Based on digital controllers offering significant advantages in DC-DC converters, this paper proposes a digital PWM controller for single-inductor dual-output (SIDO) switching converter operating in discontinuous-conduction mode (DCM). By adopting time-multiplexing (TM) scheme, this converter provides two independent supply voltages using only one inductor, which is suitable for portable devices and system-on-chip (SoC) integration. All design issues of each block including analog-to-digital converter (ADC), digital compensator and digital pulse width modulator (DPWM) are discussed. To save chip area, single look-up table based compensator and modified hybrid DPWM are developed. Simulation results are shown to verify the validity of the proposed work.