The X3100 is a protection and monitor IC for use in battery packs consisting of 4 series Lithium-Ion battery cells. The X3101 is designed to work in 3 cell applications. Both devices provide internal overcharge, over-discharge, and over-current protection circuitry, internal EEPROM memory, an internal voltage regulator, and internal drive circuitry for external FET devices that control cell charge, discharge, and cell voltage balancing. Over-charge, over-discharge, and over-current thresholds reside in an internal EEPROM memory register and are selected independently via software using a 3MHz SPI serial interface. Detection and timeout delays can also be individually varied using external capacitors.