The M61043FP is an semiconductor IC device developed for smart battery packs. It incorporates all the analog circuitry required by smart batteries in a single chip. When used in conjunction with a microprocessor, it allows the implementation of a variety of functions, such as battery capacity detection, through the addition of minimal peripheral devices and is ideal for smart battery system (SBS) battery packs. The M61043FP also has an on-chip overcurrent detect circuit so that the FET for controlling battery charging and discharging is protected regardless of the processing speed of the microprocessor. The microprocessor can change the amplifier gain of the charge/discharge current detect circuit, so battery capacity detection accuracy is increased. In addition, the M61043FP incorporates a linear regulator that allows it to function as the power supply for the microprocessor, thereby simplifying power supply block design.