Microcontroller with analog front-end for providing intelligent battery management
First Claim
1. A microcontroller for battery charging and battery monitoring applications, the microcontroller being fabricated on a semiconductor chip to execute programs and instructions and to generate control signals in response to such execution for selectively controlling a battery charging and battery monitoring system, the microcontroller including microprocessor means for executing instructions, program memory means for storing programs to be executed by the microcontroller and data memory means for storing data, the microcontroller further including:
- on-chip, analog front-end circuitry for allowing a plurality of analog input signals representing preselected respective different operating parameters of a rechargeable battery, including battery voltage, battery current, and battery temperature, to be converted to a digital count indicative of the present value of the respective parameter, said on-chip, analog front-end circuitry including;
selection means for cyclical interleaved sampling of said plurality of analog input signals at predetermined different periodic rates according to projected variation of the respective parameter value over each complete interleaving cycle, for monitoring the present value of each parameter represented by said analog input signals;
a slope analog-to-digital (A/D) converter for obtaining and storing a digital count when a predetermined ramp voltage of the slope A/D converter exceeds the signal level of a selected sampled analog input signal, whereby the stored sample digital count is indicative of the signal level of the selected analog input signal sample;
filter means for filtering the sample counts representative of a respective parameter by averaging the last-mentioned sample counts over each complete cycle of interleaving the samples of said plurality of analog input signals; and
means responsive to the filtered counts representative of each parameter for determining the status of charge on the battery and a need for charging thereof.
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Abstract
A microcontroller for use in battery charging and monitoring applications is disclosed. The microcontroller includes a microprocessor and various front-end analog circuitry including a slope A/D converter and a multiplexer for allowing a plurality of analog input signals to be converted to corresponding digital counts indicative of signal level. The slope A/D converter includes a digital-to-analog converter (DAC) for providing a programmable charging current to generate a voltage across a capacitor, a precision comparator having inputs for receiving a selected analog input and the capacitor voltage, a counter and a capture register. After a reset is performed, the capacitor is charged while the counter begins counting such that when the capacitor voltage exceeds the selected analog input voltage, the comparator switches logic states thereby causing the obtained count of the counter to be stored in the register. This stored count represents the time that it took for the capacitor to charge up and exceed the selected analog input voltage and corresponds to voltage measurement of the selected analog input.
62 Citations
15 Claims
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1. A microcontroller for battery charging and battery monitoring applications, the microcontroller being fabricated on a semiconductor chip to execute programs and instructions and to generate control signals in response to such execution for selectively controlling a battery charging and battery monitoring system, the microcontroller including microprocessor means for executing instructions, program memory means for storing programs to be executed by the microcontroller and data memory means for storing data, the microcontroller further including:
on-chip, analog front-end circuitry for allowing a plurality of analog input signals representing preselected respective different operating parameters of a rechargeable battery, including battery voltage, battery current, and battery temperature, to be converted to a digital count indicative of the present value of the respective parameter, said on-chip, analog front-end circuitry including; selection means for cyclical interleaved sampling of said plurality of analog input signals at predetermined different periodic rates according to projected variation of the respective parameter value over each complete interleaving cycle, for monitoring the present value of each parameter represented by said analog input signals; a slope analog-to-digital (A/D) converter for obtaining and storing a digital count when a predetermined ramp voltage of the slope A/D converter exceeds the signal level of a selected sampled analog input signal, whereby the stored sample digital count is indicative of the signal level of the selected analog input signal sample; filter means for filtering the sample counts representative of a respective parameter by averaging the last-mentioned sample counts over each complete cycle of interleaving the samples of said plurality of analog input signals; and means responsive to the filtered counts representative of each parameter for determining the status of charge on the battery and a need for charging thereof. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A device-implemented method for measuring a plurality of analog input signals to a microcontroller device representing the respective values of preselected parameters of an external controllable system, the microcontroller device being fabricated on a semiconductor chip to execute programs and instructions and to generate control signals as a result of such execution for selectively controlling said external controllable system, the microcontroller device including microprocessor means for executing instructions, program memory means for storing programs to be executed by the microcontroller device and data memory means for storing data, the microcontroller device also including a plurality of on-chip analog components for measuring the plurality of analog input signals, the method comprising the steps of:
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cyclically selecting said plurality of analog input signals for monitoring by sampling thereof at different periodic rates depending on rate of change of the signal level of the respective analog input signal, and thus of the value of the respective parameter, to provide an interleaved set of samples in which some of said plurality of signals are sampled more often than others in each complete interleaving cycle; generating a programmable ramp voltage; counting a number of received clock signals wherein the generation of said ramp voltage and the initiation of said counting are commenced at approximately the same time; capturing said number of received clock signals when said ramp voltage exceeds the level of a respective sample of each selected one of said plurality of analog input signals thereby obtaining a measured digital count indicative of the level of said selected analog input signal; repeating the generating, counting and capturing steps for each sample; and averaging the measured digital counts indicative of the level of the samples obtained for each parameter over each complete interleaving cycle, for determining the status of activity of said external controllable system and the need for replenishing the system to enable maintenance of capacity for a predetermined level of activity thereof. - View Dependent Claims (10, 11)
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12. A microcontroller device for charging, discharging and monitoring a battery, the microcontroller being fabricated on a semiconductor chip to execute programs and instructions and to generate control signals in response to such execution for selectively controlling a battery charging and battery monitoring system, the microcontroller device including microprocessor means for executing instructions, program memory means for storing programs to be executed by the microcontroller and data memory means for storing data, the microcontroller device further including:
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on-chip, analog front-end circuitry for providing a controlled charging current to the battery including; means for generating a digitally programmable voltage signal indicative of a desired level of charge on said battery; means for cyclically monitoring a preset group of parameters indicative of battery operation, including the battery output current, voltage, and temperature, wherein the battery output current is monitored substantially more frequently during each cycle than any of the others of said parameters, and for generating a first voltage signal indicative of the level of said battery output current; and means for providing a control signal for adjusting said first voltage to be substantially equal to the programmed value of said digitally programmable voltage signal, said control signal being used to control said charging current to the battery as a function of said digitally programmable voltage signal. - View Dependent Claims (13, 14, 15)
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Specification