Datasheet

R
r
+IN
-IN
+
-
Preamplifier
Output Buffer
Gain = K2
A1
A2
Gain = 10
OFFSET
Internal
Resistor
100 k:
OUT
Level
shift
1
5
3 4
7
8
OUT
+
-
Preamplifier
+IN
-IN
Output Buffer
Gain = K2
A1 A2
Gain = K1
OFFSET
Internal
R
1
100 k:
C
2
C
1
R
2
8
1
3 4
5
7
Level
shift
LMP8601, LMP8601-Q1
www.ti.com SNOSAR2E –SEPTEMBER 2008–REVISED MARCH 2013
Note that the frequency response achieved using this procedure will only be accurate if the cut-off frequency of
the second order filter is much smaller than the intrinsic 60 kHz low-pass filter. In other words, to have the
frequency response of the LMP8601/LMP8601Q circuit chosen such that the internal poles do not affect the
external second order filter.
K1 = 10, K2 = 2
Figure 34. Second Order Low Pass Filter
GAIN ADJUSTMENT
The gain of the LMP8601/LMP8601Q is 20; however, this gain can be adjusted as the signal path in between the
two internal amplifiers is available on the external pins.
Reduce Gain
Figure 35 shows the configuration that can be used to reduce the gain of the LMP8601/LMP8601Q.
K2 = 2
Figure 35. Reduce Gain
R
r
creates a resistive divider together with the internal 100 kΩ resistor such that the reduced gain G
r
becomes:
Copyright © 2008–2013, Texas Instruments Incorporated Submit Documentation Feedback 15
Product Folder Links: LMP8601 LMP8601-Q1