INA138-Q1

INA138-Q1

ADC programmed for differential input.

Depending on polarity of current, one INA138-Q1 provides

an output voltage, and the output of the other device is zero.

5 V

5 V

12-Bit

ADC

Mux

5 V

R

25 kΩ

L

R

S

R

25 kΩ

L

V

IN–

GND

V

IN+

V

IN–

V

IN+

GND

OUT

OUT

17

INA138-Q1, INA168-Q1

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SGLS174J – SEPTEMBER 2003 – REVISED AUGUST 2018

Product Folder Links: INA138-Q1 INA168-Q1

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Copyright © 2003–2018, Texas Instruments Incorporated

8.2.5 Bipolar Current Measurement Using Differential Input of an ADC

Use the INA1x8-Q1 with an ADC such as the ADS7870 programmed for differential-mode operation; Figure 17

shows this configuration. In this configuration, the use of two INA138-Q1s or INA168-Q1s allows for bidirectional

current measurement. Depending on the polarity of the current, one of the INA devices provides an output

voltage, while the other INA device output is zero. In this way, the ADC reads the polarity of current directly,

without the need for additional circuitry.

Figure 17. Bipolar Current Measurement Using Differential Input of the ADC