Leveraging its extensive design expertise in fuel gauge and charging ICs for mobile devices, Renesas has developed a single-chip device that delivers high-precision battery charge measurement and control that reduces the burden on the battery and contributes to longer device battery life. In addition, in order to facilitate the development using this product, Renesas is offering sample codes and evaluation tools as solutions, including the reference card circuit diagram.

The new Renesas fuel gauge IC addresses these design challenges with a two-in-one solution that combines advanced algorithmic fuel gauge IC functionality with charger IC functionality in a single device. Integrating battery charge measurement, or fuel gauge, and charging functionality on a single chip allows designers to achieve high-precision charging control that closely matches the battery status. This enables them to utilize the battery's capacity to the fullest extent to maximize the battery life per charge as well as reduce the battery load and degradation rate to extend service life.

Battery life has become an important decision factor for consumers purchasing mobile devices such as tablets and notebook PCs, creating strong demand for efficient battery charging and control technologies. In the past, battery control circuits had to treat the battery as being at ‘zero charge’ even when there was still some capacity remaining, and as ‘fully charged’ even when charging was not yet complete, in order to assure the safety of the battery. The resulting design challenge was a shorter battery life relative to charge capacity.

Battery degradation is another challenge. Li-ion batteries suffer from reduced capacity after repeated charge-discharge cycles due to deterioration of the materials they are made from. Repeated control when not fully charged or fully discharged reduces the number of charge-discharge cycles over the service life of the battery, which for many devices is equivalent to the service life of the device. To extend the usable battery duration and enable longer battery life while accounting for typical wear-and-tear changes, designers require charge control that decreases the burden placed on the battery and that reduces degradation as far as possible.