1

where:

D is the 20-bit code programmed to the DAC.