SBOA103C
Jan 2006
PGA309 Quick Start
System Reference Guide
87
PGA309 With Output Scaling
(0 to 10V)
This calculation shows how
the example configuration
shown on the previous page
can be used to take the 0.5V
to 4.5V output of the PGA309
and re-scale it to 0V to 10V.
This equation must be broken
down into an “ExtraGain” and
“ExtraOffset” factor for the
spreadsheet.
ExtraOffset
0.5
−
=
ExtraOffset
Rf
−
10 10
3
⋅
:=
ExtraGain 2.5
=
ExtraGain
Rf
R1
Rf
R2
+
1
+
:=
For the spreadsheet you need to break the function into "extra gain" and "extra
offset" as shown below.
Rf 5000.
Substitute the value of R2 into
equation 2 to solve for Rf
R2 5000.
Substitute equation 2 into
equation 3 and solve for R2
Equation 3: Vin=4.5V, Vo = 10V
10
Rf
10 10
3
⋅
Rf
R2
+
1
+
4.5
⋅
Rf
10 10
3
⋅
2.5
⋅
−
Equation 2: solve Equation 1 for Rf
Rf 2500.
R2
R2 2500.
−
⋅
Equation 1: Vin = 0.5V, Vo = 0V
0
Rf
10 10
3
⋅
Rf
R2
+
1
+
0.5
⋅
Rf
10 10
3
⋅
2.5
⋅
−
R1 10 10
3
⋅
:=
Let
