Dynamic duty-cycle limitation of the boost DC/DC converter allowing maximal output power operations

This paper describes the concept of the dynamic duty-cycle limiter of the boost dc-dc converter. Duty-cycle limitation in boost converters is usually used to protect the bottom switch against an excessive current, and also to avoid instability occurring at high duty-cycle operations. Compared to fixed limitation, dynamic limiter enables to detect and maintain maximal possible output voltage V_MAX, when desired output voltage cannot be provided e.g. due to excessive load current or increased resistance of the switches. This feature allows to extend the operation range of the converter and powered device. Developed method applies to low power converters, and it is based on the power balance condition detection circuit. This detection is realized via simple and low consumption voltage sensing. Paper presents description of the method, circuit implementation and shows simulated results obtained with integrated 0.13μm CMOS boost dc-dc converter.