The PWM DC-DC converter in continuous conduction mode underhysteretic control is modeledand analyzed using the sampled-data approach.This workcomplements other recent work of the authors onsampled-datamodeling and analysis of PWM converters,where the focus was on fixed switching frequency operation.Nonlinear and linearized sampled-data models, andthe control-to-output transfer function are derived.The analysis is exact if the source and reference signals areconstant (or constant within each cycle).