AD5421CREZ-RL7 Ver la hoja de datos (PDF) - Analog Devices

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AD5421CREZ-RL7

16-Bit, Serial Input, Loop-Powered, 4 mA to 20 mA DAC

Analog Devices 

Data Sheet

AD5421

DAC REGISTER

The DAC register is a read/write register and is addressed as

described in Table 12. The data programmed to the DAC register

determines the loop current, as shown in the Ideal Output

Transfer Function section and in Table 16.

Ideal Output Transfer Function

The transfer function describing the relationship between the

data programmed to the DAC register and the loop current is

expressed by the following three equations.

For the 4 mA to 20 mA output range, the loop current can be

expressed as follows:

 16 mA 

I LOOP =  216  × D + 4 mA

For the 3.8 mA to 21 mA output range, the loop current can be

expressed as follows:

I LOOP =

 17.2 mA 

 216 

×D

+

3.8 mA

For the 3.2 mA to 24 mA output range, the loop current can be

expressed as follows:

I LOOP =



20.8 mA

216



×D

+

3.2 mA

where D is the decimal value of the DAC register.

Table 15. DAC Register Bit Map

MSB

LSB

D15 D14 D13 D12 D11 D10 D9

D8

D7

D6

D5

D4

D3

D2

D1

D0

16-bit data

Table 16. Relationship of DAC Register Code to Ideal Loop Current (Gain = 65,536; Offset = 0)

Ideal Loop Current (mA)

DAC Register Code

4 mA to 20 mA Range

3.8 mA to 21 mA Range

0x0000

4

3.8

0x0001

4.00024

3.80026

…

…

…

0x7FFF

11.9997

12.39974

0x8000

12

12.4

…

…

…

0xFFFE

19.9995

20.99947

0xFFFF

19.9997

20.99974

3.2 mA to 24 mA Range

3.2

3.2003

…

13.5997

13.6

…

23.9994

23.9997

Rev. H | Page 27 of 36

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