Multimedia functionality in mobile phones and chipsets demands power reduction techniques such as dynamic voltage scaling. Fairchild Semiconductor has developed the FAN5365, a 6MHz, 800mA/1A, digitally programmable buck regulator packaged in a 1.27x1.29mm, nine-bump WLCSP. This is claimed to be smallest 6MHz DVS buck regulator currently available. It can power core processors in single cell lithium ion battery devices and consumes just 40µA quiescent current in light-load, efficiency-enhancing PFM mode. It will automatically switch to a fixed frequency 6MHz PWM mode, so that low cost and compact chip inductors and capacitors can be used. The regulator supports up to 800mA or 1A load currents and has a pin-selectable or I2C bus interface programmable output voltage, adjustable from 0.75 to 1.975V.
