November 2014

DocID024963 Rev 2.0

1/31

www.st.com

AN4324

Application note

STC3115 system integration

Aurelien Mazard

Introduction

Mobile application users demand accurate battery capacity monitoring. In particular, they are interested

to know if the battery state of charge (SOC) in stressful conditions is logical and accurate. To this end,

STMicroelectronics has developed a device (STC3115) which uses its internal algorithm to provide the

user with accurate and reliable information about the battery’s SOC. This tiny chip can be used in any

handheld electronic mobile phone or tablet. The purpose of this application note is to provide the basics

of how to build an accurate fuel gauge system using the STC3115.

A complete fuel gauge system is a combination of hardware and software functions. The STC3115 has

been designed to convert the physical nonlinear measurements of lithium-ion battery models to stable

and compensated information, which can easily be reported to the final user of a mobile application.

Chipset manages the real-time aspects of the battery gauging. It combines the voltage method and

coulomb counter to provide the best accuracy in every application state. The application software is

concerned with the reporting and calculation of application-dependent information.