Output current sensing for DC/DC converter with external power stage
Abstract:
A method for sensing an output current of a Direct Current-to-Direct Current (DC/DC) converter having an external power stage configured to supply a converted current to an external inductor. During a calibration phase at a first start-up of the DC/DC converter: the method includes injecting a calibration current through a switching node of the power stage and through the inductor; and determining a calibration gain of the DC/DC converter to compensate for DC Resistance (DCR) variation by comparing a gain-adjusted voltage across the inductor with a reference voltage. During a measurement phase, the method includes reducing ripple voltage of a switching voltage at the switching node to generate a ripple-reduced switching voltage; and sensing the output current based on a DCR-compensated voltage across the inductor, which is a difference between the ripple-reduced switching voltage and an output voltage of the DC/DC converter with compensation for the DCR variation based on the calibration gain.
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