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INA223EVM Software Overview

It is important to note that valid bus voltage and shunt voltage measurements must be within the linear

range of the device in order for the INA223 to correctly calculate power using Equation 1.

POWER = V

OUT

/ Power

GAIN

× R

SHUNT

(1)

Where V

OUT

is calculated based on Equation 2:

OUT

= V

× V

SENSE

× Power

GAIN

(2)

and Power

GAIN

valuse are shown in Table 5.

Table 5. Power Gain Values

Bus Voltage Gain Shunt Voltage Gain Power

GAIN

1/10 20 0.667

1/10 128 4.267

1/10 300 10

1/5 20 1.333

1/5 128 8.533

1/5 300 20

2/5 20 2.667

2/5 128 17.067

2/5 300 40

The remaining two configurations, Bus Voltage and Shunt Voltage, measure the bus voltages at the VIN-

pin and the shunt voltage developed directly across the shunt resistor, respectively. The actual output

voltage of either measurement is based on the input voltage multiplied by the corresponding gain settings,

as shown in sections Section 5.2.3 and Section 5.2.4.

NOTE: For maximum accuracy, select a gain that gives a full-scale voltage, just below the maximum

output voltage.

SBOU125–June 2012 INA223EVM User’s Guide and Software Tutorial

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