National Semiconductor LMP8271, LMP8276 Technical data

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PRELIMINARY

LMP8271, LMP8276
High Common Mode, Gain of 20, Bidirectional Precision
Voltage Difference Amplifiers

January 2005

LMP8271,LMP8276 High Common Mode, Gain of 20, Bidirectional Precision Voltage Difference

Amplifiers

General Description

The LMP™8271, LMP8276 are fixed gain differential ampli­fiers 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 specifi­cations 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 sys­tems.

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

Typical Application

Typical Application: Low side Current Sensing

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

20130801

LMP™is a trademark of National Semiconductor Corporation.

© 2005 National Semiconductor Corporation DS201308 www.national.com

Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

ESD Tolerance (Note 2)

Junction Temperature (Note 3) +150˚C max

Soldering Information

Infrared or Convection (20 sec) 235˚C

Wave Soldering Lead Temp. (10

sec) 260˚C

Human Body Model

±

For input pins only

For All other pins

Machine Model 200V

Supply Voltage (V

- GND) 5.75V

S

4000V

±

2000V

Operating Ratings (Note 1)

Temperature Range (Note 3)

Packaged devices(Note 3) -40˚C to +125˚C

Bare Die Junction Temperature(Note

3) -40˚C to +150˚C

CMVR Continuous -5 to 42 Volts

Transient (300 ms) -TBD to 45 Volts

Storage Temperature Range -65˚C to +150˚C

Supply Voltage (V

Package Thermal Resistance (θ

8–Pin SOIC 190˚C/W

–GND) 4.5V to 5.5V

S

(Note 3))

JA

5V Electrical Characteristics (Note 7)

Unless otherwise specified, all limits guaranteed for TA= 25˚C, VS= 5V, GND= 0, -2V≤VCM≤27V. Boldface limits apply at the
temperature extremes.

Symbol Parameter Conditions Min Typ

V

OS

TC V

TC V

A2 I

I

S

Input Offset Voltage VCM= Vs/2

Input Offset Voltage Drift LMP8271

OS

Input Offset Voltage Drift LMP8276

OS

Input Bias Current of A2 (Note 5)

B

Supply Current 0.6

TBD

R

CM

Input impedance Common

160 200 240 KΩ

Mode

R

DM

Input impedance Differential

320 400 480 KΩ

Mode

CMVR Input Common-Mode Voltage

Continuous -2 +27 V

Range

ECMVR Extended Common-Mode

-5 36 V

Voltage Range

DC
CMRR

AC

LMP8271, LMP8276 High Common Mode, Gain of 20, Bidirectional Precision Voltage Difference Amplifier

CMRR

DC Common Mode Rejection
Ratio

AC Common Mode Rejection
Ratio

PSRR Power Supply Rejection Ratio 4.5V≤V

-2V≤V

-5V≤V

-2V≤V

-2V≤V

≤ 27V

CM

≤ 36V

CM

≤ 27V f = 1KHz TBD dB

CM

≤ 27V f = 10KHz TBD

CM

≤ 5.5V TBD

S

80
80

TBD

R

F-INT

TCR

Filter Resistor 97 100 103 KΩ

Filter Resistor Drift TBD ppm/˚C

F-INT

Midscale Offset Scaling
Accuracy (Pin 7)

A

V

Total Gain 20 V/V

Gain Error

Gain Drift

A1 V

A1 Output Voltage Swing RL= 100KΩ on Output VOL 0.01 Volts

OUT

VOH 4.80

A2 V

A2 Output Voltage Swing RL= 100KΩ on Output VOL 0.01 Volts

OUT

VOH 4.80

(Note

±

0.25 1.0 mV

±
±

1.0 1.2

Max Units

4)

6

6

TBD

±

15 µV/˚C

±

30 µV/˚C

±

20 µA

mA

dB

dB

1%

±

1%

±

25 ppm/˚C

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