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
.
POWER = V
OUT
/ Power
GAIN
× R
SHUNT
(1)
Where V
OUT
is calculated based on
V
OUT
= V
CM
× V
SENSE
× Power
GAIN
(2)
and Power
GAIN
valuse are shown in
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
and
NOTE:
For maximum accuracy, select a gain that gives a full-scale voltage, just below the maximum
output voltage.
17
SBOU125 – June 2012
INA223EVM User’s Guide and Software Tutorial
Copyright © 2012, Texas Instruments Incorporated