Resource-constrained but widely deployed IoT devices require a new approach to ensure secure and reliable communications. That is why, in recent years, the paramount effort has been applied in lightweight cryptography. Because of its unpredictable nature, chaos is regarded as a potential candidate in cryptographic applications. Chaos mode of operation is observed not only in deliberately designed oscillators but also in switching DC-DC converters, which are part of almost every embedded design. The use of a built-in chaos source may improve performance, energy consumption, PCB area, and cost of IoT devices. In this research, the regions of robust chaos were identified using numerical analysis, and the performance of a real buck DC-DC converter under peak-current-mode control was studied experimentally. It was shown that a compensating ramp acts as a switch between different operating regimes. Despite minor performance degradation, chaos mode can be used for secure communications in IoT networks.