An inductor current sensing technique for digital controllers

Abstract

This paper explains a current sensing technique suitable for digital controller implementation. The technique uses only one analog comparator to estimate the DC as well as ripple of the inductor current of a regulated DC-DC converter. For systems where input voltage variation is anticipated, a low speed ADC can be used to take care of the variation in input voltage for inductor current estimation. The proposed technique is experimentally demonstrated for buck and boost converters and can be easily extended for other converters. A lab prototype proves the operation of the sensing technique using a DSP (TMS-F28335) based digital voltage mode control. The verification of the proposed method to implement hysteretic current mode control using PSPICE simulation is also provided to validate its effectiveness.