New Industry Products

High-Precision Li-ion Battery Fuel Gauge IC

July 23, 2015 by Jeff Shepard

Renesas Electronics Corporation today announced its new Li-ion battery fuel gauge IC, the RAJ240500, designed to extend battery life for connected mobile devices such as tablets, notebook PCs and smartphones. 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 several 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.

Additional feature highlights include: Single-chip integration for smaller form factors and reduced total system costs, including a high-efficiency power supply architecture system, the NVDC system (Narrow Vdc), designed for tablet PC and notebook PC applications, which can reduce the number of components by approximately 20 percent compared to previous systems, as well as reduce the number of design man-hours required. Rapid battery protection and response to assure a high level of system safety in abnormal battery conditions. On-chip flash memory that enables flexible settings and charging specifications, allowing easy accommodation of new product models. Support for Dynamic Battery Power Technology, an advanced system control technology, to maximize the system performance according to the remaining battery amount.

Samples of the RAJ240500 are now available, priced at US$10 per unit. Mass production of the RAJ240500 is scheduled to begin in October 2015 and is expected to reach a volume of 10,000,000 units per month in October 2016.