LMP8271, LMP8276

High Common Mode, Gain of 20, Bidirectional Precision

Voltage Difference Amplifiers

General Description

fiers with a -2V to 27V input common mode voltage range

and a supply voltage range of 4.5V to 5.5V. The LMP8271,

LMP8276 are precision amplifiers which will detect, amplify

and filter small differential signals in the presence of high

common mode voltages. The gain is fixed at 20 and is

adequate to drive an ADC to full scale in most cases. This

fixed gain is achieved in two separate stages, a pre-amplifier

with gain of +10 and a second stage amplifier with a gain of

+2. The internal signal path is brought out on two pins that

provide a connection for a filter network.

The LMP8271, LMP8276 will function with reduced specifi-

cations over the extended common mode input voltage

range of -5 to 36 Volts. This feature makes the device

suitable for applications with load dump in automotive sys-

tems.

The midrail offset adjustment pin enables the user to utilize

this device for bidirectional current sensing. This is achieved

by adjusting an externally set voltage reference. Accurate

bidirectional load current measurements are achieved when

monitoring the output with respect to this reference voltage

Features

n

Bidirectional Current Sense Capability

n

Typical Values, TA = 25˚C

n

Input Offset Voltage

1mV max

n

TCVos (LMP8271)

15µV/˚C max

n

TCVos (LMP8276)

30µV/˚C max

n

CMRR

80dB Min

n

Extended CMVR

-5V to 36V

n

Output Voltage Swing

Rail to Rail

n

Bandwidth

80KHz

n

Operating Temperature Range (Ambient) -40˚C to 125˚C

n

Operating Temperature Range (bare die) -40˚C to 150˚C

n

Supply Voltage

4.5V to 5.5V

n

Supply Current

1mA

Applications

n

Fuel Injection Control

n

Low Side Driver Configuration Current Sensing

n

Power Management Systems

Typical Application

Typical Application: Low side Current Sensing

20130801

PRELIMINARY

January 2005

© 2005 National Semiconductor Corporation

DS201308

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