All-digital DPWM/DPFM controller for low-power DC-DC converters

A digital controller for dc-dc switching converters used in battery-powered handheld devices is introduced. The controller can operate in two modes and encompasses designs of a digital pulse-width modulator (DPWM) and an all-digital pulse-frequency modulator (DPFM). The DPWM has a high resolution and can operate at very-high constant switching frequency (tens of MHz). The DPFM features very-low power consumption, programmable on-time and control over switching frequency range. An experimental FPGA prototype and an application-specific IC that employ controller architecture are built around 3.3 V, 3W, 6 MHz buck power stage and successful operation of the digital controller in both modes is verified. The low power consumption has been also verified on a chip implemented in a standard CMOS 0.18/spl mu/m process.