Abstract
A wide-load, high-efficiency step-down converter with asynchronous power saving technique is presented in this paper. To meet the growing demand over the wide load range of interest, pulse-width modulation (PWM) and pulse frequency modulation (PFM) are two widespread control schemes in the switching converters. With the proposed asynchronous power saving technique, combined with the off-time modulation, the measured efficiency is kept at least 90% from 3 to 400 mA without embedded sensing circuitry. The DC-DC converter has been fabricated in a TSMC 0.18-umCMOS process and supplied with an input voltage from 2.7 to 3.6 V. The switching frequency is from 44 KHz to 1.65 MHz and the maximum output ripple is 40 mV with a 10-uF off-chip capacitor and a 2.2-uH off-chip inductor.