Battery charge monitor

A circuit able to monitor the charge of a battery of a battery powered device comprising:

• a rechargeable battery to power said device;
• a measuring means to measure the currents charging and discharging said battery;
• an external power supply;
• a reference voltage;
• a mode setting means to set a specific mode of said mobile device;
• switching means having an input and an output wherein the input is a voltage representing said charge and discharge current, said reference voltage, said indicator of a specific mode and a signal from a switch logic controlling the timing of said input switching unit and the output is switched to integrating means of said charge/discharge currents over time to get the actual charge as an integral of currents;
• said integrating means said charge/discharge currents having an input and an output wherein the input is a signal from a switch logic unit controlling the timing of said integrating means said charge/discharge currents and alternately, controlled by said switch logic signal, said voltage representing said charge and discharge currents and, as output of compensating means to compensate the offset, a voltage representing the offset of said integrating means or the input is shorted to convert the offset of said integrating means and the output is either the integral over time of the said measured charge/discharge currents or the converted offset during the time period while the input is shorted;
• an analog-to-digital converting means having an input and an output wherein the input is the output of said integrating means to integrate the charge/discharge currents and the output of said analog-to-digital converting means is the digital magnitude of the integral of the charge/discharge currents or alternatively the digital magnitude of the offset of said integrating means to integrate the charge/discharge currents;
• a compensating means to compensate the offset of said integrating means;
• an up/down counting means representing the digital magnitude of the changes of the charge of said battery having an input and an output wherein the input is the output of said analog-to-digital converting means and the output of said up-and-down counting means is fed to a switching means which is forwarding said result of up-and-down counting to accumulating means to accumulate either a charge or a discharge accumulator according to the sign of the up-and-down counter;
• a switching means having an input and an output wherein the input is the output of said up-and-down counting means and the output is fed to said accumulating means to accumulate either a charge or a discharge accumulator according to the sign of the up-and-down counter;
• the accumulating means representing the absolute charge status of the battery having an input and an output wherein the input is the output of said up/down counting means, a power supply voltage and the output is the input to a control unit managing the required actions related to the charge/discharge status of said battery;
• a logic switching means controlling the timing of said input switching unit and said integrating means to integrate said charge/discharge currents and of latching of data in said accumulating means at the end of each time frame;
• and
• a frame counting means defining time frames of a defined number of clock signals having and input and an output wherein the input is a clock signal and the output is an input of said means of switch logic.

A method of monitoring the charge/discharge status of a battery of a battery powered device comprising:

• providing a rechargeable battery to power said device, measuring means to measure the currents charging and discharging said battery, an external power supply, a reference voltage, an input switching unit, integrating means to integrate said charge/discharge currents, analog-to-digital converting means, compensating means to compensate the offset of said integrating means to integrate the charge/discharge currents, accumulating means to accumulate said digitized results of the integration of the currents representing the current status of the charge and discharge currents of said battery;
• start with a defined charge status of said battery;
• measure the charge/discharge currents;
• integrate the charge/discharge currents while compensating the offset of the integrator;
• add the magnitude of the charge digitized to a accumulator;
• and
• signal values of the charge/discharge currents according to the related accumulator values to a controlling unit.

A method of monitoring the charge/discharge status of a battery of a battery powered device comprising:

• providing a rechargeable battery to power said device, measuring means to measure the currents charging and discharging said battery, an external power supply, a reference voltage, mode setting means to set a specific mode of said mobile device, an input switching unit, integrating means to integrate said charge/discharge currents, analog-to-digital converting means, compensating means to compensate the offset of said integrating means to integrate the charge/discharge currents, up/down counting means, forwarding means to forward said result of up/down counting to an accumulating means, an accumulating means representing the current status of the charge and discharge currents of said battery, and logic switching means controlling the timing of said input switching unit and said integrating means and of latching of data in said accumulating means at the end of each time frame and defining time frames of a defined number of clock signals;
• start with a defined charge status of said battery;
• define mode of operation of the mobile device influencing the dimension of power consumption and resolution of the battery charge monitor;
• measure the charge/discharge currents;
• integrate the charge/discharge currents while compensating the offset of the integrator the same time;
• perform analog-to-digital conversion of integrated values of previous step;
• increment up/down counter with values from previous step according to sign of charge/discharge current;
• add the magnitude of the charge digitized in said up-down counter to either the charge accumulator or to the discharge accumulator;
• use overflows from the charge/discharge accumulators to clock additional registers;
• and
• signal values of the charge/discharge currents according to the related accumulator values to a controlling unit.