A1

A2

Single-Pole Filter

Capacitor

+2.7 V to +18 V

5 kW

5 kW

96 kW

R

L

PRE OUT

BUF IN

GND

OUT

IN–

IN+

V+

Load

−16 V to +80 V

Supply

R

S

INA270

0.01 µF

0.1 µF

INA270-Q1, INA271-Q1

SBOS401B – JULY 2007 – REVISED FEBRUARY 2010

www.ti.com

APPLICATION INFORMATION

Basic Connection

Figure 1 illustrates the basic connection of the INA270 and INA271. The input pins, IN+ and IN–, should be

connected as closely as possible to the shunt resistor to minimize any resistance in series with the shunt

resistance. Power-supply bypass capacitors are required for stability. Applications with noisy or high-impedance

power supplies may require additional decoupling capacitors to reject power-supply noise. Minimum bypass

capacitors of 0.01 mF and 0.1 mF in value should be placed close to the supply pins. Although not mandatory, an

additional 10-mF electrolytic capacitor placed in parallel with the other bypass capacitors may be useful in

applications with particularly noisy supplies.

Figure 1. INA270 Basic Connections

Power Supply

The input circuitry of the INA270 and INA271 can accurately measure beyond its power-supply voltage, V+. For

example, the V+ power supply can be 5 V, whereas the load power-supply voltage is up to 80 V. The output

voltage range of the OUT terminal, however, is limited by the voltages on the power-supply pin.

Transient Protection

The –16-V to 80-V common-mode range of the INA270 and INA271 is ideal for withstanding automotive fault

conditions ranging from 12-V battery reversal up to 80-V transients, since no additional protective components

are needed up to those levels. In the event that the INA270 and INA271 are exposed to transients on the inputs

in excess of their ratings, external transient absorption with semiconductor transient absorbers (zeners or

Transzorbs) are necessary.

8

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