This document discusses, among other things, apparatus and methods for controlling a converter. In an example, a voltage-controlled oscillator (VCO) can be configured to provide a first pulse train to control the converter. The frequency of the first pulse train of the VCO can be modulated using information indicative of an operating condition of the converter to maintain a desired DC voltage at an output. In an example, the VCO can include a frequency divider configured to provide a second pulse train to the output using information from the first pulse train.