Apple Inc.
Method and Apparatus for Providing Adaptive Inductor Peak Current in DC-DC Converter

Abstract:

A DC-DC converter providing adaptive peak current control is disclosed. A DC-DC converter includes an inductor having first and second terminals coupled to a voltage source and a transistor, respectively. The DC-DC circuit further includes a control circuit configured to control activation of the transistor. A first control block of the control circuit controls the transistor (and thus the inductor peak current) using pulse frequency modulation (PFM). A second control block controls the transistor using pulse width modulation (PWM) and PFM. In a first mode of operation, the control circuit activates the transistor, using PFM, such that the peak-to-peak current through the inductor has a fixed value. In a second mode of operation, the control circuit activates the transistor such that the peak-to-peak current through the inductor is modulated, using both PWM and PFM.