Adaptive Constant On-Time Buck Converters Based on Frequency Stabilization

This paper proposes an adaptive constant on-time buck converter based on frequency stabilization. By adding a voltage-type frequency-locked loop to the control loop, the proposed converter improves the stability and accuracy of the switching frequency under different load conditions, and is beneficial to the power supply of switching frequency sensitive circuits. In this work, we first convert the switching frequency to voltage, and then stabilize this voltage to a reference voltage, which is used to stabilize the on-time control of the buck converter. Finally, a stable switching frequency is implemented in a wide load range. The technology adopted in this paper is <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\mathbf{0.18} \boldsymbol{\mu}\mathbf{m}$</tex> CMOS process. The experimental simulation results show that the frequency deviation of the proposed converter is within 0.18% with load range changing from 0.1 A to 5 A.