The current and charge are calculated from the voltage drop measured across the internal resistive element, while the power and energy are calculated after a bus voltage measurement. Power and energy are calculated based on the previous current calculation and the latest bus voltage measurement.

The current, bus voltage, and temperature values are immediate results when the number of averages is set to 1 (see Figure 6-7). However, when averaging is used, each ADC measurement is an intermediate result which is stored in the corresponding averaging registers. Following every ADC sample, the newly-calculated values for current, voltage, and temperature are appended to the corresponding averaging registers until the set number of averages is achieved. After all of the samples have been measured, the average current and voltage is determined, the power is calculated, and the results are loaded to the corresponding output registers where the results can then be read.

The energy and charge values are accumulated for each conversion cycle. Therefore the INA745x averaging function is not applied to these.

Calculations for power, charge and energy are performed in the background and do not add to the overall conversion time.

Figure 6-7 Power, Energy and Charge Calculation Scheme