A Novel Sampling Mechanism for a Digital Average Current-Mode Controlled Buck Converter Under Leading-Edge Modulation

Uniformly sampled digital average current mode control often employs dual-edge modulation to capture the average inductor current accurately. However, this technique fails to capture noise-free samples for converters that operate with a wide range of duty ratio. This happens due to the placement of the sampling clock only at interval-1 or interval-2 for the entire duty ratio range. This paper proposes a novel sampling mechanism that can capture noise-free samples by shifting the sampling clock position. With duty <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$D\geq 0.5$</tex>, the technique will produce the sampling clock in interval-1; otherwise, it will produce the sampling clock in interval-2. Thus, the proposed sampling technique can be used for capturing noise-free samples in converters that operate with a wide range of duty ratios. The proposed mechanism can also be used in other digital average current-mode controlled DC-DC converters.