INA138, INA168

SBOS122D – DECEMBER 1999 – REVISED DECEMBER 2014

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Typical Applications (continued)

Figure 14. Offsetting the Output Voltage

8.2.4 Bipolar Current Measurement

The INA138 or INA168 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-k

Ω resistor results in a gain of 20 V/V. The 10-kΩ resistors connected in

series with the INA138 or INA168 output current are used to develop a voltage across the comparator inputs.

Two diodes are required to prevent current flow into the INA138 or INA168 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.

14

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