Display system for a battery monitoring circuit

摘要

A battery detect circuit (32) is connected to a battery, with the current A battery V:the battery and the current extracted from the battery measured with a sense resistor (50) and convened to charge and discharge voltages with a V/F converter (52). A microcontroller (64) is operable to increment a nominal available charge (NAC) register (180) during a charge operation and to increment a discharge rate counter (DCR) (184) during a discharge operation. The NAC register (180) indicates the available charge, i.e. the charge state of the battery, which value is output to a display (34). The display (34) is controlled to operate in either an absolute full mode or a relative full mode. This is determined by an external programming pin which has first and second programming states associated with the two modes. In the absolute full mode, a Programmed Full Count (PFC) determines the upper capacity value of the display (34), which PFC is predetermined and represents the maximum capacity of the battery when the battery is new. The charge state value displayed is then determined relative to the maximum capacity value. In the relative full mode, the actual capacity of the battery is determined and defines the upper capacity value of the display (34). A translation device (186) is operable to vary the output of the NAC register (180) as a function of temperature, this changed in discrete steps.