Datasheet

Data Sheet AD5791
Rev. D | Page 21 of 28
Table 9. Hardware Control Pins Truth Table
LDAC CLR RESET
Function
X
1
X
1
0 The AD5791 is in reset mode. The device cannot be programmed.
X
1
X
1
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
REFNREFP
OUT
V
DVV
V +
−
×−
=
12
20
where:
V
REFN
is the negative voltage applied at the V
REFN
input pins.
V
REFP
is the positive voltage applied at the V
REFP
input pins.
D is the 20-bit code programmed to the DAC.