The PS501 combines a high-performance, low-power Microchip PIC18 microcontroller core together with proprietary monitoring/control algorithms and 3D cell models stored in 16 Kbytes of on-chip reprogrammable Flash memory. Analog resources include a 16-bit sigma-delta integrating A/D and mixed signal circuitry for precision measurement of battery current, temperature and voltage. On-chip EEPROM is provided for storage of user customizable and “learned” battery parameters. An industry standard 2-wire SMBus interface supports host communication using standard SBData commands and status. Additional integrated features include a high accuracy on-chip oscillator and temperature sensor. Twelve general purpose pins support charge or safety control or user programmable digital I/O. Eight of them can be used as LED drivers and two are open drain for direct FET drive.