In this paper, a single-inductor dual-input dual-output (SIDIDO) power converter with sequential pulse-skip modulation (SPSM) is proposed for IoT applications. It manages power from a 1.4-V zinc-air battery and a 0.55-V to 0.7-V photovoltaic (PV) module to prolong the battery life. The proposed converter employs buck-boost mode and buck mode for PV module and the battery, respectively, to produce two different output voltages. The input sources are automatically selected by mode detection circuit which monitors both PV voltage and the output voltage to minimize the battery usage. The proposed SPSM along with a constant voltage maximum power point tracking (MPPT) method controls output voltages with low cross regulation while extracting the maximum power from a PV module. The measurement results demonstrate a peak efficiency of 89 % with an available input voltage of 0.55 V to 1.4 V.