Optimizing System Operation Using a Flexible Digital PWM Controller

Abstract This paper describes a mixed-signal integrated circuit implemented in low-cost CMOS technology optimized for dc/dc and ac/dc converter applications. The device is partitioned into a hardware digital controller comprised of a digital signal processor (DSP) controller and an instructionbased microcontroller (MCU) system management processor section. The hardware digital controller includes a high-speed differential analog-to-digital converter (ADC), a low temperature-coefficient voltage-reference digital-to-analog converter (DAC), a programmable infinite-impulse response compensator, a digital pulse width modulator (DPWM) finite state machine and necessary protection circuits (e.g., current limiting circuits) to perform a high-bandwidth fully independent control loop function. The MCU-based system management processor section includes an 8-channel selfsequencing ADC, a 50 MIPs 8051-based MCU with 64K bytes of program memory and four 16-bit timers to perform medium bandwidth control loop and system monitoring functions. Other system functions include a high-precision oscillator, phase-locked-loop (PLL) based clock multiplier, UART and GPIO ports making a flexible 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 processor. Examples of several applications are also presented.