Power management circuit and methodology for battery-powered systems
First Claim
1. For a battery powered application, a power management method for providing power to both a load and a battery, comprising steps of:
- generating a battery-charging control current with a magnitude variable in accordance with an input current and a load current;
supplying a charging current to the battery for a charging period determined by a timer duration to charge the battery from a discharged state to a charged state, the charging current being controlled in accordance with the magnitude of the battery-charging control current;
generating a clock signal with a frequency variable in accordance with the magnitude of the battery-charging control current; and
counting the timer duration based on the clock signal, whereinthe timer duration is variable in accordance with the frequency of the clock signal being variable in accordance with the magnitude of the battery-charging control current,wherein the step of generating the clock signal includes charging and discharging a capacitor with a capacitor-charging current having a magnitude variable in accordance with the magnitude of battery-charging control current,wherein the frequency of the clock signal is determined in accordance with a frequency of the charge and discharge of the capacitor.
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Accused Products
Abstract
A power management system including a battery-powered application, in which an input current is supplied by a source of current that may be a current-constrained source, such as a USB port, to a battery for charging the battery and to an application load. Battery charging current is supplied to the battery for a period of time based on magnitude of battery charging current, so that charging current of lesser magnitude is applied to the battery for a greater period of time. In accord with one implementation, battery charging current is determined by monitoring the difference between a programmed charging current, dependent on battery type, and magnitude of current used by the load. Change of battery charging current due to voltage mode charging, when charge current begins to drop as the battery approaches full charge, is detected, and in response, the charging period is set to a fixed charging period based on the battery.
24 Citations
12 Claims
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1. For a battery powered application, a power management method for providing power to both a load and a battery, comprising steps of:
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generating a battery-charging control current with a magnitude variable in accordance with an input current and a load current; supplying a charging current to the battery for a charging period determined by a timer duration to charge the battery from a discharged state to a charged state, the charging current being controlled in accordance with the magnitude of the battery-charging control current; generating a clock signal with a frequency variable in accordance with the magnitude of the battery-charging control current; and counting the timer duration based on the clock signal, wherein the timer duration is variable in accordance with the frequency of the clock signal being variable in accordance with the magnitude of the battery-charging control current, wherein the step of generating the clock signal includes charging and discharging a capacitor with a capacitor-charging current having a magnitude variable in accordance with the magnitude of battery-charging control current, wherein the frequency of the clock signal is determined in accordance with a frequency of the charge and discharge of the capacitor. - View Dependent Claims (2, 3, 4, 5, 6, 12)
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7. A power management system for a battery powered application, the system providing power to a load and a battery, comprising:
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charge current programming circuitry configured for generating a battery-charging control current with a magnitude variable in accordance with an input current and a load current; battery charging circuitry configured for supplying a charging current to the battery for a charging period determined by a timer duration to charge the battery from a discharged state to a charged state, the charging current being controlled in accordance with the magnitude of the battery-charging control current; and timer circuitry configured for generating a clock signal with a frequency variable in accordance with the magnitude of the battery-charging control current, and counting the timer duration based on the clock signal, wherein the timer duration is variable in accordance with the frequency of the clock signal being variable in accordance with the magnitude of the battery-charging control current, wherein the timer circuitry is configured for generating a capacitor-charging current to charge and discharge a capacitor so as to generate the clock signal, the magnitude of the capacitor-charging current is determined in accordance with the magnitude of battery-charging control current, and the frequency of the clock signal is determined in accordance with a frequency of the charge and discharge of the capacitor. - View Dependent Claims (8, 9, 10, 11)
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Specification