5V Electrical Characteristics (Note 7) (Continued)

Unless otherwise specified, all limits guaranteed for T

≤V

CM

≤27V. Boldface limits apply at the

temperature extremes.

Symbol

Parameter

Conditions

Min

Typ

(Note

4)

Max

Units

SR

Slew Rate (Note 6)

0.7

V/µs

BW

Bandwidth

80

KHz

Noise

0.1Hz ro 10Hz

TBD

µVpp

Spectral Density

TBD

nV/

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is

intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics Tables.

Note 2: Human body model, 1.5 k

Ω in series with 100 pF. Machine model: 0Ω in series with 200 pF.

Note 4: Typical values represent the most likely parametric norm.

Note 5: Positive current corresponds to current flowing into the device.

Note 6: Slew rate is the average of the rising and falling slew rates.

Note 7: Electrical table values apply only for factory testing conditions at the temperature indicated. Factory testing conditions result in very limited self-heating of

the device.

Connection Diagram

8–Pin SOIC

20130802

Top View

Application Note

The LMP8271, LMP8276 are single supply amplifier with a

fixed gain of 20 and an extended common mode voltage

range of -2V to 36V. The fixed gain is achieved in two

separate stages, a pre-amplifier with gain of +10 and a

second stage amplifier with gain of +2. A block diagram of

the LMP8271, LMP8276 is shown in Figure 1.

The overall offset of the LMP8271, LMP8276 is minimized by

trimming amplifier A1. This is done so that the output re-

ferred offset of A1 cancels the input referred offset of A2 or

10V

Because of this offset voltage relationship, the offset of each

individual amplifier stage maybe more than the limit speci-

fied for the overall system in the datasheet tables. Care must

be given when pin 3 and 4, A1 and A2, are connected to

each other. If the signal going from A1 to A2 is amplified or

attenuated (by use of amplifiers and resistors), the overall

LMP8271, LMP8276 offset will be affected as a result. Fil-

tering the signal between A1 and A2 or simply connecting the

two pins will not change the offset of the LMP8271,

LMP8276.

Referencing input referred offset voltages, the following re-

lationship holds:

If the signal on pin 3 is scaled, attenuated or amplified, by a

factor X then the offset of the overall system will become:

20130803

FIGURE 1.

www.national.com

3