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8.2.2 Detailed Design Procedure

The maximum value of the current-sense resistor is calculated based on choice of gain, value of the maximum

current the be sensed (IMAX), and the power-supply voltage (VS). When operating at the maximum current, the

output voltage must not exceed the positive output swing specification, VSP. Using Equation 6, for the given

design parameters the maximum value for RSENSE is calculated to be 1.321 kΩ.

SENSE

MAX

GAIN

(6)

However, because this value exceeds the maximum recommended value for RSENSE, a resistance value of 1

kΩ must be used. When operating at the minimum current value, IMIN the output voltage must be greater than

the swing to GND (VSN), specification. For this example, the output voltage at the minimum current is calculated

using Equation 7 to be 25 mV, which is greater than the value for VSN.

OUTMIN

MIN

SENSE

GAIN

(7)

8.2.3 Application Curve

Figure 8-7 shows the output of the device under the conditions given in Table 8-1 and with RSENSE = 1 kΩ.

Input Current (µA)

100

125

150

0.5

1.5

2.5

3.5

D031

Figure 8-7. Typical Application DC Transfer Function

9 Power Supply Recommendations

The input circuitry of the INA186-Q1 accurately measures beyond the power-supply voltage, VS. For example,

VS can be 5 V, whereas the bus supply voltage at IN+ and IN– can be as high as 40 V. However, the output

voltage range of the OUT pin is limited by the voltage on the VS pin. The INA186-Q1 also withstands the full

differential input signal range up to 40 V at the IN+ and IN– input pins, regardless of whether the device has

power applied at the VS pin. There is no sequencing requirement for VS and VIN+ or VIN–.

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INA186-Q1

SBOS386B – MAY 2019 – REVISED MARCH 2022

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INA186 Datasheet(PDF) 23 Page - Texas Instruments