PWM and PCM techniques for control of digitally programmable switching power supplies

Abstract

This paper presents and compares two new digitally programmable structures for the control of DC to DC switching power supplies. The first structure is a switched capacitor, proportional plus integral (PI) based pulse width modulated (PWM) controller with automatic circuit offset and mismatch absorption. The second structure uses a proportional plus integral plus derivative (PID) structure as input to a first order delta-sigma (/spl Delta//spl Sigma/) modulator to eliminate circuit and matching requirements found in existing control structures. It makes use of the low-pass filtering effects of the power supply to filter out the high frequency quantization noise associated with the /spl Delta//spl Sigma/ modulator. Simulation and discrete component lab tests indicate 2% to 3% load regulation with up to 100 Watts of output power.