7.4 Device Functional Modes

7.4.1 Unidirectional Operation

The INAx290 measures the differential voltage developed by current flowing through a resistor that is commonly

referred to as a current-sensing resistor or a current-shunt resistor. The INAx290 operates in unidirectional mode

only, meaning it only senses current sourced from a power supply to a system load as shown in Figure 7-3.

+

±

Buffer

Current

Feedback

RL

R1

R1

Bias

48-V

Supply

Load

IN+

IN±

5 V

OUT

GND

Figure 7-3. Unidirectional Application (Single Channel Device)

The linear range of the output stage is limited to how close the output voltage can approach ground under zero-

input conditions. The zero current output voltage of the INAx290 is very small, with a maximum of GND + 25 mV.

Make sure to apply a sense voltage of (25 mV / Gain) or greater to keep the INAx290 output in the linear region

of operation.

7.4.2 High Signal Throughput

With a bandwidth of 1.1 MHz at a gain of 20 V/V and a slew rate of 2 V/µs, the INAx290 is specifically designed

for detecting and protecting applications from fast inrush currents. As shown in Table 7-2, the INAx290 responds

in less than 2 µs for a system measuring a 75-A threshold on a 2-mΩ shunt.

Table 7-2. Response Time

PARAMETER

EQUATION

INAx290

G

Gain

20 V/V

Maximum current

100 A

Threshold current

75 A

Current sense resistor value

2 mΩ

Output voltage at maximum current

4 V

Output voltage at threshold current

3 V

SR

Slew rate

2 V/µs

Output response time

< 2 µs

INA290, INA2290

SBOS961B – JUNE 2020 – REVISED DECEMBER 2020

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