Design and implementation of a practical digital PWM controller

In this paper, we discussed the architecture of a digital power supply controller chip, implemented in low-cost CMOS technology, consisting of a hardware-based mixed signal digital control loop providing the core digital control functionality, and an instruction-based processing section having an 8051-based MCU at the heart. The hardware digital controller handles the high-bandwidth control loop function. The MCU-based processing section handles the medium bandwidth control-loop and housekeeping functions. Other system functions include an internal oscillator, a PLL clock multiplier, a programmable nonvolatile memory, a software-coded PMBus, a UART and GPIO ports, making a fully integrated highly versatile system-on-a-chip solution for a wide range of power supply applications. This architecture generates a throughput that exceeds a DSP-only solution by moving system task loading away from the instruction-based processor. This flexible architecture allows applications in dc-dc converters, isolated and non-isolated switched power supplies where high efficiency, high speed, high dynamic response, control complexity and cost are critical.