Mixed signal and EEPROM technologies have been combined to produce a chip that extends the run time and life of 3- or 4-cell Li-Ion battery packs by keeping the voltages on the battery cells balanced during the charging process. X3100 chip, working in tandem with a µC, provides uniformly charged cells, which store the maximum amount of energy and achieve longer run times than non-uniformly charged cells. The full charges also keep each cell operating at peak efficiency, extending overall battery life.On-chip is 4 Kbits of EEPROM that can be used to store critical battery system data, such as the amount of battery power left and charging/discharging algorithms. It can also be used as the µC’s general-purpose nonvolatile storage. Other X3100 battery chip features include the ability to provide inputs to a separate µC for implementing a software gas gauge, programmable over/under voltage protection circuitry, and an accurate voltage regulator with outputs of 5V ±0.5% for driving up to 250 mA of current. The chip comes in 28-pin TSSOPs and SSOPs.