INA139Q1,INA169Q1

SGLS185B − SEPTEMBER 2003 − REVISED OCTOBER 2004

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VOLTAGE GAIN

EXACT RL (Ω)

NEAREST 1% RL (Ω)

1

2

5

10

20

50

100

1k

2k

5k

10k

20k

50k

100k

1k

2k

4.99k

10k

20k

49k

100k

2

1

8

4

6

Figure 1. Basic Circuit Connections

BASIC CONNECTION

important in high-current systems where load current could flow in the ground connections, affecting the measurement accuracy.

No power-supply bypass capacitors are required for stability of the INA139. 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

The input circuitry of the INA139 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 +36 V (or +60 V with the INA169). However, the output voltage range

of the OUT terminal is limited by the lesser of the two voltages (see the Output Voltage Range section).

for accurate measurements is 500 mV.

Some Analog-to-Digital (A/D) converters have input impedances that will significantly affect measurement gain. The input

Alternatively, an op amp can be used to buffer the A/D converter input as shown in Figure 2. See Figure 1 for recommended values