+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

100 k:

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

Copyright © 2008–2013, Texas Instruments Incorporated

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