Datasheet

R
i
= 400 k:X
G
i
- 50
G
i
G
i
=
R
i
- 900 k:
100 R
i
G
i
=
R
i
- 400 k:
50 R
i
2R
r
+IN
-IN
+
-
Preamplifier
Gain = 10
Output Buffer
Gain = K2
A1
A2
OFFSET
Internal
Resistor
100 k:
OUT
Level
shift
1
5
3 4
7
8
2R
r
V
X
= OFFSET
R
r
= 100 k:x
100 - G
r
G
r
R
r
= 100 k:X
50 - G
r
G
r
G
r
=
R
r
+ 100 k:
100 R
r
LMP8602, LMP8602Q, LMP8603, LMP8603Q
SNOSB36D –JULY 2009–REVISED MARCH 2013 www.ti.com
For the LMP8603:
(18)
Given a desired value of the reduced gain G
r
, using this equation the required value for R
r
can be calculated for
the LMP8602 with:
(19)
and for the LMP8603 with:
(20)
Figure 45 shows the configuration that can be used to reduce the gain of the LMP8602 and the LMP8603 in
bidirectional sensing applications. The required value for R
r
can be calculated with the equations above. The
maximum mid-scale offset scaling accuracy of the LMP8602 is ±1% and the maximum mid-scale offset scaling
accuracy of the LMP8603 is ±1.5%. The pair of resistors selected have to match much better than 1% and 1.5%
to prevent a significant error contribution to the offset voltage.
Figure 45. Reduce Gain for Bidirectional Application
Increase Gain
Figure 46 shows the configuration that can be used to increase the gain of the LMP8602/ LMP8602Q/ LMP8603/
LMP8603Q.
R
i
creates positive feedback from the output pin to the input of the buffer amplifier. The positive feedback
increases the gain. The increased gain G
i
for the LMP8602 becomes:
(21)
and for the LMP8603:
(22)
From this equation, for a desired value of the gain, the required value of R
i
can be calculated for the LMP8602
with:
(23)
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Product Folder Links: LMP8602 LMP8602Q LMP8603 LMP8603Q