Benchmarq Microelectronics, Inc.

Benchmarg Microelectronics, Inc.

John E Landau

Wallace E Matthews

David L Freeman

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.

Display system for a battery monitoring circuit

A battery detect circuit (32) is connected to the battery with the current input to the battery and extracted from the battery measured with a sense resistor (50) and then converted to charge and discharge pulses 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 Count Register (DCR) (184) during a discharge operation. The NAC register (180) indicates the available charge, which value is output to a display (34). The maximum value to which the NAC value can rise is limited by a value stored in the last measured discharge register (182). This value represents the value stored in the DCR (184) whenever the battery is discharged from an apparent full state to a fully discharged state. This results in a qualified transfer to the LMD register (182) such that no knowledge of the actual battery charge is necessary. The charge rate is varied as both a function of temperature, voltage and also of the state of charge. A fast charge rate is initiated when the charge state is above a predetermined low voltage threshold and less than full. When the charge state reaches a level within approximately 80% of full charge, the charge rate is reduced. At full capacity, the charge rate is further reduced to a top off charge rate which continues for approximately two hours. If the temperature falls below a predetermined low temperature threshold, the charge rate is again reduced to a safe, slow, effective rate. Trickle charge is provided to replenish charge adaptively in accordance with a self-discharge counter. The trickle charge operates to momentarily pulse the battery (10) at a predetermined charge rate.

Method and apparatus for monitoring batttery capacity with charge control

A battery detect circuit (32) is connected to the battery with the current input to the battery and extracted from the battery measured with a sense resistor (50) and then converted to charge and discharge pulses 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 Count Register (DCR) (184) during a discharge operation. The NAC register (180) indicates the available charge, which value is output to a display (34). The maximum value to which the NAC value can rise is limited by a value stored in the last measured discharge register (182). This value represents the value stored in the DCR (184) whenever the battery is discharged from an apparent full state to a fully discharged state. This results in a qualified transfer to the LMD register (182) such that no knowledge of the actual battery charge is necessary. The microcontroller (64) is operable to determine the rate of discharge corresponding to the voltage across the sense resistor (50). When the rate of discharge exceeds a predetermined discharge rate, the operation of the microcontroller (64) is partially inhibited. When the rate of discharge falls below the predetermined discharge rate, the microcontroller (64) is again allowed to operate in a normal operating mode. A resistor (61) is switched across the battery (10) by a transistor (59) for a short duration of time after the discharge rate had fallen below the discharge rate threshold voltage.

Battery monitoring circuit for operating with high battery discharge

A battery detect circuit (32) is connected to the battery with the current input to the battery and extracted from the battery measured with a sense resistor (50) and then converted to charge and discharge pulses 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 Count Register (DCR) (184) during a discharge operation. The NAC register (180) indicates the available charge, which value is output to a display (34). The maximum value to which the NAC value can rise is limited by a value stored in the last measured discharge register (182). This value represents the value stored in the DCR (184) whenever the battery is discharged from an apparent full state to a fully discharged state. This results in a qualified transfer to the LMD register (182) such that no knowledge of the actual battery charge is necessary.

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Dallas, TX, United States of America

John E Landau