Dallas Semiconductor's DS2714 is a loose-cell NiMH charger that detects and avoids charging primary alkaline cells, Lithium primary cells, and defective NiMH or NiCd cells. Designed to work with a regulated charge source, the DS2714 can charge from one to four NiMH or NiCd battery cells, including AA or AAA sizes.
The DS2714 charge cycle begins with a pre-charge qualification test that prevents the fast charging of deeply depleted cells or damaged cells. Deeply depleted cells are charged at a reduced rate to protect them from damage and extend the life of the battery. When each cell reaches a safe threshold, fast charging begins. During the fast-charge phase, the DS2714 tests for inappropriate or damaged cells that should not be charged. Fast charging terminates with the negative-delta-V or flat-V method, and is followed by a top-off phase that completely charges the cells. Finally, a maintenance phase continues indefinitely to keep the cells fully charged.
The device is available in a 20-pin TSSOP package. Prices start at $1.99 for quantities of 1000 and up. A datasheet is available at www.maxim-ic.com/DS2714.