Tolerance Analysis of a Constant-On Time Current-Mode Voltage Regulator with Adaptive Voltage Position Feature

Voltage regulators (VRs) have been widely used in many computer applications for central processing units (CPUs). In recent years, varieties of constant on-time control schemes have attracted much attention due to its high efficiency under both the light-load and the heavy load condition. In this paper, tolerance analysis was conducted for a constant on-time current-mode buck converter. Three methods are used: root-sum squared analysis (RSS), extreme value analysis (EVA) and Monte Carlo analysis. The effects of practical component tolerance and temperature variation are included in the analysis to estimate the converter output load line which is a critical performance for many applications requiring energy-saving adaptive-voltage-position (AVP) feature. A sensitivity analysis is also conducted to assess the necessity of parameter trimming for the analog power control integrated circuits.