On the Benefit of Adopting Saturable Inductors in Switching-Mode Power-Supplies: A Case Study

We follow up with recent proposals of using inductors working in weak and deep-saturation region to improve the features of switching mode power supplies. To this aim, we use a constant on-time (COT) converter including a saturable inductor as a test vehicle. The inductor model takes into account both hysteresis and dependence on the working temperature of the core and windings. The digital controller of the COT converter is considered too. Electro-thermal simulations are performed to analyse the performances of the overall analog mixed-signal circuit. It is shown that using a proper saturable inductor positively impacts on the design of the converter by mitigating its main drawback of having a working frequency largely dependent on the load conditions and input supply voltage. Some weak points of proposed design are also identified.