STMicroelectronics UM1036 User Manual page 21

UM1036
The op amp is used in follower mode with gain of the op amp set by resistors:
Equation 5
It is possible to calculate the voltage on the op amp output OP OUT - V
a bias V
BIAS
Equation 6
Total gain of the circuit with the resistor divider is equal to:
Equation 7
With the default values this gives:
●
V
BIAS
●
Maximal voltage of V
●
G = 8.02
●
G
TOT
●
Maximum current amplifiable without distortion is 16 A.
and a signal V
SIGN
V
BI AS
V
SIGN
= 0.38 V
= 2.76 V
SIGN
= 6.90
Doc ID 18293 Rev 1
( ) × 2
r1 + R r
LS
r = --------------------------------------- -
r1 + R + r2
LS
R + r
G
= ----------- -
r
component equal to:
V = V + V
OU T SIGN BIAS
3.3
--------------------------------------------------------- -
=
⎛ ⎞
1 1 1
×
------- - + ------- - + ------- -
⎝ ⎠
R1 R2 R3
×
1 R
H S
--------------------------------------------------------- -
=
⎛ ⎞
1 1 1
×
------- - + ------- - + ------- -
⎝ ⎠
R1 R2 R3
V V
SIGN SI GN
G = --------------- - = ------------------- -
TOT
V R
IN H S
Board description
as the sum of
OUT
×
G
R3
×
G
R1
×
I
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