2.5V step-down DCDCs: a radiation-hard solution for power conversion

Radiation- and magnetic field tolerant DCDC converters that step down the voltage from a 2.5 V bus are needed for the High-Luminosity detectors. This work presents the developed prototypes, based on ASICs designed in a 130 nm CMOS technology. A buck converter (bPOL2V5) is close to production readiness, showing an 89.7% peak efficiency and tolerance to 200 Mrad of Total Ionizing Dose (TID) and to a fluence of 10$^{16}$ n/cm$^2$ . A lower-volume alternative to bPOL2V5 (called rPOL2V5) uses a resonant switched-capacitor architecture and shows comparable efficiency, while employing an eight times smaller inductor. The first prototype of rPOL2V5 has shown tolerance to more than 200 Mrad of TID. For both converters, the ASIC and the PCB have been co-designed to guarantee high reliability.