System requirements for multiple power planes, several voltage levels, power sequencing, sleep mode power, high-voltage LED drivers, quality audio processing, and intelligent control of these functions has led to the need for mixed-signal ASICs that sweep up a variety of analog functions for costs savings, performance, and integration. Portable electronics include a wide range of supply voltages: 1.8V and 3.3V for digital ICs, 4.2V for a Lithium-ion battery, 5V for legacy interfaces, 36V for LED backlighting, isolated voltages for sensitive analog circuits, and high voltages for motor control.