INA138-Q1, INA168-Q1

SGLS174G – SEPTEMBER 2003 – REVISED JANUARY 2013

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APPLICATION INFORMATION

current measurement amplifier in this application is:

The maximum differential input voltage for accurate measurements is 0.5 V, which produces a 10

μA output

current. A differential input voltage of up to 2 V does not cause damage. Differential measurements (pins 3 and

4) must be unipolar with a more-positive voltage applied to pin 3. If a more-negative voltage is applied to pin 3,

BASIC CONNECTION

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

could flow in the ground connections, affecting the measurement accuracy.

No power-supply bypass capacitors are required for stability of the INA138-Q1. However, applications with noisy

or high-impedance power supplies may require decoupling capacitors to reject power-supply noise. Connect

bypass capacitors close to the device pins.

POWER SUPPLIES

Q1). The output voltage range of the OUT terminal, however, is limited by the lesser of the two voltages (see

Output Voltage Range section).

shunt voltage range of 50 mV to 100 mV. Maximum input voltage for accurate measurements is 500 mV.

accuracy.

Some analog-to-digital (A/D) converters have input impedances that significantly affects measurement gain. The

resistor to ground. Alternatively, an op amp can be used to buffer the A/D converter input. Figure 9 shows the

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