A low-power mixed-signal current-mode DC-DC converter using a one-bit /spl Delta//spl Sigma/ DAC

This work describes a dual-mode mixed-signal peak current-mode controller for high-frequency DC-DC converters. The simple controller provides peak-current protection, inherent low audio susceptibility, and is suitable for portable applications. The voltage feedback loop is implemented using a windowed ADC and a digital PI compensator based on lookup tables. The analog current command used in traditional current-mode controllers is generated by a 2nd order one-bit /spl Delta//spl Sigma/ DAC. The dual-mode controller automatically adjusts the DAC sampling frequency based on the digital error signal magnitude. The mixed-signal control strategy is experimentally verified on a 5V-to-1.5V 1 MHz buck converter prototype that exhibits a settling time of under 50 /spl mu/s.