An asynchronous digitally-controlled switching converter with adaptive resolution and dynamic power saving to achieve higher than 93.5% efficiency between 5mA and 250mA load

Conventionally for wide workload range applications, to keep good stability and high efficiency, a switching converter with multi-mode operation is necessary. With the advanced digital signal processing, this work presents an asynchronous digital controller with dynamic power saving to achieve high power efficiency. The regulation is based on the constant on-time technique, while an adaptive resolution adjustment in digital modulator is proposed for the extension toward light-loaded range. The DC-DC converter is fabricated in a 0.18-μm CMOS process. The input voltage is from 2.7 to 3.6 V and the regulated output is 1.8 V. The switching frequency is from 44 kHz to 1.65 MHz and the maximum output ripple is 20 mV with a 10-μF capacitor and a 2.2-μH inductor. The power efficiency is higher than 93.5% for the workload range from 5 to 250 mA.