Max_Current=Current_LSB

32767

´

Max_Current=0.06226

(15)

Max_ShuntVoltage=Max_Current_Before_Overflow

R

´

SHUNT

Max_ShuntVoltage=0.3113

(16)

MaximumPower=Max_Current_Before_Overflow

V

´

BUS_MAX

MaximumPower=1.992

(17)

Corrected_Full_Scale_Cal=trunc

Cal

MeasShuntCurrent

INA219_Current

´

Corrected_Full_Scale_Cal=3462

(18)

INA219

7. Compute the maximum current and shunt voltage values (before overflow), as shown by Equation 15 and

Equation 16. Note that both Equation 15 and Equation 16 involve an If - then condition.

If Max_Current

≥ Max Possible_I then

Max_Current_Before_Overflow = MaxPossible_I

Else

Max_Current_Before_Overflow = Max_Current

End If

(Note that Max_Current is less than MaxPossible_I in this example.)

Max_Current_Before_Overflow = 0.06226 (Note: This result is displayed by software as seen in Figure 22.)

If Max_ShuntVoltage

Else

Max_ShuntVoltage_Before_Overflow= Max_ShuntVoltage

End If

Max_ShuntVoltage_Before_Overflow = 0.3113 (Note: This result is displayed by software as seen in

Figure 22.)

8. Compute the maximum power with equation 8.

9. (Optional second calibration step.) Compute the corrected full-scale calibration value based on measured

current.

INA219_Current = 0.06226

MeaShuntCurrent = 0.05

Figure 22 illustrates how to perform the same procedure discussed in this example using the automated

INA219EVM software. Note that the same numbers used in the nine-step example are used in the software

example in Figure 22. Also note that Figure 22 illustrates which results correspond to which step (for

example, the information entered in Step 1 is enclosed in a box in Figure 22 and labeled).

Copyright © 2008, Texas Instruments Incorporated

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