Li-Ion Protector Reduces Pack Impedance

In addition to protecting a single Li-ion cell from overvoltage, undervoltage, overcurrent, or overtemperature, the DS2720 includes a regulated charge pump that enables control of external n-channel power MOSFETs. The FETs exhibit low impedance as the cell voltage depletes, thereby increasing battery run time. Unless a fault condition overrides this feature, the host system can control the power FETS from either a datacomm interface or a dedicated input, eliminating the need for power switch redundancy. The device integrates a one-wire interface that provides read/write access to status and control registers, instrumentation registers, and general-purpose lockable EEPROM. Each DS2720 has a unique, 64-bit ROM lasered serial number and can be individually addressed on the same serial bus to support multiple-battery operation. Targeted applications include PDAs, mobile phones, digital cameras, and other wireless products. Prices for the 8-pin microSOPs start at $1.18 each/1,000. An evaluation kit is also available. DALLAS SEMICONDUCTOR, Dallas, TX. (800) 998-8800.