数字电源电流校准

　　A major benefit of digital power solutions is the ability to read the actual load current in real time over the power management bus （PMBus）。 The load current measurement is possible with knowledge of the current-sense element’s impedance. The current measurement’s accuracy is a function of many parameters such as board parasitics， the measurement component’s tolerance， and the IC’s internal gains and offsets. If the variations in these parameters are not accounted for， the measured load current will not be as accurate as one might expect. Fortunately， the PMBus specification provides two calibration coefficients， IOUT_CAL_GAIN and IOUT_CAL_OFFSET （collectively referred to as IOUT_CAL values）， which allow the user to calibrate out the parameters that affect the current measurement’s accuracy. Every InTune IC is shipped with default values for these coefficients. These values must be calibrated to provide accurate output current measurements.