000-0046140-111
Page 67 of 169
SLG46140
V
inn
and V
inp
- absolute voltage at negative and positive PGA input correspondingly
V
cm
- common mode PGA voltage:
Note: In Pseudo-Differential mode V
cm
is replaced by V
inn
voltage for convenience
ADC code for PGA differential input voltage V
ind
can be calculated as follows:
•
Single-ended mode:
V
ind
= V
inp
Vinp[min] and Vinp[max] - positive input voltage for bit0 and bit255 correspondingly (can be found in ADC specifications)
•
Differential and Pseudo-Differential mode:
V
ind[min]
and V
ind[max]
- differential input voltage for bit0 and bit255 correspondingly (can be found in ADC specifications)
Least significant bit size (LSB) calculates as follows:
where FS is full-scale range:
FS = V
ind[max]
- V
ind[min]
V
cm
V
inn
V
inp
+
2
----------------------------
=
ADC
code
255
V
inp max
V
inp min
–
----------------------------------------------------- V
inp
V
inp min
–
=
ADC
code
255
V
ind max
V
ind min
–
----------------------------------------------------- Vind Vind min
–
=
LSB
FS
255
---------
=