Maximum Differential - B&B Electronics 4 Channel Input Buffer Board SDAIBB Product Manual

Maximum Differential

To determine the maximum differential voltage that can be
amplified, the gain and the common mode voltage must be known first.
Using this information, the most positive the differential voltage may be is
calculated using Equation 12. Equation 13 is used to calculate the most
negative that the differential voltage may swing. These two values are still
limited by the maximum allowable swing given by Equation 14.
Equation 12:
Equation 13:
Equation 14:
Example: Find the allowable swing of a signal with a common mode
voltage of 1V with a gain of 50.
From Equation 12:
From Equation 13:
From Equation 14:
The differential voltage can swing as negative as –0.0636 V and as positive
as 0.136 V. However, this full range cannot be achieved with the same
output offset setting due to the 0.0988 V range from Equation 14. To find
the output offset voltage that allows the lower end of this range, use
Equation 1 with Vout set to 0.01 V.
V
out
Rearranged to calculate the desired output offset it looks like this
OutputOffs
Substitute in the appropriate values and solve for the output offset.
OutputOffs
14
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V
DIFF
V
DIFF
InputRange
V
DIFF
V
DIFF
InputRange
IN IN G OutputOffs
et V V
out DIFF
et . 0 01
2 4 4 . V
CM
G
2 V . 0 590
CM
G
. 4 94 V
G
2 4 4 . 1
. 0
50
2 1 . 0 590
. 0
50
. 4 94
50
et
G
. 0 0636 50 . 3 19
V
136
0636
. 0 0988
V
SDAIBB1300 Manual