Datasheet
Data Sheet AD5421
Rev. G | Page 31 of 36
Transfer Function Equations with Offset and Gain Adjust
Values
When the offset adjust and gain adjust register values are taken
into account, the transfer equations can be expressed as follows.
For the 4 mA to 20 mA output range, the loop current can be
expressed as follows:
×
×
= D
Gain
I
LOOP
16
16
2
2
mA16
( )
−×
++ 768,32
2
mA16
mA4
16
Offset
For the 3.8 mA to 21 mA output range, the loop current can be
expressed as follows:
×
×
= D
Gain
I
LOOP
16
16
2
2
mA2.17
( )
−×
++ 768,32
2
mA2.17
mA8.3
16
Offset
For the 3.2 mA to 24 mA output range, the loop current can be
expressed as follows:
×
×
= D
Gain
I
LOOP
16
16
2
2
mA8.20
( )
−×
+
+ 768,32
2
mA8.20
mA2
.
3
16
Offset
where:
D is the decimal value of the DAC register.
Gain is the decimal value of the gain adjust register.
Offset is the decimal value of the offset adjust register.
Note that the offset adjust register cannot adjust the zero-scale
output value downward.