Better Battery in a Single Chip

Renesas's new li-ion battery fuel gauge IC could save your battery.

Lithium-ion batteries are similar to the tread on a car tire: the more the car is driven, the more the tread wears down. The more often a lithium-ion battery is charged and recharged, the shorter the life of the battery. Unfortunately, no matter how sophisticated the rest of a device is, if the battery no longer holds a substantial charge, the device is worthless.  Accurate readings of battery charge has been frustratingly inaccurate, however: a cellphone may show a battery at 1% when there's actually much more, or display a fully-charged battery that actually isn't. Some of this is due to safety concerns: li-ion batteries will expand and ruin a device if overcharged or charged incorrectly. In a time when many devices don't have easily swappable batteries, that's a costly mistake.

A swollen battery ruining a device.

With inaccurate battery control circuits, designers were left to approximate battery useage, but Renesas has changed that with the announcement of its new li-ion battery fuel gauge IC, the RAJ240500. The new single-chip IC extends the life of the battery by maximizing charging capacity and, as a result, maximizes the life of a device. It does this by combining advanced algorithmic fuel gauge IC functionality with charger IC functionality. The single-chip integration allows for smaller designs and is also much more cost effective.

If the battery experiences abnormal conditions--such as incorrect charging or extreme temperatures-- the IC detects and responds to those, too. As designers work toward alternative batteries, it's important to perfect the sensing of current li-ion battery charges before exposing new battery technologies to the same old clunky approximations.