5 k

5 k

VIN+

VIN±

OUT

V+

GND

5 k

5 k

VIN+

VIN±

OUT

V+

GND

100 m

+

INA138

or

INA168

INA138

or

INA168

1N4148

1N4148

10 k

10 k

100 k

Sign

Output

TLV3201

+5 V

+5 V

Bus

Voltage

Load

Current

RSH

±1 A

Load Curent

15

INA138, INA168

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SBOS122E – DECEMBER 1999 – REVISED DECEMBER 2017

Product Folder Links: INA138 INA168

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Copyright © 1999–2017, Texas Instruments Incorporated

Typical Applications (continued)

8.2.4 Bipolar Current Measurement

The INA1x8 devices can be configured as shown in Figure 15 in applications where measuring current bi-

directionally is required. Two INA devices are required connecting their inputs across the shunt resistor as shown

in Figure 15. A comparator, such as the TLV3201, is used to detect the polarity of the load current. The

magnitude of the load current is monitored across the resistor connected between ground and the connection

labeled Output. In this example the 100-kΩ resistor results in a gain of 20 V/V. The 10-kΩ resistors connected in

series with the INA1x8 output current are used to develop a voltage across the comparator inputs. Two diodes

are required to prevent current flow into the INA1x8 output, as only one device at a time is providing current to

the Output connection of the circuit. The circuit functionality is illustrated in Figure 16.

Figure 15. Bipolar Current Measurement