A DIGITAL CONTROLLER FOR DC-DC SWITCHING CONVERTERS THAT ALLOWS OPERATION AT ULTRA-HIGH CONSTANT SWITCHING FREQUENCIES

摘要

A digital controller for low-power DC-DC switch mode power supplies (SMPS)suitable for on-chip implementation and use in portable battery-poweredsystems isprovided. The digital controller allows operation at relatively high constantswitchingfrequencies and can be implemented with a simple low-power digital hardware.Thedigital controller includes a digital pulse width modulator (DPWM), based on amulti-bit sigma-delta (.SIGMA.-.DELTA.) principle, and a dual-sampling mode PIDcompensator. Theoutput voltage is either sampled at a frequency lower than the switchingfrequency(undersampled) or sampled at the switching rate. In steady-state,undersamplingresults in reduced power consumption, while during transients, sampling at theswitching rate provides fast transient response. Another aspect of the presentinvention is a dual sampling/clocking scheme, which is relied on by the DPWMdescribed. A method is also provided for controlling low power DC-DC switchmodepower supplies at relatively high constant switching frequencies.