1 Introduction

These days, processors have higher and higher requirements such as high-accuracy supply voltage and dynamic adjustable voltage for DC/DC power converter to maintain system operating in high performance. Therefore, how to design an excellent power supply with price advantage to meet the improvement of system performance will be the topic in the future.

When designing the power supply, the target output voltage is usually higher than the reference voltage. Normally the reference voltage is 0.6 V to 0.8 V for most of buck ICs. Sometimes the SoC needs a voltage lower than 0.6 V. How to receive a lower output voltage than reference voltage with current IC is a challenge.

Adaptive voltage scaling (AVS) is a closed-loop dynamic power minimization technique that adjusts the voltage supplied for main chip or device to meet the required power during operation. From power-saving benefits, reducing the self-heating of the main-chip while operating in high temperature environments creates a need for optimizing power supply solutions such as Figure 1-1. The application note Adaptive (Dynamic) Voltage (Frequency) Scaling—Motivation and Implementation detail introduces AVS process.

AVS can be used to fix voltage dropping problem. A main chip claims a certain voltage for the supply, the voltage dropping issue is very common because of conduction loss on PCB. AVS process is also used to keep a certain voltage level for Main chip supply.

This article uses the AVS process to receive a lower output voltage than reference voltage. By adjusting the voltage of AVS, output voltage can be lower than reference voltage.