+IN

-IN

LMP8278

+

-

A1

A2

Internal

Resistor

100 k:

OUT

1

5

3

4

8

Preamplifier

Gain = 7

Output Buffer

Gain = 2

+IN

-IN

LMP8278

+

-

A1

A2

Internal

Resistor

100 k:

OUT

1

5

3

4

8

Preamplifier

Gain = 7

Output Buffer

Gain = 2

LMP8278

www.ti.com

SNAS575A – FEBRUARY 2012 – REVISED MARCH 2013

Figure 22. Reduce Gain

Figure 23. Increase Gain

POWER SUPPLY DECOUPLING

In order to decouple the LMP8278 from AC noise on the power supply, it is recommended to use a 0.1 µF

supply pins. In some cases an additional 10 µF bypass capacitor may further reduce the supply noise.

DRIVING SWITCHED CAPACITIVE LOADS

Some ADCs load their signal source with a sample and hold capacitor. The capacitor may be discharged prior to

being connected to the signal source. If the LMP8278 is driving such ADCs the sudden current that should be

delivered when the sampling occurs may disturb the output signal. This effect was simulated with the circuit

shown in Figure 24 where the output is connected to a capacitor that is driven by a rail to rail square wave.

Copyright © 2012–2013, Texas Instruments Incorporated

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Product Folder Links: LMP8278